to ensure we don't mess up any of the overrides. Necessary for cleaning
up the Value use iterators and enabling range-based traversing of use
lists.
llvm-svn: 202958
a bit surprising, as the class is almost entirely abstracted away from
any particular IR, however it encodes the comparsion predicates which
mutate ranges as ICmp predicate codes. This is reasonable as they're
used for both instructions and constants. Thus, it belongs in the IR
library with instructions and constants.
llvm-svn: 202838
Move the test for this class into the IR unittests as well.
This uncovers that ValueMap too is in the IR library. Ironically, the
unittest for ValueMap is useless in the Support library (honestly, so
was the ValueHandle test) and so it already lives in the IR unittests.
Mmmm, tasty layering.
llvm-svn: 202821
name might indicate, it is an iterator over the types in an instruction
in the IR.... You see where this is going.
Another step of modularizing the support library.
llvm-svn: 202815
business.
This header includes Function and BasicBlock and directly uses the
interfaces of both classes. It has to do with the IR, it even has that
in the name. =] Put it in the library it belongs to.
This is one step toward making LLVM's Support library survive a C++
modules bootstrap.
llvm-svn: 202814
operand_values. The first provides a range view over operand Use
objects, and the second provides a range view over the Value*s being
used by those operands.
The naming is "STL-style" rather than "LLVM-style" because we have
historically named iterator methods STL-style, and range methods seem to
have far more in common with their iterator counterparts than with
"normal" APIs. Feel free to bikeshed on this one if you want, I'm happy
to change these around if people feel strongly.
I've switched code in SROA and LCG to exercise these mostly to ensure
they work correctly -- we don't really have an easy way to unittest this
and they're trivial.
llvm-svn: 202687
Eventually DataLayoutPass should go away, but for now that is the only easy
way to get a DataLayout in some APIs. This patch only changes the ones that
have easy access to a Module.
One interesting issue with sometimes using DataLayoutPass and sometimes
fetching it from the Module is that we have to make sure they are equivalent.
We can get most of the way there by always constructing the pass with a Module.
In fact, the pass could be changed to point to an external DataLayout instead
of owning one to make this stricter.
Unfortunately, the C api passes a DataLayout, so it has to be up to the caller
to make sure the pass and the module are in sync.
llvm-svn: 202204
After this I will set the default back to F_None. The advantage is that
before this patch forgetting to set F_Binary would corrupt a file on windows.
Forgetting to set F_Text produces one that cannot be read in notepad, which
is a better failure mode :-)
llvm-svn: 202052
in the dependence test, we used to discard some information that the
delinearization provides: the size of the innermost dimension of an array,
i.e., the size of scalars stored in the array, and the remainder of the
delinearization that provides the offset from which the array reads start,
i.e., the base address of the array.
To avoid losing this data in the rest of the data dependence analysis, the fix
is to multiply the access function in the last delinearized dimension by its
size, effectively making the size of the last dimension to always be in bytes,
and then add the remainder of delinearization to the last subscript,
effectively making the last subscript start at the base address of the array.
llvm-svn: 201867
Because the delinearization is not a global analysis pass, it will compute the
delinearization independently of knowledge about the way the delinearization
happened for other data accesses to the same array: the dependence analysis will
only trigger the delinearization on a tuple of access functions, and thus
delinearization may compute different subscripts sizes for a same array. When
that happens the safest is to discard the delinearized information.
llvm-svn: 201866
I am really sorry for the noise, but the current state where some parts of the
code use TD (from the old name: TargetData) and other parts use DL makes it
hard to write a patch that changes where those variables come from and how
they are passed along.
llvm-svn: 201827
During LSR of one loop we can run into a situation where we have to expand the
start of a recurrence of a loop induction variable in this loop. This start
value is a value derived of the induction variable of a preceeding loop. SCEV
has cannonicalized this value to a different recurrence than the recurrence of
the preceeding loop's induction variable (the type and/or step direction) has
changed). When we come to instantiate this SCEV we created a second induction
variable in this preceeding loop. This patch tries to base such derived
induction variables of the preceeding loop's induction variable.
This helps twolf on arm and seems to help scimark2 on x86.
Reapply with a fix for the case of a value derived from a pointer.
radar://15970709
llvm-svn: 201496
During LSR of one loop we can run into a situation where we have to expand the
start of a recurrence of a loop induction variable in this loop. This start
value is a value derived of the induction variable of a preceeding loop. SCEV
has cannonicalized this value to a different recurrence than the recurrence of
the preceeding loop's induction variable (the type and/or step direction) has
changed). When we come to instantiate this SCEV we created a second induction
variable in this preceeding loop. This patch tries to base such derived
induction variables of the preceeding loop's induction variable.
This helps twolf on arm and seems to help scimark2 on x86.
radar://15970709
llvm-svn: 201465
'OK_NonUniformConstValue' to identify operands which are constants but
not constant splats.
The cost model now allows returning 'OK_NonUniformConstValue'
for non splat operands that are instances of ConstantVector or
ConstantDataVector.
With this change, targets are now able to compute different costs
for instructions with non-uniform constant operands.
For example, On X86 the cost of a vector shift may vary depending on whether
the second operand is a uniform or non-uniform constant.
This patch applies the following changes:
- The cost model computation now takes into account non-uniform constants;
- The cost of vector shift instructions has been improved in
X86TargetTransformInfo analysis pass;
- BBVectorize, SLPVectorizer and LoopVectorize now know how to distinguish
between non-uniform and uniform constant operands.
