[PATCH] D148182: ValueTracking: Handle extractelement and extractvalue in computeKnownFPClass

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: jcranmer-intel, kpn, nikic, sepavloff, foad.
Herald added subscribers: StephenFan, okura, kuter, hiraditya.
Herald added a project: All.
arsenm requested review of this revision.
Herald added a subscriber: wdng.
Herald added a reviewer: jdoerfert.
Herald added a reviewer: sstefan1.
Herald added a project: LLVM.

https://reviews.llvm.org/D148182

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Transforms/Attributor/nofpclass.ll


Index: llvm/test/Transforms/Attributor/nofpclass.ll
===================================================================
--- llvm/test/Transforms/Attributor/nofpclass.ll
+++ llvm/test/Transforms/Attributor/nofpclass.ll
@@ -742,3 +742,46 @@
   ret float %arg
 }
 
+define float @returned_extractelement_dynamic_index(<4 x float> nofpclass(nan) %vec, i32 %idx) {
+; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
+; CHECK-LABEL: define nofpclass(nan) float @returned_extractelement_dynamic_index
+; CHECK-SAME: (<4 x float> nofpclass(nan) [[VEC:%.*]], i32 [[IDX:%.*]]) #[[ATTR2]] {
+; CHECK-NEXT:    [[EXTRACT:%.*]] = extractelement <4 x float> [[VEC]], i32 [[IDX]]
+; CHECK-NEXT:    ret float [[EXTRACT]]
+;
+  %extract = extractelement <4 x float> %vec, i32 %idx
+  ret float %extract
+}
+
+define float @returned_extractelement_index0(<4 x float> nofpclass(nan) %vec) {
+; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
+; CHECK-LABEL: define nofpclass(nan) float @returned_extractelement_index0
+; CHECK-SAME: (<4 x float> nofpclass(nan) [[VEC:%.*]]) #[[ATTR2]] {
+; CHECK-NEXT:    [[EXTRACT:%.*]] = extractelement <4 x float> [[VEC]], i32 0
+; CHECK-NEXT:    ret float [[EXTRACT]]
+;
+  %extract = extractelement <4 x float> %vec, i32 0
+  ret float %extract
+}
+
+define float @returned_extractelement_scalable(<vscale x 4 x float> nofpclass(nan) %vec) {
+; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
+; CHECK-LABEL: define float @returned_extractelement_scalable
+; CHECK-SAME: (<vscale x 4 x float> nofpclass(nan) [[VEC:%.*]]) #[[ATTR2]] {
+; CHECK-NEXT:    [[EXTRACT:%.*]] = extractelement <vscale x 4 x float> [[VEC]], i32 0
+; CHECK-NEXT:    ret float [[EXTRACT]]
+;
+  %extract = extractelement <vscale x 4 x float> %vec, i32 0
+  ret float %extract
+}
+
+define float @returned_extractvalue([4 x float] nofpclass(nan) %array) {
+; CHECK: Function Attrs: nofree norecurse nosync nounwind willreturn memory(none)
+; CHECK-LABEL: define nofpclass(nan) float @returned_extractvalue
+; CHECK-SAME: ([4 x float] nofpclass(nan) [[ARRAY:%.*]]) #[[ATTR2]] {
+; CHECK-NEXT:    [[EXTRACT:%.*]] = extractvalue [4 x float] [[ARRAY]], 0
+; CHECK-NEXT:    ret float [[EXTRACT]]
+;
+  %extract = extractvalue [4 x float] %array, 0
+  ret float %extract
+}
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4502,6 +4502,29 @@
 
     break;
   }
+  case Instruction::ExtractElement: {
+    // Look through extract element. If the index is non-constant or
+    // out-of-range demand all elements, otherwise just the extracted element.
+    const Value *Vec = Op->getOperand(0);
+    const Value *Idx = Op->getOperand(1);
+    auto *CIdx = dyn_cast<ConstantInt>(Idx);
+
+    if (auto *VecTy = dyn_cast<FixedVectorType>(Vec->getType())) {
+      unsigned NumElts = VecTy->getNumElements();
+      APInt DemandedVecElts = APInt::getAllOnes(NumElts);
+      if (CIdx && CIdx->getValue().ult(NumElts))
+        DemandedVecElts = APInt::getOneBitSet(NumElts, CIdx->getZExtValue());
+      return computeKnownFPClass(Vec, DemandedVecElts, InterestedClasses, Known,
+                                 Depth + 1, Q, TLI);
+    }
+
+    break;
+  }
+  case Instruction::ExtractValue: {
+    computeKnownFPClass(Op->getOperand(0), DemandedElts, InterestedClasses,
+                        Known, Depth + 1, Q, TLI);
+    break;
+  }
   default:
     break;
   }


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