[Dwarf] Emit DW_AT_bit_size for non-byte-sized types

Author: dtcxzyw

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -1749,6 +1749,10 @@ void DwarfCompileUnit::createBaseTypeDIEs() {
     // Round up to smallest number of bytes that contains this number of bits.
     addUInt(Die, dwarf::DW_AT_byte_size, std::nullopt,
             divideCeil(Btr.BitSize, 8));
+    // If the size is not a multiple of 8 (e.g., boolean), add the bit size
+    // field.
+    if (Btr.BitSize % 8 != 0)
+      addUInt(Die, dwarf::DW_AT_bit_size, std::nullopt, Btr.BitSize);
 
     Btr.Die = &Die;
   }

llvm/test/DebugInfo/X86/convert-bool.ll

@@ -0,0 +1,43 @@
+; RUN: llc -mtriple=x86_64 -dwarf-version=5 -filetype=obj -O0 < %s | llvm-dwarfdump - | FileCheck %s
+
+; CHECK: DW_TAG_base_type
+; CHECK-NEXT: DW_AT_name      ("DW_ATE_unsigned_1")
+; CHECK-NEXT: DW_AT_encoding  (DW_ATE_unsigned)
+; CHECK-NEXT: DW_AT_byte_size (0x01)
+; CHECK-NEXT: DW_AT_bit_size  (0x01)
+
+define void @main() !dbg !18 {
+entry:
+    #dbg_value(i1 false, !22, !DIExpression(DW_OP_not, DW_OP_LLVM_convert, 1, DW_ATE_unsigned, DW_OP_LLVM_convert, 32, DW_ATE_unsigned, DW_OP_stack_value), !23)
+  ret void, !dbg !24
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!10, !11, !12, !13, !14, !15, !16}
+!llvm.ident = !{!17}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 21.0.0git", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/home/dtcxzyw/WorkSpace/Projects/compilers/LLVM/llvm-build", checksumkind: CSK_MD5, checksum: "100bdbce655d729c24c7c0e8523a58ae")
+!2 = !{!3, !6, !8}
+!3 = !DIGlobalVariableExpression(var: !4, expr: !DIExpression())
+!4 = distinct !DIGlobalVariable(name: "a", scope: !0, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true)
+!5 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!6 = !DIGlobalVariableExpression(var: !7, expr: !DIExpression())
+!7 = distinct !DIGlobalVariable(name: "b", scope: !0, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true)
+!8 = !DIGlobalVariableExpression(var: !9, expr: !DIExpression())
+!9 = distinct !DIGlobalVariable(name: "c", scope: !0, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true)
+!10 = !{i32 7, !"Dwarf Version", i32 5}
+!11 = !{i32 2, !"Debug Info Version", i32 3}
+!12 = !{i32 1, !"wchar_size", i32 4}
+!13 = !{i32 8, !"PIC Level", i32 2}
+!14 = !{i32 7, !"PIE Level", i32 2}
+!15 = !{i32 7, !"uwtable", i32 2}
+!16 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
+!17 = !{!"clang version 21.0.0git"}
+!18 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 3, type: !19, scopeLine: 3, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !21)
+!19 = !DISubroutineType(types: !20)
+!20 = !{null}
+!21 = !{!22}
+!22 = !DILocalVariable(name: "l_4516", scope: !18, file: !1, line: 4, type: !5)
+!23 = !DILocation(line: 0, scope: !18)
+!24 = !DILocation(line: 9, column: 1, scope: !18)