[llvm] r354144 - [InstCombine] fix crash while trying to narrow a binop of shuffles (PR40734)

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Fri Feb 15 08:31:55 2019
New Revision: 354144

URL: http://llvm.org/viewvc/llvm-project?rev=354144&view=rev
Log:
[InstCombine] fix crash while trying to narrow a binop of shuffles (PR40734)

https://bugs.llvm.org/show_bug.cgi?id=40734

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
    llvm/trunk/test/Transforms/InstCombine/vec_shuffle.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=354144&r1=354143&r2=354144&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Fri Feb 15 08:31:55 2019
@@ -1375,7 +1375,8 @@ Instruction *InstCombiner::foldVectorBin
   if (match(LHS, m_ShuffleVector(m_Value(L0), m_Value(L1), m_Constant(Mask))) &&
       match(RHS, m_ShuffleVector(m_Value(R0), m_Value(R1), m_Specific(Mask))) &&
       LHS->hasOneUse() && RHS->hasOneUse() &&
-      cast<ShuffleVectorInst>(LHS)->isConcat()) {
+      cast<ShuffleVectorInst>(LHS)->isConcat() &&
+      cast<ShuffleVectorInst>(RHS)->isConcat()) {
     // This transform does not have the speculative execution constraint as
     // below because the shuffle is a concatenation. The new binops are
     // operating on exactly the same elements as the existing binop.

Modified: llvm/trunk/test/Transforms/InstCombine/vec_shuffle.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/vec_shuffle.ll?rev=354144&r1=354143&r2=354144&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/vec_shuffle.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/vec_shuffle.ll Fri Feb 15 08:31:55 2019
@@ -1125,3 +1125,18 @@ define <2 x float> @frem_splat_constant1
   ret <2 x float> %r
 }
 
+; Equivalent shuffle masks, but only one is a narrowing op.
+
+define <2 x i1> @PR40734(<1 x i1> %x, <4 x i1> %y) {
+; CHECK-LABEL: @PR40734(
+; CHECK-NEXT:    [[WIDEN:%.*]] = shufflevector <1 x i1> zeroinitializer, <1 x i1> [[X:%.*]], <2 x i32> <i32 0, i32 1>
+; CHECK-NEXT:    [[NARROW:%.*]] = shufflevector <4 x i1> [[Y:%.*]], <4 x i1> undef, <2 x i32> <i32 0, i32 1>
+; CHECK-NEXT:    [[R:%.*]] = and <2 x i1> [[WIDEN]], [[NARROW]]
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %widen = shufflevector <1 x i1> zeroinitializer, <1 x i1> %x, <2 x i32> <i32 0, i32 1>
+  %narrow = shufflevector <4 x i1> %y, <4 x i1> undef, <2 x i32> <i32 0, i32 1>
+  %r = and <2 x i1> %widen, %narrow
+  ret <2 x i1> %r
+}
+