Added a new test to verify that the output of opt
'-cost-model -analyze' is valid in the following configurations: SSE2,
SSE4.1, AVX, AVX2.
llvm-svn: 201272
build but spectacularly changed behavior of the C++98 build. =]
This shows my one problem with not having unittests -- basic API
expectations aren't well exercised by the integration tests because they
*happen* to not come up, even though they might later. I'll probably add
a basic unittest to complement the integration testing later, but
I wanted to revive the bots.
llvm-svn: 200905
The primary motivation for this pass is to separate the call graph
analysis used by the new pass manager's CGSCC pass management from the
existing call graph analysis pass. That analysis pass is (somewhat
unfortunately) over-constrained by the existing CallGraphSCCPassManager
requirements. Those requirements make it *really* hard to cleanly layer
the needed functionality for the new pass manager on top of the existing
analysis.
However, there are also a bunch of things that the pass manager would
specifically benefit from doing differently from the existing call graph
analysis, and this new implementation tries to address several of them:
- Be lazy about scanning function definitions. The existing pass eagerly
scans the entire module to build the initial graph. This new pass is
significantly more lazy, and I plan to push this even further to
maximize locality during CGSCC walks.
- Don't use a single synthetic node to partition functions with an
indirect call from functions whose address is taken. This node creates
a huge choke-point which would preclude good parallelization across
the fanout of the SCC graph when we got to the point of looking at
such changes to LLVM.
- Use a memory dense and lightweight representation of the call graph
rather than value handles and tracking call instructions. This will
require explicit update calls instead of some updates working
transparently, but should end up being significantly more efficient.
The explicit update calls ended up being needed in many cases for the
existing call graph so we don't really lose anything.
- Doesn't explicitly model SCCs and thus doesn't provide an "identity"
for an SCC which is stable across updates. This is essential for the
new pass manager to work correctly.
- Only form the graph necessary for traversing all of the functions in
an SCC friendly order. This is a much simpler graph structure and
should be more memory dense. It does limit the ways in which it is
appropriate to use this analysis. I wish I had a better name than
"call graph". I've commented extensively this aspect.
This is still very much a WIP, in fact it is really just the initial
bits. But it is about the fourth version of the initial bits that I've
implemented with each of the others running into really frustrating
problms. This looks like it will actually work and I'd like to split the
actual complexity across commits for the sake of my reviewers. =] The
rest of the implementation along with lots of wiring will follow
somewhat more rapidly now that there is a good path forward.
Naturally, this doesn't impact any of the existing optimizer. This code
is specific to the new pass manager.
A bunch of thanks are deserved for the various folks that have helped
with the design of this, especially Nick Lewycky who actually sat with
me to go through the fundamentals of the final version here.
llvm-svn: 200903
Ideally only those transform passes that run at -O0 remain enabled,
in reality we get as close as we reasonably can.
Passes are responsible for disabling themselves, it's not the job of
the pass manager to do it for them.
llvm-svn: 200892
No functional change. Updated loops from:
for (I = scc_begin(), E = scc_end(); I != E; ++I)
to:
for (I = scc_begin(); !I.isAtEnd(); ++I)
for teh win.
llvm-svn: 200789
cost so that they don't impact the vector bonus. Fundamentally, counting
unsimplified instructions is just *wrong*; it will continue to introduce
instability as things which do not generate code bizarrely impact
inlining. For example, sufficiently nested inlined functions could turn
off the vector bonus with lifetime markers just like the debug
intrinsics do. =/
This is a short-term tactical fix. Long term, I think we need to remove
the vector bonus entirely. That's a separate patch and discussion
though.
The patch to fix this provided by Dario Domizioli. I've added some
comments about the planned direction and used a heavily pruned form of
debug info intrinsics for the test case. While this debug info doesn't
work or "do" anything useful, it lets us easily test all manner of
interference easily, and I suspect this will not be the last time we
want to craft a pattern where debug info interferes with the inliner in
a problematic way.
llvm-svn: 200609
Summary:
I searched Transforms/ and Analysis/ for 'ByVal' and updated those call
sites to check for inalloca if appropriate.
I added tests for any change that would allow an optimization to fire on
inalloca.
Reviewers: nlewycky
Differential Revision: http://llvm-reviews.chandlerc.com/D2449
llvm-svn: 200281
Unfortunately, this in turn led to some lower quality SCEVs due to some different paths through expression simplification, so add getUDivExactExpr and use it. This fixes all instances of the problems that I found, but we can make that function smarter as necessary.
Merge test "xor-and.ll" into "and-xor.ll" since I needed to update it anyways. Test 'nsw-offset.ll' analyzes a little deeper, %n now gets a scev in terms of %no instead of a SCEVUnknown.
llvm-svn: 200203
This commit caused -Woverloaded-virtual warnings. The two new
TargetTransformInfo::getIntImmCost functions were only added to the superclass,
and to the X86 subclass. The other targets were not updated, and the
warning highlighted this by pointing out that e.g. ARMTTI::getIntImmCost was
hiding the two new getIntImmCost variants.
We could pacify the warning by adding "using TargetTransformInfo::getIntImmCost"
to the various subclasses, or turning it off, but I suspect that it's wrong to
leave the functions unimplemnted in those targets. The default implementations
return TCC_Free, which I don't think is right e.g. for ARM.
llvm-svn: 200058
Retry commit r200022 with a fix for the build bot errors. Constant expressions
have (unlike instructions) module scope use lists and therefore may have users
in different functions. The fix is to simply ignore these out-of-function uses.
llvm-svn: 200034
This pass identifies expensive constants to hoist and coalesces them to
better prepare it for SelectionDAG-based code generation. This works around the
limitations of the basic-block-at-a-time approach.
First it scans all instructions for integer constants and calculates its
cost. If the constant can be folded into the instruction (the cost is
TCC_Free) or the cost is just a simple operation (TCC_BASIC), then we don't
consider it expensive and leave it alone. This is the default behavior and
the default implementation of getIntImmCost will always return TCC_Free.
If the cost is more than TCC_BASIC, then the integer constant can't be folded
into the instruction and it might be beneficial to hoist the constant.
Similar constants are coalesced to reduce register pressure and
materialization code.
