[llvm] r348423 - [InstCombine] remove dead code from visitExtractElement

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Wed Dec  5 15:09:33 2018
New Revision: 348423

URL: http://llvm.org/viewvc/llvm-project?rev=348423&view=rev
Log:
[InstCombine] remove dead code from visitExtractElement

Extracting from a splat constant is always handled by InstSimplify.
Move the test for this from InstCombine to InstSimplify to make
sure that stays true.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
    llvm/trunk/test/Transforms/InstCombine/scalarization.ll
    llvm/trunk/test/Transforms/InstSimplify/extract-element.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp?rev=348423&r1=348422&r2=348423&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp Wed Dec  5 15:09:33 2018
@@ -267,12 +267,6 @@ Instruction *InstCombiner::visitExtractE
                                             SQ.getWithInstruction(&EI)))
     return replaceInstUsesWith(EI, V);
 
-  // If vector val is constant with all elements the same, replace EI with
-  // that element.  We handle a known element # below.
-  if (auto *C = dyn_cast<Constant>(SrcVec))
-    if (cheapToScalarize(C, false))
-      return replaceInstUsesWith(EI, C->getAggregateElement(0U));
-
   // If extracting a specified index from the vector, see if we can recursively
   // find a previously computed scalar that was inserted into the vector.
   auto *IndexC = dyn_cast<ConstantInt>(Index);

Modified: llvm/trunk/test/Transforms/InstCombine/scalarization.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/scalarization.ll?rev=348423&r1=348422&r2=348423&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/scalarization.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/scalarization.ll Wed Dec  5 15:09:33 2018
@@ -97,14 +97,6 @@ define i32 @extelt_binop_binop_insertelt
   ret i32 %E
 }
 
-define float @extract_element_splat_constant_vector_variable_index(i32 %y) {
-; CHECK-LABEL: @extract_element_splat_constant_vector_variable_index(
-; CHECK-NEXT:    ret float 2.000000e+00
-;
-  %r = extractelement <4 x float> <float 2.0, float 2.0, float 2.0, float 2.0>, i32 %y
-  ret float %r
-}
-
 define float @extract_element_constant_vector_variable_index(i32 %y) {
 ; CHECK-LABEL: @extract_element_constant_vector_variable_index(
 ; CHECK-NEXT:    [[R:%.*]] = extractelement <4 x float> <float 1.000000e+00, float 2.000000e+00, float 3.000000e+00, float 4.000000e+00>, i32 [[Y:%.*]]

Modified: llvm/trunk/test/Transforms/InstSimplify/extract-element.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/extract-element.ll?rev=348423&r1=348422&r2=348423&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/extract-element.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/extract-element.ll Wed Dec  5 15:09:33 2018
@@ -39,9 +39,18 @@ define i129 @vec_extract_undef_index(<3
 
 define i129 @vec_extract_in_bounds(<3 x i129> %a) {
 ; CHECK-LABEL: @vec_extract_in_bounds(
-; CHECK-NEXT:    %E1 = extractelement <3 x i129> %a, i129 2
-; CHECK-NEXT:     ret i129 %E1
+; CHECK-NEXT:    [[E1:%.*]] = extractelement <3 x i129> [[A:%.*]], i129 2
+; CHECK-NEXT:    ret i129 [[E1]]
 ;
   %E1 = extractelement <3 x i129> %a, i129 2
   ret i129 %E1
 }
+
+define float @extract_element_splat_constant_vector_variable_index(i32 %y) {
+; CHECK-LABEL: @extract_element_splat_constant_vector_variable_index(
+; CHECK-NEXT:    ret float 2.000000e+00
+;
+  %r = extractelement <4 x float> <float 2.0, float 2.0, float 2.0, float 2.0>, i32 %y
+  ret float %r
+}
+