[PATCH] D124015: [InstCombine] Don't look through bitcast from vector in collectInsertionElements.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: spatel, RKSimon, lebedev.ri.
Herald added subscribers: StephenFan, hiraditya.
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Herald added a project: LLVM.

We're making a recursive call here and everything in the function
assumes we're looking at scalars. This would be violated if we
looked through a bitcast from vectors.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D124015

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
  llvm/test/Transforms/InstCombine/bitcast.ll


Index: llvm/test/Transforms/InstCombine/bitcast.ll
===================================================================
--- llvm/test/Transforms/InstCombine/bitcast.ll
+++ llvm/test/Transforms/InstCombine/bitcast.ll
@@ -435,8 +435,10 @@
 ; The bitcast from vector is confusing it.
 define <2 x i64> @int2vec_insertion_bitcast_from_vec(i64 %x) {
 ; CHECK-LABEL: @int2vec_insertion_bitcast_from_vec(
-; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <2 x i64> <i64 poison, i64 0>, i64 [[X:%.*]], i64 0
-; CHECK-NEXT:    ret <2 x i64> [[TMP1]]
+; CHECK-NEXT:    [[A:%.*]] = bitcast i64 [[X:%.*]] to <8 x i8>
+; CHECK-NEXT:    [[B:%.*]] = zext <8 x i8> [[A]] to <8 x i16>
+; CHECK-NEXT:    [[D:%.*]] = bitcast <8 x i16> [[B]] to <2 x i64>
+; CHECK-NEXT:    ret <2 x i64> [[D]]
 ;
   %a = bitcast i64 %x to <8 x i8>
   %b = zext <8 x i8> %a to <8 x i16>
Index: llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -2271,6 +2271,8 @@
   switch (I->getOpcode()) {
   default: return false; // Unhandled case.
   case Instruction::BitCast:
+    if (I->getOperand(0)->getType()->isVectorTy())
+      return false;
     return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
                                     isBigEndian);
   case Instruction::ZExt:


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