[clang] [flang] [mlir] [flang] Add support for -mrecip[=<list>] (PR #142172)
via cfe-commits
cfe-commits at lists.llvm.org
Fri May 30 08:53:50 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-flang-fir-hlfir
@llvm/pr-subscribers-clang
Author: Cameron McInally (mcinally)
<details>
<summary>Changes</summary>
This patch adds support for the -mrecip command line option. The parsing of this options is equivalent to Clang's and it is implemented by setting the "reciprocal-estimates" function attribute.
---
Full diff: https://github.com/llvm/llvm-project/pull/142172.diff
14 Files Affected:
- (modified) clang/include/clang/Driver/Options.td (+2-1)
- (modified) flang/include/flang/Frontend/CodeGenOptions.h (+3)
- (modified) flang/include/flang/Optimizer/Transforms/Passes.td (+3)
- (modified) flang/include/flang/Tools/CrossToolHelpers.h (+3)
- (modified) flang/lib/Frontend/CompilerInvocation.cpp (+159)
- (modified) flang/lib/Frontend/FrontendActions.cpp (+2)
- (modified) flang/lib/Optimizer/Passes/Pipelines.cpp (+2-1)
- (modified) flang/lib/Optimizer/Transforms/FunctionAttr.cpp (+4)
- (added) flang/test/Driver/mrecip.f90 (+27)
- (modified) mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td (+1)
- (modified) mlir/lib/Target/LLVMIR/ModuleImport.cpp (+5)
- (modified) mlir/lib/Target/LLVMIR/ModuleTranslation.cpp (+3)
- (added) mlir/test/Target/LLVMIR/Import/mrecip.ll (+9)
- (added) mlir/test/Target/LLVMIR/mrecip.mlir (+8)
``````````diff
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 5ca31c253ed8f..291e9ae223805 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5472,9 +5472,10 @@ def mno_implicit_float : Flag<["-"], "mno-implicit-float">, Group<m_Group>,
HelpText<"Don't generate implicit floating point or vector instructions">;
def mimplicit_float : Flag<["-"], "mimplicit-float">, Group<m_Group>;
def mrecip : Flag<["-"], "mrecip">, Group<m_Group>,
+ Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>,
HelpText<"Equivalent to '-mrecip=all'">;
def mrecip_EQ : CommaJoined<["-"], "mrecip=">, Group<m_Group>,
- Visibility<[ClangOption, CC1Option]>,
+ Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>,
HelpText<"Control use of approximate reciprocal and reciprocal square root instructions followed by <n> iterations of "
"Newton-Raphson refinement. "
"<value> = ( ['!'] ['vec-'] ('rcp'|'sqrt') [('h'|'s'|'d')] [':'<n>] ) | 'all' | 'default' | 'none'">,
diff --git a/flang/include/flang/Frontend/CodeGenOptions.h b/flang/include/flang/Frontend/CodeGenOptions.h
index 61e56e51c4bbb..5c1f7ef52ca14 100644
--- a/flang/include/flang/Frontend/CodeGenOptions.h
+++ b/flang/include/flang/Frontend/CodeGenOptions.h
@@ -56,6 +56,9 @@ class CodeGenOptions : public CodeGenOptionsBase {
// The prefered vector width, if requested by -mprefer-vector-width.
std::string PreferVectorWidth;
+ // List of reciprocal estimate sub-options.
+ std::string Reciprocals;
+
/// List of filenames passed in using the -fembed-offload-object option. These
/// are offloading binaries containing device images and metadata.
