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[CIR] Add support for comparisons between pointers to member functions #1390

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Feb 25, 2025
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[CIR] Add support for comparisons between pointers to member functions #1390

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4 changes: 4 additions & 0 deletions clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.h
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Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,10 @@ class CIRCXXABI {
mlir::Value loweredRhs,
mlir::OpBuilder &builder) const = 0;

virtual mlir::Value lowerMethodCmp(cir::CmpOp op, mlir::Value loweredLhs,
mlir::Value loweredRhs,
mlir::OpBuilder &builder) const = 0;

virtual mlir::Value
lowerDataMemberBitcast(cir::CastOp op, mlir::Type loweredDstTy,
mlir::Value loweredSrc,
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59 changes: 59 additions & 0 deletions clang/lib/CIR/Dialect/Transforms/TargetLowering/ItaniumCXXABI.cpp
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Expand Up @@ -103,6 +103,10 @@ class ItaniumCXXABI : public CIRCXXABI {
mlir::Value loweredRhs,
mlir::OpBuilder &builder) const override;

mlir::Value lowerMethodCmp(cir::CmpOp op, mlir::Value loweredLhs,
mlir::Value loweredRhs,
mlir::OpBuilder &builder) const override;

mlir::Value lowerDataMemberBitcast(cir::CastOp op, mlir::Type loweredDstTy,
mlir::Value loweredSrc,
mlir::OpBuilder &builder) const override;
Expand Down Expand Up @@ -478,6 +482,61 @@ mlir::Value ItaniumCXXABI::lowerDataMemberCmp(cir::CmpOp op,
loweredRhs);
}

mlir::Value ItaniumCXXABI::lowerMethodCmp(cir::CmpOp op, mlir::Value loweredLhs,
mlir::Value loweredRhs,
mlir::OpBuilder &builder) const {
assert(op.getKind() == cir::CmpOpKind::eq ||
op.getKind() == cir::CmpOpKind::ne);

cir::IntType ptrdiffCIRTy = getPtrDiffCIRTy(LM);
mlir::Value ptrdiffZero = builder.create<cir::ConstantOp>(
op.getLoc(), ptrdiffCIRTy, cir::IntAttr::get(ptrdiffCIRTy, 0));

mlir::Value lhsPtrField = builder.create<cir::ExtractMemberOp>(
op.getLoc(), ptrdiffCIRTy, loweredLhs, 0);
mlir::Value rhsPtrField = builder.create<cir::ExtractMemberOp>(
op.getLoc(), ptrdiffCIRTy, loweredRhs, 0);
mlir::Value ptrCmp = builder.create<cir::CmpOp>(op.getLoc(), op.getKind(),
lhsPtrField, rhsPtrField);
mlir::Value ptrCmpToNull = builder.create<cir::CmpOp>(
op.getLoc(), op.getKind(), lhsPtrField, ptrdiffZero);

mlir::Value lhsAdjField = builder.create<cir::ExtractMemberOp>(
op.getLoc(), ptrdiffCIRTy, loweredLhs, 1);
mlir::Value rhsAdjField = builder.create<cir::ExtractMemberOp>(
op.getLoc(), ptrdiffCIRTy, loweredRhs, 1);
mlir::Value adjCmp = builder.create<cir::CmpOp>(op.getLoc(), op.getKind(),
lhsAdjField, rhsAdjField);

// We use cir.select to represent "||" and "&&" operations below:
// - cir.select if %a then %b else false => %a && %b
// - cir.select if %a then true else %b => %a || %b
// TODO: Do we need to invent dedicated "cir.logical_or" and "cir.logical_and"
// operations for this?
auto boolTy = cir::BoolType::get(op.getContext());
mlir::Value trueValue = builder.create<cir::ConstantOp>(
op.getLoc(), boolTy, cir::BoolAttr::get(op.getContext(), boolTy, true));
mlir::Value falseValue = builder.create<cir::ConstantOp>(
op.getLoc(), boolTy, cir::BoolAttr::get(op.getContext(), boolTy, false));
auto create_and = [&](mlir::Value lhs, mlir::Value rhs) {
return builder.create<cir::SelectOp>(op.getLoc(), lhs, rhs, falseValue);
};
auto create_or = [&](mlir::Value lhs, mlir::Value rhs) {
return builder.create<cir::SelectOp>(op.getLoc(), lhs, trueValue, rhs);
};

mlir::Value result;
if (op.getKind() == cir::CmpOpKind::eq) {
// (lhs.ptr == null || lhs.adj == rhs.adj) && lhs.ptr == rhs.ptr
result = create_and(create_or(ptrCmpToNull, adjCmp), ptrCmp);
} else {
// (lhs.ptr != null && lhs.adj != rhs.adj) || lhs.ptr != rhs.ptr
result = create_or(create_and(ptrCmpToNull, adjCmp), ptrCmp);
}

return result;
}

mlir::Value
ItaniumCXXABI::lowerDataMemberBitcast(cir::CastOp op, mlir::Type loweredDstTy,
mlir::Value loweredSrc,
Expand Down
13 changes: 10 additions & 3 deletions clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
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Expand Up @@ -2893,10 +2893,17 @@ mlir::LogicalResult CIRToLLVMCmpOpLowering::matchAndRewrite(
mlir::ConversionPatternRewriter &rewriter) const {
auto type = cmpOp.getLhs().getType();

