https://github.com/andykaylor updated
https://github.com/llvm/llvm-project/pull/153243
>From 5e3ab0b4e314b970eb1f1d61aa2d05a0de2cfc55 Mon Sep 17 00:00:00 2001
From: Andy Kaylor <akay...@nvidia.com>
Date: Thu, 7 Aug 2025 17:15:17 -0700
Subject: [PATCH 1/2] [CIR] Add lowering for the cir.vtable.address_point
operation
This adds support for lowering the cir.vtable.address_point
operation to the LLVM dialect, as well as type converter support
for the cir.vptr type.
---
.../CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp | 47 ++++++++++++++++++-
.../CIR/Lowering/DirectToLLVM/LowerToLLVM.h | 10 ++++
.../CIR/CodeGen/virtual-function-calls.cpp | 26 +++++++++-
3 files changed, 81 insertions(+), 2 deletions(-)
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
index ad5f52034f92a..f9486addcb4ac 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
@@ -2083,6 +2083,10 @@ static void prepareTypeConverter(mlir::LLVMTypeConverter
&converter,
return mlir::LLVM::LLVMPointerType::get(type.getContext(), targetAS);
});
+ converter.addConversion([&](cir::VPtrType type) -> mlir::Type {
+ assert(!cir::MissingFeatures::addressSpace());
+ return mlir::LLVM::LLVMPointerType::get(type.getContext());
+ });
converter.addConversion([&](cir::ArrayType type) -> mlir::Type {
mlir::Type ty =
convertTypeForMemory(converter, dataLayout, type.getElementType());
@@ -2314,6 +2318,7 @@ void ConvertCIRToLLVMPass::runOnOperation() {
CIRToLLVMSwitchFlatOpLowering,
CIRToLLVMTrapOpLowering,
CIRToLLVMUnaryOpLowering,
+ CIRToLLVMUnreachableOpLowering,
CIRToLLVMVecCmpOpLowering,
CIRToLLVMVecCreateOpLowering,
CIRToLLVMVecExtractOpLowering,
@@ -2322,7 +2327,8 @@ void ConvertCIRToLLVMPass::runOnOperation() {
CIRToLLVMVecShuffleOpLowering,
CIRToLLVMVecSplatOpLowering,
CIRToLLVMVecTernaryOpLowering,
- CIRToLLVMUnreachableOpLowering
+ CIRToLLVMVTableAddrPointOpLowering
+ // clang-format on
>(converter, patterns.getContext());
processCIRAttrs(module);
@@ -2400,6 +2406,45 @@ mlir::LogicalResult
CIRToLLVMTrapOpLowering::matchAndRewrite(
return mlir::success();
}
+static mlir::Value
+getValueForVTableSymbol(mlir::Operation *op,
+ mlir::ConversionPatternRewriter &rewriter,
+ const mlir::TypeConverter *converter,
+ mlir::FlatSymbolRefAttr nameAttr, mlir::Type &eltType)
{
+ auto module = op->getParentOfType<mlir::ModuleOp>();
+ mlir::Operation *symbol = mlir::SymbolTable::lookupSymbolIn(module,
nameAttr);
+ if (auto llvmSymbol = mlir::dyn_cast<mlir::LLVM::GlobalOp>(symbol))
+ eltType = llvmSymbol.getType();
+ else if (auto cirSymbol = mlir::dyn_cast<cir::GlobalOp>(symbol))
+ eltType = converter->convertType(cirSymbol.getSymType());
+
+ return mlir::LLVM::AddressOfOp::create(
+ rewriter, op->getLoc(),
+ mlir::LLVM::LLVMPointerType::get(op->getContext()), nameAttr.getValue());
+}
+
+mlir::LogicalResult CIRToLLVMVTableAddrPointOpLowering::matchAndRewrite(
+ cir::VTableAddrPointOp op, OpAdaptor adaptor,
+ mlir::ConversionPatternRewriter &rewriter) const {
+ const mlir::TypeConverter *converter = getTypeConverter();
