[MLIR][LLVM] Add fast-math related function attribute support #79812
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Adds unsafe-fp-math, no-infs-fp-math, no-nans-fp-math, approx-func-fp-math, and no-signed-zeros-fp-math function attributes.
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@llvm/pr-subscribers-mlir-llvm @llvm/pr-subscribers-mlir Author: Alex Bradbury (asb) ChangesAdds unsafe-fp-math, no-infs-fp-math, no-nans-fp-math, approx-func-fp-math, and no-signed-zeros-fp-math function attributes. This allows code generators using the LLVMIR dialect to match the codegen of Clang. Full diff: https://github.com/llvm/llvm-project/pull/79812.diff 6 Files Affected:
diff --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
index 01d476f530b1c5..ad67fba5a81cf8 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
@@ -1428,7 +1428,12 @@ def LLVM_LLVMFuncOp : LLVM_Op<"func", [
OptionalAttr<LLVM_VScaleRangeAttr>:$vscale_range,
OptionalAttr<FramePointerKindAttr>:$frame_pointer,
OptionalAttr<StrAttr>:$target_cpu,
- OptionalAttr<LLVM_TargetFeaturesAttr>:$target_features
+ OptionalAttr<LLVM_TargetFeaturesAttr>:$target_features,
+ OptionalAttr<BoolAttr>:$unsafe_fp_math,
+ OptionalAttr<BoolAttr>:$no_infs_fp_math,
+ OptionalAttr<BoolAttr>:$no_nans_fp_math,
+ OptionalAttr<BoolAttr>:$approx_func_fp_math,
+ OptionalAttr<BoolAttr>:$no_signed_zeros_fp_math
);
let regions = (region AnyRegion:$body);
diff --git a/mlir/lib/Target/LLVMIR/ModuleImport.cpp b/mlir/lib/Target/LLVMIR/ModuleImport.cpp
index 928d8077175ccf..5ca4a9fd68d650 100644
--- a/mlir/lib/Target/LLVMIR/ModuleImport.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleImport.cpp
@@ -1646,6 +1646,11 @@ static constexpr std::array ExplicitAttributes{
StringLiteral("vscale_range"),
StringLiteral("frame-pointer"),
StringLiteral("target-features"),
+ StringLiteral("unsafe-fp-math"),
+ StringLiteral("no-infs-fp-math"),
+ StringLiteral("no-nans-fp-math"),
+ StringLiteral("approx-func-fp-math"),
+ StringLiteral("no-signed-zeros-fp-math"),
};
static void processPassthroughAttrs(llvm::Function *func, LLVMFuncOp funcOp) {
@@ -1752,6 +1757,26 @@ void ModuleImport::processFunctionAttributes(llvm::Function *func,
attr.isStringAttribute())
funcOp.setTargetFeaturesAttr(
LLVM::TargetFeaturesAttr::get(context, attr.getValueAsString()));
+
+ if (llvm::Attribute attr = func->getFnAttribute("unsafe-fp-math");
+ attr.isStringAttribute())
+ funcOp.setUnsafeFpMath(attr.getValueAsBool());
+
+ if (llvm::Attribute attr = func->getFnAttribute("no-infs-fp-math");
+ attr.isStringAttribute())
+ funcOp.setNoInfsFpMath(attr.getValueAsBool());
+
+ if (llvm::Attribute attr = func->getFnAttribute("no-nans-fp-math");
+ attr.isStringAttribute())
+ funcOp.setNoNansFpMath(attr.getValueAsBool());
+
+ if (llvm::Attribute attr = func->getFnAttribute("approx-func-fp-math");
+ attr.isStringAttribute())
+ funcOp.setApproxFuncFpMath(attr.getValueAsBool());
+
+ if (llvm::Attribute attr = func->getFnAttribute("no-signed-zeros-fp-math");
+ attr.isStringAttribute())
+ funcOp.setNoSignedZerosFpMath(attr.getValueAsBool());
}
DictionaryAttr
diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index 69a1cbe5969e85..6364cacbd19245 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -37,6 +37,7 @@
