[llvm] AMDGPU: Reduce intrinsics for single demanded vector element (PR #141810)
Maksim Levental via llvm-commits
llvm-commits at lists.llvm.org
Wed May 28 10:41:35 PDT 2025
https://github.com/makslevental created https://github.com/llvm/llvm-project/pull/141810
Fixes https://github.com/llvm/llvm-project/issues/131734
- [x] `readlane`
- [ ] `update_dpp`
- [ ] `permlane16`
- [ ] `permlanex16`
- [ ] `permlane64`
- [ ] `mov_dpp8`
>From ffae977fc6460e02483421ff15f5c33bb43cdd26 Mon Sep 17 00:00:00 2001
From: Maksim Levental <maksim.levental at gmail.com>
Date: Wed, 28 May 2025 13:39:28 -0400
Subject: [PATCH] AMDGPU: Reduce readlane for single demanded vector element
---
.../AMDGPU/AMDGPUInstCombineIntrinsic.cpp | 23 ++++++----
...fy-demanded-vector-elts-lane-intrinsics.ll | 42 +++++++++++++++----
2 files changed, 47 insertions(+), 18 deletions(-)
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
index 5f6ab24182d5e..565064657b64f 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
@@ -635,7 +635,8 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
break;
auto IID = SrcCI->getIntrinsicID();
- // llvm.amdgcn.rcp(llvm.amdgcn.sqrt(x)) -> llvm.amdgcn.rsq(x) if contractable
+ // llvm.amdgcn.rcp(llvm.amdgcn.sqrt(x)) -> llvm.amdgcn.rsq(x) if
+ // contractable
//
// llvm.amdgcn.rcp(llvm.sqrt(x)) -> llvm.amdgcn.rsq(x) if contractable and
// relaxed.
@@ -845,13 +846,13 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
break;
}
case Intrinsic::amdgcn_cvt_off_f32_i4: {
- Value* Arg = II.getArgOperand(0);
+ Value *Arg = II.getArgOperand(0);
Type *Ty = II.getType();
if (isa<PoisonValue>(Arg))
return IC.replaceInstUsesWith(II, PoisonValue::get(Ty));
- if(IC.getSimplifyQuery().isUndefValue(Arg))
+ if (IC.getSimplifyQuery().isUndefValue(Arg))
return IC.replaceInstUsesWith(II, Constant::getNullValue(Ty));
ConstantInt *CArg = dyn_cast<ConstantInt>(II.getArgOperand(0));
@@ -1629,7 +1630,7 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
}
}
if (const AMDGPU::ImageDimIntrinsicInfo *ImageDimIntr =
- AMDGPU::getImageDimIntrinsicInfo(II.getIntrinsicID())) {
+ AMDGPU::getImageDimIntrinsicInfo(II.getIntrinsicID())) {
return simplifyAMDGCNImageIntrinsic(ST, ImageDimIntr, II, IC);
}
return std::nullopt;
@@ -1637,10 +1638,10 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
/// Implement SimplifyDemandedVectorElts for amdgcn buffer and image intrinsics.
///
-/// The result of simplifying amdgcn image and buffer store intrinsics is updating
-/// definitions of the intrinsics vector argument, not Uses of the result like
-/// image and buffer loads.
-/// Note: This only supports non-TFE/LWE image intrinsic calls; those have
+/// The result of simplifying amdgcn image and buffer store intrinsics is
+/// updating definitions of the intrinsics vector argument, not Uses of the
+/// result like image and buffer loads. Note: This only supports non-TFE/LWE
+/// image intrinsic calls; those have
/// struct returns.
static Value *simplifyAMDGCNMemoryIntrinsicDemanded(InstCombiner &IC,
IntrinsicInst &II,
@@ -1837,7 +1838,10 @@ Value *GCNTTIImpl::simplifyAMDGCNLaneIntrinsicDemanded(
Value *Extract = IC.Builder.CreateExtractElement(Src, FirstElt);
// TODO: Preserve callsite attributes?
