LoopVectorizer: Fix 15830. When scalarizing and unrolling stores make sure that the...

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

diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index 162587c5659b51aeec7cf5fa60063facad849df1..0988a4032fd5b451db51ce7cd4987caea2ce5152 100644 (file)
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -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");

diff --git a/test/Transforms/LoopVectorize/bsd_regex.ll b/test/Transforms/LoopVectorize/bsd_regex.ll
new file mode 100644 (file)
index 0000000..a2aef1c
--- /dev/null
+++ b/test/Transforms/LoopVectorize/bsd_regex.ll
@@ -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
+}
+
+