+ mlir::Type targetType = converter->convertType(op.getType());
+ llvm::SmallVector<mlir::LLVM::GEPArg> offsets;
+ mlir::Type eltType;
+ mlir::Value symAddr = getValueForVTableSymbol(op, rewriter, converter,
+ op.getNameAttr(), eltType);
+ offsets = llvm::SmallVector<mlir::LLVM::GEPArg>{
+ 0, op.getAddressPointAttr().getIndex(),
+ op.getAddressPointAttr().getOffset()};
+
+ assert(eltType && "Shouldn't ever be missing an eltType here");
+ mlir::LLVM::GEPNoWrapFlags inboundsNuw =
+ mlir::LLVM::GEPNoWrapFlags::inbounds | mlir::LLVM::GEPNoWrapFlags::nuw;
+ rewriter.replaceOpWithNewOp<mlir::LLVM::GEPOp>(op, targetType, eltType,
+ symAddr, offsets,
inboundsNuw);
+
+ return mlir::success();
+}
+
mlir::LogicalResult CIRToLLVMStackSaveOpLowering::matchAndRewrite(
cir::StackSaveOp op, OpAdaptor adaptor,
mlir::ConversionPatternRewriter &rewriter) const {
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h
b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h
index a6d2d6559005b..6fbe0079b90d0 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h
@@ -457,6 +457,16 @@ class CIRToLLVMBaseClassAddrOpLowering
mlir::ConversionPatternRewriter &) const override;
};
+class CIRToLLVMVTableAddrPointOpLowering
+ : public mlir::OpConversionPattern<cir::VTableAddrPointOp> {
+public:
+ using mlir::OpConversionPattern<cir::VTableAddrPointOp>::OpConversionPattern;
+
+ mlir::LogicalResult
+ matchAndRewrite(cir::VTableAddrPointOp op, OpAdaptor,
+ mlir::ConversionPatternRewriter &) const override;
+};
+
class CIRToLLVMStackSaveOpLowering
: public mlir::OpConversionPattern<cir::StackSaveOp> {
public:
diff --git a/clang/test/CIR/CodeGen/virtual-function-calls.cpp
b/clang/test/CIR/CodeGen/virtual-function-calls.cpp
index f3b134b135c85..004b6dab30563 100644
--- a/clang/test/CIR/CodeGen/virtual-function-calls.cpp
+++ b/clang/test/CIR/CodeGen/virtual-function-calls.cpp
@@ -1,5 +1,9 @@
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -mconstructor-aliases
-fclangir -emit-cir %s -o %t.cir
// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -mconstructor-aliases
-fclangir -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --input-file=%t-cir.ll %s -check-prefix=LLVM
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -mconstructor-aliases
-emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=OGCG
struct A {
A();
@@ -14,7 +18,11 @@ A::A() {}
// CIR: cir.global "private" external @_ZTV1A : !rec_anon_struct
-// CIR: cir.func dso_local @_ZN1AC2Ev(%arg0: !cir.ptr<!rec_A> {{.*}})
+// LLVM: @_ZTV1A = external global { [3 x ptr] }
+
+// OGCG: @_ZTV1A = external unnamed_addr constant { [3 x ptr] }
+
+// CIR: cir.func{{.*}} @_ZN1AC2Ev(%arg0: !cir.ptr<!rec_A> {{.*}})
// CIR: %[[THIS_ADDR:.*]] = cir.alloca !cir.ptr<!rec_A>,
!cir.ptr<!cir.ptr<!rec_A>>, ["this", init]
// CIR: cir.store %arg0, %[[THIS_ADDR]] : !cir.ptr<!rec_A>,
!cir.ptr<!cir.ptr<!rec_A>>
// CIR: %[[THIS:.*]] = cir.load %[[THIS_ADDR]] :
!cir.ptr<!cir.ptr<!rec_A>>, !cir.ptr<!rec_A>
