[llvm] 14fae4d - [InstCombine] Add undef elements support for shrinkFPConstantVector

[Chenbing Zheng via llvm-commits]

Author: Chenbing Zheng
Date: 2022-08-25T10:38:48+08:00
New Revision: 14fae4d136036d7967a3d819945677f7a892f2da

URL: https://github.com/llvm/llvm-project/commit/14fae4d136036d7967a3d819945677f7a892f2da
DIFF: https://github.com/llvm/llvm-project/commit/14fae4d136036d7967a3d819945677f7a892f2da.diff

LOG: [InstCombine] Add undef elements support for shrinkFPConstantVector

Reviewed By: RKSimon, spatel

Differential Revision: https://reviews.llvm.org/D132343

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
    llvm/test/Transforms/InstCombine/fpextend.ll

Removed: 
    


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diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index d68169db61cf..1e6149220159 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1659,7 +1659,6 @@ static Type *shrinkFPConstant(ConstantFP *CFP) {
 
 // Determine if this is a vector of ConstantFPs and if so, return the minimal
 // type we can safely truncate all elements to.
-// TODO: Make these support undef elements.
 static Type *shrinkFPConstantVector(Value *V) {
   auto *CV = dyn_cast<Constant>(V);
   auto *CVVTy = dyn_cast<FixedVectorType>(V->getType());
@@ -1673,6 +1672,9 @@ static Type *shrinkFPConstantVector(Value *V) {
   // For fixed-width vectors we find the minimal type by looking
   // through the constant values of the vector.
   for (unsigned i = 0; i != NumElts; ++i) {
+    if (isa<UndefValue>(CV->getAggregateElement(i)))
+      continue;
+
     auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i));
     if (!CFP)
       return nullptr;
@@ -1688,7 +1690,7 @@ static Type *shrinkFPConstantVector(Value *V) {
   }
 
   // Make a vector type from the minimal type.
-  return FixedVectorType::get(MinType, NumElts);
+  return MinType ? FixedVectorType::get(MinType, NumElts) : nullptr;
 }
 
 /// Find the minimum FP type we can safely truncate to.

diff  --git a/llvm/test/Transforms/InstCombine/fpextend.ll b/llvm/test/Transforms/InstCombine/fpextend.ll
index c991f5d8c957..a41f2a4ca300 100644
--- a/llvm/test/Transforms/InstCombine/fpextend.ll
+++ b/llvm/test/Transforms/InstCombine/fpextend.ll
@@ -83,12 +83,9 @@ define <2 x float> @test6(<2 x float> %x) nounwind  {
 }
 
 ; Test with an undef element
-; TODO: Support undef elements.
 define <2 x float> @test6_undef(<2 x float> %x) nounwind  {
 ; CHECK-LABEL: @test6_undef(
-; CHECK-NEXT:    [[T1:%.*]] = fpext <2 x float> [[X:%.*]] to <2 x double>
-; CHECK-NEXT:    [[T3:%.*]] = fadd <2 x double> [[T1]], <double 0.000000e+00, double undef>
-; CHECK-NEXT:    [[T34:%.*]] = fptrunc <2 x double> [[T3]] to <2 x float>
+; CHECK-NEXT:    [[T34:%.*]] = fadd <2 x float> [[X:%.*]], <float 0.000000e+00, float undef>
 ; CHECK-NEXT:    ret <2 x float> [[T34]]
 ;
   %t1 = fpext <2 x float> %x to <2 x double>