[llvm-branch-commits] [llvm] AMDGPU: Fold bitcasts into readfirstlane, readlane, and permlane64 (PR #128494)
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Mon Feb 24 03:12:11 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-amdgpu
Author: Matt Arsenault (arsenm)
<details>
<summary>Changes</summary>
We should handle this for all the handled readlane and dpp ops.
---
Full diff: https://github.com/llvm/llvm-project/pull/128494.diff
3 Files Affected:
- (modified) llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp (+16)
- (modified) llvm/test/Transforms/InstCombine/AMDGPU/bitcast-fold-lane-ops.ll (+25-27)
- (modified) llvm/test/Transforms/InstCombine/AMDGPU/permlane64.ll (+3-3)
``````````diff
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
index bac3bb5fde7b0..1f56b0bfc86dc 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
@@ -1128,9 +1128,25 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
simplifyDemandedLaneMaskArg(IC, II, 1))
return &II;
+ // readfirstlane.ty0 (bitcast ty1 x to ty0) -> bitcast (readfirstlane.ty1)
+ if (auto *BC = dyn_cast<BitCastInst>(Src); BC && BC->hasOneUse()) {
+ Value *BCSrc = BC->getOperand(0);
+
+ // TODO: Handle this for update_dpp, mov_ddp8, and all permlane variants.
+ if (isTypeLegal(BCSrc->getType())) {
+ SmallVector<Value *, 2> Args(II.args());
+ Args[0] = BCSrc;
+ CallInst *NewCall = IC.Builder.CreateIntrinsic(
+ II.getIntrinsicID(), {BCSrc->getType()}, Args);
+ NewCall->takeName(&II);
+ return new BitCastInst(NewCall, II.getType());
+ }
+ }
+
return std::nullopt;
}
case Intrinsic::amdgcn_writelane: {
+ // TODO: Fold bitcast like readlane.
if (simplifyDemandedLaneMaskArg(IC, II, 1))
return &II;
return std::nullopt;
diff --git a/llvm/test/Transforms/InstCombine/AMDGPU/bitcast-fold-lane-ops.ll b/llvm/test/Transforms/InstCombine/AMDGPU/bitcast-fold-lane-ops.ll
index 13347fd1a280e..6d6da3b5b8fb2 100644
--- a/llvm/test/Transforms/InstCombine/AMDGPU/bitcast-fold-lane-ops.ll
+++ b/llvm/test/Transforms/InstCombine/AMDGPU/bitcast-fold-lane-ops.ll
@@ -4,8 +4,8 @@
define i32 @test_bitcast_f32_to_i32_readfirstlane(float %val) {
; CHECK-LABEL: define i32 @test_bitcast_f32_to_i32_readfirstlane(
; CHECK-SAME: float [[VAL:%.*]]) #[[ATTR0:[0-9]+]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast float [[VAL]] to i32
-; CHECK-NEXT: [[RESULT:%.*]] = call i32 @llvm.amdgcn.readfirstlane.i32(i32 [[BITCAST]])
+; CHECK-NEXT: [[RESULT1:%.*]] = call float @llvm.amdgcn.readfirstlane.f32(float [[VAL]])
+; CHECK-NEXT: [[RESULT:%.*]] = bitcast float [[RESULT1]] to i32
; CHECK-NEXT: ret i32 [[RESULT]]
;
%bitcast = bitcast float %val to i32
@@ -16,9 +16,9 @@ define i32 @test_bitcast_f32_to_i32_readfirstlane(float %val) {
define i32 @test_bitcast_f32_to_i32_readfirstlane_multi_use_store(float %val, ptr %use.ptr) {
; CHECK-LABEL: define i32 @test_bitcast_f32_to_i32_readfirstlane_multi_use_store(
; CHECK-SAME: float [[VAL:%.*]], ptr [[USE_PTR:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast float [[VAL]] to i32