When a constant is hoisted, it is also hidden behind a bitcast to force it to
be live-out of the basic block. Otherwise the constant would be just
duplicated and each basic block would have its own copy in the SelectionDAG.
The SelectionDAG recognizes such constants as opaque and doesn't perform
certain transformations on them, which would create a new expensive constant.
This optimization is only applied to integer constants in instructions and
simple (this means not nested) constant cast experessions. For example:
%0 = load i64* inttoptr (i64 big_constant to i64*)
Reviewed by Eric
llvm-svn: 200022
This makes the 'verifyFunction' and 'verifyModule' functions totally
independent operations on the LLVM IR. It also cleans up their API a bit
by lifting the abort behavior into their clients and just using an
optional raw_ostream parameter to control printing.
The implementation of the verifier is now just an InstVisitor with no
multiple inheritance. It also is significantly more const-correct, and
hides the const violations internally. The two layers that force us to
break const correctness are building a DomTree and dispatching through
the InstVisitor.
A new VerifierPass is used to implement the legacy pass manager
interface in terms of the other pieces.
The error messages produced may be slightly different now, and we may
have slightly different short circuiting behavior with different usage
models of the verifier, but generally everything works equivalently and
this unblocks wiring the verifier up to the new pass manager.
llvm-svn: 199569
can be used by both the new pass manager and the old.
This removes it from any of the virtual mess of the pass interfaces and
lets it derive cleanly from the DominatorTreeBase<> template. In turn,
tons of boilerplate interface can be nuked and it turns into a very
straightforward extension of the base DominatorTree interface.
The old analysis pass is now a simple wrapper. The names and style of
this split should match the split between CallGraph and
CallGraphWrapperPass. All of the users of DominatorTree have been
updated to match using many of the same tricks as with CallGraph. The
goal is that the common type remains the resulting DominatorTree rather
than the pass. This will make subsequent work toward the new pass
manager significantly easier.
Also in numerous places things became cleaner because I switched from
re-running the pass (!!! mid way through some other passes run!!!) to
directly recomputing the domtree.
llvm-svn: 199104
trees into the Support library.
These are all expressed in terms of the generic GraphTraits and CFG,
with no reliance on any concrete IR types. Putting them in support
clarifies that and makes the fact that the static analyzer in Clang uses
them much more sane. When moving the Dominators.h file into the IR
library I claimed that this was the right home for it but not something
I planned to work on. Oops.
So why am I doing this? It happens to be one step toward breaking the
requirement that IR verification can only be performed from inside of
a pass context, which completely blocks the implementation of
verification for the new pass manager infrastructure. Fixing it will
also allow removing the concept of the "preverify" step (WTF???) and
allow the verifier to cleanly flag functions which fail verification in
a way that precludes even computing dominance information. Currently,
that results in a fatal error even when you ask the verifier to not
fatally error. It's awesome like that.
The yak shaving will continue...
llvm-svn: 199095
directory. These passes are already defined in the IR library, and it
doesn't make any sense to have the headers in Analysis.
Long term, I think there is going to be a much better way to divide
these matters. The dominators code should be fully separated into the
abstract graph algorithm and have that put in Support where it becomes
obvious that evn Clang's CFGBlock's can use it. Then the verifier can
manually construct dominance information from the Support-driven
interface while the Analysis library can provide a pass which both
caches, reconstructs, and supports a nice update API.
But those are very long term, and so I don't want to leave the really
confusing structure until that day arrives.
llvm-svn: 199082
name to match the source file which I got earlier. Update the include
sites. Also modernize the comments in the header to use the more
recommended doxygen style.
llvm-svn: 199041
operand into the Value interface just like the core print method is.
That gives a more conistent organization to the IR printing interfaces
-- they are all attached to the IR objects themselves. Also, update all
the users.
This removes the 'Writer.h' header which contained only a single function
declaration.
llvm-svn: 198836
are part of the core IR library in order to support dumping and other
basic functionality.
Rename the 'Assembly' include directory to 'AsmParser' to match the
library name and the only functionality left their -- printing has been
in the core IR library for quite some time.
Update all of the #includes to match.
All of this started because I wanted to have the layering in good shape
before I started adding support for printing LLVM IR using the new pass
infrastructure, and commandline support for the new pass infrastructure.
llvm-svn: 198688
subsequent changes are easier to review. About to fix some layering
issues, and wanted to separate out the necessary churn.
Also comment and sink the include of "Windows.h" in three .inc files to
match the usage in Memory.inc.
llvm-svn: 198685
Missed this when adding the skeleton analysis. Caught by a build break
in the next patch I'm working on when trying to use the analysis.
llvm-svn: 198556
cycles
This allows the value equality check to work even if we don't have a dominator
tree. Also add some more comments.
I was worried about compile time impacts and did not implement reachability but
used the dominance check in the initial patch. The trade-off was that the
dominator tree was required.
The llvm utility function isPotentiallyReachable cuts off the recursive search
after 32 visits. Testing did not show any compile time regressions showing my
worries unjustfied.
No compile time or performance regressions at O3 -flto -mavx on test-suite +
externals.
Addresses review comments from r198290.
llvm-svn: 198400
When there are cycles in the value graph we have to be careful interpreting
"Value*" identity as "value" equivalence. We interpret the value of a phi node
as the value of its operands.
When we check for value equivalence now we make sure that the "Value*" dominates
all cycles (phis).
%0 = phi [%noaliasval, %addr2]
%l = load %ptr
%addr1 = gep @a, 0, %l
%addr2 = gep @a, 0, (%l + 1)
store %ptr ...
Before this patch we would return NoAlias for (%0, %addr1) which is wrong
because the value of the load is from different iterations of the loop.
Tested on x86_64 -mavx at O3 and O3 -flto with no performance or compile time
regressions.
