[PATCH] D136099: [instsimplify] Move (extelt (inselt Vec, Value, Index), Index) -> Value from InstCombine

[Daniel Sanders via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG021e6e05d3d9: [instsimplify] Move (extelt (inselt Vec, Value, Index), Index) -> Value from… (authored by dsanders).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D136099/new/

https://reviews.llvm.org/D136099

Files:
  llvm/lib/Analysis/InstructionSimplify.cpp
  llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
  llvm/test/Transforms/InstCombine/vector-inseltextelt.ll
  llvm/test/Transforms/InstSimplify/vector-inseltextelt.ll


Index: llvm/test/Transforms/InstSimplify/vector-inseltextelt.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/vector-inseltextelt.ll
+++ llvm/test/Transforms/InstSimplify/vector-inseltextelt.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+; RUN: opt < %s -passes=instsimplify -S | FileCheck %s
 
 ; extracting a just-inserted element should yield the original value
 define float @constant_index(<4 x float> %x, float %val) {
Index: llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -474,11 +474,6 @@
 
   if (auto *I = dyn_cast<Instruction>(SrcVec)) {
     if (auto *IE = dyn_cast<InsertElementInst>(I)) {
-      // If the possibly-variable indices are trivially known to be equal
-      // (because they are the same operand) then use the value that was
-      // inserted directly.
-      if (IE->getOperand(2) == Index)
-        return replaceInstUsesWith(EI, IE->getOperand(1));
       // instsimplify already handled the case where the indices are constants
       // and equal by value, if both are constants, they must not be the same
       // value, extract from the pre-inserted value instead.
Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4857,6 +4857,14 @@
     if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue()))
       return Elt;
   } else {
+    // extractelt x, (insertelt y, elt, n), n -> elt
+    // If the possibly-variable indices are trivially known to be equal
+    // (because they are the same operand) then use the value that was
+    // inserted directly.
+    auto *IE = dyn_cast<InsertElementInst>(Vec);
+    if (IE && IE->getOperand(2) == Idx)
+      return IE->getOperand(1);
+
     // The index is not relevant if our vector is a splat.
     if (Value *Splat = getSplatValue(Vec))
       return Splat;


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