[llvm-branch-commits] [llvm] [AMDGPU][InstCombine] Canonicalize dot constant operands (PR #225083)

via llvm-branch-commits Mon, 21 Sep 2026 06:33:22 -0700

llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Harrison Hao (harrisonGPU)

<details>
<summary>Changes</summary>

Move constant dot product source operands to the right hand side
and add tests for signed and unsigned dot intrinsics.

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---
Full diff: https://github.com/llvm/llvm-project/pull/225083.diff


2 Files Affected:

- (modified) llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp (+9) 
- (modified) llvm/test/Transforms/InstCombine/AMDGPU/llvm.amdgcn.dot.ll 
(+12-12) 


``````````diff
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp 
b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
index dcbdde6ccbdfa..f6c08bdc58d3d 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
@@ -1974,6 +1974,15 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, 
IntrinsicInst &II) const {
   case Intrinsic::amdgcn_udot4:
   case Intrinsic::amdgcn_sdot8:
   case Intrinsic::amdgcn_udot8: {
+    Value *Src0 = II.getArgOperand(0);
+    Value *Src1 = II.getArgOperand(1);
+
+    if (isa<Constant>(Src0) && !isa<Constant>(Src1)) {
+      II.setArgOperand(0, Src1);
+      II.setArgOperand(1, Src0);
+      return &II;
+    }
+
     if (!match(II.getArgOperand(3), m_Zero()) || !II.hasOneUse())
       break;
 
diff --git a/llvm/test/Transforms/InstCombine/AMDGPU/llvm.amdgcn.dot.ll 
b/llvm/test/Transforms/InstCombine/AMDGPU/llvm.amdgcn.dot.ll
index 09bebfb29fdf0..d73048239288d 100644
--- a/llvm/test/Transforms/InstCombine/AMDGPU/llvm.amdgcn.dot.ll
+++ b/llvm/test/Transforms/InstCombine/AMDGPU/llvm.amdgcn.dot.ll
@@ -26,7 +26,7 @@ define i32 @sdot2_sub(<2 x i16> %a, <2 x i16> %b) {
 define i32 @sdot2_a_zero(<2 x i16> %b) {
 ; CHECK-LABEL: define i32 @sdot2_a_zero(
 ; CHECK-SAME: <2 x i16> [[B:%.*]]) {
-; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.sdot2(<2 x i16> 
zeroinitializer, <2 x i16> [[B]], i32 16, i1 false)
+; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.sdot2(<2 x i16> [[B]], <2 x 
i16> zeroinitializer, i32 16, i1 false)
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %dot = call i32 @llvm.amdgcn.sdot2(<2 x i16> zeroinitializer, <2 x i16> %b, 
i32 7, i1 false)
@@ -37,7 +37,7 @@ define i32 @sdot2_a_zero(<2 x i16> %b) {
 define i32 @sdot2_const_lhs(<2 x i16> %b, i32 %acc) {
 ; CHECK-LABEL: define i32 @sdot2_const_lhs(
 ; CHECK-SAME: <2 x i16> [[B:%.*]], i32 [[ACC:%.*]]) {
-; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.sdot2(<2 x i16> 
zeroinitializer, <2 x i16> [[B]], i32 [[ACC]], i1 false)
+; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.sdot2(<2 x i16> [[B]], <2 
x i16> zeroinitializer, i32 [[ACC]], i1 false)
 ; CHECK-NEXT:    ret i32 [[DOT]]
 ;
   %dot = call i32 @llvm.amdgcn.sdot2(<2 x i16> zeroinitializer, <2 x i16> %b, 
i32 %acc, i1 false)
@@ -129,7 +129,7 @@ define i32 @udot2_sub(<2 x i16> %a, <2 x i16> %b) {
 define i32 @udot2_a_zero(<2 x i16> %b) {
 ; CHECK-LABEL: define i32 @udot2_a_zero(
 ; CHECK-SAME: <2 x i16> [[B:%.*]]) {
-; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.udot2(<2 x i16> 
zeroinitializer, <2 x i16> [[B]], i32 16, i1 false)
+; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.udot2(<2 x i16> [[B]], <2 x 
i16> zeroinitializer, i32 16, i1 false)
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %dot = call i32 @llvm.amdgcn.udot2(<2 x i16> zeroinitializer, <2 x i16> %b, 
i32 7, i1 false)
@@ -140,7 +140,7 @@ define i32 @udot2_a_zero(<2 x i16> %b) {
 define i32 @udot2_const_lhs(<2 x i16> %b, i32 %acc) {
 ; CHECK-LABEL: define i32 @udot2_const_lhs(
 ; CHECK-SAME: <2 x i16> [[B:%.*]], i32 [[ACC:%.*]]) {
-; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.udot2(<2 x i16> 
zeroinitializer, <2 x i16> [[B]], i32 [[ACC]], i1 false)
+; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.udot2(<2 x i16> [[B]], <2 
x i16> zeroinitializer, i32 [[ACC]], i1 false)
 ; CHECK-NEXT:    ret i32 [[DOT]]
 ;
   %dot = call i32 @llvm.amdgcn.udot2(<2 x i16> zeroinitializer, <2 x i16> %b, 
i32 %acc, i1 false)
@@ -217,7 +217,7 @@ define i32 @sdot4_sub(i32 %a, i32 %b) {
 define i32 @sdot4_a_zero(i32 %b) {
