[clang] [CIR] Intitial upstreaming of LibOpt pass (PR #172487)
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Tue Dec 16 06:53:26 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Hendrik Hübner (HendrikHuebner)
<details>
<summary>Changes</summary>
This PR Upstreams the structure for the LibOpt pass
cc @<!-- -->bcardosolopes
---
Full diff: https://github.com/llvm/llvm-project/pull/172487.diff
10 Files Affected:
- (modified) clang/include/clang/CIR/CIRToCIRPasses.h (+2-1)
- (modified) clang/include/clang/CIR/Dialect/Passes.h (+2)
- (modified) clang/include/clang/CIR/Dialect/Passes.td (+19)
- (modified) clang/include/clang/Frontend/FrontendOptions.h (+3)
- (modified) clang/include/clang/Options/Options.td (+8-1)
- (modified) clang/lib/CIR/Dialect/Transforms/CMakeLists.txt (+1)
- (added) clang/lib/CIR/Dialect/Transforms/LibOpt.cpp (+108)
- (modified) clang/lib/CIR/FrontendAction/CIRGenAction.cpp (+4-1)
- (modified) clang/lib/CIR/Lowering/CIRPasses.cpp (+15-1)
- (added) clang/test/CIR/Transforms/lib-opt.cpp (+3)
``````````diff
diff --git a/clang/include/clang/CIR/CIRToCIRPasses.h b/clang/include/clang/CIR/CIRToCIRPasses.h
index 4a23790ee8b76..ed82fe4477e82 100644
--- a/clang/include/clang/CIR/CIRToCIRPasses.h
+++ b/clang/include/clang/CIR/CIRToCIRPasses.h
@@ -33,7 +33,8 @@ mlir::LogicalResult runCIRToCIRPasses(mlir::ModuleOp theModule,
mlir::MLIRContext &mlirCtx,
clang::ASTContext &astCtx,
bool enableVerifier,
- bool enableCIRSimplify);
+ bool enableCIRSimplify,
+ llvm::StringRef libOptOptions);
} // namespace cir
diff --git a/clang/include/clang/CIR/Dialect/Passes.h b/clang/include/clang/CIR/Dialect/Passes.h
index 32c3e27d07dfb..dbd6fb198b845 100644
--- a/clang/include/clang/CIR/Dialect/Passes.h
+++ b/clang/include/clang/CIR/Dialect/Passes.h
@@ -27,6 +27,8 @@ std::unique_ptr<Pass> createHoistAllocasPass();
std::unique_ptr<Pass> createLoweringPreparePass();
std::unique_ptr<Pass> createLoweringPreparePass(clang::ASTContext *astCtx);
std::unique_ptr<Pass> createGotoSolverPass();
+std::unique_ptr<Pass> createLibOptPass();
+std::unique_ptr<Pass> createLibOptPass(clang::ASTContext *astCtx);
void populateCIRPreLoweringPasses(mlir::OpPassManager &pm);
diff --git a/clang/include/clang/CIR/Dialect/Passes.td b/clang/include/clang/CIR/Dialect/Passes.td
index 0f5783945f8ae..043292377bbed 100644
--- a/clang/include/clang/CIR/Dialect/Passes.td
+++ b/clang/include/clang/CIR/Dialect/Passes.td
@@ -93,4 +93,23 @@ def LoweringPrepare : Pass<"cir-lowering-prepare"> {
let dependentDialects = ["cir::CIRDialect"];
}
+def LibOpt : Pass<"cir-lib-opt"> {
+ let summary = "Optimize C/C++ library calls";
+ let description = [{
+ By using higher level information from `cir-idiom-recognize`, this pass
+ apply transformations to CIR based on specific C/C++ library semantics.
+
+ Transformations done by this pass can be inspected by users by using
+ remarks. Currently supported are `all` and `transforms`.
+ }];
+ let constructor = "mlir::createLibOptPass()";
+ let dependentDialects = ["cir::CIRDialect"];
+
+ let options = [
+ ListOption<"remarksList", "remarks", "std::string",
+ "Diagnostic remarks to enable"
+ " Supported styles: {all|transforms}", "llvm::cl::ZeroOrMore">,
+ ];
+}
+
#endif // CLANG_CIR_DIALECT_PASSES_TD
diff --git a/clang/include/clang/Frontend/FrontendOptions.h b/clang/include/clang/Frontend/FrontendOptions.h
index ba7da56cb9fce..6cee55f09c47d 100644
--- a/clang/include/clang/Frontend/FrontendOptions.h
+++ b/clang/include/clang/Frontend/FrontendOptions.h
@@ -422,6 +422,9 @@ class FrontendOptions {
LLVM_PREFERRED_TYPE(bool)
unsigned ClangIRDisableCIRVerifier : 1;
+ // Options to control ClangIR library optimization
+ std::string clangIRLibOptOptions;
+
CodeCompleteOptions CodeCompleteOpts;
/// Specifies the output format of the AST.
diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td
index 756d6deed7130..c4230a9c3bab4 100644
--- a/clang/include/clang/Options/Options.td
+++ b/clang/include/clang/Options/Options.td
@@ -3181,7 +3181,14 @@ def clangir_disable_verifier : Flag<["-"], "clangir-disable-verifier">,
Visibility<[ClangOption, CC1Option]>,
HelpText<"ClangIR: Disable MLIR module verifier">,
MarshallingInfoFlag<FrontendOpts<"ClangIRDisableCIRVerifier">>;
-
+def fclangir_lib_opt_EQ : Joined<["-"], "fclangir-lib-opt=">,
+ Visibility<[ClangOption, CC1Option]>, Group<f_Group>,
+ HelpText<"Enable C/C++ library based optimizations (with options)">,
+ MarshallingInfoString<FrontendOpts<"clangIRLibOptOptions">>;
+def fclangir_lib_opt : Flag<["-"], "fclangir-lib-opt">,
+ Visibility<[ClangOption, CC1Option]>, Group<f_Group>,
+ Alias<fclangir_lib_opt_EQ>, AliasArgs<[""]>,
+ HelpText<"Enable C/C++ library based optimizations">;
defm clangir : BoolFOption<"clangir",
FrontendOpts<"UseClangIRPipeline">, DefaultFalse,
PosFlag<SetTrue, [], [ClangOption, CC1Option], "Use the ClangIR pipeline to compile">,
diff --git a/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt b/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt
index 3fc5b06b74e4d..b11695172d12e 100644
--- a/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt
+++ b/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt
@@ -6,6 +6,7 @@ add_clang_library(MLIRCIRTransforms
LoweringPrepare.cpp
LoweringPrepareItaniumCXXABI.cpp
GotoSolver.cpp
+ LibOpt.cpp
DEPENDS
MLIRCIRPassIncGen
diff --git a/clang/lib/CIR/Dialect/Transforms/LibOpt.cpp b/clang/lib/CIR/Dialect/Transforms/LibOpt.cpp
new file mode 100644
index 0000000000000..6b75d961ce4b0
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Transforms/LibOpt.cpp
@@ -0,0 +1,108 @@
+//===- LibOpt.cpp - Optimize CIR raised C/C++ library idioms --------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass optimizes C/C++ standard library idioms in Clang IR.
+//
+//===----------------------------------------------------------------------===//
+
+#include "PassDetail.h"
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+#include "mlir/IR/BuiltinAttributes.h"
+#include "mlir/IR/Region.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Mangle.h"
+#include "clang/Basic/Module.h"
+#include "clang/CIR/Dialect/Builder/CIRBaseBuilder.h"
+#include "clang/CIR/Dialect/IR/CIRDialect.h"
+#include "clang/CIR/Dialect/Passes.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Path.h"
+
+using cir::CIRBaseBuilderTy;
+using namespace mlir;
+using namespace cir;
+
+namespace mlir {
+#define GEN_PASS_DEF_LIBOPT
+#include "clang/CIR/Dialect/Passes.h.inc"
+} // namespace mlir
+
+namespace {
+
+struct LibOptPass : public impl::LibOptBase<LibOptPass> {
+ LibOptPass() = default;
+ void runOnOperation() override;
+
+ class PassOptions {
+ enum : unsigned {
+ None = 0,
+ RemarkTransforms = 1,
+ RemarkAll = 1 << 1,
+ };
+
+ public:
+ void parseOption(const llvm::StringRef remark) {
+ value |= StringSwitch<unsigned>(remark)
+ .Case("transforms", RemarkTransforms)
+ .Case("all", RemarkAll)
+ .Default(None);
+ }
+
+ void parseOptions(LibOptPass &pass) {
+ if (isOptionsParsed)
+ return;
+
+ for (const llvm::StringRef &remark : pass.remarksList)
+ parseOption(remark);
+
+ isOptionsParsed = true;
+ }
+
+ bool emitRemarkAll() { return value & RemarkAll; }
+ bool emitRemarkTransforms() {
+ return emitRemarkAll() || value & RemarkTransforms;
+ }
+
+ private:
+ unsigned value = None;
+ bool isOptionsParsed = false;
+ };
+
+ PassOptions passOptions;
+
+ ///
+ /// AST related
+ /// -----------
+ clang::ASTContext *astCtx;
+ void setASTContext(clang::ASTContext *c) { astCtx = c; }
+
+ /// Tracks current module.
