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[Scalarizer] Propagate IR flags 

Summary:
The motivation for this was to propagate fast-math flags like nnan and
ninf on vector floating point operations to the corresponding scalar
operations to take advantage of follow-on optimizations. But I think
the same argument applies to all of our IR flags: if they apply to the
vector operation then they also apply to all the individual scalar
operations, and they might enable follow-on optimizations.

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63593

llvm-svn: 364051
This commit is contained in:
Jay Foad 2019-06-21 14:10:18 +00:00
parent 5b4cc84b87
commit d9d3c91b48
2 changed files with 59 additions and 4 deletions
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10
llvm/lib/Transforms/Scalar/Scalarizer.cpp
View File

@ -200,7 +200,7 @@ private:
Scatterer scatter(Instruction *Point, Value *V);
void gather(Instruction *Op, const ValueVector &CV);
bool canTransferMetadata(unsigned Kind);
void transferMetadata(Instruction *Op, const ValueVector &CV);
void transferMetadataAndIRFlags(Instruction *Op, const ValueVector &CV);
bool getVectorLayout(Type *Ty, unsigned Alignment, VectorLayout &Layout,
const DataLayout &DL);
bool finish();
@ -361,7 +361,7 @@ void ScalarizerVisitor::gather(Instruction *Op, const ValueVector &CV) {
for (unsigned I = 0, E = Op->getNumOperands(); I != E; ++I)
Op->setOperand(I, UndefValue::get(Op->getOperand(I)->getType()));
transferMetadata(Op, CV);
transferMetadataAndIRFlags(Op, CV);
// If we already have a scattered form of Op (created from ExtractElements
// of Op itself), replace them with the new form.
@ -397,7 +397,8 @@ bool ScalarizerVisitor::canTransferMetadata(unsigned Tag) {
// Transfer metadata from Op to the instructions in CV if it is known
// to be safe to do so.
void ScalarizerVisitor::transferMetadata(Instruction *Op, const ValueVector &CV) {
void ScalarizerVisitor::transferMetadataAndIRFlags(Instruction *Op,
const ValueVector &CV) {
SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
Op->getAllMetadataOtherThanDebugLoc(MDs);
for (unsigned I = 0, E = CV.size(); I != E; ++I) {
@ -405,6 +406,7 @@ void ScalarizerVisitor::transferMetadata(Instruction *Op, const ValueVector &CV)
for (const auto &MD : MDs)
if (canTransferMetadata(MD.first))
New->setMetadata(MD.first, MD.second);
New->copyIRFlags(Op);
if (Op->getDebugLoc() && !New->getDebugLoc())
New->setDebugLoc(Op->getDebugLoc());
}
@ -809,7 +811,7 @@ bool ScalarizerVisitor::visitStoreInst(StoreInst &SI) {
unsigned Align = Layout.getElemAlign(I);
Stores[I] = Builder.CreateAlignedStore(Val[I], Ptr[I], Align);
}
transferMetadata(&SI, Stores);
transferMetadataAndIRFlags(&SI, Stores);
return true;
}

53
llvm/test/Transforms/Scalarizer/basic.ll
View File

@ -506,6 +506,59 @@ exit:
ret void
}
; Check that IR flags are preserved.
define <2 x i32> @f16(<2 x i32> %i, <2 x i32> %j) {
; CHECK-LABEL: @f16(
; CHECK: %res.i0 = add nuw nsw i32
; CHECK: %res.i1 = add nuw nsw i32
%res = add nuw nsw <2 x i32> %i, %j
ret <2 x i32> %res
}
define <2 x i32> @f17(<2 x i32> %i, <2 x i32> %j) {
; CHECK-LABEL: @f17(
; CHECK: %res.i0 = sdiv exact i32
; CHECK: %res.i1 = sdiv exact i32
%res = sdiv exact <2 x i32> %i, %j
ret <2 x i32> %res
}
define <2 x float> @f18(<2 x float> %x, <2 x float> %y) {
; CHECK-LABEL: @f18(
; CHECK: %res.i0 = fadd fast float
; CHECK: %res.i1 = fadd fast float
%res = fadd fast <2 x float> %x, %y
ret <2 x float> %res
}
define <2 x float> @f19(<2 x float> %x) {
; CHECK-LABEL: @f19(
; CHECK: %res.i0 = fneg fast float
; CHECK: %res.i1 = fneg fast float
%res = fneg fast <2 x float> %x
ret <2 x float> %res
}
define <2 x i1> @f20(<2 x float> %x, <2 x float> %y) {
; CHECK-LABEL: @f20(
; CHECK: %res.i0 = fcmp fast ogt float
; CHECK: %res.i1 = fcmp fast ogt float
%res = fcmp fast ogt <2 x float> %x, %y
ret <2 x i1> %res
}
declare <2 x float> @llvm.sqrt.v2f32(<2 x float>)
define <2 x float> @f21(<2 x float> %x) {
; CHECK-LABEL: @f21(
; CHECK: %res.i0 = call fast float @llvm.sqrt.f32
; CHECK: %res.i1 = call fast float @llvm.sqrt.f32
%res = call fast <2 x float> @llvm.sqrt.v2f32(<2 x float> %x)
ret <2 x float> %res
}
declare <2 x float> @llvm.fma.v2f32(<2 x float>, <2 x float>, <2 x float>)
define <2 x float> @f22(<2 x float> %x, <2 x float> %y, <2 x float> %z) {
; CHECK-LABEL: @f22(
; CHECK: %res.i0 = call fast float @llvm.fma.f32
; CHECK: %res.i1 = call fast float @llvm.fma.f32
%res = call fast <2 x float> @llvm.fma.v2f32(<2 x float> %x, <2 x float> %y, <2 x float> %z)
ret <2 x float> %res
}
!0 = !{ !"root" }
!1 = !{ !"set1", !0 }
!2 = !{ !"set2", !0 }