[llvm] r361559 - [InstSimplify] insertelement V, undef, ? --> V

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Thu May 23 14:49:47 2019
New Revision: 361559

URL: http://llvm.org/viewvc/llvm-project?rev=361559&view=rev
Log:
[InstSimplify] insertelement V, undef, ? --> V

This was part of InstCombine, but it's better placed in
InstSimplify. InstCombine also had an unreachable but weaker
fold for insertelement with undef index, so that is deleted.

Removed:
    llvm/trunk/test/Transforms/InstCombine/vec_insertelt.ll
Modified:
    llvm/trunk/lib/Analysis/InstructionSimplify.cpp
    llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
    llvm/trunk/test/Transforms/InstSimplify/insertelement.ll

Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=361559&r1=361558&r2=361559&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Thu May 23 14:49:47 2019
@@ -4011,6 +4011,11 @@ Value *llvm::SimplifyInsertElementInst(V
   if (isa<UndefValue>(Idx))
     return UndefValue::get(Vec->getType());
 
+  // Inserting an undef scalar? Assume it is the same value as the existing
+  // vector element.
+  if (isa<UndefValue>(Val))
+    return Vec;
+
   return nullptr;
 }
 

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp?rev=361559&r1=361558&r2=361559&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp Thu May 23 14:49:47 2019
@@ -863,10 +863,6 @@ Instruction *InstCombiner::visitInsertEl
           VecOp, ScalarOp, IdxOp, SQ.getWithInstruction(&IE)))
     return replaceInstUsesWith(IE, V);
 
-  // Inserting an undef or into an undefined place, remove this.
-  if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
-    replaceInstUsesWith(IE, VecOp);
-
   // If the vector and scalar are both bitcast from the same element type, do
   // the insert in that source type followed by bitcast.
   Value *VecSrc, *ScalarSrc;

Removed: llvm/trunk/test/Transforms/InstCombine/vec_insertelt.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/vec_insertelt.ll?rev=361558&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/vec_insertelt.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/vec_insertelt.ll (removed)
@@ -1,8 +0,0 @@
-; RUN: opt < %s -instcombine -S | FileCheck %s
-; CHECK: ret <4 x i32> %A
-
-; PR1286
-define <4 x i32> @test1(<4 x i32> %A) {
-	%B = insertelement <4 x i32> %A, i32 undef, i32 1
-	ret <4 x i32> %B
-}

Modified: llvm/trunk/test/Transforms/InstSimplify/insertelement.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/insertelement.ll?rev=361559&r1=361558&r2=361559&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/insertelement.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/insertelement.ll Thu May 23 14:49:47 2019
@@ -1,31 +1,51 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -S -instsimplify < %s | FileCheck %s
 
 define <4 x i32> @test1(<4 x i32> %A) {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT:    ret <4 x i32> undef
+;
   %I = insertelement <4 x i32> %A, i32 5, i64 4294967296
-  ; CHECK: ret <4 x i32> undef
   ret <4 x i32> %I
 }
 
 define <4 x i32> @test2(<4 x i32> %A) {
+; CHECK-LABEL: @test2(
+; CHECK-NEXT:    ret <4 x i32> undef
+;
   %I = insertelement <4 x i32> %A, i32 5, i64 4
-  ; CHECK: ret <4 x i32> undef
   ret <4 x i32> %I
 }
 
 define <4 x i32> @test3(<4 x i32> %A) {
+; CHECK-LABEL: @test3(
+; CHECK-NEXT:    [[I:%.*]] = insertelement <4 x i32> [[A:%.*]], i32 5, i64 1
+; CHECK-NEXT:    ret <4 x i32> [[I]]
+;
   %I = insertelement <4 x i32> %A, i32 5, i64 1
-  ; CHECK: ret <4 x i32> %I
   ret <4 x i32> %I
 }
 
 define <4 x i32> @test4(<4 x i32> %A) {
+; CHECK-LABEL: @test4(
+; CHECK-NEXT:    ret <4 x i32> undef
+;
   %I = insertelement <4 x i32> %A, i32 5, i128 100
-  ; CHECK: ret <4 x i32> undef
   ret <4 x i32> %I
 }
 
 define <4 x i32> @test5(<4 x i32> %A) {
+; CHECK-LABEL: @test5(
+; CHECK-NEXT:    ret <4 x i32> undef
+;
   %I = insertelement <4 x i32> %A, i32 5, i64 undef
-  ; CHECK: ret <4 x i32> undef
   ret <4 x i32> %I
 }
+
+define <4 x i32> @PR1286(<4 x i32> %A) {
+; CHECK-LABEL: @PR1286(
+; CHECK-NEXT:    ret <4 x i32> [[A:%.*]]
+;
+  %B = insertelement <4 x i32> %A, i32 undef, i32 1
+  ret <4 x i32> %B
+}