[DebugInfo] Improvements to representation of enumeration types (PR36168)

This patch is the LLVM part of fixing the issues, described in
https://bugs.llvm.org/show_bug.cgi?id=36168

* The representation of enumerator values in the debug info metadata now
  contains a boolean flag isUnsigned, which determines how the bits of
  the value are interpreted.
* The DW_TAG_enumeration type DIE now always (for DWARF version >= 3)
  includes a DW_AT_type attribute, which refers to the underlying
  integer type, as suggested in DWARFv4 (5.7 Enumeration Type Entries).
* The debug info metadata for enumeration type contains (in flags)
  indication whether this is a C++11 "fixed enum".
* For C++11 enumeration with a fixed underlying type, the DIE also
  includes the DW_AT_enum_class attribute (for DWARF version >= 4).
* Encoding of enumerator constants uses DW_FORM_sdata for signed values
  and DW_FORM_udata for unsigned values, as suggested by DWARFv4 (7.5.4
  Attribute Encodings).

The changes should be backwards compatible:

* the isUnsigned attribute is optional and defaults to false.
* if the underlying type for the enumeration is not available, the
  enumerator values are considered signed.
* the FixedEnum flag defaults to clear.
* the bitcode format for DIEnumerator stores the unsigned flag bit #1 of
  the first record element, so the format does not change and the zero
  previously stored there is consistent with the false default for
  IsUnsigned.