@@ -22,3 +30,19 @@ A::A() {}
// CIR: %[[THIS_VPTR_PTR:.*]] = cir.cast(bitcast, %[[THIS]] :
!cir.ptr<!rec_A>), !cir.ptr<!cir.vptr>
// CIR: cir.store align(8) %[[VPTR]], %[[THIS_VPTR_PTR]] : !cir.vptr,
!cir.ptr<!cir.vptr>
// CIR: cir.return
+
+// LLVM: define{{.*}} void @_ZN1AC2Ev(ptr %[[ARG0:.*]])
+// LLVM: %[[THIS_ADDR:.*]] = alloca ptr
+// LLVM: store ptr %[[ARG0]], ptr %[[THIS_ADDR]]
+// LLVM: %[[THIS:.*]] = load ptr, ptr %[[THIS_ADDR]]
+// LLVM: store ptr getelementptr inbounds nuw (i8, ptr @_ZTV1A, i64 16), ptr
%[[THIS]]
+
+// OGCG: define{{.*}} void @_ZN1AC2Ev(ptr {{.*}} %[[ARG0:.*]])
+// OGCG: %[[THIS_ADDR:.*]] = alloca ptr
+// OGCG: store ptr %[[ARG0]], ptr %[[THIS_ADDR]]
+// OGCG: %[[THIS:.*]] = load ptr, ptr %[[THIS_ADDR]]
+// OGCG: store ptr getelementptr inbounds inrange(-16, 8) ({ [3 x ptr] },
ptr @_ZTV1A, i32 0, i32 0, i32 2), ptr %[[THIS]]
+
+// NOTE: The GEP in OGCG looks very different from the one generated with CIR,
+// but it is equivalent. The OGCG GEP indexes by base pointer, then
+// structure, then array, whereas the CIR GEP indexes by byte offset.
>From 7ac51e76d5a41ec77b95e3ef4b2470b99e1661fc Mon Sep 17 00:00:00 2001
From: Andy Kaylor <akay...@nvidia.com>
Date: Wed, 13 Aug 2025 16:52:07 -0700
Subject: [PATCH 2/2] Address feedback
---
clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
index f9486addcb4ac..c3715c28f6890 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
@@ -2413,10 +2413,14 @@ getValueForVTableSymbol(mlir::Operation *op,
mlir::FlatSymbolRefAttr nameAttr, mlir::Type &eltType)
{
auto module = op->getParentOfType<mlir::ModuleOp>();
mlir::Operation *symbol = mlir::SymbolTable::lookupSymbolIn(module,
nameAttr);
- if (auto llvmSymbol = mlir::dyn_cast<mlir::LLVM::GlobalOp>(symbol))
+ if (auto llvmSymbol = mlir::dyn_cast<mlir::LLVM::GlobalOp>(symbol)) {
eltType = llvmSymbol.getType();
- else if (auto cirSymbol = mlir::dyn_cast<cir::GlobalOp>(symbol))
+ } else if (auto cirSymbol = mlir::dyn_cast<cir::GlobalOp>(symbol)) {
eltType = converter->convertType(cirSymbol.getSymType());
+ } else {
+ op->emitError() << "unexpected symbol type for " << symbol;
+ return {};
+ }
return mlir::LLVM::AddressOfOp::create(
rewriter, op->getLoc(),
@@ -2432,6 +2436,9 @@ mlir::LogicalResult
CIRToLLVMVTableAddrPointOpLowering::matchAndRewrite(
mlir::Type eltType;
mlir::Value symAddr = getValueForVTableSymbol(op, rewriter, converter,
op.getNameAttr(), eltType);
+ if (!symAddr)
+ return op.emitError() << "Unable to get value for vtable symbol";
+
offsets = llvm::SmallVector<mlir::LLVM::GEPArg>{
0, op.getAddressPointAttr().getIndex(),
op.getAddressPointAttr().getOffset()};
@@ -2441,7 +2448,6 @@ mlir::LogicalResult
CIRToLLVMVTableAddrPointOpLowering::matchAndRewrite(
mlir::LLVM::GEPNoWrapFlags::inbounds | mlir::LLVM::GEPNoWrapFlags::nuw;
rewriter.replaceOpWithNewOp<mlir::LLVM::GEPOp>(op, targetType, eltType,
symAddr, offsets,
inboundsNuw);
-
return mlir::success();
}
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