PR18068
radar://15653794
llvm-svn: 198290
IMHO At some point BasicBlock should be refactored along the lines of
MachineBasicBlock so that successors/weights are actually embedded within the
block. Now is not that time though.
llvm-svn: 197303
through an invoke instruction.
The original patch for this was written by Mark Seaborn, but I've
reworked his test case into the existing returns_twice test case and
implemented the fix by the prior refactoring to actually run the cost
analysis over invoke instructions, and then here fixing our detection of
the returns_twice attribute to work for both calls and invokes. We never
noticed because we never saw an invoke. =[
llvm-svn: 197216
handles terminator instructions.
The inline cost analysis inheritted some pretty rough handling of
terminator insts from the original cost analysis, and then made it much,
much worse by factoring all of the important analyses into a separate
instruction visitor. That instruction visitor never visited the
terminator.
This works fine for things like conditional branches, but for many other
things we simply computed The Wrong Value. First example are
unconditional branches, which should be free but were counted as full
cost. This is most significant for conditional branches where the
condition simplifies and folds during inlining. We paid a 1 instruction
tax on every branch in a straight line specialized path. =[
Oh, we also claimed that the unreachable instruction had cost.
But it gets worse. Let's consider invoke. We never applied the call
penalty. We never accounted for the cost of the arguments. Nope. Worse
still, we didn't handle the *correctness* constraints of not inlining
recursive invokes, or exception throwing returns_twice functions. Oops.
See PR18206. Sadly, PR18206 requires yet another fix, but this
refactoring is at least a huge step in that direction.
llvm-svn: 197215
CallGraph.
This makes the CallGraph a totally generic analysis object that is the
container for the graph data structure and the primary interface for
querying and manipulating it. The pass logic is separated into its own
class. For compatibility reasons, the pass provides wrapper methods for
most of the methods on CallGraph -- they all just forward.
This will allow the new pass manager infrastructure to provide its own
analysis pass that constructs the same CallGraph object and makes it
available. The idea is that in the new pass manager, the analysis pass's
'run' method returns a concrete analysis 'result'. Here, that result is
a 'CallGraph'. The 'run' method will typically do only minimal work,
deferring much of the work into the implementation of the result object
in order to be lazy about computing things, but when (like DomTree)
there is *some* up-front computation, the analysis does it prior to
handing the result back to the querying pass.
I know some of this is fairly ugly. I'm happy to change it around if
folks can suggest a cleaner interim state, but there is going to be some
amount of unavoidable ugliness during the transition period. The good
thing is that this is very limited and will naturally go away when the
old pass infrastructure goes away. It won't hang around to bother us
later.
Next up is the initial new-PM-style call graph analysis. =]
llvm-svn: 195722
(except functions marked always_inline).
Functions with 'optnone' must also have 'noinline' so they don't get
inlined into any other function.
Based on work by Andrea Di Biagio.
llvm-svn: 195046
The tests just hit this with a different sized
address space since I haven't figured out how
to use this to break it.
I thought I committed this a long time ago,
and I'm not sure why missing this hasn't caused
any problems.
llvm-svn: 194903
This is useful for debugging issues in the BlockFrequency implementation since
one can easily visualize where probability mass and other errors occur in the
propagation.
llvm-svn: 194654
with and without -g.
Adding a test case to make sure that the threshold used in the memory
dependence analysis is respected. The test case also checks that debug
intrinsics are not counted towards this threshold.
Differential Revision: http://llvm-reviews.chandlerc.com/D2141
llvm-svn: 194646
give the files a legacy prefix in the right directory. Use forwarding
headers in the old locations to paper over the name change for most
clients during the transitional period.
No functionality changed here! This is just clearing some space to
reduce renaming churn later on with a new system.
Even when the new stuff starts to go in, it is going to be hidden behind
a flag and off-by-default as it is still WIP and under development.
This patch is specifically designed so that very little out-of-tree code
has to change. I'm going to work as hard as I can to keep that the case.
Only direct forward declarations of the PassManager class are impacted
by this change.
llvm-svn: 194324
Patch by Michele Scandale!
Rewrite of the functions used to compute the backedge taken count of a
loop on LT and GT comparisons.
I decided to split the handling of LT and GT cases becasue the trick
"a > b == -a < -b" in some cases prevents the trip count computation
due to the multiplication by -1 on the two operands of the
comparison. This issue comes from the conservative computation of
value range of SCEVs: taking the negative SCEV of an expression that
have a small positive range (e.g. [0,31]), we would have a SCEV with a
fullset as value range.
Indeed, in the new rewritten function I tried to better handle the
maximum backedge taken count computation when MAX/MIN expression are
used to handle the cases where no entry guard is found.
Some test have been modified in order to check the new value correctly
(I manually check them and reasoning on possible overflow the new
values seem correct).
I finally added a new test case related to the multiplication by -1
issue on GT comparisons.
llvm-svn: 194116
This adds another heuristic to BPI, similar to the existing heuristic that
considers (x == 0) unlikely to be true. As suggested in the PACT'98 paper by
Deitrich, Cheng, and Hwu, -1 is often used to indicate an invalid index, and
equality comparisons with -1 are also unlikely to succeed. Local
experimentation supports this hypothesis: This yields a 1-2% speedup in the
test-suite sqlite benchmark on the PPC A2 core, with no significant
regressions.
llvm-svn: 193855
We can't do this for the general case as saying a GEP with a negative index
doesn't have unsigned wrap isn't valid for negative indices.
%gep = getelementptr inbounds i32* %p, i64 -1
But an inbounds GEP cannot run past the end of address space. So we check for
the very common case of a positive index and make GEPs derived from that NUW.
Together with Andy's recent non-unit stride work this lets us analyze loops
like
void foo3(int *a, int *b) {
for (; a < b; a++) {}
}
PR12375, PR12376.
