[PATCH] D104867: [InstSimplify] fold extractelement of splat even with variable index

[Sanjay Patel via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG3d3c0ed9323b: [InstSimplify] fold extractelement of splat with variable extract index (authored by spatel).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D104867/new/

https://reviews.llvm.org/D104867

Files:
  llvm/lib/Analysis/InstructionSimplify.cpp
  llvm/test/Transforms/InstSimplify/extract-element.ll
  llvm/test/Transforms/InstSimplify/vscale-inseltpoison.ll
  llvm/test/Transforms/InstSimplify/vscale.ll


Index: llvm/test/Transforms/InstSimplify/vscale.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/vscale.ll
+++ llvm/test/Transforms/InstSimplify/vscale.ll
@@ -210,10 +210,7 @@
 
 define i32 @extractelement_splat_variable_index(i32 %v, i32 %idx) {
 ; CHECK-LABEL: @extractelement_splat_variable_index(
-; CHECK-NEXT:    [[IN:%.*]] = insertelement <vscale x 4 x i32> undef, i32 [[V:%.*]], i32 0
-; CHECK-NEXT:    [[SPLAT:%.*]] = shufflevector <vscale x 4 x i32> [[IN]], <vscale x 4 x i32> undef, <vscale x 4 x i32> zeroinitializer
-; CHECK-NEXT:    [[R:%.*]] = extractelement <vscale x 4 x i32> [[SPLAT]], i32 [[IDX:%.*]]
-; CHECK-NEXT:    ret i32 [[R]]
+; CHECK-NEXT:    ret i32 [[V:%.*]]
 ;
   %in = insertelement <vscale x 4 x i32> undef, i32 %v, i32 0
   %splat = shufflevector <vscale x 4 x i32> %in, <vscale x 4 x i32> undef, <vscale x 4 x i32> zeroinitializer
Index: llvm/test/Transforms/InstSimplify/vscale-inseltpoison.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/vscale-inseltpoison.ll
+++ llvm/test/Transforms/InstSimplify/vscale-inseltpoison.ll
@@ -210,10 +210,7 @@
 
 define i32 @extractelement_splat_variable_index(i32 %v, i32 %idx) {
 ; CHECK-LABEL: @extractelement_splat_variable_index(
-; CHECK-NEXT:    [[IN:%.*]] = insertelement <vscale x 4 x i32> poison, i32 [[V:%.*]], i32 0
-; CHECK-NEXT:    [[SPLAT:%.*]] = shufflevector <vscale x 4 x i32> [[IN]], <vscale x 4 x i32> undef, <vscale x 4 x i32> zeroinitializer
-; CHECK-NEXT:    [[R:%.*]] = extractelement <vscale x 4 x i32> [[SPLAT]], i32 [[IDX:%.*]]
-; CHECK-NEXT:    ret i32 [[R]]
+; CHECK-NEXT:    ret i32 [[V:%.*]]
 ;
   %in = insertelement <vscale x 4 x i32> poison, i32 %v, i32 0
   %splat = shufflevector <vscale x 4 x i32> %in, <vscale x 4 x i32> undef, <vscale x 4 x i32> zeroinitializer
Index: llvm/test/Transforms/InstSimplify/extract-element.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/extract-element.ll
+++ llvm/test/Transforms/InstSimplify/extract-element.ll
@@ -62,10 +62,7 @@
 
 define i32 @extractelement_splat_variable_index(i32 %v, i32 %index) {
 ; CHECK-LABEL: @extractelement_splat_variable_index(
-; CHECK-NEXT:    [[IN:%.*]] = insertelement <3 x i32> poison, i32 [[V:%.*]], i32 0
-; CHECK-NEXT:    [[SPLAT:%.*]] = shufflevector <3 x i32> [[IN]], <3 x i32> poison, <3 x i32> zeroinitializer
-; CHECK-NEXT:    [[R:%.*]] = extractelement <3 x i32> [[SPLAT]], i32 [[INDEX:%.*]]
-; CHECK-NEXT:    ret i32 [[R]]
+; CHECK-NEXT:    ret i32 [[V:%.*]]
 ;
   %in = insertelement <3 x i32> poison, i32 %v, i32 0
   %splat = shufflevector <3 x i32> %in, <3 x i32> poison, <3 x i32> zeroinitializer
Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4531,10 +4531,6 @@
     if (auto *CIdx = dyn_cast<Constant>(Idx))
       return ConstantExpr::getExtractElement(CVec, CIdx);
 
-    // The index is not relevant if our vector is a splat.
-    if (auto *Splat = CVec->getSplatValue())
-      return Splat;
-
     if (Q.isUndefValue(Vec))
       return UndefValue::get(VecVTy->getElementType());
   }
@@ -4557,6 +4553,10 @@
         return Splat;
     if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue()))
       return Elt;
+  } else {
+    // The index is not relevant if our vector is a splat.
+    if (Value *Splat = getSplatValue(Vec))
+      return Splat;
   }
   return nullptr;
 }


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