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[CIR] Add bitfield offset calculation for big-endian targets #145067

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Merged
merged 1 commit into from
Jun 23, 2025
Merged

[CIR] Add bitfield offset calculation for big-endian targets #145067

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1 change: 0 additions & 1 deletion clang/include/clang/CIR/MissingFeatures.h
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Original file line number Diff line number Diff line change
Expand Up @@ -150,7 +150,6 @@ struct MissingFeatures {
static bool cxxabiAppleARM64CXXABI() { return false; }
static bool cxxabiStructorImplicitParam() { return false; }
static bool isDiscreteBitFieldABI() { return false; }
static bool isBigEndian() { return false; }

// Address class
static bool addressOffset() { return false; }
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3 changes: 2 additions & 1 deletion clang/lib/CIR/CodeGen/CIRGenRecordLayoutBuilder.cpp
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Expand Up @@ -228,7 +228,8 @@ void CIRRecordLowering::setBitFieldInfo(const FieldDecl *fd,
// out as packed bits within an integer-sized unit, we can imagine the bits
// counting from the most-significant-bit instead of the
// least-significant-bit.
assert(!cir::MissingFeatures::isBigEndian());
if (dataLayout.isBigEndian())
info.offset = info.storageSize - (info.offset + info.size);

info.volatileStorageSize = 0;
info.volatileOffset = 0;
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17 changes: 17 additions & 0 deletions clang/test/CIR/CodeGen/bitfields_be.c
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@@ -0,0 +1,17 @@
// RUN: %clang_cc1 -triple aarch64_be-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
// RUN: FileCheck --input-file=%t.cir %s --check-prefix=CIR
// RUN: %clang_cc1 -triple aarch64_be-unknown-linux-gnu -fclangir -emit-llvm %s -o %t-cir.ll
// RUN: FileCheck --input-file=%t-cir.ll %s --check-prefix=LLVM
// RUN: %clang_cc1 -triple aarch64_be-unknown-linux-gnu -emit-llvm %s -o %t.ll
// RUN: FileCheck --input-file=%t.ll %s --check-prefix=OGCG

typedef struct {
int a : 4;
int b : 11;
int c : 17;
} S;
S s;

// CIR: !rec_S = !cir.record<struct "S" {!u32i}>
// LLVM: %struct.S = type { i32 }
// OGCG: %struct.S = type { i32 }
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