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[CIR] CIRGen for bit cast builtin (#762)
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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3 files changed

+179
-4
lines changed

3 files changed

+179
-4
lines changed

‎clang/lib/CIR/CodeGen/CIRGenExprAgg.cpp

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -907,6 +907,30 @@ void AggExprEmitter::VisitCastExpr(CastExpr *E) {
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if (const auto *ECE = dyn_cast<ExplicitCastExpr>(E))
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CGF.CGM.buildExplicitCastExprType(ECE, &CGF);
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switch (E->getCastKind()) {
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case CK_LValueToRValueBitCast: {
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if (Dest.isIgnored()) {
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CGF.buildAnyExpr(E->getSubExpr(), AggValueSlot::ignored(),
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/*ignoreResult=*/true);
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break;
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}
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LValue SourceLV = CGF.buildLValue(E->getSubExpr());
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Address SourceAddress = SourceLV.getAddress();
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Address DestAddress = Dest.getAddress();
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auto Loc = CGF.getLoc(E->getExprLoc());
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mlir::Value SrcPtr = CGF.getBuilder().createBitcast(
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Loc, SourceAddress.getPointer(), CGF.VoidPtrTy);
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mlir::Value DstPtr = CGF.getBuilder().createBitcast(
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Loc, DestAddress.getPointer(), CGF.VoidPtrTy);
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mlir::Value SizeVal = CGF.getBuilder().getConstInt(
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Loc, CGF.SizeTy,
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CGF.getContext().getTypeSizeInChars(E->getType()).getQuantity());
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CGF.getBuilder().createMemCpy(Loc, DstPtr, SrcPtr, SizeVal);
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break;
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}
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case CK_LValueToRValue:
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// If we're loading from a volatile type, force the destination

‎clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

Lines changed: 19 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1548,11 +1548,26 @@ mlir::Value ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
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llvm_unreachable("builtin functions are handled elsewhere");
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case CK_LValueBitCast:
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llvm_unreachable("NYI");
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case CK_ObjCObjectLValueCast:
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llvm_unreachable("NYI");
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case CK_LValueToRValueBitCast:
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llvm_unreachable("NYI");
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case CK_LValueToRValueBitCast: {
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LValue SourceLVal = CGF.buildLValue(E);
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Address SourceAddr = SourceLVal.getAddress();
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mlir::Type DestElemTy = CGF.convertTypeForMem(DestTy);
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mlir::Type DestPtrTy = CGF.getBuilder().getPointerTo(DestElemTy);
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mlir::Value DestPtr = CGF.getBuilder().createBitcast(
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CGF.getLoc(E->getExprLoc()), SourceAddr.getPointer(), DestPtrTy);
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Address DestAddr =
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SourceAddr.withPointer(DestPtr).withElementType(DestElemTy);
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LValue DestLVal = CGF.makeAddrLValue(DestAddr, DestTy);
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if (Kind == CK_LValueToRValueBitCast)
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assert(!MissingFeatures::tbaa());
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return buildLoadOfLValue(DestLVal, CE->getExprLoc());
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}
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case CK_CPointerToObjCPointerCast:
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case CK_BlockPointerToObjCPointerCast:
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case CK_AnyPointerToBlockPointerCast:

