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SLPVectorizer: Fix invalid iterator errors 

Update iterator when the SLP vectorizer changes the instructions in the basic
block by restarting the traversal of the basic block.

Patch by Yi Jiang!

Fixes PR 16899.

llvm-svn: 188832
This commit is contained in:
Arnold Schwaighofer 2013-08-20 21:21:45 +00:00
parent 7a960a8455
commit e1f3ab69d1
2 changed files with 81 additions and 13 deletions
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64
llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
View File

@ -1875,6 +1875,8 @@ bool SLPVectorizer::tryToVectorize(BinaryOperator *V, BoUpSLP &R) {
bool SLPVectorizer::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
bool Changed = false;
SmallVector<Value *, 4> Incoming;
SmallSet<Instruction *, 16> VisitedInstrs;
// Collect the incoming values from the PHIs.
for (BasicBlock::iterator instr = BB->begin(), ie = BB->end(); instr != ie;
++instr) {
@ -1883,9 +1885,21 @@ bool SLPVectorizer::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
if (!P)
break;
// We may go through BB multiple times so skip the one we have checked.
if (VisitedInstrs.count(instr))
continue;
VisitedInstrs.insert(instr);
// Stop constructing the list when you reach a different type.
if (Incoming.size() && P->getType() != Incoming[0]->getType()) {
Changed |= tryToVectorizeList(Incoming, R);
if (tryToVectorizeList(Incoming, R)) {
// We would like to start over since some instructions are deleted
// and the iterator may become invalid value.
Changed = true;
instr = BB->begin();
ie = BB->end();
}
Incoming.clear();
}
@ -1895,14 +1909,20 @@ bool SLPVectorizer::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
if (Incoming.size() > 1)
Changed |= tryToVectorizeList(Incoming, R);
llvm::Instruction *I;
for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e;) {
I = it++;
if (isa<DbgInfoIntrinsic>(I))
VisitedInstrs.clear();
for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; it++) {
// We may go through BB multiple times so skip the one we have checked.
if (VisitedInstrs.count(it))
continue;
VisitedInstrs.insert(it);
if (isa<DbgInfoIntrinsic>(it))
continue;
// Try to vectorize reductions that use PHINodes.
if (PHINode *P = dyn_cast<PHINode>(I)) {
if (PHINode *P = dyn_cast<PHINode>(it)) {
// Check that the PHI is a reduction PHI.
if (P->getNumIncomingValues() != 2)
return Changed;
@ -1919,20 +1939,38 @@ bool SLPVectorizer::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
if (Inst == P)
Inst = BI->getOperand(1);
Changed |= tryToVectorize(dyn_cast<BinaryOperator>(Inst), R);
if (tryToVectorize(dyn_cast<BinaryOperator>(Inst), R)) {
// We would like to start over since some instructions are deleted
// and the iterator may become invalid value.
Changed = true;
it = BB->begin();
e = BB->end();
}
continue;
}
// Try to vectorize trees that start at compare instructions.
if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
if (CmpInst *CI = dyn_cast<CmpInst>(it)) {
if (tryToVectorizePair(CI->getOperand(0), CI->getOperand(1), R)) {
Changed |= true;
Changed = true;
// We would like to start over since some instructions are deleted
// and the iterator may become invalid value.
it = BB->begin();
e = BB->end();
continue;
}
for (int i = 0; i < 2; ++i)
if (BinaryOperator *BI = dyn_cast<BinaryOperator>(CI->getOperand(i)))
Changed |=
tryToVectorizePair(BI->getOperand(0), BI->getOperand(1), R);
for (int i = 0; i < 2; ++i) {
if (BinaryOperator *BI = dyn_cast<BinaryOperator>(CI->getOperand(i))) {
if (tryToVectorizePair(BI->getOperand(0), BI->getOperand(1), R)) {
Changed = true;
// We would like to start over since some instructions are deleted
// and the iterator may become invalid value.
it = BB->begin();
e = BB->end();
}
}
}
continue;
}
}

30
llvm/test/Transforms/SLPVectorizer/X86/pr16899.ll Normal file
View File

@ -0,0 +1,30 @@
; RUN: opt < %s -slp-vectorizer -S -mtriple=i386--netbsd -mcpu=i486
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32-S128"
target triple = "i386--netbsd"
@a = common global i32* null, align 4
; Function Attrs: noreturn nounwind readonly
define i32 @fn1() #0 {
entry:
%0 = load i32** @a, align 4, !tbaa !0
%1 = load i32* %0, align 4, !tbaa !3
%arrayidx1 = getelementptr inbounds i32* %0, i32 1
%2 = load i32* %arrayidx1, align 4, !tbaa !3
br label %do.body
do.body: ; preds = %do.body, %entry
%c.0 = phi i32 [ %2, %entry ], [ %add2, %do.body ]
%b.0 = phi i32 [ %1, %entry ], [ %add, %do.body ]
%add = add nsw i32 %b.0, %c.0
%add2 = add nsw i32 %add, 1
br label %do.body
}
attributes #0 = { noreturn nounwind readonly "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
!0 = metadata !{metadata !"any pointer", metadata !1}
!1 = metadata !{metadata !"omnipotent char", metadata !2}
!2 = metadata !{metadata !"Simple C/C++ TBAA"}
!3 = metadata !{metadata !"int", metadata !1}