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[CIR] CIRGen for bit cast builtin (#762)
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This PR adds CIRGen support for the `__builtin_bit_cast` builtin. No new
operations are added so the LLVM IR lowering is also added
automatically.
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@Lancern @lanza
Lancern authored and lanza committed Nov 3, 2024
1 parent 79cb853 commit e5cefb7
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Showing 3 changed files with 179 additions and 4 deletions.
24 changes: 24 additions & 0 deletions clang/lib/CIR/CodeGen/CIRGenExprAgg.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -907,6 +907,30 @@ void AggExprEmitter::VisitCastExpr(CastExpr *E) {
if (const auto *ECE = dyn_cast<ExplicitCastExpr>(E))
CGF.CGM.buildExplicitCastExprType(ECE, &CGF);
switch (E->getCastKind()) {
case CK_LValueToRValueBitCast: {
if (Dest.isIgnored()) {
CGF.buildAnyExpr(E->getSubExpr(), AggValueSlot::ignored(),
/*ignoreResult=*/true);
break;
}

LValue SourceLV = CGF.buildLValue(E->getSubExpr());
Address SourceAddress = SourceLV.getAddress();
Address DestAddress = Dest.getAddress();

auto Loc = CGF.getLoc(E->getExprLoc());
mlir::Value SrcPtr = CGF.getBuilder().createBitcast(
Loc, SourceAddress.getPointer(), CGF.VoidPtrTy);
mlir::Value DstPtr = CGF.getBuilder().createBitcast(
Loc, DestAddress.getPointer(), CGF.VoidPtrTy);

mlir::Value SizeVal = CGF.getBuilder().getConstInt(
Loc, CGF.SizeTy,
CGF.getContext().getTypeSizeInChars(E->getType()).getQuantity());
CGF.getBuilder().createMemCpy(Loc, DstPtr, SrcPtr, SizeVal);

break;
}

case CK_LValueToRValue:
// If we're loading from a volatile type, force the destination
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23 changes: 19 additions & 4 deletions clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
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Expand Up @@ -1548,11 +1548,26 @@ mlir::Value ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
llvm_unreachable("builtin functions are handled elsewhere");

case CK_LValueBitCast:
llvm_unreachable("NYI");
case CK_ObjCObjectLValueCast:
llvm_unreachable("NYI");
case CK_LValueToRValueBitCast:
llvm_unreachable("NYI");
case CK_LValueToRValueBitCast: {
LValue SourceLVal = CGF.buildLValue(E);
Address SourceAddr = SourceLVal.getAddress();

mlir::Type DestElemTy = CGF.convertTypeForMem(DestTy);
mlir::Type DestPtrTy = CGF.getBuilder().getPointerTo(DestElemTy);
mlir::Value DestPtr = CGF.getBuilder().createBitcast(
CGF.getLoc(E->getExprLoc()), SourceAddr.getPointer(), DestPtrTy);

Address DestAddr =
SourceAddr.withPointer(DestPtr).withElementType(DestElemTy);
LValue DestLVal = CGF.makeAddrLValue(DestAddr, DestTy);

if (Kind == CK_LValueToRValueBitCast)
assert(!MissingFeatures::tbaa());

return buildLoadOfLValue(DestLVal, CE->getExprLoc());
}

case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:
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136 changes: 136 additions & 0 deletions clang/test/CIR/CodeGen/builtin-bit-cast.cpp
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@@ -0,0 +1,136 @@
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++20 -fclangir -emit-cir %s -o %t.cir
// RUN: FileCheck --input-file=%t.cir --check-prefix=CIR %s
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++20 -fclangir -emit-llvm %s -o %t.ll
// RUN: FileCheck --input-file=%t.ll --check-prefix=LLVM %s

float test_scalar(int &oper) {
return __builtin_bit_cast(float, oper);
}

// CIR-LABEL: cir.func @_Z11test_scalarRi
// CIR: %[[#SRC_PTR:]] = cir.load %{{.+}} : !cir.ptr<!cir.ptr<!s32i>>, !cir.ptr<!s32i>
// CIR-NEXT: %[[#DST_PTR:]] = cir.cast(bitcast, %[[#SRC_PTR]] : !cir.ptr<!s32i>), !cir.ptr<!cir.float>
// CIR-NEXT: %{{.+}} = cir.load %[[#DST_PTR]] : !cir.ptr<!cir.float>, !cir.float
// CIR: }