std::vector<std::string> OffloadObjects;
diff --git a/flang/include/flang/Optimizer/Transforms/Passes.td b/flang/include/flang/Optimizer/Transforms/Passes.td
index 1b1970412676d..34842f9785942 100644
--- a/flang/include/flang/Optimizer/Transforms/Passes.td
+++ b/flang/include/flang/Optimizer/Transforms/Passes.td
@@ -429,6 +429,9 @@ def FunctionAttr : Pass<"function-attr", "mlir::func::FuncOp"> {
"module.">,
Option<"unsafeFPMath", "unsafe-fp-math", "bool", /*default=*/"false",
"Set the unsafe-fp-math attribute on functions in the module.">,
+ Option<"reciprocals", "mrecip", "std::string", /*default=*/"",
+ "Set the reciprocal-estimates attribute on functions in the "
+ "module.">,
Option<"preferVectorWidth", "prefer-vector-width", "std::string",
/*default=*/"",
"Set the prefer-vector-width attribute on functions in the "
diff --git a/flang/include/flang/Tools/CrossToolHelpers.h b/flang/include/flang/Tools/CrossToolHelpers.h
index 058024a4a04c5..337685c82af5f 100644
--- a/flang/include/flang/Tools/CrossToolHelpers.h
+++ b/flang/include/flang/Tools/CrossToolHelpers.h
@@ -102,6 +102,7 @@ struct MLIRToLLVMPassPipelineConfig : public FlangEPCallBacks {
UnsafeFPMath = mathOpts.getAssociativeMath() &&
mathOpts.getReciprocalMath() && NoSignedZerosFPMath &&
ApproxFuncFPMath && mathOpts.getFPContractEnabled();
+ Reciprocals = opts.Reciprocals;
PreferVectorWidth = opts.PreferVectorWidth;
if (opts.InstrumentFunctions) {
InstrumentFunctionEntry = "__cyg_profile_func_enter";
@@ -127,6 +128,8 @@ struct MLIRToLLVMPassPipelineConfig : public FlangEPCallBacks {
bool NoSignedZerosFPMath =
false; ///< Set no-signed-zeros-fp-math attribute for functions.
bool UnsafeFPMath = false; ///< Set unsafe-fp-math attribute for functions.
+ std::string Reciprocals = ""; ///< Set reciprocal-estimate attribute for
+ ///< functions.
std::string PreferVectorWidth = ""; ///< Set prefer-vector-width attribute for
///< functions.
bool NSWOnLoopVarInc = true; ///< Add nsw flag to loop variable increments.
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 90a002929eff0..957f2041ffd8d 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -1251,6 +1251,164 @@ static bool parseIntegerOverflowArgs(CompilerInvocation &invoc,
return true;
}
+/// This is a helper function for validating the optional refinement step
+/// parameter in reciprocal argument strings. Return false if there is an error
+/// parsing the refinement step. Otherwise, return true and set the Position
+/// of the refinement step in the input string.
+///
+/// \param [in] in The input string
+/// \param [in] a The compiler invocation arguments to parse
+/// \param [out] position The position of the refinement step in input string
+/// \param [out] diags DiagnosticsEngine to report erros with
+static bool getRefinementStep(llvm::StringRef in, const llvm::opt::Arg &a,
+ size_t &position,
+ clang::DiagnosticsEngine &diags) {
+ const char refinementStepToken = ':';
+ position = in.find(refinementStepToken);
+ if (position != llvm::StringRef::npos) {
+ llvm::StringRef option = a.getOption().getName();
+ llvm::StringRef refStep = in.substr(position + 1);
+ // Allow exactly one numeric character for the additional refinement
+ // step parameter. This is reasonable for all currently-supported
+ // operations and architectures because we would expect that a larger value
+ // of refinement steps would cause the estimate "optimization" to
+ // under-perform the native operation. Also, if the estimate does not
+ // converge quickly, it probably will not ever converge, so further
+ // refinement steps will not produce a better answer.
+ if (refStep.size() != 1) {
+ diags.Report(clang::diag::err_drv_invalid_value) << option << refStep;
+ return false;
+ }
+ char refStepChar = refStep[0];
+ if (refStepChar < '0' || refStepChar > '9') {
+ diags.Report(clang::diag::err_drv_invalid_value) << option << refStep;
+ return false;
+ }
+ }
+ return true;
+}
+
+/// Parses all -mrecip=<list> arguments and populates the
+/// CompilerInvocation accordingly. Returns false if new errors are generated.
