[llvm] r357385 - [InstCombine] Handle vector gep with scalar argument in evaluateInDifferentElementOrder

[Mikael Holmen via llvm-commits]

Author: uabelho
Date: Mon Apr  1 06:48:56 2019
New Revision: 357385

URL: http://llvm.org/viewvc/llvm-project?rev=357385&view=rev
Log:
[InstCombine] Handle vector gep with scalar argument in evaluateInDifferentElementOrder

This fixes PR41270.

The recursive function evaluateInDifferentElementOrder expects to be called
on a vector Value, so when we call it on a vector GEP's arguments, we must
first check that the argument is indeed a vector.

Added:
    llvm/trunk/test/Transforms/InstCombine/vec_gep_scalar_arg.ll
Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp?rev=357385&r1=357384&r2=357385&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp Mon Apr  1 06:48:56 2019
@@ -1171,7 +1171,14 @@ static Value *evaluateInDifferentElement
       SmallVector<Value*, 8> NewOps;
       bool NeedsRebuild = (Mask.size() != I->getType()->getVectorNumElements());
       for (int i = 0, e = I->getNumOperands(); i != e; ++i) {
-        Value *V = evaluateInDifferentElementOrder(I->getOperand(i), Mask);
+        Value *V;
+        // Recursively call evaluateInDifferentElementOrder on vector arguments
+        // as well. E.g. GetElementPtr may have scalar operands even if the
+        // return value is a vector, so we need to examine the operand type.
+        if (I->getOperand(i)->getType()->isVectorTy())
+          V = evaluateInDifferentElementOrder(I->getOperand(i), Mask);
+        else
+          V = I->getOperand(i);
         NewOps.push_back(V);
         NeedsRebuild |= (V != I->getOperand(i));
       }

Added: llvm/trunk/test/Transforms/InstCombine/vec_gep_scalar_arg.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/vec_gep_scalar_arg.ll?rev=357385&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/vec_gep_scalar_arg.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/vec_gep_scalar_arg.ll Mon Apr  1 06:48:56 2019
@@ -0,0 +1,16 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -instcombine -S < %s | FileCheck %s
+
+define <4 x i16*> @PR41270([4 x i16]* %x) {
+; CHECK-LABEL: @PR41270(
+; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <4 x [4 x i16]*> undef, [4 x i16]* [[X:%.*]], i32 0
+; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds [4 x i16], <4 x [4 x i16]*> [[TMP1]], i64 0, i64 3
+; CHECK-NEXT:    ret <4 x i16*> [[TMP2]]
+;
+  %ins = insertelement <4 x [4 x i16]*> undef, [4 x i16]* %x, i32 0
+  %splat = shufflevector <4 x [4 x i16]*> %ins, <4 x [4 x i16]*> undef, <4 x i32> zeroinitializer
+  %t2 = getelementptr inbounds [4 x i16], <4 x [4 x i16]*> %splat, i32 0, i32 3
+  %t3 = extractelement <4 x i16*> %t2, i32 3
+  %ins2 = insertelement <4 x i16*> undef, i16* %t3, i32 0
+  ret <4 x i16*> %ins2
+}