e927f4bbf4
Handle empty unions in CIR record lowering and LLVM conversion by emitting padding when needed, guarding `getLargestMember` for empty/padded unions, and lowering to empty or padded LLVM structs based on language rules. Added regression tests for C and C++ empty union lowering in `clang/test/CIR/CodeGen/empty-union.c` and `empty-union.cpp`.
36 lines
1.5 KiB
C++
36 lines
1.5 KiB
C++
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o - | FileCheck %s --check-prefix=CIR
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// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - | FileCheck %s --check-prefix=LLVM
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// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefix=OGCG
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// Empty union (should be padded to size 1)
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union Empty {};
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// CIR: !rec_Empty = !cir.record<union "Empty" padded {!u8i}>
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// LLVM: %union.Empty = type { i8 }
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// OGCG: %union.Empty = type { i8 }
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// Aligned empty union (should have aligned integer member in CIR)
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union alignas(16) EmptyAligned {};
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// CIR: !rec_EmptyAligned = !cir.record<union "EmptyAligned" padded {!cir.array<!u8i x 16>}>
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// LLVM: %union.EmptyAligned = type { [16 x i8] }
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// OGCG: %union.EmptyAligned = type { [16 x i8] }
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void useEmpty() {
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Empty e;
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}
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// CIR: cir.func {{.*}}@_Z8useEmptyv()
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// CIR: cir.alloca !rec_Empty, !cir.ptr<!rec_Empty>, ["e"] {alignment = 1 : i64}
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// LLVM: define {{.*}} void @_Z8useEmptyv()
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// LLVM: alloca %union.Empty, i64 1, align 1
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// OGCG: define {{.*}} void @_Z8useEmptyv()
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// OGCG: alloca %union.Empty, align 1
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void useEmptyAligned() {
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EmptyAligned e;
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}
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// CIR: cir.func {{.*}}@_Z15useEmptyAlignedv()
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// CIR: cir.alloca !rec_EmptyAligned, !cir.ptr<!rec_EmptyAligned>, ["e"] {alignment = 16 : i64}
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// LLVM: define {{.*}} void @_Z15useEmptyAlignedv()
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// LLVM: alloca %union.EmptyAligned, i64 1, align 16
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// OGCG: define {{.*}} void @_Z15useEmptyAlignedv()
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// OGCG: alloca %union.EmptyAligned, align 16
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