+///
+/// \param [out] invoc Stores the processed arguments
+/// \param [in] args The compiler invocation arguments to parse
+/// \param [out] diags DiagnosticsEngine to report erros with
+static bool parseMRecip(CompilerInvocation &invoc, llvm::opt::ArgList &args,
+ clang::DiagnosticsEngine &diags) {
+ llvm::StringRef disabledPrefixIn = "!";
+ llvm::StringRef disabledPrefixOut = "!";
+ llvm::StringRef enabledPrefixOut = "";
+ llvm::StringRef out = "";
+ Fortran::frontend::CodeGenOptions &opts = invoc.getCodeGenOpts();
+
+ const llvm::opt::Arg *a =
+ args.getLastArg(clang::driver::options::OPT_mrecip,
+ clang::driver::options::OPT_mrecip_EQ);
+ if (!a)
+ return true;
+
+ unsigned numOptions = a->getNumValues();
+ if (numOptions == 0) {
+ // No option is the same as "all".
+ opts.Reciprocals = "all";
+ return true;
+ }
+
+ // Pass through "all", "none", or "default" with an optional refinement step.
+ if (numOptions == 1) {
+ llvm::StringRef val = a->getValue(0);
+ size_t refStepLoc;
+ if (!getRefinementStep(val, *a, refStepLoc, diags))
+ return false;
+ llvm::StringRef valBase = val.slice(0, refStepLoc);
+ if (valBase == "all" || valBase == "none" || valBase == "default") {
+ opts.Reciprocals = args.MakeArgString(val);
+ return true;
+ }
+ }
+
+ // Each reciprocal type may be enabled or disabled individually.
+ // Check each input value for validity, concatenate them all back together,
+ // and pass through.
+
+ llvm::StringMap<bool> optionStrings;
+ optionStrings.insert(std::make_pair("divd", false));
+ optionStrings.insert(std::make_pair("divf", false));
+ optionStrings.insert(std::make_pair("divh", false));
+ optionStrings.insert(std::make_pair("vec-divd", false));
+ optionStrings.insert(std::make_pair("vec-divf", false));
+ optionStrings.insert(std::make_pair("vec-divh", false));
+ optionStrings.insert(std::make_pair("sqrtd", false));
+ optionStrings.insert(std::make_pair("sqrtf", false));
+ optionStrings.insert(std::make_pair("sqrth", false));
+ optionStrings.insert(std::make_pair("vec-sqrtd", false));
+ optionStrings.insert(std::make_pair("vec-sqrtf", false));
+ optionStrings.insert(std::make_pair("vec-sqrth", false));
+
+ for (unsigned i = 0; i != numOptions; ++i) {
+ llvm::StringRef val = a->getValue(i);
+
+ bool isDisabled = val.starts_with(disabledPrefixIn);
+ // Ignore the disablement token for string matching.
+ if (isDisabled)
+ val = val.substr(1);
+
+ size_t refStep;
+ if (!getRefinementStep(val, *a, refStep, diags))
+ return false;
+
+ llvm::StringRef valBase = val.slice(0, refStep);
+ llvm::StringMap<bool>::iterator optionIter = optionStrings.find(valBase);
+ if (optionIter == optionStrings.end()) {
+ // Try again specifying float suffix.
+ optionIter = optionStrings.find(valBase.str() + 'f');
+ if (optionIter == optionStrings.end()) {
+ // The input name did not match any known option string.
+ diags.Report(clang::diag::err_drv_invalid_value)
+ << a->getOption().getName() << val;
+ return false;
+ }
+ // The option was specified without a half or float or double suffix.
+ // Make sure that the double or half entry was not already specified.
+ // The float entry will be checked below.
+ if (optionStrings[valBase.str() + 'd'] ||
+ optionStrings[valBase.str() + 'h']) {
+ diags.Report(clang::diag::err_drv_invalid_value)
+ << a->getOption().getName() << val;
+ return false;
+ }
+ }
+
+ if (optionIter->second == true) {
+ // Duplicate option specified.