; CHECK-NEXT: store float [[VAL]], ptr [[USE_PTR]], align 4
-; CHECK-NEXT: [[TMP1:%.*]] = call i32 @llvm.amdgcn.readfirstlane.i32(i32 [[BITCAST]])
+; CHECK-NEXT: [[RESULT:%.*]] = call float @llvm.amdgcn.readfirstlane.f32(float [[VAL]])
+; CHECK-NEXT: [[TMP1:%.*]] = bitcast float [[RESULT]] to i32
; CHECK-NEXT: ret i32 [[TMP1]]
;
%bitcast = bitcast float %val to i32
@@ -46,9 +46,7 @@ define i32 @test_bitcast_f32_to_i32_readfirstlane_multi_use_call(float %val) {
define float @test_bitcast_f32_to_i32_readfirstlane_bitcast(float %val) {
; CHECK-LABEL: define float @test_bitcast_f32_to_i32_readfirstlane_bitcast(
; CHECK-SAME: float [[VAL:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast float [[VAL]] to i32
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @llvm.amdgcn.readfirstlane.i32(i32 [[BITCAST]])
-; CHECK-NEXT: [[RESULT:%.*]] = bitcast i32 [[CALL]] to float
+; CHECK-NEXT: [[RESULT:%.*]] = call float @llvm.amdgcn.readfirstlane.f32(float [[VAL]])
; CHECK-NEXT: ret float [[RESULT]]
;
%bitcast = bitcast float %val to i32
@@ -60,8 +58,8 @@ define float @test_bitcast_f32_to_i32_readfirstlane_bitcast(float %val) {
define i32 @test_bitcast_v2f16_to_i32_readfirstlane(<2 x half> %val) {
; CHECK-LABEL: define i32 @test_bitcast_v2f16_to_i32_readfirstlane(
; CHECK-SAME: <2 x half> [[VAL:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast <2 x half> [[VAL]] to i32
-; CHECK-NEXT: [[RESULT:%.*]] = call i32 @llvm.amdgcn.readfirstlane.i32(i32 [[BITCAST]])
+; CHECK-NEXT: [[RESULT1:%.*]] = call <2 x half> @llvm.amdgcn.readfirstlane.v2f16(<2 x half> [[VAL]])
+; CHECK-NEXT: [[RESULT:%.*]] = bitcast <2 x half> [[RESULT1]] to i32
; CHECK-NEXT: ret i32 [[RESULT]]
;
%bitcast = bitcast <2 x half> %val to i32
@@ -72,8 +70,8 @@ define i32 @test_bitcast_v2f16_to_i32_readfirstlane(<2 x half> %val) {
define i32 @test_bitcast_v2bf16_to_i32_readfirstlane(<2 x bfloat> %val) {
; CHECK-LABEL: define i32 @test_bitcast_v2bf16_to_i32_readfirstlane(
; CHECK-SAME: <2 x bfloat> [[VAL:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast <2 x bfloat> [[VAL]] to i32
-; CHECK-NEXT: [[RESULT:%.*]] = call i32 @llvm.amdgcn.readfirstlane.i32(i32 [[BITCAST]])
+; CHECK-NEXT: [[RESULT1:%.*]] = call <2 x bfloat> @llvm.amdgcn.readfirstlane.v2bf16(<2 x bfloat> [[VAL]])
+; CHECK-NEXT: [[RESULT:%.*]] = bitcast <2 x bfloat> [[RESULT1]] to i32
; CHECK-NEXT: ret i32 [[RESULT]]
;
%bitcast = bitcast <2 x bfloat> %val to i32
@@ -84,8 +82,8 @@ define i32 @test_bitcast_v2bf16_to_i32_readfirstlane(<2 x bfloat> %val) {
define i64 @test_bitcast_f64_to_i64_readfirstlane(double %val) {
; CHECK-LABEL: define i64 @test_bitcast_f64_to_i64_readfirstlane(
; CHECK-SAME: double [[VAL:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast double [[VAL]] to i64
-; CHECK-NEXT: [[RESULT:%.*]] = call i64 @llvm.amdgcn.readfirstlane.i64(i64 [[BITCAST]])
+; CHECK-NEXT: [[RESULT1:%.*]] = call double @llvm.amdgcn.readfirstlane.f64(double [[VAL]])
+; CHECK-NEXT: [[RESULT:%.*]] = bitcast double [[RESULT1]] to i64