- CallInst *NewCall = IC.Builder.CreateCall(Remangled, {Extract}, OpBundles);
+ SmallVector<Value *> Args{Extract};
+ if (II.arg_size() > 1)
+ Args.push_back(II.getArgOperand(1));
+ CallInst *NewCall = IC.Builder.CreateCall(Remangled, Args, OpBundles);
return IC.Builder.CreateInsertElement(PoisonValue::get(II.getType()),
NewCall, FirstElt);
@@ -1872,6 +1876,7 @@ std::optional<Value *> GCNTTIImpl::simplifyDemandedVectorEltsIntrinsic(
SimplifyAndSetOp) const {
switch (II.getIntrinsicID()) {
case Intrinsic::amdgcn_readfirstlane:
+ case Intrinsic::amdgcn_readlane:
SimplifyAndSetOp(&II, 0, DemandedElts, UndefElts);
return simplifyAMDGCNLaneIntrinsicDemanded(IC, II, DemandedElts, UndefElts);
case Intrinsic::amdgcn_raw_buffer_load:
diff --git a/llvm/test/Transforms/InstCombine/AMDGPU/simplify-demanded-vector-elts-lane-intrinsics.ll b/llvm/test/Transforms/InstCombine/AMDGPU/simplify-demanded-vector-elts-lane-intrinsics.ll
index 056caabb6d60a..5f2686d2f3909 100644
--- a/llvm/test/Transforms/InstCombine/AMDGPU/simplify-demanded-vector-elts-lane-intrinsics.ll
+++ b/llvm/test/Transforms/InstCombine/AMDGPU/simplify-demanded-vector-elts-lane-intrinsics.ll
@@ -13,16 +13,40 @@ define i16 @extract_elt0_v2i16_readfirstlane(<2 x i16> %src) {
ret i16 %elt
}
-define i16 @extract_elt0_v1i16_readfirstlane(<1 x i16> %src) {
-; CHECK-LABEL: define i16 @extract_elt0_v1i16_readfirstlane(
-; CHECK-SAME: <1 x i16> [[SRC:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[TMP1:%.*]] = extractelement <1 x i16> [[SRC]], i64 0
-; CHECK-NEXT: [[ELT:%.*]] = call i16 @llvm.amdgcn.readfirstlane.i16(i16 [[TMP1]])
-; CHECK-NEXT: ret i16 [[ELT]]
+define half @extract_elt0_v2f16_readlane_imm_0(<2 x half> %src) {
+; CHECK-LABEL: define half @extract_elt0_v2f16_readlane_imm_0(
+; CHECK-SAME: <2 x half> [[SRC:%.*]]) #[[ATTR0]] {
+; CHECK-NEXT: [[TMP1:%.*]] = extractelement <2 x half> [[SRC]], i64 0
+; CHECK-NEXT: [[TMP2:%.*]] = call half @llvm.amdgcn.readlane.f16(half [[TMP1]], i32 0)
+; CHECK-NEXT: ret half [[TMP2]]
;
- %vec = call <1 x i16> @llvm.amdgcn.readfirstlane.v1i16(<1 x i16> %src)
- %elt = extractelement <1 x i16> %vec, i32 0
- ret i16 %elt
+ %x = call <2 x half> @llvm.amdgcn.readlane.v2f16(<2 x half> %src, i32 0)
+ %elt = extractelement <2 x half> %x, i32 0
+ ret half %elt
+}
+
+define half @extract_elt0_v2f16_readlane_imm_1(<2 x half> %src) {
+; CHECK-LABEL: define half @extract_elt0_v2f16_readlane_imm_1(
+; CHECK-SAME: <2 x half> [[SRC:%.*]]) #[[ATTR0]] {
+; CHECK-NEXT: [[TMP1:%.*]] = extractelement <2 x half> [[SRC]], i64 1
+; CHECK-NEXT: [[TMP2:%.*]] = call half @llvm.amdgcn.readlane.f16(half [[TMP1]], i32 1)
+; CHECK-NEXT: ret half [[TMP2]]
+;
+ %x = call <2 x half> @llvm.amdgcn.readlane.v2f16(<2 x half> %src, i32 1)
+ %elt = extractelement <2 x half> %x, i32 1
+ ret half %elt
+}
+
+define half @extract_elt0_v2f16_readlane(<2 x half> %src, i32 %idx) {
+; CHECK-LABEL: define half @extract_elt0_v2f16_readlane(
+; CHECK-SAME: <2 x half> [[SRC:%.*]], i32 [[IDX:%.*]]) #[[ATTR0]] {
+; CHECK-NEXT: [[X:%.*]] = call <2 x half> @llvm.amdgcn.readlane.v2f16(<2 x half> [[SRC]], i32 [[IDX]])
+; CHECK-NEXT: [[ELT:%.*]] = extractelement <2 x half> [[X]], i32 [[IDX]]
+; CHECK-NEXT: ret half [[ELT]]
+;
+ %x = call <2 x half> @llvm.amdgcn.readlane.v2f16(<2 x half> %src, i32 %idx)
+ %elt = extractelement <2 x half> %x, i32 %idx
+ ret half %elt
}
define i16 @extract_elt1_v2i16_readfirstlane(<2 x i16> %src) {
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