+ diags.Report(clang::diag::err_drv_invalid_value)
+ << a->getOption().getName() << val;
+ return false;
+ }
+
+ // Mark the matched option as found. Do not allow duplicate specifiers.
+ optionIter->second = true;
+
+ // If the precision was not specified, also mark the double and half entry
+ // as found.
+ if (valBase.back() != 'f' && valBase.back() != 'd' &&
+ valBase.back() != 'h') {
+ optionStrings[valBase.str() + 'd'] = true;
+ optionStrings[valBase.str() + 'h'] = true;
+ }
+
+ // Build the output string.
+ llvm::StringRef prefix = isDisabled ? disabledPrefixOut : enabledPrefixOut;
+ out = args.MakeArgString(out + prefix + val);
+ if (i != numOptions - 1)
+ out = args.MakeArgString(out + ",");
+ }
+
+ opts.Reciprocals = args.MakeArgString(out); // Handle the rest.
+ return true;
+}
+
/// Parses all floating point related arguments and populates the
/// CompilerInvocation accordingly.
/// Returns false if new errors are generated.
@@ -1398,6 +1556,7 @@ static bool parseLangOptionsArgs(CompilerInvocation &invoc,
success &= parseIntegerOverflowArgs(invoc, args, diags);
success &= parseFloatingPointArgs(invoc, args, diags);
+ success &= parseMRecip(invoc, args, diags);
success &= parseVScaleArgs(invoc, args, diags);
return success;
diff --git a/flang/lib/Frontend/FrontendActions.cpp b/flang/lib/Frontend/FrontendActions.cpp
index 012d0fdfe645f..31803b27b8ceb 100644
--- a/flang/lib/Frontend/FrontendActions.cpp
+++ b/flang/lib/Frontend/FrontendActions.cpp
@@ -743,6 +743,8 @@ void CodeGenAction::generateLLVMIR() {
config.PreferVectorWidth = opts.PreferVectorWidth;
+ config.Reciprocals = opts.Reciprocals;
+
if (ci.getInvocation().getFrontendOpts().features.IsEnabled(
Fortran::common::LanguageFeature::OpenMP))
config.EnableOpenMP = true;
diff --git a/flang/lib/Optimizer/Passes/Pipelines.cpp b/flang/lib/Optimizer/Passes/Pipelines.cpp
index 0c774eede4c9a..06eaa18fe7284 100644
--- a/flang/lib/Optimizer/Passes/Pipelines.cpp
+++ b/flang/lib/Optimizer/Passes/Pipelines.cpp
@@ -358,7 +358,8 @@ void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
{framePointerKind, config.InstrumentFunctionEntry,
config.InstrumentFunctionExit, config.NoInfsFPMath, config.NoNaNsFPMath,
config.ApproxFuncFPMath, config.NoSignedZerosFPMath, config.UnsafeFPMath,
- config.PreferVectorWidth, /*tuneCPU=*/"", setNoCapture, setNoAlias}));
+ config.Reciprocals, config.PreferVectorWidth, /*tuneCPU=*/"",
+ setNoCapture, setNoAlias}));
if (config.EnableOpenMP) {
pm.addNestedPass<mlir::func::FuncOp>(
diff --git a/flang/lib/Optimizer/Transforms/FunctionAttr.cpp b/flang/lib/Optimizer/Transforms/FunctionAttr.cpp
index 041aa8717d20e..5ac4ed8a93b6b 100644
--- a/flang/lib/Optimizer/Transforms/FunctionAttr.cpp
+++ b/flang/lib/Optimizer/Transforms/FunctionAttr.cpp
@@ -107,6 +107,10 @@ void FunctionAttrPass::runOnOperation() {
func->setAttr(
mlir::LLVM::LLVMFuncOp::getUnsafeFpMathAttrName(llvmFuncOpName),
mlir::BoolAttr::get(context, true));
+ if (!reciprocals.empty())
+ func->setAttr(
+ mlir::LLVM::LLVMFuncOp::getReciprocalEstimatesAttrName(llvmFuncOpName),
+ mlir::StringAttr::get(context, reciprocals));
if (!preferVectorWidth.empty())
func->setAttr(
mlir::LLVM::LLVMFuncOp::getPreferVectorWidthAttrName(llvmFuncOpName),
diff --git a/flang/test/Driver/mrecip.f90 b/flang/test/Driver/mrecip.f90
new file mode 100644
index 0000000000000..9ec65c0ef4dde
--- /dev/null
+++ b/flang/test/Driver/mrecip.f90
@@ -0,0 +1,27 @@
+! Test that -mrecip[=<list>] works as expected.