; CHECK-NEXT: ret i64 [[RESULT]]
;
%bitcast = bitcast double %val to i64
@@ -96,8 +94,8 @@ define i64 @test_bitcast_f64_to_i64_readfirstlane(double %val) {
define <2 x i32> @test_bitcast_f64_to_v2i32_readfirstlane(double %val) {
; CHECK-LABEL: define <2 x i32> @test_bitcast_f64_to_v2i32_readfirstlane(
; CHECK-SAME: double [[VAL:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast double [[VAL]] to <2 x i32>
-; CHECK-NEXT: [[RESULT:%.*]] = call <2 x i32> @llvm.amdgcn.readfirstlane.v2i32(<2 x i32> [[BITCAST]])
+; CHECK-NEXT: [[RESULT1:%.*]] = call double @llvm.amdgcn.readfirstlane.f64(double [[VAL]])
+; CHECK-NEXT: [[RESULT:%.*]] = bitcast double [[RESULT1]] to <2 x i32>
; CHECK-NEXT: ret <2 x i32> [[RESULT]]
;
%bitcast = bitcast double %val to <2 x i32>
@@ -108,8 +106,8 @@ define <2 x i32> @test_bitcast_f64_to_v2i32_readfirstlane(double %val) {
define i64 @test_bitcast_v4i16_to_i64_readfirstlane(<4 x i16> %val) {
; CHECK-LABEL: define i64 @test_bitcast_v4i16_to_i64_readfirstlane(
; CHECK-SAME: <4 x i16> [[VAL:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast <4 x i16> [[VAL]] to i64
-; CHECK-NEXT: [[RESULT:%.*]] = call i64 @llvm.amdgcn.readfirstlane.i64(i64 [[BITCAST]])
+; CHECK-NEXT: [[RESULT1:%.*]] = call <4 x i16> @llvm.amdgcn.readfirstlane.v4i16(<4 x i16> [[VAL]])
+; CHECK-NEXT: [[RESULT:%.*]] = bitcast <4 x i16> [[RESULT1]] to i64
; CHECK-NEXT: ret i64 [[RESULT]]
;
%bitcast = bitcast <4 x i16> %val to i64
@@ -145,8 +143,8 @@ define i32 @test_bitcast_v8i4_to_i32_readfirstlane(<8 x i4> %val) {
define float @test_bitcast_i32_to_f32_readfirstlane(i32 %val) {
; CHECK-LABEL: define float @test_bitcast_i32_to_f32_readfirstlane(
; CHECK-SAME: i32 [[VAL:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast i32 [[VAL]] to float
-; CHECK-NEXT: [[RESULT:%.*]] = call float @llvm.amdgcn.readfirstlane.f32(float [[BITCAST]])
+; CHECK-NEXT: [[RESULT1:%.*]] = call i32 @llvm.amdgcn.readfirstlane.i32(i32 [[VAL]])
+; CHECK-NEXT: [[RESULT:%.*]] = bitcast i32 [[RESULT1]] to float
; CHECK-NEXT: ret float [[RESULT]]
;
%bitcast = bitcast i32 %val to float
@@ -157,8 +155,8 @@ define float @test_bitcast_i32_to_f32_readfirstlane(i32 %val) {
define i16 @test_bitcast_f16_to_i16_readfirstlane(half %val) {
; CHECK-LABEL: define i16 @test_bitcast_f16_to_i16_readfirstlane(
; CHECK-SAME: half [[VAL:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast half [[VAL]] to i16
-; CHECK-NEXT: [[RESULT:%.*]] = call i16 @llvm.amdgcn.readfirstlane.i16(i16 [[BITCAST]])
+; CHECK-NEXT: [[RESULT1:%.*]] = call half @llvm.amdgcn.readfirstlane.f16(half [[VAL]])
+; CHECK-NEXT: [[RESULT:%.*]] = bitcast half [[RESULT1]] to i16
; CHECK-NEXT: ret i16 [[RESULT]]
;
%bitcast = bitcast half %val to i16
@@ -181,8 +179,8 @@ define i16 @test_bitcast_v2i8_to_i16_readfirstlane(<2 x i8> %val) {
define <16 x i32> @test_bitcast_v16f32_to_v16i32_readfirstlane(<16 x float> %val) {
; CHECK-LABEL: define <16 x i32> @test_bitcast_v16f32_to_v16i32_readfirstlane(