‎clang/test/CIR/CodeGen/builtin-bit-cast.cpp

Lines changed: 136 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,136 @@
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// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++20 -fclangir -emit-cir %s -o %t.cir
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// RUN: FileCheck --input-file=%t.cir --check-prefix=CIR %s
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// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++20 -fclangir -emit-llvm %s -o %t.ll
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// RUN: FileCheck --input-file=%t.ll --check-prefix=LLVM %s
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float test_scalar(int &oper) {
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return __builtin_bit_cast(float, oper);
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}
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// CIR-LABEL: cir.func @_Z11test_scalarRi
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// CIR: %[[#SRC_PTR:]] = cir.load %{{.+}} : !cir.ptr<!cir.ptr<!s32i>>, !cir.ptr<!s32i>
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// CIR-NEXT: %[[#DST_PTR:]] = cir.cast(bitcast, %[[#SRC_PTR]] : !cir.ptr<!s32i>), !cir.ptr<!cir.float>
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// CIR-NEXT: %{{.+}} = cir.load %[[#DST_PTR]] : !cir.ptr<!cir.float>, !cir.float
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// CIR: }
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// LLVM-LABEL: define dso_local float @_Z11test_scalarRi
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// LLVM: %[[#PTR:]] = load ptr, ptr %{{.+}}, align 8
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// LLVM-NEXT: %{{.+}} = load float, ptr %[[#PTR]], align 4
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// LLVM: }
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struct two_ints {
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int x;
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int y;
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};
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unsigned long test_aggregate_to_scalar(two_ints &ti) {
27+
return __builtin_bit_cast(unsigned long, ti);
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}
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// CIR-LABEL: cir.func @_Z24test_aggregate_to_scalarR8two_ints
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// CIR: %[[#SRC_PTR:]] = cir.load %{{.+}} : !cir.ptr<!cir.ptr<!ty_22two_ints22>>, !cir.ptr<!ty_22two_ints22>
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// CIR-NEXT: %[[#DST_PTR:]] = cir.cast(bitcast, %[[#SRC_PTR]] : !cir.ptr<!ty_22two_ints22>), !cir.ptr<!u64i>
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// CIR-NEXT: %{{.+}} = cir.load %[[#DST_PTR]] : !cir.ptr<!u64i>, !u64i
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// CIR: }
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// LLVM-LABEL: define dso_local i64 @_Z24test_aggregate_to_scalarR8two_ints
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// LLVM: %[[#PTR:]] = load ptr, ptr %{{.+}}, align 8
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// LLVM-NEXT: %{{.+}} = load i64, ptr %[[#PTR]], align 8
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// LLVM: }
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struct two_floats {
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float x;
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float y;
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};
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two_floats test_aggregate_record(two_ints& ti) {
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return __builtin_bit_cast(two_floats, ti);
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}
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// CIR-LABEL: cir.func @_Z21test_aggregate_recordR8two_ints
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// CIR: %[[#SRC_PTR:]] = cir.load %{{.+}} : !cir.ptr<!cir.ptr<!ty_22two_ints22>>, !cir.ptr<!ty_22two_ints22>
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// CIR-NEXT: %[[#SRC_VOID_PTR:]] = cir.cast(bitcast, %[[#SRC_PTR]] : !cir.ptr<!ty_22two_ints22>), !cir.ptr<!void>
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// CIR-NEXT: %[[#DST_VOID_PTR:]] = cir.cast(bitcast, %{{.+}} : !cir.ptr<!ty_22two_floats22>), !cir.ptr<!void>
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// CIR-NEXT: %[[#SIZE:]] = cir.const #cir.int<8> : !u64i
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// CIR-NEXT: cir.libc.memcpy %[[#SIZE]] bytes from %[[#SRC_VOID_PTR]] to %[[#DST_VOID_PTR]] : !u64i, !cir.ptr<!void> -> !cir.ptr<!void>
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// CIR: }
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// LLVM-LABEL: define dso_local %struct.two_floats @_Z21test_aggregate_recordR8two_ints
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// LLVM: %[[#DST_SLOT:]] = alloca %struct.two_floats, i64 1, align 4
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// LLVM: %[[#SRC_PTR:]] = load ptr, ptr %2, align 8
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// LLVM-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr %[[#DST_SLOT]], ptr %[[#SRC_PTR]], i64 8, i1 false)
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// LLVM-NEXT: %{{.+}} = load %struct.two_floats, ptr %[[#DST_SLOT]], align 4
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// LLVM: }
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two_floats test_aggregate_array(int (&ary)[2]) {
66+
return __builtin_bit_cast(two_floats, ary);
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}
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// CIR-LABEL: cir.func @_Z20test_aggregate_arrayRA2_i
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// CIR: %[[#SRC_PTR:]] = cir.load %{{.+}} : !cir.ptr<!cir.ptr<!cir.array<!s32i x 2>>>, !cir.ptr<!cir.array<!s32i x 2>>
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// CIR-NEXT: %[[#SRC_VOID_PTR:]] = cir.cast(bitcast, %[[#SRC_PTR]] : !cir.ptr<!cir.array<!s32i x 2>>), !cir.ptr<!void>