Differential Revision: http://llvm-reviews.chandlerc.com/D2033
llvm-svn: 193514
Partial fix for PR17459: wrong code at -O3 on x86_64-linux-gnu
(affecting trunk and 3.3)
When SCEV expands a recurrence outside of a loop it attempts to scale
by the stride of the recurrence. Chained recurrences don't work that
way. We could compute binomial coefficients, but would hve to
guarantee that the chained AddRec's are in a perfectly reduced form.
llvm-svn: 193438
Partial fix for PR17459: wrong code at -O3 on x86_64-linux-gnu
(affecting trunk and 3.3)
ScalarEvolutionNormalization was attempting to normalize by adding and
subtracting strides. Chained recurrences don't work that way.
llvm-svn: 193437
This fix a memory leak found by valgrind.
Calling it from the base class destructor would not destroy the BasicCallGraph
bits.
FIXME: BasicCallGraph is the only thing that inherits from CallGraph. Can
we merge the two?
llvm-svn: 193412
LLVM optimizers may widen accesses to packed structures that overflow the structure itself, but should be in bounds up to the alignment of the object
llvm-svn: 193317
Major steps include:
1). introduces a not-addr-taken bit-field in GlobalVariable
2). GlobalOpt pass sets "not-address-taken" if it proves a global varirable
dosen't have its address taken.
3). AA use this info for disambiguation.
llvm-svn: 193251
We can have a struct type with a single field and the field does not start
with 0. In that case, we should correctly update the offset.
llvm-svn: 193137
The test before wasn't successfully testing this
since it was missing the datalayout piece to change
the size of the second address space.
llvm-svn: 193102
SCEV currently fails to compute loop counts for nonunit stride
loops. This comes up frequently. It prevents loop optimization and
forces vectorization to insert extra loop checks.
For example:
void foo(int n, int *x) {
for (int i = 0; i < n; i += 3) {
x[i] = i;
x[i+1] = i+1;
x[i+2] = i+2;
}
}
We need to properly handle the case in which limit > INT_MAX-stride. In
the above case: n > INT_MAX-3. In this case the loop counter will step
beyond the limit and overflow at the same time. However, knowing that
signed integer overlow in undefined, we can assume the loop test
behavior is arbitrary after overflow. This obeys both C undefined
behavior rules, and the more strict LLVM poison value rules.
I'm finally fixing this in response to Hal Finkel's persistence.
The most probable reason that we never optimized this before is that
we were being careful to handle case where the developer expected a
side-effect free infinite loop relying on overflow:
for (int i = 0; i < n; i += s) {
++j;
}
return j;
If INT_MAX+1 is a multiple of s and n > INT_MAX-s, then we might
expect an infinite loop. However there are plenty of ways to achieve
this effect without relying on undefined behavior of signed overflow.
llvm-svn: 193015
The heuristic was added to avoid spending too much compile time A specially
crafted test case (PR17461, PR16474) with many uses on a select or bitcast
instruction can still trigger the slow case. Add a check for that case.
This only affects compile time, don't have a good way to test it.
llvm-svn: 191896
infrastructure.
This was essentially work toward PGO based on a design that had several
flaws, partially dating from a time when LLVM had a different
architecture, and with an effort to modernize it abandoned without being
completed. Since then, it has bitrotted for several years further. The
result is nearly unusable, and isn't helping any of the modern PGO
efforts. Instead, it is getting in the way, adding confusion about PGO
in LLVM and distracting everyone with maintenance on essentially dead
code. Removing it paves the way for modern efforts around PGO.
Among other effects, this removes the last of the runtime libraries from
LLVM. Those are being developed in the separate 'compiler-rt' project
now, with somewhat different licensing specifically more approriate for
runtimes.
llvm-svn: 191835
Remove the command line argument "struct-path-tbaa" since we should not depend
on command line argument to decide which format the IR file is using. Instead,
we check the first operand of the tbaa tag node, if it is a MDNode, we treat
it as struct-path aware TBAA format, otherwise, we treat it as scalar TBAA
format.
When clang starts to use struct-path aware TBAA format no matter whether
struct-path-tbaa is no, and we can auto-upgrade existing bc files, the support
for scalar TBAA format can be dropped.
Existing testing cases are updated to use the struct-path aware TBAA format.
llvm-svn: 191538
This code isn't ready to deal with allocation functions where the return is not
the allocated pointer. The checks below will reject posix_memalign anyways.
llvm-svn: 191319
This is safe per C++11 18.6.1.1p3: [operator new returns] a non-null pointer to
suitably aligned storage (3.7.4), or else throw a bad_alloc exception. This
requirement is binding on a replacement version of this function.
Brings us a tiny bit closer to eliminating more vector push_backs.
llvm-svn: 191310
Overflow doesn't affect the correctness of equalities. Computing this is cheap,
we just reuse the computation for the inbounds case and try to peel of more
non-inbounds GEPs. This pattern is unlikely to ever appear in code generated by
Clang, but SCEV occasionally produces it.
llvm-svn: 191200
Upcoming SLP vectorization improvements will want to be able to estimate costs
of horizontal reductions. Add infrastructure to support this.
We model reductions as a series of (shufflevector,add) tuples ultimately
followed by an extractelement. For example, for an add-reduction of <4 x float>
we could generate the following sequence:
(v0, v1, v2, v3)
\ \ / /
\ \ /
+ +
(v0+v2, v1+v3, undef, undef)
\ /
((v0+v2) + (v1+v3), undef, undef)
%rdx.shuf = shufflevector <4 x float> %rdx, <4 x float> undef,
<4 x i32> <i32 2, i32 3, i32 undef, i32 undef>
%bin.rdx = fadd <4 x float> %rdx, %rdx.shuf
%rdx.shuf7 = shufflevector <4 x float> %bin.rdx, <4 x float> undef,
<4 x i32> <i32 1, i32 undef, i32 undef, i32 undef>
%bin.rdx8 = fadd <4 x float> %bin.rdx, %rdx.shuf7
%r = extractelement <4 x float> %bin.rdx8, i32 0
This commit adds a cost model interface "getReductionCost(Opcode, Ty, Pairwise)"
that will allow clients to ask for the cost of such a reduction (as backends
might generate more efficient code than the cost of the individual instructions
summed up). This interface is excercised by the CostModel analysis pass which
looks for reduction patterns like the one above - starting at extractelements -
and if it sees a matching sequence will call the cost model interface.