+
+! RUN: %flang_fc1 -emit-llvm -o - %s 2>&1| FileCheck %s --check-prefix=CHECK-OMIT
+! RUN: %flang_fc1 -mrecip -emit-llvm -o - %s 2>&1| FileCheck %s --check-prefix=CHECK-NOARG
+! RUN: %flang_fc1 -mrecip=all -emit-llvm -o - %s 2>&1| FileCheck %s --check-prefix=CHECK-ALL
+! RUN: %flang_fc1 -mrecip=none -emit-llvm -o - %s 2>&1| FileCheck %s --check-prefix=CHECK-NONE
+! RUN: %flang_fc1 -mrecip=default -emit-llvm -o - %s 2>&1| FileCheck %s --check-prefix=CHECK-DEF
+! RUN: %flang_fc1 -mrecip=divd,divf,divh,vec-divd,vec-divf,vec-divh,sqrtd,sqrtf,sqrth,vec-sqrtd,vec-sqrtf,vec-sqrth -emit-llvm -o - %s 2>&1| FileCheck %s --check-prefix=CHECK-POS
+! RUN: %flang_fc1 -mrecip=!divd,!divf,!divh,!vec-divd,!vec-divf,!vec-divh,!sqrtd,!sqrtf,!sqrth,!vec-sqrtd,!vec-sqrtf,!vec-sqrth
+! -emit-llvm -o - %s 2>&1| FileCheck %s --check-prefix=CHECK-NEG
+! RUN: %flang_fc1 -mrecip=!divd,divf,!divh,sqrtd,!sqrtf,sqrth -emit-llvm -o - %s 2>&1| FileCheck %s --check-prefix=CHECK-MIX
+! RUN: not %flang_fc1 -mrecip=xxx -emit-llvm -o - %s 2>&1| FileCheck %s --check-prefix=CHECK-INV
+! RUN: not %flang_fc1 -mrecip=divd,divd -emit-llvm -o - %s 2>&1| FileCheck %s --check-prefix=CHECK-DUP
+
+subroutine func
+end subroutine func
+
+! CHECK-OMIT-NOT: attributes #0 = { "reciprocal-estimates"={{.*}} }
+! CHECK-NOARG: attributes #0 = { "reciprocal-estimates"="all" }
+! CHECK-ALL: attributes #0 = { "reciprocal-estimates"="all" }
+! CHECK-NONE: attributes #0 = { "reciprocal-estimates"="none" }
+! CHECK-DEF: attributes #0 = { "reciprocal-estimates"="default" }
+! CHECK-POS: attributes #0 = { "reciprocal-estimates"="divd,divf,divh,vec-divd,vec-divf,vec-divh,sqrtd,sqrtf,sqrth,vec-sqrtd,vec-sqrtf,vec-sqrth" }
+! CHECK-NEG: attributes #0 = { "reciprocal-estimates"="!divd,!divf,!divh,!vec-divd,!vec-divf,!vec-divh,!sqrtd,!sqrtf,!sqrth,!vec-sqrtd,!vec-sqrtf,!vec-sqrth" }
+! CHECK-MIX: attributes #0 = { "reciprocal-estimates"="!divd,divf,!divh,sqrtd,!sqrtf,sqrth" }
+! CHECK-INV: error: invalid value 'xxx' in 'mrecip='
+! CHECK-DUP: error: invalid value 'divd' in 'mrecip='
diff --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
index c0324d561b77b..e5d35fa82fbce 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
@@ -1895,6 +1895,7 @@ def LLVM_LLVMFuncOp : LLVM_Op<"func", [
OptionalAttr<StrAttr>:$tune_cpu,
OptionalAttr<StrAttr>:$prefer_vector_width,
OptionalAttr<LLVM_TargetFeaturesAttr>:$target_features,
+ OptionalAttr<StrAttr>:$reciprocal_estimates,
OptionalAttr<BoolAttr>:$unsafe_fp_math,
