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Commit Graph

7443 Commits

Author SHA1 Message Date
Chris Lattner
dbad0b5e40 Enhance earlycse to do CSE of casts, instsimplify and die.
Add a testcase.

llvm-svn: 122715
2011-01-02 23:04:14 +00:00
Chris Lattner
e396e846b4 split dom frontier handling stuff out to its own DominanceFrontier header,
so that Dominators.h is *just* domtree.  Also prune #includes a bit.

llvm-svn: 122714
2011-01-02 22:09:33 +00:00
Chris Lattner
688675a0be sketch out a new early cse pass. No functionality yet.
llvm-svn: 122713
2011-01-02 21:47:05 +00:00
Chris Lattner
0c2cfcf430 fix a miscompilation of tramp3d-v4: when forming a memcpy, we have to make
sure that the loop we're promoting into a memcpy doesn't mutate the input
of the memcpy.  Before we were just checking that the dest of the memcpy
wasn't mod/ref'd by the loop.

llvm-svn: 122712
2011-01-02 21:14:18 +00:00
Chris Lattner
c655681b32 If a loop iterates exactly once (has backedge count = 0) then don't
mess with it.  We'd rather peel/unroll it than convert all of its 
stores into memsets.

llvm-svn: 122711
2011-01-02 20:24:21 +00:00
Nick Lewycky
06b94a5e5b Also remove functions that use complex constant expressions in terms of
another function.

llvm-svn: 122705
2011-01-02 19:16:44 +00:00
Chris Lattner
c78e4bc366 enhance loop idiom recognition to scan *all* unconditionally executed
blocks in a loop, instead of just the header block.  This makes it more
aggressive, able to handle Duncan's Ada examples.

llvm-svn: 122704
2011-01-02 19:01:03 +00:00
Chris Lattner
3bb2e83433 make inSubLoop much more efficient.
llvm-svn: 122703
2011-01-02 18:53:08 +00:00
Chris Lattner
2bcd2564d6 rip out isExitBlockDominatedByBlockInLoop, calling DomTree::dominates instead.
isExitBlockDominatedByBlockInLoop is a relic of the days when domtree was 
*just* a tree and didn't have DFS numbers.  Checking DFS numbers is faster
and easier than "limiting the search of the tree".

llvm-svn: 122702
2011-01-02 18:45:39 +00:00
Chris Lattner
bbae3ddf12 add a list of opportunities for future improvement.
llvm-svn: 122701
2011-01-02 18:32:09 +00:00
Duncan Sands
2d1c116071 Fix PR8702 by not having LoopSimplify claim to preserve LCSSA form. As described
in the PR, the pass could break LCSSA form when inserting preheaders.  It probably
would be easy enough to fix this, but since currently we always go into LCSSA form
after running this pass, doing so is not urgent.

llvm-svn: 122695
2011-01-02 13:38:21 +00:00
Chris Lattner
f669d6a901 Allow loop-idiom to run on multiple BB loops, but still only scan the loop
header for now for memset/memcpy opportunities.  It turns out that loop-rotate
is successfully rotating loops, but *DOESN'T MERGE THE BLOCKS*, turning "for 
loops" into 2 basic block loops that loop-idiom was ignoring.

With this fix, we form many *many* more memcpy and memsets than before, including
on the "history" loops in the viterbi benchmark, which look like this:

        for (j=0; j<MAX_history; ++j) {
          history_new[i][j+1] = history[2*i][j];
        }

Transforming these loops into memcpy's speeds up the viterbi benchmark from
11.98s to 3.55s on my machine.  Woo.

llvm-svn: 122685
2011-01-02 07:58:36 +00:00
Chris Lattner
8a72a8f315 remove debugging code.
llvm-svn: 122683
2011-01-02 07:37:13 +00:00
Chris Lattner
bbd22e0c3c add some -stats output.
llvm-svn: 122682
2011-01-02 07:36:44 +00:00
Chris Lattner
2afc3c0dc4 improve loop rotation to use CodeMetrics to analyze the
size of a loop header instead of its own code size estimator.
This allows it to handle bitcasts etc more precisely.

llvm-svn: 122681
2011-01-02 07:35:53 +00:00
Chris Lattner
34a61ab676 teach loop idiom recognition to form memcpy's from simple loops.
llvm-svn: 122678
2011-01-02 03:37:56 +00:00
Nick Lewycky
68d915ae1a Remove functions from the FnSet when one of their callee's is being merged. This
maintains the guarantee that the DenseSet expects two elements it contains to
not go from inequal to equal under its nose.