 ; CHECK-LABEL: define i32 @sdot4_a_zero(
 ; CHECK-SAME: i32 [[B:%.*]]) {
-; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.sdot4(i32 0, i32 [[B]], i32 
16, i1 false)
+; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.sdot4(i32 [[B]], i32 0, i32 
16, i1 false)
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %dot = call i32 @llvm.amdgcn.sdot4(i32 0, i32 %b, i32 7, i1 false)
@@ -228,7 +228,7 @@ define i32 @sdot4_a_zero(i32 %b) {
 define i32 @sdot4_const_lhs(i32 %b, i32 %acc) {
 ; CHECK-LABEL: define i32 @sdot4_const_lhs(
 ; CHECK-SAME: i32 [[B:%.*]], i32 [[ACC:%.*]]) {
-; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.sdot4(i32 16843009, i32 
[[B]], i32 [[ACC]], i1 false)
+; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.sdot4(i32 [[B]], i32 
16843009, i32 [[ACC]], i1 false)
 ; CHECK-NEXT:    ret i32 [[DOT]]
 ;
   %dot = call i32 @llvm.amdgcn.sdot4(i32 16843009, i32 %b, i32 %acc, i1 false)
@@ -367,7 +367,7 @@ define i32 @udot4_sub(i32 %a, i32 %b) {
 define i32 @udot4_a_zero(i32 %b) {
 ; CHECK-LABEL: define i32 @udot4_a_zero(
 ; CHECK-SAME: i32 [[B:%.*]]) {
-; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.udot4(i32 0, i32 [[B]], i32 
16, i1 false)
+; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.udot4(i32 [[B]], i32 0, i32 
16, i1 false)
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %dot = call i32 @llvm.amdgcn.udot4(i32 0, i32 %b, i32 7, i1 false)
@@ -378,7 +378,7 @@ define i32 @udot4_a_zero(i32 %b) {
 define i32 @udot4_const_lhs(i32 %b, i32 %acc) {
 ; CHECK-LABEL: define i32 @udot4_const_lhs(
 ; CHECK-SAME: i32 [[B:%.*]], i32 [[ACC:%.*]]) {
-; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.udot4(i32 6, i32 [[B]], 
i32 [[ACC]], i1 false)
+; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.udot4(i32 [[B]], i32 6, 
i32 [[ACC]], i1 false)
 ; CHECK-NEXT:    ret i32 [[DOT]]
 ;
   %dot = call i32 @llvm.amdgcn.udot4(i32 6, i32 %b, i32 %acc, i1 false)
@@ -444,7 +444,7 @@ define i32 @sdot8_sub(i32 %a, i32 %b) {
 define i32 @sdot8_a_zero(i32 %b) {
 ; CHECK-LABEL: define i32 @sdot8_a_zero(
 ; CHECK-SAME: i32 [[B:%.*]]) {
-; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.sdot8(i32 0, i32 [[B]], i32 
16, i1 false)
+; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.sdot8(i32 [[B]], i32 0, i32 
16, i1 false)
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %dot = call i32 @llvm.amdgcn.sdot8(i32 0, i32 %b, i32 7, i1 false)
@@ -455,7 +455,7 @@ define i32 @sdot8_a_zero(i32 %b) {
 define i32 @sdot8_const_lhs(i32 %b, i32 %acc) {
 ; CHECK-LABEL: define i32 @sdot8_const_lhs(
 ; CHECK-SAME: i32 [[B:%.*]], i32 [[ACC:%.*]]) {
-; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.sdot8(i32 16843009, i32 
[[B]], i32 [[ACC]], i1 false)
+; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.sdot8(i32 [[B]], i32 
16843009, i32 [[ACC]], i1 false)
 ; CHECK-NEXT:    ret i32 [[DOT]]
 ;
   %dot = call i32 @llvm.amdgcn.sdot8(i32 16843009, i32 %b, i32 %acc, i1 false)
@@ -521,7 +521,7 @@ define i32 @udot8_sub(i32 %a, i32 %b) {
 define i32 @udot8_a_zero(i32 %b) {
 ; CHECK-LABEL: define i32 @udot8_a_zero(
 ; CHECK-SAME: i32 [[B:%.*]]) {
-; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.udot8(i32 0, i32 [[B]], i32 
16, i1 false)
+; CHECK-NEXT:    [[R:%.*]] = call i32 @llvm.amdgcn.udot8(i32 [[B]], i32 0, i32 
16, i1 false)
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %dot = call i32 @llvm.amdgcn.udot8(i32 0, i32 %b, i32 7, i1 false)
@@ -532,7 +532,7 @@ define i32 @udot8_a_zero(i32 %b) {
 define i32 @udot8_const_lhs(i32 %b, i32 %acc) {
 ; CHECK-LABEL: define i32 @udot8_const_lhs(
 ; CHECK-SAME: i32 [[B:%.*]], i32 [[ACC:%.*]]) {
-; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.udot8(i32 0, i32 [[B]], 
i32 [[ACC]], i1 false)
+; CHECK-NEXT:    [[DOT:%.*]] = call i32 @llvm.amdgcn.udot8(i32 [[B]], i32 0, 
i32 [[ACC]], i1 false)
 ; CHECK-NEXT:    ret i32 [[DOT]]
 ;
   %dot = call i32 @llvm.amdgcn.udot8(i32 0, i32 %b, i32 %acc, i1 false)

``````````

</details>


https://github.com/llvm/llvm-project/pull/225083
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[llvm-branch-commits] [llvm] [AMDGPU][InstCombine] Canonicalize dot constant operands (PR #225083)

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