We will also support a second form of pairwise reduction that is well supported
on common architectures (haddps, vpadd, faddp).
(v0, v1, v2, v3)
\ / \ /
(v0+v1, v2+v3, undef, undef)
\ /
((v0+v1)+(v2+v3), undef, undef, undef)
%rdx.shuf.0.0 = shufflevector <4 x float> %rdx, <4 x float> undef,
<4 x i32> <i32 0, i32 2 , i32 undef, i32 undef>
%rdx.shuf.0.1 = shufflevector <4 x float> %rdx, <4 x float> undef,
<4 x i32> <i32 1, i32 3, i32 undef, i32 undef>
%bin.rdx.0 = fadd <4 x float> %rdx.shuf.0.0, %rdx.shuf.0.1
%rdx.shuf.1.0 = shufflevector <4 x float> %bin.rdx.0, <4 x float> undef,
<4 x i32> <i32 0, i32 undef, i32 undef, i32 undef>
%rdx.shuf.1.1 = shufflevector <4 x float> %bin.rdx.0, <4 x float> undef,
<4 x i32> <i32 1, i32 undef, i32 undef, i32 undef>
%bin.rdx.1 = fadd <4 x float> %rdx.shuf.1.0, %rdx.shuf.1.1
%r = extractelement <4 x float> %bin.rdx.1, i32 0
llvm-svn: 190876
Allow targets to customize the default behavior of the generic loop unrolling
transformation. This will be used by the PowerPC backend when targeting the A2
core (which is in-order with a deep pipeline), and using more aggressive
defaults is important.
llvm-svn: 190542
instead of having its own implementation.
The implementation of isTBAAVtableAccess is in TypeBasedAliasAnalysis.cpp
since it is related to the format of TBAA metadata.
The path for struct-path tbaa will be exercised by
test/Instrumentation/ThreadSanitizer/read_from_global.ll, vptr_read.ll, and
vptr_update.ll when struct-path tbaa is on by default.
llvm-svn: 190216
Revert unintentional commit (of an unreviewed change).
Original commit message:
Add getUnrollingPreferences to TTI
Allow targets to customize the default behavior of the generic loop unrolling
transformation. This will be used by the PowerPC backend when targeting the A2
core (which is in-order with a deep pipeline), and using more aggressive
defaults is important.
llvm-svn: 189566
Allow targets to customize the default behavior of the generic loop unrolling
transformation. This will be used by the PowerPC backend when targeting the A2
core (which is in-order with a deep pipeline), and using more aggressive
defaults is important.
llvm-svn: 189565
...so that it can be used for z too. Most of the code is the same.
The only real change is to use TargetTransformInfo to test when a sqrt
instruction is available.
The pass is opt-in because at the moment it only handles sqrt.
llvm-svn: 189097
This fixes SCEVExpander so that it does not create multiple distinct induction
variables for duplicate PHI entries. Specifically, given some code like this:
do.body6: ; preds = %do.body6, %do.body6, %if.then5
%end.0 = phi i8* [ undef, %if.then5 ], [ %incdec.ptr, %do.body6 ], [ %incdec.ptr, %do.body6 ]
...
Note that it is legal to have multiple entries for a basic block so long as the
associated value is the same. So the above input is okay, but expanding an
AddRec in this loop could produce code like this:
do.body6: ; preds = %do.body6, %do.body6, %if.then5
%indvar = phi i64 [ %indvar.next, %do.body6 ], [ %indvar.next1, %do.body6 ], [ 0, %if.then5 ]
%end.0 = phi i8* [ undef, %if.then5 ], [ %incdec.ptr, %do.body6 ], [ %incdec.ptr, %do.body6 ]
...
%indvar.next = add i64 %indvar, 1
%indvar.next1 = add i64 %indvar, 1
And this is not legal because there are two PHI entries for %do.body6 each with
a distinct value.
Unfortunately, I don't have an in-tree test case.
llvm-svn: 188614
to find loops if the From and To instructions were in the same block.
Refactor the code a little now that we need to fill to start the CFG-walking
algorithm with more than one starting basic block sometimes.
Special thanks to Andrew Trick for catching an error in my understanding of
natural loops in code review.
llvm-svn: 188236
All libm floating-point rounding functions, except for round(), had their own
ISD nodes. Recent PowerPC cores have an instruction for round(), and so here I'm
adding ISD::FROUND so that round() can be custom lowered as well.
For the most part, this is straightforward. I've added an intrinsic
and a matching ISD node just like those for nearbyint() and friends. The
SelectionDAG pattern I've named frnd (because ISD::FP_ROUND has already claimed
fround).
This will be used by the PowerPC backend in a follow-up commit.
llvm-svn: 187926
This fix is very lightweight. The same fix already existed for AddRec
but was missing for NAry expressions.
This is obviously an improvement and I'm unsure how to test compile
time problems.
Patch by Xiaoyi Guo!
llvm-svn: 187475
Call into ComputeMaskedBits to figure out which bits are set on both add
operands and determine if the value is a power-of-two-or-zero or not.
llvm-svn: 187445
Adds unit tests for it too.
Split BasicBlockUtils into an analysis-half and a transforms-half, and put the
analysis bits into a new Analysis/CFG.{h,cpp}. Promote isPotentiallyReachable
into llvm::isPotentiallyReachable and move it into Analysis/CFG.
llvm-svn: 187283
Merge consecutive if-regions if they contain identical statements.
