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LoopVectorizer: Fix 15830. When scalarizing and unrolling stores make sure that the order in which the elements are scalarized is the same as the original order.

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This fixes a miscompilation in FreeBSD's regex library.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180121 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem 2013-04-23 17:12:42 +00:00
parent 3d7b39e7d4
commit a7d9a6ee63
2 changed files with 40 additions and 4 deletions
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8
lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -1085,10 +1085,10 @@ void InnerLoopVectorizer::scalarizeInstruction(Instruction *Instr) {
// Create a new entry in the WidenMap and initialize it to Undef or Null.
VectorParts &VecResults = WidenMap.splat(Instr, UndefVec);
// For each scalar that we create:
for (unsigned Width = 0; Width < VF; ++Width) {
// For each vector unroll 'part':
for (unsigned Part = 0; Part < UF; ++Part) {
// For each vector unroll 'part':
for (unsigned Part = 0; Part < UF; ++Part) {
// For each scalar that we create:
for (unsigned Width = 0; Width < VF; ++Width) {
Instruction *Cloned = Instr->clone();
if (!IsVoidRetTy)
Cloned->setName(Instr->getName() + ".cloned");

36
test/Transforms/LoopVectorize/bsd_regex.ll Normal file
View File

@ -0,0 +1,36 @@
; RUN: opt -S -loop-vectorize -dce -instcombine -force-vector-width=2 -force-vector-unroll=2 < %s | FileCheck %s
;PR 15830.
;CHECK: foo
; When scalarizing stores we need to preserve the original order.
; Make sure that we are extracting in the correct order (0101, and not 0011).
;CHECK: extractelement <2 x i64> {{.*}}, i32 0
;CHECK: extractelement <2 x i64> {{.*}}, i32 1
;CHECK: extractelement <2 x i64> {{.*}}, i32 0
;CHECK: extractelement <2 x i64> {{.*}}, i32 1
;CHECK: store
;CHECK: store
;CHECK: store
;CHECK: store
;CHECK: ret
define i32 @foo(i32* nocapture %A) {
entry:
br label %for.body
for.body:
%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
%0 = shl nsw i64 %indvars.iv, 2
%arrayidx = getelementptr inbounds i32* %A, i64 %0
store i32 4, i32* %arrayidx, align 4
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, 10000
br i1 %exitcond, label %for.end, label %for.body
for.end:
ret i32 undef
}