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SLPVectorizer: Fix invalid iterator errors

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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 474ae7ebd0
commit 276cfe784a
2 changed files with 81 additions and 13 deletions
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64
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
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}