Both transformations reduce number of branches. The transformation
is guarded by a target-hook, and is currently enabled only for +R600,
but the correctness has been tested on X86 target using a variety of
CPU benchmarks.
Patch by: Mei Ye
llvm-svn: 187278
The great thing about the SCEVAddRec No-Wrap flag (unlike nsw/nuw) is
that is can be preserved while normalizing (reassociating and
factoring).
The bad thing is that is can't be tranfered back to IR, which is one
of the reasons I don't like the concept of SCEVExpander.
Sorry, I can't think of a direct way to test this, which is why these
were FIXMEs for so long. I just think it's a good time to finally
clean it up.
llvm-svn: 186273
Address calculation for gather/scather in vectorized code can incur a
significant cost making vectorization unbeneficial. Add infrastructure to add
cost.
Tests and cost model for targets will be in follow-up commits.
radar://14351991
llvm-svn: 186187
ScalarEvolution::getSignedRange uses ComputeNumSignBits from ValueTracking on
ashr instructions. ComputeNumSignBits can return zero, but this case was not
handled correctly by the code in getSignedRange which was calling:
APInt::getSignedMinValue(BitWidth).ashr(NS - 1)
with NS = 0, resulting in an assertion failure in APInt::ashr.
Now, we just return the conservative result (as with NS == 1).
Another bug found by llvm-stress.
llvm-svn: 185955
(add nsw x, (and x, y)) isn't a power of two if x is zero, it's zero
(add nsw x, (xor x, y)) isn't a power of two if y has bits set that aren't set in x
llvm-svn: 185954
The symptom is seg-fault, and the root cause is that a SCEV contains a SCEVUnknown
which has null-pointer to a llvm::Value.
This is how the problem take place:
===================================
1). In the pristine input IR, there are two relevant instrutions Op1 and Op2,
Op1's corresponding SCEV (denoted as SCEV(op1)) is a SCEVUnknown, and
SCEV(Op2) contains SCEV(Op1). None of these instructions are dead.
Op1 : V1 = ...
...
Op2 : V2 = ... // directly or indirectly (data-flow) depends on Op1
2) Optimizer (LSR in my case) generates an instruction holding the equivalent
value of Op1, making Op1 dead.
Op1': V1' = ...
Op1: V1 = ... ; now dead)
Op2 : V2 = ... //Now deps on Op1', but the SCEV(Op2) still contains SCEV(Op1)
3) Op1 is deleted, and call-back function is called to reset
SCEV(Op1) to indicate it is invalid. However, SCEV(Op2) is not
invalidated as well.
4) Following pass get the cached, invalid SCEV(Op2), and try to manipulate it,
and cause segfault.
The fix:
========
It seems there is no clean yet inexpensive fix. I write to dev-list
soliciting good solution, unforunately no ack. So, I decide to fix this
problem in a brute-force way:
When ScalarEvolution::getSCEV is called, check if the cached SCEV
contains a invalid SCEVUnknow, if yes, remove the cached SCEV, and
re-evaluate the SCEV from scratch.
I compile buch of big *.c and *.cpp, fortunately, I don't see any increase
in compile time.
Misc:
=====
The reduced test-case has 2357 lines of code+other-stuff, too big to commit.
rdar://14283433
llvm-svn: 185843
The Builtin attribute is an attribute that can be placed on function call site that signal that even though a function is declared as being a builtin,
rdar://problem/13727199
llvm-svn: 185049
This is a band-aid to fix the most severe regressions we're seeing from basing
spill decisions on block frequencies, until we have a better solution.
llvm-svn: 184835
Fixes rdar:14036816, PR16130.
There is an opportunity to compute precise trip counts for 'or'
expressions and multi-exit loops.
rdar:14038809: Optimize trip count computation for multi-exit loops.
To do this we need to record the fact that ExitLimit assumes NSW. When
it does not we can safely assume that the loop trip count is the
minimum ExitLimt across all subexpressions and loop exits.
llvm-svn: 183060
Account for the cost of scaling factor in Loop Strength Reduce when rating the
formulae. This uses a target hook.
The default implementation of the hook is: if the addressing mode is legal, the
scaling factor is free.
<rdar://problem/13806271>
llvm-svn: 183045
Fixes PR16130 - clang produces incorrect code with loop/expression at -O2.
This is a 2+ year old bug that's now holding up the release. It's a
case where we knowingly made aggressive assumptions about undefined
behavior. These assumptions are wrong when SCEV is computing a
subexpression that does not directly control the branch. With this
fix, we avoid making assumptions in those cases but still optimize the
common case. SCEV's trip count computation for exits controlled by
'or' expressions is now analagous to the trip count computation for
loops with multiple exits. I had already fixed the multiple exit case
to be conservative.
llvm-svn: 182989
- llvm.loop.parallel metadata has been renamed to llvm.loop to be more generic
by making the root of additional loop metadata.
- Loop::isAnnotatedParallel now looks for llvm.loop and associated
llvm.mem.parallel_loop_access
- document llvm.loop and update llvm.mem.parallel_loop_access
- add support for llvm.vectorizer.width and llvm.vectorizer.unroll
- document llvm.vectorizer.* metadata
- add utility class LoopVectorizerHints for getting/setting loop metadata
- use llvm.vectorizer.width=1 to indicate already vectorized instead of
already_vectorized
- update existing tests that used llvm.loop.parallel and
llvm.vectorizer.already_vectorized
Reviewed by: Nadav Rotem
llvm-svn: 182802
Other than recognizing the attribute, the patch does little else.
It changes the branch probability analyzer so that edges into
blocks postdominated by a cold function are given low weight.
Added analysis and code generation tests. Added documentation for the
new attribute.
llvm-svn: 182638
BitVector/SmallBitVector::reference::operator bool remain implicit since
they model more exactly a bool, rather than something else that can be
boolean tested.
