[clang] [CIR] Initial implementation of CIR-to-LLVM IR lowering pass (PR #125260)
Andy Kaylor via cfe-commits
cfe-commits at lists.llvm.org
Fri Jan 31 09:46:03 PST 2025
https://github.com/andykaylor created https://github.com/llvm/llvm-project/pull/125260
This change introduces lowering from CIR to LLVM IR of global integer variables, using defaults for attributes that aren't yet implemented.
>From 4801886dd4c45d32891a7337ad7430a6c5137929 Mon Sep 17 00:00:00 2001
From: Andy Kaylor <akaylor at nvidia.com>
Date: Tue, 28 Jan 2025 12:28:58 -0800
Subject: [PATCH] [CIR] Initial implementation of CIR-to-LLVM IR lowering pass
This change introduces lowering from CIR to LLVM IR of global integer
variables, using defaults for attributes that aren't yet implemented.
---
clang/include/clang/CIR/LowerToLLVM.h | 22 ++-
.../CIR/Lowering/DirectToLLVM/CMakeLists.txt | 7 +
.../CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp | 130 +++++++++++++++++-
clang/test/CIR/Lowering/global-var-simple.cpp | 63 +++++++++
clang/test/CIR/Lowering/hello.c | 10 +-
5 files changed, 225 insertions(+), 7 deletions(-)
create mode 100644 clang/test/CIR/Lowering/global-var-simple.cpp
diff --git a/clang/include/clang/CIR/LowerToLLVM.h b/clang/include/clang/CIR/LowerToLLVM.h
index afa1c1923ed516c..1135dbcbe0354b8 100644
--- a/clang/include/clang/CIR/LowerToLLVM.h
+++ b/clang/include/clang/CIR/LowerToLLVM.h
@@ -12,7 +12,9 @@
#ifndef CLANG_CIR_LOWERTOLLVM_H
#define CLANG_CIR_LOWERTOLLVM_H
-#include "mlir/Pass/Pass.h"
+#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
+#include "mlir/Transforms/DialectConversion.h"
+#include "clang/CIR/Dialect/IR/CIRDialect.h"
#include <memory>
@@ -31,6 +33,24 @@ namespace direct {
std::unique_ptr<llvm::Module>
lowerDirectlyFromCIRToLLVMIR(mlir::ModuleOp mlirModule,
llvm::LLVMContext &llvmCtx);
+
+class CIRToLLVMGlobalOpLowering
+ : public mlir::OpConversionPattern<cir::GlobalOp> {
+ mlir::DataLayout const &dataLayout;
+
+public:
+ CIRToLLVMGlobalOpLowering(const mlir::TypeConverter &typeConverter,
+ mlir::MLIRContext *context,
+ mlir::DataLayout const &dataLayout)
+ : OpConversionPattern(typeConverter, context), dataLayout(dataLayout) {
+ setHasBoundedRewriteRecursion();
+ }
+
+ mlir::LogicalResult
+ matchAndRewrite(cir::GlobalOp op, OpAdaptor adaptor,
+ mlir::ConversionPatternRewriter &rewriter) const override;
+};
+
} // namespace direct
} // namespace cir
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/CMakeLists.txt b/clang/lib/CIR/Lowering/DirectToLLVM/CMakeLists.txt
index 0268234c3a28968..da802605676ac07 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/CMakeLists.txt
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/CMakeLists.txt
@@ -3,6 +3,13 @@ set(LLVM_LINK_COMPONENTS
Support
)
+get_property(dialect_libs GLOBAL PROPERTY MLIR_DIALECT_LIBS)
+
add_clang_library(clangCIRLoweringDirectToLLVM
LowerToLLVM.cpp
+
+ LINK_LIBS
+ ${dialect_libs}
+ MLIRBuiltinToLLVMIRTranslation
+ MLIRLLVMToLLVMIRTranslation
)
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
index 63d2b51b4283570..b24c41a93082d47 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
@@ -12,7 +12,19 @@
#include "clang/CIR/LowerToLLVM.h"
+#include "mlir/Conversion/LLVMCommon/TypeConverter.h"
+#include "mlir/Dialect/DLTI/DLTI.h"
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
+#include "mlir/IR/BuiltinDialect.h"
#include "mlir/IR/BuiltinOps.h"
+#include "mlir/Pass/Pass.h"
+#include "mlir/Pass/PassManager.h"
+#include "mlir/Target/LLVMIR/Dialect/Builtin/BuiltinToLLVMIRTranslation.h"
+#include "mlir/Target/LLVMIR/Dialect/LLVMIR/LLVMToLLVMIRTranslation.h"
+#include "mlir/Target/LLVMIR/Export.h"
+#include "mlir/Transforms/DialectConversion.h"
+#include "clang/CIR/Dialect/IR/CIRDialect.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/TimeProfiler.h"
@@ -22,13 +34,127 @@ using namespace llvm;
namespace cir {
namespace direct {
+struct ConvertCIRToLLVMPass
+ : public mlir::PassWrapper<ConvertCIRToLLVMPass,
+ mlir::OperationPass<mlir::ModuleOp>> {
+ void getDependentDialects(mlir::DialectRegistry ®istry) const override {
+ registry.insert<mlir::BuiltinDialect, mlir::DLTIDialect,
+ mlir::LLVM::LLVMDialect, mlir::func::FuncDialect>();
+ }
+ void runOnOperation() final;
+
+ StringRef getDescription() const override {
+ return "Convert the prepared CIR dialect module to LLVM dialect";
+ }
+
+ StringRef getArgument() const override { return "cir-flat-to-llvm"; }
+};
+
+mlir::LogicalResult CIRToLLVMGlobalOpLowering::matchAndRewrite(
+ cir::GlobalOp op, OpAdaptor adaptor,
+ mlir::ConversionPatternRewriter &rewriter) const {
+
+ // Fetch required values to create LLVM op.
