https://github.com/Andres-Salamanca created
https://github.com/llvm/llvm-project/pull/145096
This PR introduces support for bitfields inside unions in CIR.
>From 51aa8f274cbf8f7044e3c9dbd27b1e26b09a22ed Mon Sep 17 00:00:00 2001
From: Andres Salamanca <andrealebarbari...@gmail.com>
Date: Fri, 20 Jun 2025 14:53:25 -0500
Subject: [PATCH] Add support for bitfields in unions
---
.../CIR/CodeGen/CIRGenRecordLayoutBuilder.cpp | 11 +++++++----
clang/test/CIR/CodeGen/bitfield-union.c | 19 +++++++++++++++++++
2 files changed, 26 insertions(+), 4 deletions(-)
create mode 100644 clang/test/CIR/CodeGen/bitfield-union.c
diff --git a/clang/lib/CIR/CodeGen/CIRGenRecordLayoutBuilder.cpp
b/clang/lib/CIR/CodeGen/CIRGenRecordLayoutBuilder.cpp
index 8dbf1b36a93b2..3d50a537e676b 100644
--- a/clang/lib/CIR/CodeGen/CIRGenRecordLayoutBuilder.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenRecordLayoutBuilder.cpp
@@ -655,11 +655,14 @@ void CIRRecordLowering::lowerUnion() {
// locate the "most appropriate" storage type.
for (const FieldDecl *field : recordDecl->fields()) {
mlir::Type fieldType;
- if (field->isBitField())
- cirGenTypes.getCGModule().errorNYI(recordDecl->getSourceRange(),
- "bitfields in lowerUnion");
- else
+ if (field->isBitField()) {
+ if (field->isZeroLengthBitField())
+ continue;
+ fieldType = getBitfieldStorageType(field->getBitWidthValue());
+ setBitFieldInfo(field, CharUnits::Zero(), fieldType);
+ } else {
fieldType = getStorageType(field);
+ }
// This maps a field to its index. For unions, the index is always 0.
fieldIdxMap[field->getCanonicalDecl()] = 0;
diff --git a/clang/test/CIR/CodeGen/bitfield-union.c
b/clang/test/CIR/CodeGen/bitfield-union.c
new file mode 100644
index 0000000000000..72e14c5fb71f3
--- /dev/null
+++ b/clang/test/CIR/CodeGen/bitfield-union.c
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o
%t.cir
+// RUN: FileCheck --input-file=%t.cir %s --check-prefix=CIR
+// RUN: %clang_cc1 -triple x86_64-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 x86_64-unknown-linux-gnu -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s --check-prefix=OGCG
+
+typedef union {
+ int x;
+ int y : 4;
+ int z : 8;
+} demo;
+
+// CIR: !rec_demo = !cir.record<union "demo" {!s32i, !u8i, !u8i}>
+// LLVM: %union.demo = type { i32 }
+// OGCG: %union.demo = type { i32 }
+demo d;
+
+
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