As a side-effect, this also lets us switch from iterating to a fixed-point to
actually maintaining a work queue of functions to look at again, and we don't
add thunks to our work queue so we don't need to detect and ignore them.

llvm-svn: 122677
2011-01-02 02:46:33 +00:00
Chris Lattner
fda382af51 fix a globalopt crash on two Adobe-C++ testcases that the recent
loop idiom pass exposed.

llvm-svn: 122674
2011-01-01 22:31:46 +00:00
Chris Lattner
b9c1684fce add a validity check that was missed, fixing a crash on the
new testcase.

llvm-svn: 122662
2011-01-01 20:12:04 +00:00
Chris Lattner
9a9f43c4a2 improve validity check to handle constant-trip-count loops more
aggressively.  In practice, this doesn't help anything though,
see the todo.

llvm-svn: 122660
2011-01-01 19:54:22 +00:00
Chris Lattner
4651f8b037 implement the "no aliasing accesses in loop" safety check. This pass
should be correct now.

llvm-svn: 122659
2011-01-01 19:39:01 +00:00
Duncan Sands
74270e8100 Simplify this pass by using a depth-first iterator to ensure that all
operands are visited before the instructions themselves.

llvm-svn: 122647
2010-12-31 17:49:05 +00:00
Duncan Sands
ca280dbcd5 Zap dead instructions harder.
llvm-svn: 122645
2010-12-31 16:17:54 +00:00
Benjamin Kramer
c84434924f Make a bunch of symbols internal.
llvm-svn: 122642
2010-12-30 22:34:44 +00:00
Chris Lattner
51a906ce92 simplify this, isBytewiseValue handles the extra check. We still
check for "multiple of a byte" in size to make it clear that the
>> 3 below is safe.

llvm-svn: 122604
2010-12-28 18:53:48 +00:00
Duncan Sands
1395f115d8 Silence gcc warning about an unused variable when doing a release build.
llvm-svn: 122593
2010-12-28 09:41:15 +00:00
Chris Lattner
2658d522b1 fix some issues Frits noticed, add AliasAnalysis as a dependency
llvm-svn: 122585
2010-12-27 18:39:08 +00:00
Benjamin Kramer
30e1ba0fcc BuildLibCalls: Nuke EmitMemCpy, EmitMemMove and EmitMemSet. They are dead and superseded by IRBuilder.
llvm-svn: 122576
2010-12-27 00:25:32 +00:00
Benjamin Kramer
c66455a774 SimplifyLibCalls: Use IRBuilder to simplify code.
llvm-svn: 122575
2010-12-27 00:16:46 +00:00
Chris Lattner
a4249272b5 have loop-idiom nuke instructions that feed stores that get removed.
llvm-svn: 122574
2010-12-27 00:03:23 +00:00
Chris Lattner
d4daf9f002 implement enough of the memset inference algorithm to recognize and insert
memsets.  This is still missing one important validity check, but this is enough
to compile stuff like this:

void test0(std::vector<char> &X) {
  for (std::vector<char>::iterator I = X.begin(), E = X.end(); I != E; ++I)
    *I = 0;
}

void test1(std::vector<int> &X) {
  for (long i = 0, e = X.size(); i != e; ++i)
    X[i] = 0x01010101;
}

With:
 $ clang t.cpp -S -o - -O2 -emit-llvm | opt -loop-idiom | opt -O3 | llc 

to:

__Z5test0RSt6vectorIcSaIcEE:            ## @_Z5test0RSt6vectorIcSaIcEE
## BB#0:                                ## %entry
	subq	$8, %rsp
	movq	(%rdi), %rax
	movq	8(%rdi), %rsi
	cmpq	%rsi, %rax
	je	LBB0_2
## BB#1:                                ## %bb.nph
	subq	%rax, %rsi
	movq	%rax, %rdi
	callq	___bzero
LBB0_2:                                 ## %for.end
	addq	$8, %rsp
	ret
...
__Z5test1RSt6vectorIiSaIiEE:            ## @_Z5test1RSt6vectorIiSaIiEE
## BB#0:                                ## %entry
	subq	$8, %rsp
	movq	(%rdi), %rax
	movq	8(%rdi), %rdx
	subq	%rax, %rdx
	cmpq	$4, %rdx
	jb	LBB1_2
## BB#1:                                ## %for.body.preheader
	andq	$-4, %rdx
	movl	$1, %esi
	movq	%rax, %rdi
	callq	_memset
LBB1_2:                                 ## %for.end
	addq	$8, %rsp
	ret

