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[InstCombine] simplify masked scatter/gather intrinsics with zero masks

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A masked scatter with a zero mask means there's no store.
A masked gather with a zero mask means the passthru arg is returned.

This is a continuation of:
http://reviews.llvm.org/rL259369
http://reviews.llvm.org/rL259392

llvm-svn: 259421
This commit is contained in:
Sanjay Patel 2016-02-01 22:10:26 +00:00
parent f6407af598
commit 14ae72b119
2 changed files with 42 additions and 7 deletions
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26
lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -792,6 +792,24 @@ static Instruction *simplifyMaskedStore(IntrinsicInst &II, InstCombiner &IC) {
return nullptr;
}
static Instruction *simplifyMaskedGather(IntrinsicInst &II, InstCombiner &IC) {
// If the mask is all zeros, return the "passthru" argument of the gather.
auto *ConstMask = dyn_cast<Constant>(II.getArgOperand(2));
if (ConstMask && ConstMask->isNullValue())
return IC.ReplaceInstUsesWith(II, II.getArgOperand(3));
return nullptr;
}
static Instruction *simplifyMaskedScatter(IntrinsicInst &II, InstCombiner &IC) {
// If the mask is all zeros, a scatter does nothing.
auto *ConstMask = dyn_cast<Constant>(II.getArgOperand(3));
if (ConstMask && ConstMask->isNullValue())
return IC.EraseInstFromFunction(II);
return nullptr;
}
/// CallInst simplification. This mostly only handles folding of intrinsic
/// instructions. For normal calls, it allows visitCallSite to do the heavy
/// lifting.
@ -922,10 +940,10 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
break;
case Intrinsic::masked_store:
return simplifyMaskedStore(*II, *this);
// TODO: Handle the other masked ops.
// case Intrinsic::masked_gather:
// case Intrinsic::masked_scatter:
case Intrinsic::masked_gather:
return simplifyMaskedGather(*II, *this);
case Intrinsic::masked_scatter:
return simplifyMaskedScatter(*II, *this);
case Intrinsic::powi:
if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getArgOperand(1))) {

23
test/Transforms/InstCombine/masked_intrinsics.ll
View File

@ -2,7 +2,8 @@
declare <2 x double> @llvm.masked.load.v2f64(<2 x double>* %ptrs, i32, <2 x i1> %mask, <2 x double> %src0)
declare void @llvm.masked.store.v2f64(<2 x double> %val, <2 x double>* %ptrs, i32, <2 x i1> %mask)
declare <2 x double> @llvm.masked.gather.v2f64(<2 x double*> %ptrs, i32, <2 x i1> %mask, <2 x double> %passthru)
declare void @llvm.masked.scatter.v2f64(<2 x double> %val, <2 x double*> %ptrs, i32, <2 x i1> %mask)
define <2 x double> @load_zeromask(<2 x double>* %ptr, <2 x double> %passthru) {
%res = call <2 x double> @llvm.masked.load.v2f64(<2 x double>* %ptr, i32 1, <2 x i1> zeroinitializer, <2 x double> %passthru)
@ -26,7 +27,7 @@ define void @store_zeromask(<2 x double>* %ptr, <2 x double> %val) {
ret void
; CHECK-LABEL: @store_zeromask(
; CHECK-NEXT: ret void
; CHECK-NEXT: ret void
}
define void @store_onemask(<2 x double>* %ptr, <2 x double> %val) {
@ -35,6 +36,22 @@ define void @store_onemask(<2 x double>* %ptr, <2 x double> %val) {
; CHECK-LABEL: @store_onemask(
; CHECK-NEXT: store <2 x double> %val, <2 x double>* %ptr, align 4
; CHECK-NEXT: ret void
; CHECK-NEXT: ret void
}
define <2 x double> @gather_zeromask(<2 x double*> %ptrs, <2 x double> %passthru) {
%res = call <2 x double> @llvm.masked.gather.v2f64(<2 x double*> %ptrs, i32 5, <2 x i1> zeroinitializer, <2 x double> %passthru)
ret <2 x double> %res
; CHECK-LABEL: @gather_zeromask(
; CHECK-NEXT: ret <2 x double> %passthru
}
define void @scatter_zeromask(<2 x double*> %ptrs, <2 x double> %val) {
call void @llvm.masked.scatter.v2f64(<2 x double> %val, <2 x double*> %ptrs, i32 6, <2 x i1> zeroinitializer)
ret void
; CHECK-LABEL: @scatter_zeromask(
; CHECK-NEXT: ret void
}