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// CIR-NEXT: %[[#DST_VOID_PTR:]] = cir.cast(bitcast, %{{.+}} : !cir.ptr<!ty_22two_floats22>), !cir.ptr<!void>
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// CIR-NEXT: %[[#SIZE:]] = cir.const #cir.int<8> : !u64i
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// CIR-NEXT: cir.libc.memcpy %[[#SIZE]] bytes from %[[#SRC_VOID_PTR]] to %[[#DST_VOID_PTR]] : !u64i, !cir.ptr<!void> -> !cir.ptr<!void>
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// CIR: }
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// LLVM-LABEL: define dso_local %struct.two_floats @_Z20test_aggregate_arrayRA2_i
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// LLVM: %[[#DST_SLOT:]] = alloca %struct.two_floats, i64 1, align 4
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// LLVM: %[[#SRC_PTR:]] = load ptr, ptr %2, align 8
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// LLVM-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr %[[#DST_SLOT]], ptr %[[#SRC_PTR]], i64 8, i1 false)
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// LLVM-NEXT: %{{.+}} = load %struct.two_floats, ptr %[[#DST_SLOT]], align 4
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// LLVM: }
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two_ints test_scalar_to_aggregate(unsigned long ul) {
85+
return __builtin_bit_cast(two_ints, ul);
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}
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// CIR-LABEL: cir.func @_Z24test_scalar_to_aggregatem
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// CIR: %[[#SRC_VOID_PTR:]] = cir.cast(bitcast, %{{.+}} : !cir.ptr<!u64i>), !cir.ptr<!void>
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// CIR-NEXT: %[[#DST_VOID_PTR:]] = cir.cast(bitcast, %{{.+}} : !cir.ptr<!ty_22two_ints22>), !cir.ptr<!void>
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// CIR-NEXT: %[[#SIZE:]] = cir.const #cir.int<8> : !u64i
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// CIR-NEXT: cir.libc.memcpy %[[#SIZE]] bytes from %[[#SRC_VOID_PTR]] to %[[#DST_VOID_PTR]] : !u64i, !cir.ptr<!void> -> !cir.ptr<!void>
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// CIR: }
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// LLVM-LABEL: define dso_local %struct.two_ints @_Z24test_scalar_to_aggregatem
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// LLVM: %[[#DST_SLOT:]] = alloca %struct.two_ints, i64 1, align 4
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// LLVM: call void @llvm.memcpy.p0.p0.i64(ptr %[[#DST_SLOT]], ptr %{{.+}}, i64 8, i1 false)
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// LLVM-NEXT: %{{.+}} = load %struct.two_ints, ptr %[[#DST_SLOT]], align 4
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// LLVM: }
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unsigned long test_array(int (&ary)[2]) {
102+
return __builtin_bit_cast(unsigned long, ary);
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}
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// CIR-LABEL: cir.func @_Z10test_arrayRA2_i
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// CIR: %[[#SRC_PTR:]] = cir.load %{{.+}} : !cir.ptr<!cir.ptr<!cir.array<!s32i x 2>>>, !cir.ptr<!cir.array<!s32i x 2>>
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// CIR-NEXT: %[[#DST_PTR:]] = cir.cast(bitcast, %[[#SRC_PTR]] : !cir.ptr<!cir.array<!s32i x 2>>), !cir.ptr<!u64i>
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// CIR-NEXT: %{{.+}} = cir.load %[[#DST_PTR]] : !cir.ptr<!u64i>, !u64i
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// CIR: }
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// LLVM-LABEL: define dso_local i64 @_Z10test_arrayRA2_i
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// LLVM: %[[#SRC_PTR:]] = load ptr, ptr %{{.+}}, align 8
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// LLVM-NEXT: %{{.+}} = load i64, ptr %[[#SRC_PTR]], align 8
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// LLVM: }
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116+
two_ints test_rvalue_aggregate() {
117+
return __builtin_bit_cast(two_ints, 42ul);
118+
}
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// CIR-LABEL: cir.func @_Z21test_rvalue_aggregatev()
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// CIR: cir.scope {
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// CIR-NEXT: %[[#TMP_SLOT:]] = cir.alloca !u64i, !cir.ptr<!u64i>
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// CIR-NEXT: %[[#A:]] = cir.const #cir.int<42> : !u64i
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// CIR-NEXT: cir.store %[[#A]], %[[#TMP_SLOT]] : !u64i, !cir.ptr<!u64i>
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// CIR-NEXT: %[[#SRC_VOID_PTR:]] = cir.cast(bitcast, %[[#TMP_SLOT]] : !cir.ptr<!u64i>), !cir.ptr<!void>
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// CIR-NEXT: %[[#DST_VOID_PTR:]] = cir.cast(bitcast, %0 : !cir.ptr<!ty_22two_ints22>), !cir.ptr<!void>
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// CIR-NEXT: %[[#SIZE:]] = cir.const #cir.int<8> : !u64i
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// CIR-NEXT: cir.libc.memcpy %[[#SIZE]] bytes from %[[#SRC_VOID_PTR]] to %[[#DST_VOID_PTR]] : !u64i, !cir.ptr<!void> -> !cir.ptr<!void>
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// CIR-NEXT: }
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// CIR: }
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// LLVM-LABEL: define dso_local %struct.two_ints @_Z21test_rvalue_aggregatev
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// LLVM: %[[#SRC_SLOT:]] = alloca i64, i64 1, align 8
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// LLVM-NEXT: store i64 42, ptr %[[#SRC_SLOT]], align 8
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// LLVM-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr %{{.+}}, ptr %[[#SRC_SLOT]], i64 8, i1 false)
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// LLVM: }

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