this was a tree of hashtables, and a query recursed into the table for the immediate dominator ad infinitum
if the initial lookup failed. This led to really bad performance on tall, narrow CFGs.
We can instead replace it with what is conceptually a multimap of value numbers to leaders (actually
represented by a hashtable with a list of Value*'s as the value type), and then
determine which leader from that set to use very cheaply thanks to the DFS numberings maintained by
DominatorTree. Because there are typically few duplicates of a given value, this scan tends to be
quite fast. Additionally, we use a custom linked list and BumpPtr allocation to avoid any unnecessary
allocation in representing the value-side of the multimap.
This change brings with it a 15% (!) improvement in the total running time of GVN on 403.gcc, which I
think is pretty good considering that includes all the "real work" being done by MemDep as well.
The one downside to this approach is that we can no longer use GVN to perform simple conditional progation,
but that seems like an acceptable loss since we now have LVI and CorrelatedValuePropagation to pick up
the slack. If you see conditional propagation that's not happening, please file bugs against LVI or CVP.
llvm-svn: 119714
refusing to optimize two memcpy's like this:
copy A <- B
copy C <- A
if it couldn't prove that noalias(B,C). We can eliminate
the copy by producing a memmove instead of memcpy.
llvm-svn: 119694
if it is passed as a byval argument. The byval argument will just be a
read, so it is safe to read from the original global instead. This allows
us to promote away the %agg.tmp alloca in PR8582
llvm-svn: 119686
sahf movl 344(%rdi),%r14d
we used to produce:
t.s:2:1: error: unexpected token in argument list
^
we now produce:
t.s:1:11: error: unexpected token in argument list
sahf movl 344(%rdi),%r14d
^
rdar://8581401
llvm-svn: 119676
and testing is easier. A good example is the unknown-location.ll test that
now can just look for ".loc 1 0 0". We also don't use a DW_LNE_set_address for
every address change anymore.
llvm-svn: 119613
It is generally not sufficient to check if the starting offset is in range
of the maximum offset that can be efficiently used for the target.
llvm-svn: 119565
This makes it more clear that the symbol is an internal, compiler-generated
name and gives a little more description about its contents.
llvm-svn: 119564
It was mistakenly looking at the pointer type when checking for the size of
global variables. This is a partial fix for Radar 8673120.
llvm-svn: 119563
needs to be checked that this won't break LCSSA form.
Change the existing checking method to a more direct one:
rather than seeing if all predecessors belong to the loop,
check that the replacing value is either not in any loop or
is in a loop that contains the phi node.
llvm-svn: 119556
and xor. The 32-bit move immediates can be hoisted out of loops by machine
LICM but the isel hacks were preventing them.
Instead, let peephole optimization pass recognize registers that are defined by
immediates and the ARM target hook will fold the immediates in.
Other changes include 1) do not fold and / xor into cmp to isel TST / TEQ
instructions if there are multiple uses. This happens when the 'and' is live
out, machine sink would have sinked the computation and that ends up pessimizing
code. The peephole pass would recognize situations where the 'and' can be
toggled to define CPSR and eliminate the comparison anyway.
2) Move peephole pass to after machine LICM, sink, and CSE to avoid blocking
important optimizations.
rdar://8663787, rdar://8241368
llvm-svn: 119548
instructions out of InstCombine and into InstructionSimplify. While
there, introduce an m_AllOnes pattern to simplify matching with integers
and vectors with all bits equal to one.
llvm-svn: 119536
hasConstantValue. I was leery of using SimplifyInstruction
while the IR was still in a half-baked state, which is the
reason for delaying the simplification until the IR is fully
cooked.
llvm-svn: 119494
simplified to itself (this can only happen in unreachable blocks).
Change it to return null instead. Hopefully this will fix some
buildbot failures.
llvm-svn: 119490
SrcMgrDiagHandler, we can improve clang diagnostics for inline asm:
instead of reporting them on a source line of the original line,
we can report it on the correct line wherever the string literal came
from. For something like this:
void foo() {
asm("push %rax\n"
".code32\n");
}
we used to get this: (note that the line in t.c isn't helpful)
t.c:4:7: error: warning: ignoring directive for now
asm("push %rax\n"
^
<inline asm>:2:1: note: instantiated into assembly here
.code32
^
now we get:
t.c:5:8: error: warning: ignoring directive for now
".code32\n"
^
<inline asm>:2:1: note: instantiated into assembly here
.code32
^
Note that we're pointing to line 5 properly now.
llvm-svn: 119488
cookie argument to the SourceMgr diagnostic stuff. This cleanly separates
LLVMContext's inlineasm handler from the sourcemgr error handling
definition, increasing type safety and cleaning things up.
llvm-svn: 119486
instructions have to distinguish between lists of single- and double-precision
registers in order for the ASM matcher to do a proper job. In all other
respects, a list of single- or double-precision registers are the same as a list
of GPR registers.
llvm-svn: 119460
class, uses DominatorTree which is an analysis. This change moves all of
the tricky hasConstantValue logic to SimplifyInstruction, and replaces it
with a very simple literal implementation. I already taught users of
hasConstantValue that need tricky stuff to use SimplifyInstruction instead.
I didn't update InlineFunction because the IR looks like it might be in a
funky state at the point it calls hasConstantValue, which makes calling
SimplifyInstruction dangerous since it can in theory do a lot of tricky
reasoning. This may be a pessimization, for example in the case where
all phi node operands are either undef or a fixed constant.
llvm-svn: 119459
systematically, CollapsePhi will always return null here. Note
that CollapsePhi did an extra check, isSafeReplacement, which
the SimplifyInstruction logic does not do. I think that check
was bogus - I guess we will soon find out! (It was originally
added in commit 41998 without a testcase).
llvm-svn: 119456
Always spill the full representative register at any point where any subregister
is live.
This fixes PR8620 which caused the old logic to get confused and not spill
anything at all.
The fundamental problem here is that the coalescer is too aggressive about
physical register coalescing. It sometimes makes it impossible to allocate
registers without these emergency spills.
llvm-svn: 119375
The system API's will be shifted over to returning an error_code, and returning
other return values as out parameters to the function.
Code that needs to check error conditions will use the errc enum values which
are the same as the posix_errno defines (EBADF, E2BIG, etc...), and are
compatable with the error codes in WinError.h due to some magic in system_error.
An example would be:
if (error_code ec = KillEvil("Java")) { // error_code can be converted to bool.
handle_error(ec);
}
llvm-svn: 119360
