[llvm] 7e30989 - [IR] ShuffleVectorInst::isIdentityWithPadding - bail on non-fixed-type vector shuffles.

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2020-11-17T16:16:51Z
New Revision: 7e30989dabce9ddbca0cbad7a8f25fb4e756d334

URL: https://github.com/llvm/llvm-project/commit/7e30989dabce9ddbca0cbad7a8f25fb4e756d334
DIFF: https://github.com/llvm/llvm-project/commit/7e30989dabce9ddbca0cbad7a8f25fb4e756d334.diff

LOG: [IR] ShuffleVectorInst::isIdentityWithPadding - bail on non-fixed-type vector shuffles.

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=27416

Added: 
    

Modified: 
    llvm/lib/IR/Instructions.cpp
    llvm/test/Transforms/InstCombine/vscale_insertelement.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 7a5670dc100b..91340e2333ad 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -2225,6 +2225,12 @@ bool ShuffleVectorInst::isExtractSubvectorMask(ArrayRef<int> Mask,
 bool ShuffleVectorInst::isIdentityWithPadding() const {
   if (isa<UndefValue>(Op<2>()))
     return false;
+
+  // FIXME: Not currently possible to express a shuffle mask for a scalable
+  // vector for this case.
+  if (isa<ScalableVectorType>(getType()))
+    return false;
+
   int NumOpElts = cast<FixedVectorType>(Op<0>()->getType())->getNumElements();
   int NumMaskElts = cast<FixedVectorType>(getType())->getNumElements();
   if (NumMaskElts <= NumOpElts)
@@ -2248,7 +2254,7 @@ bool ShuffleVectorInst::isIdentityWithExtract() const {
     return false;
 
   // FIXME: Not currently possible to express a shuffle mask for a scalable
-  // vector for this case
+  // vector for this case.
   if (isa<ScalableVectorType>(getType()))
     return false;
 

diff  --git a/llvm/test/Transforms/InstCombine/vscale_insertelement.ll b/llvm/test/Transforms/InstCombine/vscale_insertelement.ll
index e1962d731bf1..9df4bc99cab4 100644
--- a/llvm/test/Transforms/InstCombine/vscale_insertelement.ll
+++ b/llvm/test/Transforms/InstCombine/vscale_insertelement.ll
@@ -83,3 +83,20 @@ define <vscale x 4 x float> @insertelement_sequene_may_not_be_splat(float %x) {
   %t3 = insertelement <vscale x 4 x float> %t2, float %x, i32 3
   ret <vscale x 4 x float> %t3
 }
+
+; OSS-Fuzz #27416
+; https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=27416
+define void @ossfuzz_27416(i32 %v) {
+; CHECK-LABEL: @ossfuzz_27416(
+; CHECK-NEXT:    [[IN:%.*]] = insertelement <vscale x 4 x i32> undef, i32 [[V:%.*]], i32 0
+; CHECK-NEXT:    [[SPLAT:%.*]] = shufflevector <vscale x 4 x i32> [[IN]], <vscale x 4 x i32> undef, <vscale x 4 x i32> zeroinitializer
+; CHECK-NEXT:    [[I1:%.*]] = insertelement <vscale x 4 x i32> [[SPLAT]], i32 undef, i8 -128
+; CHECK-NEXT:    store <vscale x 4 x i32> [[I1]], <vscale x 4 x i32>* undef, align 16
+; CHECK-NEXT:    ret void
+;
+  %in = insertelement <vscale x 4 x i32> undef, i32 %v, i32 0
+  %splat = shufflevector <vscale x 4 x i32> %in, <vscale x 4 x i32> undef, <vscale x 4 x i32> zeroinitializer
+  %I1 = insertelement <vscale x 4 x i32> %splat, i32 undef, i8 -128
+  store <vscale x 4 x i32> %I1, <vscale x 4 x i32>* undef, align 16
+  ret void
+}