[Mlir-commits] [mlir] [mlir][llvm] Changes to support munsafe-atomics (PR #139801)

[Anchu Rajendran S]

https://github.com/anchuraj created https://github.com/llvm/llvm-project/pull/139801

None

>From 61923bd788da066624db490580c9ca63856515f5 Mon Sep 17 00:00:00 2001
From: Anchu Rajendran <asudhaku at amd.com>
Date: Mon, 5 May 2025 15:58:51 -0500
Subject: [PATCH] [mlir][llvm] Changes to support amdgpu unsafe floating point
 atomic operations

---
 mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td           | 1 +
 mlir/lib/Target/LLVMIR/ModuleImport.cpp               | 3 +++
 mlir/lib/Target/LLVMIR/ModuleTranslation.cpp          | 4 ++++
 mlir/test/Dialect/LLVMIR/func.mlir                    | 6 ++++++
 mlir/test/Target/LLVMIR/Import/function-attributes.ll | 6 ++++++
 mlir/test/Target/LLVMIR/llvmir.mlir                   | 9 +++++++++
 6 files changed, 29 insertions(+)

diff --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
index f19f9d5a3083c..93f754607fdac 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
@@ -1899,6 +1899,7 @@ def LLVM_LLVMFuncOp : LLVM_Op<"func", [
     OptionalAttr<BoolAttr>:$no_nans_fp_math,
     OptionalAttr<BoolAttr>:$approx_func_fp_math,
     OptionalAttr<BoolAttr>:$no_signed_zeros_fp_math,
+    OptionalAttr<BoolAttr>:$amdgpu_unsafe_fp_atomics,
     OptionalAttr<StrAttr>:$denormal_fp_math,
     OptionalAttr<StrAttr>:$denormal_fp_math_f32,
     OptionalAttr<StrAttr>:$fp_contract,
diff --git a/mlir/lib/Target/LLVMIR/ModuleImport.cpp b/mlir/lib/Target/LLVMIR/ModuleImport.cpp
index 0b77a3d23d392..930da645d96fc 100644
--- a/mlir/lib/Target/LLVMIR/ModuleImport.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleImport.cpp
@@ -2140,6 +2140,7 @@ static constexpr std::array kExplicitAttributes{
     StringLiteral("aarch64_pstate_sm_body"),
     StringLiteral("aarch64_pstate_sm_compatible"),
     StringLiteral("aarch64_pstate_sm_enabled"),
+    StringLiteral("amdgpu-unsafe-fp-atomics"),
     StringLiteral("alwaysinline"),
     StringLiteral("approx-func-fp-math"),
     StringLiteral("convergent"),
@@ -2256,6 +2257,8 @@ void ModuleImport::processFunctionAttributes(llvm::Function *func,
   else if (func->hasFnAttribute("aarch64_preserves_za"))
     funcOp.setArmPreservesZa(true);
 
+  if (func->hasFnAttribute("amdgpu-unsafe-fp-atomics"))
+    funcOp.setAmdgpuUnsafeFpAtomics(true);
   llvm::Attribute attr = func->getFnAttribute(llvm::Attribute::VScaleRange);
   if (attr.isValid()) {
     MLIRContext *context = funcOp.getContext();
diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index ad4f65da9d7f5..bf8d9f74318b3 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -1496,6 +1496,10 @@ LogicalResult ModuleTranslation::convertOneFunction(LLVMFuncOp func) {
   else if (func.getArmPreservesZa())
     llvmFunc->addFnAttr("aarch64_preserves_za");
 
+  if (auto amdgpuUnsafeFpAtomics = func.getAmdgpuUnsafeFpAtomics())
+    llvmFunc->addFnAttr("amdgpu-unsafe-fp-atomics",
+                        llvm::toStringRef(*amdgpuUnsafeFpAtomics));
+
   if (auto targetCpu = func.getTargetCpu())
     llvmFunc->addFnAttr("target-cpu", *targetCpu);
 
diff --git a/mlir/test/Dialect/LLVMIR/func.mlir b/mlir/test/Dialect/LLVMIR/func.mlir
index a168cebff019b..90a24b5f4a40e 100644
--- a/mlir/test/Dialect/LLVMIR/func.mlir
+++ b/mlir/test/Dialect/LLVMIR/func.mlir
@@ -236,6 +236,12 @@ module {
     llvm.return
   }
 
+  llvm.func @amdgpu_fp_unsafe_atomics() attributes {amdgpu_fp_unsafe_atomics = true} {
+    // CHECK: @amdgpu_fp_unsafe_atomics
+    // CHECK-SAME: attributes {amdgpu_fp_unsafe_atomics = true}
+    llvm.return
+  }
+
   // CHECK: llvm.comdat @__llvm_comdat
   llvm.comdat @__llvm_comdat {
     // CHECK: llvm.comdat_selector @any any
diff --git a/mlir/test/Target/LLVMIR/Import/function-attributes.ll b/mlir/test/Target/LLVMIR/Import/function-attributes.ll
index 0b13645853cea..e9f8b707b85a7 100644
--- a/mlir/test/Target/LLVMIR/Import/function-attributes.ll
+++ b/mlir/test/Target/LLVMIR/Import/function-attributes.ll
@@ -267,6 +267,12 @@ define void @arm_preserves_za_func() "aarch64_preserves_za" {
   ret void
 }
 
+; // -----
+
+; CHECK-LABEL: @func_attr_amdgpu_unsafe_fp_atomics_true
+; CHECK-SAME: attributes {amdgpu_unsafe_fp_atomics = true}
+declare void @func_attr_amdgpu_unsafe_fp_atomics_true() "amdgpu-unsafe-fp-atomics"="true"
+
 // -----
 
 ; CHECK-LABEL: @section_func
diff --git a/mlir/test/Target/LLVMIR/llvmir.mlir b/mlir/test/Target/LLVMIR/llvmir.mlir
index 9852c4051f0d0..ade6cbf505e9e 100644
--- a/mlir/test/Target/LLVMIR/llvmir.mlir
+++ b/mlir/test/Target/LLVMIR/llvmir.mlir
@@ -2474,6 +2474,15 @@ llvm.func @preserves_za_func() attributes {arm_preserves_za} {
 
 // -----
 
+// CHECK-LABEL: @amdgpu_unsafe_fp_atomics_func
+// CHECK-SAME: #[[ATTR:[0-9]*]]
+llvm.func @amdgpu_unsafe_fp_atomics_func() attributes {amdgpu_unsafe_fp_atomics = true} {
+  llvm.return
+}
+// CHECK: #[[ATTR]] = { "amdgpu-unsafe-fp-atomics"="true" }
+
+// -----
+
 //
 // frame pointer attribute.
 //