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/TypeSwitch.h"
#include "llvm/Frontend/OpenMP/OMPIRBuilder.h"
#include "llvm/IR/BasicBlock.h"
@@ -1214,6 +1215,23 @@ LogicalResult ModuleTranslation::convertOneFunction(LLVMFuncOp func) {
getLLVMContext(), attr->getMinRange().getInt(),
attr->getMaxRange().getInt()));
+ if (auto unsafeFpMath = func.getUnsafeFpMath())
+ llvmFunc->addFnAttr("unsafe-fp-math", llvm::toStringRef(*unsafeFpMath));
+
+ if (auto noInfsFpMath = func.getNoInfsFpMath())
+ llvmFunc->addFnAttr("no-infs-fp-math", llvm::toStringRef(*noInfsFpMath));
+
+ if (auto noNansFpMath = func.getNoNansFpMath())
+ llvmFunc->addFnAttr("no-nans-fp-math", llvm::toStringRef(*noNansFpMath));
+
+ if (auto approxFuncFpMath = func.getApproxFuncFpMath())
+ llvmFunc->addFnAttr("approx-func-fp-math",
+ llvm::toStringRef(*approxFuncFpMath));
+
+ if (auto noSignedZerosFpMath = func.getNoSignedZerosFpMath())
+ llvmFunc->addFnAttr("no-signed-zeros-fp-math",
+ llvm::toStringRef(*noSignedZerosFpMath));
+
// Add function attribute frame-pointer, if found.
if (FramePointerKindAttr attr = func.getFramePointerAttr())
llvmFunc->addFnAttr("frame-pointer",
diff --git a/mlir/test/Dialect/LLVMIR/func.mlir b/mlir/test/Dialect/LLVMIR/func.mlir
index 9dc1bc57034e02..006f2f64a27277 100644
--- a/mlir/test/Dialect/LLVMIR/func.mlir
+++ b/mlir/test/Dialect/LLVMIR/func.mlir
@@ -257,6 +257,36 @@ module {
llvm.func @frame_pointer_roundtrip() attributes {frame_pointer = #llvm.framePointerKind<"non-leaf">} {
llvm.return
}
+
+ llvm.func @unsafe_fp_math_roundtrip() attributes {unsafe_fp_math = true} {
+ // CHECK: @unsafe_fp_math_roundtrip
+ // CHECK-SAME: attributes {unsafe_fp_math = true}
+ llvm.return
+ }
+
+ llvm.func @no_infs_fp_math_roundtrip() attributes {no_infs_fp_math = true} {
+ // CHECK: @no_infs_fp_math_roundtrip
+ // CHECK-SAME: attributes {no_infs_fp_math = true}
+ llvm.return
+ }
+
+ llvm.func @no_nans_fp_math_roundtrip() attributes {no_nans_fp_math = true} {
+ // CHECK: @no_nans_fp_math_roundtrip
+ // CHECK-SAME: attributes {no_nans_fp_math = true}
+ llvm.return
+ }
+
+ llvm.func @approx_func_fp_math_roundtrip() attributes {approx_func_fp_math = true} {
+ // CHECK: @approx_func_fp_math_roundtrip
+ // CHECK-SAME: attributes {approx_func_fp_math = true}
+ llvm.return
+ }
+
+ llvm.func @no_signed_zeros_fp_math_roundtrip() attributes {no_signed_zeros_fp_math = true} {
+ // CHECK: @no_signed_zeros_fp_math_roundtrip
+ // CHECK-SAME: attributes {no_signed_zeros_fp_math = true}
+ llvm.return
+ }
}
// -----
diff --git a/mlir/test/Target/LLVMIR/Import/function-attributes.ll b/mlir/test/Target/LLVMIR/Import/function-attributes.ll
index af2ef9db96ae33..70387789aa97e4 100644
--- a/mlir/test/Target/LLVMIR/Import/function-attributes.ll
+++ b/mlir/test/Target/LLVMIR/Import/function-attributes.ll
@@ -272,3 +272,33 @@ define void @align_func() align 2 {
; CHECK-LABEL: @align_decl
; CHECK-SAME: attributes {alignment = 64 : i64}
declare void @align_decl() align 64
+
+; // -----
+
+; CHECK-LABEL: @func_attr_unsafe_fp_math
+; CHECK-SAME: attributes {unsafe_fp_math = true}
+declare void @func_attr_unsafe_fp_math() "unsafe-fp-math"="true"