+ const mlir::Type cirSymType = op.getSymType();
+
+ // This is the LLVM dialect type
+ const mlir::Type llvmType = getTypeConverter()->convertType(cirSymType);
+ // These defaults are just here until the equivalent attributes are
+ // available on cir.global ops.
+ const bool isConst = false;
+ const bool isDsoLocal = true;
+ const mlir::LLVM::Linkage linkage = mlir::LLVM::Linkage::External;
+ const StringRef symbol = op.getSymName();
+ std::optional<mlir::Attribute> init = op.getInitialValue();
+
+ SmallVector<mlir::NamedAttribute> attributes;
+
+ // Check for missing funcionalities.
+ if (!init.has_value()) {
+ rewriter.replaceOpWithNewOp<mlir::LLVM::GlobalOp>(
+ op, llvmType, isConst, linkage, symbol, mlir::Attribute(),
+ /*alignment*/ 0, /*addrSpace*/ 0, /*dsoLocal*/ isDsoLocal,
+ /*threadLocal*/ false, /*comdat*/ mlir::SymbolRefAttr(), attributes);
+ return mlir::success();
+ }
+
+ // Initializer is a constant array: convert it to a compatible llvm init.
+ if (auto intAttr = mlir::dyn_cast<cir::IntAttr>(init.value())) {
+ init = rewriter.getIntegerAttr(llvmType, intAttr.getValue());
+ } else {
+ op.emitError() << "unsupported initializer '" << init.value() << "'";
+ return mlir::failure();
+ }
+
+ // Rewrite op.
+ rewriter.replaceOpWithNewOp<mlir::LLVM::GlobalOp>(
+ op, llvmType, isConst, linkage, symbol, init.value(), /*alignment*/ 0,
+ /*addrSpace*/ 0, /*dsoLocal*/ isDsoLocal, /*threadLocal*/ false,
+ /*comdat*/ mlir::SymbolRefAttr(), attributes);
+
+ return mlir::success();
+}
+
+static void prepareTypeConverter(mlir::LLVMTypeConverter &converter,
+ mlir::DataLayout &dataLayout) {
+ converter.addConversion([&](cir::IntType type) -> mlir::Type {
+ // LLVM doesn't work with signed types, so we drop the CIR signs here.