The most common (non-buggy) case are where such objects are used as
return expressions in bool-returning functions or as boolean function
arguments. In those cases I've used (& added if necessary) a named
function to provide the equivalent (or sometimes negative, depending on
convenient wording) test.
One behavior change (YAMLParser) was made, though no test case is
included as I'm not sure how to reach that code path. Essentially any
comparison of llvm::yaml::document_iterators would be invalid if neither
iterator was at the end.
This helped uncover a couple of bugs in Clang - test cases provided for
those in a separate commit along with similar changes to `operator bool`
instances in Clang.
llvm-svn: 181868
the things, and renames it to CBindingWrapping.h. I also moved
CBindingWrapping.h into Support/.
This new file just contains the macros for defining different wrap/unwrap
methods.
The calls to those macros, as well as any custom wrap/unwrap definitions
(like for array of Values for example), are put into corresponding C++
headers.
Doing this required some #include surgery, since some .cpp files relied
on the fact that including Wrap.h implicitly caused the inclusion of a
bunch of other things.
This also now means that the C++ headers will include their corresponding
C API headers; for example Value.h must include llvm-c/Core.h. I think
this is harmless, since the C API headers contain just external function
declarations and some C types, so I don't believe there should be any
nasty dependency issues here.
llvm-svn: 180881
We switch the order of offset and field type to make TBAAStructType node
(name, parent node, offset) similar to scalar TBAA node (name, parent node).
TypeIsImmutable is added to TBAAStructTag node.
llvm-svn: 180654
The tag is of type TBAANode when flag EnableStructPathTBAA is off.
Move implementation of MDNode::getMostGenericTBAA to TypeBasedAliasAnalysis.cpp
since it depends on how to interprete the MDNodes for scalar TBAA and
struct-path aware TBAA.
llvm-svn: 180068
PR15000 has a testcase where the time to compile was bordering on 30s. When I
dropped the limit value to 100, it became a much more managable 6s. The compile
time seems to increase in a roughly linear fashion based on increasing the limit
value. (See the runtimes below.)
So, let's lower the limit to 100 so that they can get a more reasonable compile
time.
Limit Value Time
----------- ----
10 0.9744s
20 1.8035s
30 2.3618s
40 2.9814s
50 3.6988s
60 4.5486s
70 4.9314s
80 5.8012s
90 6.4246s
100 7.0852s
110 7.6634s
120 8.3553s
130 9.0552s
140 9.6820s
150 9.8804s
160 10.8901s
170 10.9855s
180 12.0114s
190 12.6816s
200 13.2754s
210 13.9942s
220 13.8097s
230 14.3272s
240 15.7753s
250 15.6673s
260 16.0541s
270 16.7625s
280 17.3823s
290 18.8213s
300 18.6120s
310 20.0333s
320 19.5165s
330 20.2505s
340 20.7068s
350 21.1833s
360 22.9216s
370 22.2152s
380 23.9390s
390 23.4609s
400 24.0426s
410 24.6410s
420 26.5208s
430 27.7155s
440 26.4142s
450 28.5646s
460 27.3494s
470 29.7255s
480 29.4646s
490 30.5001s
llvm-svn: 179713
This is basically the same fix in three different places. We use a set to avoid
walking the whole tree of a big ConstantExprs multiple times.
For example: (select cmp, (add big_expr 1), (add big_expr 2))
We don't want to visit big_expr twice here, it may consist of thousands of
nodes.
The testcase exercises this by creating an insanely large ConstantExprs out of
a loop. It's questionable if the optimizer should ever create those, but this
can be triggered with real C code. Fixes PR15714.
llvm-svn: 179458
On certain architectures we can support efficient vectorized version of
instructions if the operand value is uniform (splat) or a constant scalar.
An example of this is a vector shift on x86.
We can efficiently support
for (i = 0 ; i < ; i += 4)
w[0:3] = v[0:3] << <2, 2, 2, 2>
but not
for (i = 0; i < ; i += 4)
w[0:3] = v[0:3] << x[0:3]
This patch adds a parameter to getArithmeticInstrCost to further qualify operand
values as uniform or uniform constant.
Targets can then choose to return a different cost for instructions with such
operand values.
A follow-up commit will test this feature on x86.
radar://13576547
llvm-svn: 178807
This is a compile time optimization. Before the patch we would do two traversals
on each call to aliasGEP - one with a set size parameter one with UnknownSize.
We can do better by first checking the result of the alias query with
UnknownSize.
Only if this one returns MayAlias do we query a second time using size and type.
This recovers an about 7% compile time regression on spec/ammp.
radar://12349960
llvm-svn: 178045
Fixes PR15570: SEGV: SCEV back-edge info invalid after dead code removal.
Indvars creates a SCEV expression for the loop's back edge taken
count, then determines that the comparison is always true and
removes it.
When loop-unroll asks for the expression, it contains a NULL
SCEVUnknkown (as a CallbackVH).
forgetMemoizedResults should invalidate the loop back edges expression.
llvm-svn: 177986
Add "evaluate-tbaa" to print alias queries of loads/stores. Alias queries
between pointers do not include TBAA tags.
Add testing case for "placement new". TBAA currently says NoAlias.
llvm-svn: 177772
This handles the case where we have an inbounds GEP with alloca as the pointer.
This fixes the regression in PR12750 and rdar://13286434.
Note that we can also fix this by handling some GEP cases in isKnownNonNull.
llvm-svn: 177321
This pass hasn't been touched in two years & would fail with assertions against
the current debug info metadata format (the only test case for it still uses a
many-versions old debug info metadata format)
llvm-svn: 176707
The "invariant.load" metadata indicates the memory unit being accessed is immutable.
A load annotated with this metadata can be moved across any store.
As I am not sure if it is legal to move such loads across barrier/fence, this
change dose not allow such transformation.
rdar://11311484
Thank Arnold for code review.
llvm-svn: 176562