+ ModuleOp theModule;
+};
+} // namespace
+
+void LibOptPass::runOnOperation() {
+ passOptions.parseOptions(*this);
+ auto *op = getOperation();
+ if (isa<::mlir::ModuleOp>(op))
+ theModule = cast<::mlir::ModuleOp>(op);
+}
+
+std::unique_ptr<Pass> mlir::createLibOptPass() {
+ return std::make_unique<LibOptPass>();
+}
+
+std::unique_ptr<Pass> mlir::createLibOptPass(clang::ASTContext *astCtx) {
+ auto pass = std::make_unique<LibOptPass>();
+ pass->setASTContext(astCtx);
+ return std::move(pass);
+}
diff --git a/clang/lib/CIR/FrontendAction/CIRGenAction.cpp b/clang/lib/CIR/FrontendAction/CIRGenAction.cpp
index 67bb5657d4001..de4e3b176edfe 100644
--- a/clang/lib/CIR/FrontendAction/CIRGenAction.cpp
+++ b/clang/lib/CIR/FrontendAction/CIRGenAction.cpp
@@ -108,11 +108,14 @@ class CIRGenConsumer : public clang::ASTConsumer {
mlir::ModuleOp MlirModule = Gen->getModule();
mlir::MLIRContext &MlirCtx = Gen->getMLIRContext();
+
if (!FEOptions.ClangIRDisablePasses) {
+ std::string libOptOptions = FEOptions.clangIRLibOptOptions;
+
// Setup and run CIR pipeline.
if (runCIRToCIRPasses(MlirModule, MlirCtx, C,
!FEOptions.ClangIRDisableCIRVerifier,
- CGO.OptimizationLevel > 0)
+ CGO.OptimizationLevel > 0, libOptOptions)
.failed()) {
CI.getDiagnostics().Report(diag::err_cir_to_cir_transform_failed);
return;
diff --git a/clang/lib/CIR/Lowering/CIRPasses.cpp b/clang/lib/CIR/Lowering/CIRPasses.cpp
index ccc838717e421..9b292fb4502b1 100644
--- a/clang/lib/CIR/Lowering/CIRPasses.cpp
+++ b/clang/lib/CIR/Lowering/CIRPasses.cpp
@@ -21,16 +21,30 @@ mlir::LogicalResult runCIRToCIRPasses(mlir::ModuleOp theModule,
mlir::MLIRContext &mlirContext,
clang::ASTContext &astContext,
bool enableVerifier,
- bool enableCIRSimplify) {
+ bool enableCIRSimplify,
+ llvm::StringRef libOptOptions) {
llvm::TimeTraceScope scope("CIR To CIR Passes");
+ // TODO(CIR): Make this actually propagate errors correctly. This is stubbed
+ // in to get rebases going.
+
+ auto errorHandler = [](const llvm::Twine &) -> mlir::LogicalResult {
+ return mlir::LogicalResult::failure();
+ };
+
mlir::PassManager pm(&mlirContext);
pm.addPass(mlir::createCIRCanonicalizePass());
if (enableCIRSimplify)
pm.addPass(mlir::createCIRSimplifyPass());
+ auto libOpPass = mlir::createLibOptPass();
+ if (libOpPass->initializeOptions(libOptOptions, errorHandler).failed()) {
+ return mlir::failure();
+ }
+
+ pm.addPass(std::move(libOpPass));
pm.addPass(mlir::createLoweringPreparePass(&astContext));
pm.enableVerifier(enableVerifier);
diff --git a/clang/test/CIR/Transforms/lib-opt.cpp b/clang/test/CIR/Transforms/lib-opt.cpp
new file mode 100644
index 0000000000000..ea4c265a1a584
--- /dev/null
+++ b/clang/test/CIR/Transforms/lib-opt.cpp
@@ -0,0 +1,3 @@
+// RUN: %clang_cc1 -fclangir -emit-cir -mmlir --mlir-print-ir-after-all %s -o - 2>&1 | FileCheck %s -check-prefix=CIR
+
+// CIR: IR Dump After LibOpt (cir-lib-opt)
``````````
</details>
https://github.com/llvm/llvm-project/pull/172487
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