+ return mlir::IntegerType::get(type.getContext(), type.getWidth());
+ });
+}
+
+void ConvertCIRToLLVMPass::runOnOperation() {
+ llvm::TimeTraceScope scope("Convert CIR to LLVM Pass");
+
+ mlir::ModuleOp module = getOperation();
+ mlir::DataLayout dl(module);
+ mlir::LLVMTypeConverter converter(&getContext());
+ prepareTypeConverter(converter, dl); // , lowerModule.get());
+
+ mlir::RewritePatternSet patterns(&getContext());
+
+ patterns.add<CIRToLLVMGlobalOpLowering>(converter, patterns.getContext(), dl);
+
+ mlir::ConversionTarget target(getContext());
+ target.addLegalOp<mlir::ModuleOp>();
+ target.addLegalDialect<mlir::LLVM::LLVMDialect>();
+ target.addIllegalDialect<mlir::BuiltinDialect, cir::CIRDialect,
+ mlir::func::FuncDialect>();
+
+ if (failed(applyPartialConversion(module, target, std::move(patterns))))
+ signalPassFailure();
+}
+
+static std::unique_ptr<mlir::Pass> createConvertCIRToLLVMPass() {
+ return std::make_unique<ConvertCIRToLLVMPass>();
+}
+
+static void populateCIRToLLVMPasses(mlir::OpPassManager &pm) {
+ pm.addPass(createConvertCIRToLLVMPass());
+}
+
std::unique_ptr<llvm::Module>
lowerDirectlyFromCIRToLLVMIR(mlir::ModuleOp mlirModule, LLVMContext &llvmCtx) {
llvm::TimeTraceScope scope("lower from CIR to LLVM directly");
+ mlir::MLIRContext *mlirCtx = mlirModule.getContext();
+
+ mlir::PassManager pm(mlirCtx);
+ populateCIRToLLVMPasses(pm);
+
+ bool result = !mlir::failed(pm.run(mlirModule));
+ if (!result)
+ report_fatal_error(
+ "The pass manager failed to lower CIR to LLVMIR dialect!");
+
+ mlir::registerBuiltinDialectTranslation(*mlirCtx);
+ mlir::registerLLVMDialectTranslation(*mlirCtx);
+
+ llvm::TimeTraceScope translateScope("translateModuleToLLVMIR");
+
std::optional<StringRef> moduleName = mlirModule.getName();
- auto llvmModule = std::make_unique<llvm::Module>(
- moduleName ? *moduleName : "CIRToLLVMModule", llvmCtx);
+ std::unique_ptr<llvm::Module> llvmModule = mlir::translateModuleToLLVMIR(
+ mlirModule, llvmCtx, moduleName ? *moduleName : "CIRToLLVMModule");
if (!llvmModule)
report_fatal_error("Lowering from LLVMIR dialect to llvm IR failed!");
diff --git a/clang/test/CIR/Lowering/global-var-simple.cpp b/clang/test/CIR/Lowering/global-var-simple.cpp
new file mode 100644
index 000000000000000..e8d2138de3f58ba
--- /dev/null
+++ b/clang/test/CIR/Lowering/global-var-simple.cpp
@@ -0,0 +1,63 @@
+// Global variables of intergal types
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - | FileCheck %s
+
+// Note: Currently unsupported features include default zero-initialization
+// and alignment. The fact that "external" is only printed for globals
+// without an initializer is a quirk of the LLVM AsmWriter.
+
+char c;
+// CHECK: @c = external dso_local global i8
+
+signed char sc;
+// CHECK: @sc = external dso_local global i8
+
+unsigned char uc;
+// CHECK: @uc = external dso_local global i8
+
+short ss;
+// CHECK: @ss = external dso_local global i16
+
+unsigned short us = 100;
+// CHECK: @us = dso_local global i16 100
+
+int si = 42;
+// CHECK: @si = dso_local global i32 42
+
+unsigned ui;
+// CHECK: @ui = external dso_local global i32
+
+long sl;
+// CHECK: @sl = external dso_local global i64
+
+unsigned long ul;
+// CHECK: @ul = external dso_local global i64
+
+long long sll;
+// CHECK: @sll = external dso_local global i64
+
+unsigned long long ull = 123456;
+// CHECK: @ull = dso_local global i64 123456
+
+__int128 s128;
+// CHECK: @s128 = external dso_local global i128
+
+unsigned __int128 u128;
+// CHECK: @u128 = external dso_local global i128
+
+wchar_t wc;
+// CHECK: @wc = external dso_local global i32
+
+char8_t c8;
+// CHECK: @c8 = external dso_local global i8
+
+char16_t c16;
+// CHECK: @c16 = external dso_local global i16
+
+char32_t c32;
+// CHECK: @c32 = external dso_local global i32
+
+_BitInt(20) sb20;
+// CHECK: @sb20 = external dso_local global i20
+
+unsigned _BitInt(48) ub48;
+// CHECK: @ub48 = external dso_local global i48
diff --git a/clang/test/CIR/Lowering/hello.c b/clang/test/CIR/Lowering/hello.c
index 320041f0ab7dc90..ff78b6e6f6a5e2a 100644
--- a/clang/test/CIR/Lowering/hello.c
+++ b/clang/test/CIR/Lowering/hello.c
@@ -1,8 +1,10 @@
// Smoke test for ClangIR-to-LLVM IR code generation
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - | FileCheck %s
-// TODO: Add checks when proper lowering is implemented.
-// For now, we're just creating an empty module.
-// CHECK: ModuleID
+int a;
-void foo() {}
+// CHECK: @a = external dso_local global i32
+
+int b = 2;
+
+// CHECK: @b = dso_local global i32 2
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