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BBVectorize should ignore unreachable blocks.

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Unreachable blocks can have invalid instructions. For example,
jump threading can produce self-referential instructions in
unreachable blocks. Also, we should not be spending time
optimizing unreachable code. Fixes PR14133.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166423 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel 2012-10-22 18:00:55 +00:00
parent e743942bc8
commit e29c19091c
2 changed files with 45 additions and 0 deletions
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13
lib/Transforms/Vectorize/BBVectorize.cpp
View File

@ -34,6 +34,7 @@
#include "llvm/ADT/StringExtras.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AliasSetTracker.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ValueTracking.h"
@ -177,6 +178,7 @@ namespace {
BBVectorize(Pass *P, const VectorizeConfig &C)
: BasicBlockPass(ID), Config(C) {
AA = &P->getAnalysis<AliasAnalysis>();
DT = &P->getAnalysis<DominatorTree>();
SE = &P->getAnalysis<ScalarEvolution>();
TD = P->getAnalysisIfAvailable<DataLayout>();
}
@ -191,6 +193,7 @@ namespace {
VPPIteratorPair;
AliasAnalysis *AA;
DominatorTree *DT;
ScalarEvolution *SE;
DataLayout *TD;
@ -330,6 +333,12 @@ namespace {
void combineMetadata(Instruction *K, const Instruction *J);
bool vectorizeBB(BasicBlock &BB) {
if (!DT->isReachableFromEntry(&BB)) {
DEBUG(dbgs() << "BBV: skipping unreachable " << BB.getName() <<
" in " << BB.getParent()->getName() << "\n");
return false;
}
bool changed = false;
// Iterate a sufficient number of times to merge types of size 1 bit,
// then 2 bits, then 4, etc. up to half of the target vector width of the
@ -363,6 +372,7 @@ namespace {
virtual bool runOnBasicBlock(BasicBlock &BB) {
AA = &getAnalysis<AliasAnalysis>();
DT = &getAnalysis<DominatorTree>();
SE = &getAnalysis<ScalarEvolution>();
TD = getAnalysisIfAvailable<DataLayout>();
@ -372,8 +382,10 @@ namespace {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
BasicBlockPass::getAnalysisUsage(AU);
AU.addRequired<AliasAnalysis>();
AU.addRequired<DominatorTree>();
AU.addRequired<ScalarEvolution>();
AU.addPreserved<AliasAnalysis>();
AU.addPreserved<DominatorTree>();
AU.addPreserved<ScalarEvolution>();
AU.setPreservesCFG();
}
@ -2397,6 +2409,7 @@ char BBVectorize::ID = 0;
static const char bb_vectorize_name[] = "Basic-Block Vectorization";
INITIALIZE_PASS_BEGIN(BBVectorize, BBV_NAME, bb_vectorize_name, false, false)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_DEPENDENCY(DominatorTree)
INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
INITIALIZE_PASS_END(BBVectorize, BBV_NAME, bb_vectorize_name, false, false)

32
test/Transforms/BBVectorize/simple-ldstr.ll
View File

@ -108,3 +108,35 @@ entry:
; CHECK-AO: store <2 x float> %mulf, <2 x float>* %0, align 8
; CHECK-AO: ret void
}
; Simple 3-pair chain with loads and stores (unreachable)
define void @test4(i1 %bool, double* %a, double* %b, double* %c) nounwind uwtable readonly {
entry:
br i1 %bool, label %if.then1, label %if.end
if.then1:
unreachable
br label %if.then
if.then:
%i0 = load double* %a, align 8
%i1 = load double* %b, align 8
%mul = fmul double %i0, %i1
%arrayidx3 = getelementptr inbounds double* %a, i64 1
%i3 = load double* %arrayidx3, align 8
%arrayidx4 = getelementptr inbounds double* %b, i64 1
%i4 = load double* %arrayidx4, align 8
%mul5 = fmul double %i3, %i4
store double %mul, double* %c, align 8
%arrayidx5 = getelementptr inbounds double* %c, i64 1
store double %mul5, double* %arrayidx5, align 8
br label %if.end
if.end:
ret void
; CHECK: @test4
; CHECK-NOT: <2 x double>
; CHECK-AO: @test4
; CHECK-AO-NOT: <2 x double>
}