OptionalAttr<BoolAttr>:$no_infs_fp_math,
OptionalAttr<BoolAttr>:$no_nans_fp_math,
diff --git a/mlir/lib/Target/LLVMIR/ModuleImport.cpp b/mlir/lib/Target/LLVMIR/ModuleImport.cpp
index 85417da798b22..1e6e60a78b37d 100644
--- a/mlir/lib/Target/LLVMIR/ModuleImport.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleImport.cpp
@@ -2640,6 +2640,11 @@ void ModuleImport::processFunctionAttributes(llvm::Function *func,
attr.isStringAttribute())
funcOp.setPreferVectorWidth(attr.getValueAsString());
+ if (llvm::Attribute attr = func->getFnAttribute("reciprocal-estimates");
+ attr.isStringAttribute())
+ funcOp.setReciprocalEstimatesAttr(
+ StringAttr::get(context, attr.getValueAsString()));
+
if (llvm::Attribute attr = func->getFnAttribute("unsafe-fp-math");
attr.isStringAttribute())
funcOp.setUnsafeFpMath(attr.getValueAsBool());
diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index 4cc419c7cde5b..bc66625bf374e 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -1557,6 +1557,9 @@ LogicalResult ModuleTranslation::convertOneFunction(LLVMFuncOp func) {
getLLVMContext(), attr->getMinRange().getInt(),
attr->getMaxRange().getInt()));
+ if (auto reciprocalEstimates = func.getReciprocalEstimates())
+ llvmFunc->addFnAttr("reciprocal-estimates", *reciprocalEstimates);
+
if (auto unsafeFpMath = func.getUnsafeFpMath())
llvmFunc->addFnAttr("unsafe-fp-math", llvm::toStringRef(*unsafeFpMath));
diff --git a/mlir/test/Target/LLVMIR/Import/mrecip.ll b/mlir/test/Target/LLVMIR/Import/mrecip.ll
new file mode 100644
index 0000000000000..01814cce70059
--- /dev/null
+++ b/mlir/test/Target/LLVMIR/Import/mrecip.ll
@@ -0,0 +1,9 @@
+; RUN: mlir-translate -import-llvm -split-input-file %s | FileCheck %s
+
+; CHECK-LABEL: llvm.func @reciprocal_estimates()
+; CHECK-SAME: reciprocal_estimates = "all"
+define void @reciprocal_estimates() #0 {
+ ret void
+}
+
+attributes #0 = { "reciprocal-estimates" = "all" }
diff --git a/mlir/test/Target/LLVMIR/mrecip.mlir b/mlir/test/Target/LLVMIR/mrecip.mlir
new file mode 100644
index 0000000000000..e0bc66c272f6a
--- /dev/null
+++ b/mlir/test/Target/LLVMIR/mrecip.mlir
@@ -0,0 +1,8 @@
+// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s
+
+// CHECK: define void @reciprocal_estimates() #[[ATTRS:.*]] {
+// CHECK: attributes #[[ATTRS]] = { "reciprocal-estimates"="all" }
+
+llvm.func @reciprocal_estimates() attributes {reciprocal_estimates = "all"} {
+ llvm.return
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/142172
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