// LLVM-LABEL: define dso_local float @_Z11test_scalarRi
// LLVM: %[[#PTR:]] = load ptr, ptr %{{.+}}, align 8
// LLVM-NEXT: %{{.+}} = load float, ptr %[[#PTR]], align 4
// LLVM: }

struct two_ints {
int x;
int y;
};

unsigned long test_aggregate_to_scalar(two_ints &ti) {
return __builtin_bit_cast(unsigned long, ti);
}

// CIR-LABEL: cir.func @_Z24test_aggregate_to_scalarR8two_ints
// CIR: %[[#SRC_PTR:]] = cir.load %{{.+}} : !cir.ptr<!cir.ptr<!ty_22two_ints22>>, !cir.ptr<!ty_22two_ints22>
// CIR-NEXT: %[[#DST_PTR:]] = cir.cast(bitcast, %[[#SRC_PTR]] : !cir.ptr<!ty_22two_ints22>), !cir.ptr<!u64i>
// CIR-NEXT: %{{.+}} = cir.load %[[#DST_PTR]] : !cir.ptr<!u64i>, !u64i
// CIR: }

// LLVM-LABEL: define dso_local i64 @_Z24test_aggregate_to_scalarR8two_ints
// LLVM: %[[#PTR:]] = load ptr, ptr %{{.+}}, align 8
// LLVM-NEXT: %{{.+}} = load i64, ptr %[[#PTR]], align 8
// LLVM: }

struct two_floats {
float x;
float y;
};

two_floats test_aggregate_record(two_ints& ti) {
return __builtin_bit_cast(two_floats, ti);
}

// CIR-LABEL: cir.func @_Z21test_aggregate_recordR8two_ints
// CIR: %[[#SRC_PTR:]] = cir.load %{{.+}} : !cir.ptr<!cir.ptr<!ty_22two_ints22>>, !cir.ptr<!ty_22two_ints22>
// CIR-NEXT: %[[#SRC_VOID_PTR:]] = cir.cast(bitcast, %[[#SRC_PTR]] : !cir.ptr<!ty_22two_ints22>), !cir.ptr<!void>
// CIR-NEXT: %[[#DST_VOID_PTR:]] = cir.cast(bitcast, %{{.+}} : !cir.ptr<!ty_22two_floats22>), !cir.ptr<!void>
// CIR-NEXT: %[[#SIZE:]] = cir.const #cir.int<8> : !u64i
// CIR-NEXT: cir.libc.memcpy %[[#SIZE]] bytes from %[[#SRC_VOID_PTR]] to %[[#DST_VOID_PTR]] : !u64i, !cir.ptr<!void> -> !cir.ptr<!void>
// CIR: }

// LLVM-LABEL: define dso_local %struct.two_floats @_Z21test_aggregate_recordR8two_ints
// LLVM: %[[#DST_SLOT:]] = alloca %struct.two_floats, i64 1, align 4
// LLVM: %[[#SRC_PTR:]] = load ptr, ptr %2, align 8
// LLVM-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr %[[#DST_SLOT]], ptr %[[#SRC_PTR]], i64 8, i1 false)
// LLVM-NEXT: %{{.+}} = load %struct.two_floats, ptr %[[#DST_SLOT]], align 4
// LLVM: }

two_floats test_aggregate_array(int (&ary)[2]) {
return __builtin_bit_cast(two_floats, ary);
}

// CIR-LABEL: cir.func @_Z20test_aggregate_arrayRA2_i
// CIR: %[[#SRC_PTR:]] = cir.load %{{.+}} : !cir.ptr<!cir.ptr<!cir.array<!s32i x 2>>>, !cir.ptr<!cir.array<!s32i x 2>>
// CIR-NEXT: %[[#SRC_VOID_PTR:]] = cir.cast(bitcast, %[[#SRC_PTR]] : !cir.ptr<!cir.array<!s32i x 2>>), !cir.ptr<!void>
// CIR-NEXT: %[[#DST_VOID_PTR:]] = cir.cast(bitcast, %{{.+}} : !cir.ptr<!ty_22two_floats22>), !cir.ptr<!void>
// CIR-NEXT: %[[#SIZE:]] = cir.const #cir.int<8> : !u64i
// CIR-NEXT: cir.libc.memcpy %[[#SIZE]] bytes from %[[#SRC_VOID_PTR]] to %[[#DST_VOID_PTR]] : !u64i, !cir.ptr<!void> -> !cir.ptr<!void>
// CIR: }