if (mlir::isa<cir::DataMemberType>(type)) {
if (mlir::isa<cir::DataMemberType, cir::MethodType>(type)) {
assert(lowerMod && "lowering module is not available");
mlir::Value loweredResult = lowerMod->getCXXABI().lowerDataMemberCmp(
cmpOp, adaptor.getLhs(), adaptor.getRhs(), rewriter);

mlir::Value loweredResult;
if (mlir::isa<cir::DataMemberType>(type))
loweredResult = lowerMod->getCXXABI().lowerDataMemberCmp(
cmpOp, adaptor.getLhs(), adaptor.getRhs(), rewriter);
else
loweredResult = lowerMod->getCXXABI().lowerMethodCmp(
cmpOp, adaptor.getLhs(), adaptor.getRhs(), rewriter);

rewriter.replaceOp(cmpOp, loweredResult);
return mlir::success();
}
Expand Down
40 changes: 40 additions & 0 deletions clang/test/CIR/CodeGen/pointer-to-member-func.cpp
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Expand Up @@ -78,3 +78,43 @@ void call(Foo *obj, void (Foo::*func)(int), int arg) {
// LLVM-NEXT: %[[#arg:]] = load i32, ptr %{{.+}}
// LLVM-NEXT: call void %[[#callee_ptr]](ptr %[[#adjusted_this]], i32 %[[#arg]])
// LLVM: }

bool cmp_eq(void (Foo::*lhs)(int), void (Foo::*rhs)(int)) {
return lhs == rhs;
}

// CHECK-LABEL: @_Z6cmp_eqM3FooFviES1_
// CHECK: %{{.+}} = cir.cmp(eq, %{{.+}}, %{{.+}}) : !cir.method<!cir.func<(!s32i)> in !ty_Foo>, !cir.bool

// LLVM-LABEL: @_Z6cmp_eqM3FooFviES1_
// LLVM: %[[#lhs:]] = load { i64, i64 }, ptr %{{.+}}
// LLVM-NEXT: %[[#rhs:]] = load { i64, i64 }, ptr %{{.+}}
// LLVM-NEXT: %[[#lhs_ptr:]] = extractvalue { i64, i64 } %[[#lhs]], 0
// LLVM-NEXT: %[[#rhs_ptr:]] = extractvalue { i64, i64 } %[[#rhs]], 0
// LLVM-NEXT: %[[#ptr_cmp:]] = icmp eq i64 %[[#lhs_ptr]], %[[#rhs_ptr]]
// LLVM-NEXT: %[[#ptr_null:]] = icmp eq i64 %[[#lhs_ptr]], 0
// LLVM-NEXT: %[[#lhs_adj:]] = extractvalue { i64, i64 } %[[#lhs]], 1
// LLVM-NEXT: %[[#rhs_adj:]] = extractvalue { i64, i64 } %[[#rhs]], 1
// LLVM-NEXT: %[[#adj_cmp:]] = icmp eq i64 %[[#lhs_adj]], %[[#rhs_adj]]
// LLVM-NEXT: %[[#tmp:]] = or i1 %[[#ptr_null]], %[[#adj_cmp]]
// LLVM-NEXT: %{{.+}} = and i1 %[[#tmp]], %[[#ptr_cmp]]

bool cmp_ne(void (Foo::*lhs)(int), void (Foo::*rhs)(int)) {
return lhs != rhs;
}

// CHECK-LABEL: @_Z6cmp_neM3FooFviES1_
// CHECK: %{{.+}} = cir.cmp(ne, %{{.+}}, %{{.+}}) : !cir.method<!cir.func<(!s32i)> in !ty_Foo>, !cir.bool

// LLVM-LABEL: @_Z6cmp_neM3FooFviES1_
// LLVM: %[[#lhs:]] = load { i64, i64 }, ptr %{{.+}}
// LLVM-NEXT: %[[#rhs:]] = load { i64, i64 }, ptr %{{.+}}
// LLVM-NEXT: %[[#lhs_ptr:]] = extractvalue { i64, i64 } %[[#lhs]], 0
// LLVM-NEXT: %[[#rhs_ptr:]] = extractvalue { i64, i64 } %[[#rhs]], 0
// LLVM-NEXT: %[[#ptr_cmp:]] = icmp ne i64 %[[#lhs_ptr]], %[[#rhs_ptr]]
// LLVM-NEXT: %[[#ptr_null:]] = icmp ne i64 %[[#lhs_ptr]], 0
// LLVM-NEXT: %[[#lhs_adj:]] = extractvalue { i64, i64 } %[[#lhs]], 1
// LLVM-NEXT: %[[#rhs_adj:]] = extractvalue { i64, i64 } %[[#rhs]], 1
// LLVM-NEXT: %[[#adj_cmp:]] = icmp ne i64 %[[#lhs_adj]], %[[#rhs_adj]]
// LLVM-NEXT: %[[#tmp:]] = and i1 %[[#ptr_null]], %[[#adj_cmp]]
// LLVM-NEXT: %{{.+}} = or i1 %[[#tmp]], %[[#ptr_cmp]]
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