; CHECK-SAME: <16 x float> [[VAL:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast <16 x float> [[VAL]] to <16 x i32>
-; CHECK-NEXT: [[TMP1:%.*]] = call <16 x i32> @llvm.amdgcn.readfirstlane.v16i32(<16 x i32> [[BITCAST]])
+; CHECK-NEXT: [[RESULT:%.*]] = call <16 x float> @llvm.amdgcn.readfirstlane.v16f32(<16 x float> [[VAL]])
+; CHECK-NEXT: [[TMP1:%.*]] = bitcast <16 x float> [[RESULT]] to <16 x i32>
; CHECK-NEXT: ret <16 x i32> [[TMP1]]
;
%bitcast = bitcast <16 x float> %val to <16 x i32>
@@ -193,8 +191,8 @@ define <16 x i32> @test_bitcast_v16f32_to_v16i32_readfirstlane(<16 x float> %val
define <8 x i64> @test_bitcast_v16f32_to_v8i64_readfirstlane(<16 x float> %val) {
; CHECK-LABEL: define <8 x i64> @test_bitcast_v16f32_to_v8i64_readfirstlane(
; CHECK-SAME: <16 x float> [[VAL:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast <16 x float> [[VAL]] to <8 x i64>
-; CHECK-NEXT: [[TMP1:%.*]] = call <8 x i64> @llvm.amdgcn.readfirstlane.v8i64(<8 x i64> [[BITCAST]])
+; CHECK-NEXT: [[RESULT:%.*]] = call <16 x float> @llvm.amdgcn.readfirstlane.v16f32(<16 x float> [[VAL]])
+; CHECK-NEXT: [[TMP1:%.*]] = bitcast <16 x float> [[RESULT]] to <8 x i64>
; CHECK-NEXT: ret <8 x i64> [[TMP1]]
;
%bitcast = bitcast <16 x float> %val to <8 x i64>
@@ -205,8 +203,8 @@ define <8 x i64> @test_bitcast_v16f32_to_v8i64_readfirstlane(<16 x float> %val)
define i32 @test_bitcast_f32_to_i32_readlane(float %val, i32 inreg %lane.index) {
; CHECK-LABEL: define i32 @test_bitcast_f32_to_i32_readlane(
; CHECK-SAME: float [[VAL:%.*]], i32 inreg [[LANE_INDEX:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast float [[VAL]] to i32
-; CHECK-NEXT: [[RESULT:%.*]] = call i32 @llvm.amdgcn.readlane.i32(i32 [[BITCAST]], i32 [[LANE_INDEX]])
+; CHECK-NEXT: [[RESULT1:%.*]] = call float @llvm.amdgcn.readlane.f32(float [[VAL]], i32 [[LANE_INDEX]])
+; CHECK-NEXT: [[RESULT:%.*]] = bitcast float [[RESULT1]] to i32
; CHECK-NEXT: ret i32 [[RESULT]]
;
%bitcast = bitcast float %val to i32
diff --git a/llvm/test/Transforms/InstCombine/AMDGPU/permlane64.ll b/llvm/test/Transforms/InstCombine/AMDGPU/permlane64.ll
index 5eaab6107192e..88d98b21c0f7d 100644
--- a/llvm/test/Transforms/InstCombine/AMDGPU/permlane64.ll
+++ b/llvm/test/Transforms/InstCombine/AMDGPU/permlane64.ll
@@ -12,9 +12,9 @@ define i32 @test_constant() {
define i32 @test_bitcast_f32_to_i32_permlane64(float %val) {
; CHECK-LABEL: @test_bitcast_f32_to_i32_permlane64(
-; CHECK-NEXT: [[BITCAST:%.*]] = bitcast float [[VAL:%.*]] to i32
-; CHECK-NEXT: [[RESULT:%.*]] = call i32 @llvm.amdgcn.permlane64.i32(i32 [[BITCAST]])
-; CHECK-NEXT: ret i32 [[RESULT]]
+; CHECK-NEXT: [[VAL:%.*]] = call float @llvm.amdgcn.permlane64.f32(float [[VAL1:%.*]])
+; CHECK-NEXT: [[BITCAST:%.*]] = bitcast float [[VAL]] to i32
+; CHECK-NEXT: ret i32 [[BITCAST]]
;
%bitcast = bitcast float %val to i32
%result = call i32 @llvm.amdgcn.permlane64.i32(i32 %bitcast)
``````````
</details>
https://github.com/llvm/llvm-project/pull/128494
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