// LLVM-LABEL: define dso_local %struct.two_floats @_Z20test_aggregate_arrayRA2_i
// LLVM: %[[#DST_SLOT:]] = alloca %struct.two_floats, i64 1, align 4
// LLVM: %[[#SRC_PTR:]] = load ptr, ptr %2, align 8
// LLVM-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr %[[#DST_SLOT]], ptr %[[#SRC_PTR]], i64 8, i1 false)
// LLVM-NEXT: %{{.+}} = load %struct.two_floats, ptr %[[#DST_SLOT]], align 4
// LLVM: }

two_ints test_scalar_to_aggregate(unsigned long ul) {
return __builtin_bit_cast(two_ints, ul);
}

// CIR-LABEL: cir.func @_Z24test_scalar_to_aggregatem
// CIR: %[[#SRC_VOID_PTR:]] = cir.cast(bitcast, %{{.+}} : !cir.ptr<!u64i>), !cir.ptr<!void>
// CIR-NEXT: %[[#DST_VOID_PTR:]] = cir.cast(bitcast, %{{.+}} : !cir.ptr<!ty_22two_ints22>), !cir.ptr<!void>
// CIR-NEXT: %[[#SIZE:]] = cir.const #cir.int<8> : !u64i
// CIR-NEXT: cir.libc.memcpy %[[#SIZE]] bytes from %[[#SRC_VOID_PTR]] to %[[#DST_VOID_PTR]] : !u64i, !cir.ptr<!void> -> !cir.ptr<!void>
// CIR: }

// LLVM-LABEL: define dso_local %struct.two_ints @_Z24test_scalar_to_aggregatem
// LLVM: %[[#DST_SLOT:]] = alloca %struct.two_ints, i64 1, align 4
// LLVM: call void @llvm.memcpy.p0.p0.i64(ptr %[[#DST_SLOT]], ptr %{{.+}}, i64 8, i1 false)
// LLVM-NEXT: %{{.+}} = load %struct.two_ints, ptr %[[#DST_SLOT]], align 4
// LLVM: }

unsigned long test_array(int (&ary)[2]) {
return __builtin_bit_cast(unsigned long, ary);
}

// CIR-LABEL: cir.func @_Z10test_arrayRA2_i
// CIR: %[[#SRC_PTR:]] = cir.load %{{.+}} : !cir.ptr<!cir.ptr<!cir.array<!s32i x 2>>>, !cir.ptr<!cir.array<!s32i x 2>>
// CIR-NEXT: %[[#DST_PTR:]] = cir.cast(bitcast, %[[#SRC_PTR]] : !cir.ptr<!cir.array<!s32i x 2>>), !cir.ptr<!u64i>
// CIR-NEXT: %{{.+}} = cir.load %[[#DST_PTR]] : !cir.ptr<!u64i>, !u64i
// CIR: }

// LLVM-LABEL: define dso_local i64 @_Z10test_arrayRA2_i
// LLVM: %[[#SRC_PTR:]] = load ptr, ptr %{{.+}}, align 8
// LLVM-NEXT: %{{.+}} = load i64, ptr %[[#SRC_PTR]], align 8
// LLVM: }

two_ints test_rvalue_aggregate() {
return __builtin_bit_cast(two_ints, 42ul);
}

// CIR-LABEL: cir.func @_Z21test_rvalue_aggregatev()
// CIR: cir.scope {
// CIR-NEXT: %[[#TMP_SLOT:]] = cir.alloca !u64i, !cir.ptr<!u64i>
// CIR-NEXT: %[[#A:]] = cir.const #cir.int<42> : !u64i
// CIR-NEXT: cir.store %[[#A]], %[[#TMP_SLOT]] : !u64i, !cir.ptr<!u64i>
// CIR-NEXT: %[[#SRC_VOID_PTR:]] = cir.cast(bitcast, %[[#TMP_SLOT]] : !cir.ptr<!u64i>), !cir.ptr<!void>
// CIR-NEXT: %[[#DST_VOID_PTR:]] = cir.cast(bitcast, %0 : !cir.ptr<!ty_22two_ints22>), !cir.ptr<!void>
// CIR-NEXT: %[[#SIZE:]] = cir.const #cir.int<8> : !u64i
// CIR-NEXT: cir.libc.memcpy %[[#SIZE]] bytes from %[[#SRC_VOID_PTR]] to %[[#DST_VOID_PTR]] : !u64i, !cir.ptr<!void> -> !cir.ptr<!void>
// CIR-NEXT: }
// CIR: }

// LLVM-LABEL: define dso_local %struct.two_ints @_Z21test_rvalue_aggregatev
// LLVM: %[[#SRC_SLOT:]] = alloca i64, i64 1, align 8
// LLVM-NEXT: store i64 42, ptr %[[#SRC_SLOT]], align 8
// LLVM-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr %{{.+}}, ptr %[[#SRC_SLOT]], i64 8, i1 false)
// LLVM: }

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