+
+; // -----
+
+; CHECK-LABEL: @func_attr_no_infs_fp_math
+; CHECK-SAME: attributes {no_infs_fp_math = true}
+declare void @func_attr_no_infs_fp_math() "no-infs-fp-math"="true"
+
+; // -----
+
+; CHECK-LABEL: @func_attr_no_nans_fp_math
+; CHECK-SAME: attributes {no_nans_fp_math = true}
+declare void @func_attr_no_nans_fp_math() "no-nans-fp-math"="true"
+
+; // -----
+
+; CHECK-LABEL: @func_attr_approx_func_fp_math
+; CHECK-SAME: attributes {approx_func_fp_math = true}
+declare void @func_attr_approx_func_fp_math() "approx-func-fp-math"="true"
+
+; // -----
+
+; CHECK-LABEL: @func_attr_no_signed_zeros_fp_math
+; CHECK-SAME: attributes {no_signed_zeros_fp_math = true}
+declare void @func_attr_no_signed_zeros_fp_math() "no-signed-zeros-fp-math"="true"
diff --git a/mlir/test/Target/LLVMIR/fp-math-function-attributes.mlir b/mlir/test/Target/LLVMIR/fp-math-function-attributes.mlir
new file mode 100644
index 00000000000000..ccae06cc3dd76d
--- /dev/null
+++ b/mlir/test/Target/LLVMIR/fp-math-function-attributes.mlir
@@ -0,0 +1,44 @@
+// RUN: mlir-translate -mlir-to-llvmir -split-input-file %s | FileCheck %s
+
+// CHECK-LABEL: define void @unsafe_fp_math_func()
+// CHECK-SAME: #[[ATTRS:[0-9]+]]
+llvm.func @unsafe_fp_math_func() attributes {unsafe_fp_math = true} {
+ llvm.return
+}
+// CHECK: attributes #[[ATTRS]] = { "unsafe-fp-math"="true" }
+
+// -----
+
+// CHECK-LABEL: define void @no_infs_fp_math_func()
+// CHECK-SAME: #[[ATTRS:[0-9]+]]
+llvm.func @no_infs_fp_math_func() attributes {no_infs_fp_math = true} {
+ llvm.return
+}
+// CHECK: attributes #[[ATTRS]] = { "no-infs-fp-math"="true" }
+
+// -----
+
+// CHECK-LABEL: define void @no_nans_fp_math_func()
+// CHECK-SAME: #[[ATTRS:[0-9]+]]
+llvm.func @no_nans_fp_math_func() attributes {no_nans_fp_math = true} {
+ llvm.return
+}
+// CHECK: attributes #[[ATTRS]] = { "no-nans-fp-math"="true" }
+
+// -----
+
+// CHECK-LABEL: define void @approx_func_fp_math_func()
+// CHECK-SAME: #[[ATTRS:[0-9]+]]
+llvm.func @approx_func_fp_math_func() attributes {approx_func_fp_math = true} {
+ llvm.return
+}
+// CHECK: attributes #[[ATTRS]] = { "approx-func-fp-math"="true" }
+
+// -----
+
+// CHECK-LABEL: define void @no_signed_zeros_fp_math_func()
+// CHECK-SAME: #[[ATTRS:[0-9]+]]
+llvm.func @no_signed_zeros_fp_math_func() attributes {no_signed_zeros_fp_math = true} {
+ llvm.return
+}
+// CHECK: attributes #[[ATTRS]] = { "no-signed-zeros-fp-math"="true" }
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This was referenced Jan 29, 2024
zero9178
reviewed
Jan 29, 2024
There was a problem hiding this comment.
Thank you so much for working on this! Code itself looks good to me although I am curious about the OptionalAttr<BoolAttr>.
Is there any documentation one can read up on these attributes? They do not seem to be present in the language reference, requiring to resort to reading LLVM code to try and deduce semantics it seems.
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Adds unsafe-fp-math, no-infs-fp-math, no-nans-fp-math, approx-func-fp-math, and no-signed-zeros-fp-math function attributes.
This allows code generators using the LLVMIR dialect to match the codegen of Clang.