llvm-svn: 122573
2010-12-26 23:42:51 +00:00
Chris Lattner
9007b56712 start using irbuilder to make mem intrinsics in a few passes.
llvm-svn: 122572
2010-12-26 22:57:41 +00:00
Chris Lattner
27961b5180 sketch more of this out.
llvm-svn: 122567
2010-12-26 20:45:45 +00:00
Chris Lattner
c56d20aa48 move isBytewiseValue out to ValueTracking.h/cpp
llvm-svn: 122565
2010-12-26 20:15:01 +00:00
Chris Lattner
73f562af94 actually add the file...
llvm-svn: 122563
2010-12-26 19:39:38 +00:00
Chris Lattner
e210c31646 Start of a pass for recognizing memset and memcpy idioms.
No functionality yet.

llvm-svn: 122562
2010-12-26 19:32:44 +00:00
Benjamin Kramer
626fccab8b Simplify code.
llvm-svn: 122561
2010-12-26 15:23:45 +00:00
Chris Lattner
a73a53e67f don't lose TD info
llvm-svn: 122556
2010-12-25 20:52:04 +00:00
Chris Lattner
38d6d6d367 switch the inliner alignment enforcement stuff to use the
getOrEnforceKnownAlignment function, which simplifies the code
and makes it stronger.

llvm-svn: 122555
2010-12-25 20:42:38 +00:00
Chris Lattner
c4cb20b9bf Move getOrEnforceKnownAlignment out of instcombine into Transforms/Utils.
llvm-svn: 122554
2010-12-25 20:37:57 +00:00
Benjamin Kramer
720b32b319 Fix a thinko pointed out by Frits van Bommel: looking through global variables in isBytewiseValue is not safe.
llvm-svn: 122550
2010-12-24 22:23:59 +00:00
Benjamin Kramer
49e40d4c4b MemCpyOpt: Turn memcpys from a constant into a memset if possible.
This allows us to compile "int cst[] = {-1, -1, -1};" into
  movl  $-1, 16(%rsp)
  movq  $-1, 8(%rsp)
instead of
  movl  _cst+8(%rip), %eax
  movl  %eax, 16(%rsp)
  movq  _cst(%rip), %rax
  movq  %rax, 8(%rsp)

llvm-svn: 122548
2010-12-24 21:17:12 +00:00
Owen Anderson
6afd90810e When determining if we can fold (x >> C1) << C2, the bits that we need to verify are zero
are not the low bits of x, but the bits that WILL be the low bits after the operation completes.

llvm-svn: 122529
2010-12-23 23:56:24 +00:00
Owen Anderson
be8084acdd It is possible for SimplifyCFG to cause PHI nodes to become redundant too late in the optimization
pipeline to be caught by instcombine, and it's not feasible to catch them in SimplifyCFG because the
use-lists are in an inconsistent state at the point where it could know that it need to simplify them.
Instead, have CodeGenPrepare look for trivially redundant PHIs as part of its general cleanup effort.

llvm-svn: 122516
2010-12-23 20:57:35 +00:00
Mon P Wang
eb2ae28352 Preserve the address space when generating bitcasts for MemTransferInst in ConvertToScalarInfo
llvm-svn: 122462
2010-12-23 01:41:32 +00:00
Jeffrey Yasskin
a199652a3e Change all self assignments X=X to (void)X, so that we can turn on a
new gcc warning that complains on self-assignments and
self-initializations.

llvm-svn: 122458
2010-12-23 00:58:24 +00:00
Benjamin Kramer
27d13684f5 InstCombine: creating selects from -1 and 0 is fine, they combine into a sext from i1.
llvm-svn: 122453
2010-12-22 23:12:15 +00:00
Duncan Sands
922251757b Add a generic expansion transform: A op (B op' C) -> (A op B) op' (A op C)
if both A op B and A op C simplify.  This fires fairly often but doesn't
make that much difference.  On gcc-as-one-file it removes two "and"s and
turns one branch into a select.

llvm-svn: 122399
2010-12-22 13:36:08 +00:00
Duncan Sands
9b28a173fe Add some statistics, good for understanding how much more powerful
instcombine is compared to instsimplify.

llvm-svn: 122397
2010-12-22 09:40:51 +00:00
Owen Anderson
b4f1511864 Give GVN back the ability to perform simple conditional propagation on conditional branch values.
I still think that LVI should be handling this, but that capability is some ways off in the future,
and this matters for some significant benchmarks.

llvm-svn: 122378
2010-12-21 23:54:34 +00:00