Differential Revision: https://reviews.llvm.org/D42734

llvm-svn: 324489

1 files changed, 85 insertions, 0 deletions

diff --git a/llvm/test/Assembler/DIEnumerator.ll b/llvm/test/Assembler/DIEnumerator.ll
new file mode 100644
index 00000000000..9dc3d7c9ec2
--- /dev/null
+++ b/llvm/test/Assembler/DIEnumerator.ll
@@ -0,0 +1,85 @@
+; Round-trip test for the following program:
+; ```
+; enum E0 {  A0 = -2147483648, B0 = 2147483647 } x0;
+; enum E1 : signed int { A1 = -2147483648, B1 = 2147483647 } x1;
+; enum E2 : signed long long { A2 = -9223372036854775807LL - 1,
+;                              B2 = 9223372036854775807LL } x2;
+; enum E3 : unsigned long long { A3 = 0x8000000000000000ULL } x3;
+; ```
+; Test FixedEnum flag presence/absence, the underlying integer type and
+; enumerator values (signed and unsigned, and extreme cases) all survive through
+; the round-trip.
+
+; RUN: llvm-as %s -o - | llvm-dis | llvm-as | llvm-dis | FileCheck %s
+
+@x0 = global i32 0, align 4, !dbg !0
+@x1 = global i32 0, align 4, !dbg !24
+@x2 = global i64 0, align 8, !dbg !26
+@x3 = global i64 0, align 8, !dbg !28
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!30, !31, !32}
+!llvm.ident = !{!33}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "x0", scope: !2, file: !3, line: 1, type: !5, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "clang version 7.0.0 (/data/src/llvm/tools/clang 697b0cb4c2e712a28767c2f7fe50c90bae7255f5) (/data/src/llvm 5ba8dcca7470b5da405bc92b9681b1f36e5d6772)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !23)
+!3 = !DIFile(filename: "e.cc", directory: "/work/build/clang-dev")
+!4 = !{!5, !10, !14, !19}
+
+
+!5 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "E0", file: !3, line: 1, baseType: !6, size: 32, elements: !7, identifier: "_ZTS2E0")
+; CHECK: !DICompositeType(tag: DW_TAG_enumeration_type, name: "E0"{{.*}}, baseType: ![[INT:[0-9]+]]
+; CHECK-NOT: FixedEnum
+!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+; CHECK: ![[INT]] = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!7 = !{!8, !9}
+!8 = !DIEnumerator(name: "A0", value: -2147483648)
+!9 = !DIEnumerator(name: "B0", value: 2147483647)
+; CHECK: !DIEnumerator(name: "A0", value: -2147483648)
+; CHECK: !DIEnumerator(name: "B0", value: 2147483647)
+
+
+!10 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "E1", file: !3, line: 3, baseType: !6, size: 32, flags: DIFlagFixedEnum, elements: !11, identifier: "_ZTS2E1")
+; CHECK: !DICompositeType(tag: DW_TAG_enumeration_type, name: "E1"{{.*}}, baseType: ![[INT]]
+; CHECK-SAME: DIFlagFixedEnum
+!11 = !{!12, !13}
+!12 = !DIEnumerator(name: "A1", value: -2147483648)
+!13 = !DIEnumerator(name: "B1", value: 2147483647)
+; CHECK: !DIEnumerator(name: "A1", value: -2147483648)
+; CHECK: !DIEnumerator(name: "B1", value: 2147483647)
+
+
+!14 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "E2", file: !3, line: 5, baseType: !15, size: 64, flags: DIFlagFixedEnum, elements: !16, identifier: "_ZTS2E2")
+; CHECK: !DICompositeType(tag: DW_TAG_enumeration_type, name: "E2"{{.*}}, baseType: ![[LONG:[0-9]+]]
+; CHECK-SAME: DIFlagFixedEnum
+!15 = !DIBasicType(name: "long long int", size: 64, encoding: DW_ATE_signed)
+; CHECK: ![[LONG]] = !DIBasicType(name: "long long int", size: 64, encoding: DW_ATE_signed)
+!16 = !{!17, !18}
+!17 = !DIEnumerator(name: "A2", value: -9223372036854775808)
+!18 = !DIEnumerator(name: "B2", value: 9223372036854775807)
+; CHECK: !DIEnumerator(name: "A2", value: -9223372036854775808)
+; CHECK: !DIEnumerator(name: "B2", value: 9223372036854775807)
+
+
+!19 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "E3", file: !3, line: 7, baseType: !20, size: 64, flags: DIFlagFixedEnum, elements: !21, identifier: "_ZTS2E3")
+; CHECK: !DICompositeType(tag: DW_TAG_enumeration_type, name: "E3"{{.*}}, baseType: ![[ULONG:[0-9]+]]
+; CHECK-SAME: DIFlagFixedEnum
+!20 = !DIBasicType(name: "long long unsigned int", size: 64, encoding: DW_ATE_unsigned)
+; CHECK: ![[ULONG]] = !DIBasicType(name: "long long unsigned int", size: 64, encoding: DW_ATE_unsigned)
+!21 = !{!22}
+!22 = !DIEnumerator(name: "A3", value: 9223372036854775808, isUnsigned: true)
+; CHECK: !DIEnumerator(name: "A3", value: 9223372036854775808, isUnsigned: true)
+
+
+!23 = !{!0, !24, !26, !28}
+!24 = !DIGlobalVariableExpression(var: !25, expr: !DIExpression())
+!25 = distinct !DIGlobalVariable(name: "x1", scope: !2, file: !3, line: 3, type: !10, isLocal: false, isDefinition: true)
+!26 = !DIGlobalVariableExpression(var: !27, expr: !DIExpression())
+!27 = distinct !DIGlobalVariable(name: "x2", scope: !2, file: !3, line: 5, type: !14, isLocal: false, isDefinition: true)
+!28 = !DIGlobalVariableExpression(var: !29, expr: !DIExpression())
+!29 = distinct !DIGlobalVariable(name: "x3", scope: !2, file: !3, line: 7, type: !19, isLocal: false, isDefinition: true)
+!30 = !{i32 2, !"Dwarf Version", i32 4}
+!31 = !{i32 2, !"Debug Info Version", i32 3}
+!32 = !{i32 1, !"wchar_size", i32 4}
+!33 = !{!"clang version 7.0.0 (/data/src/llvm/tools/clang 697b0cb4c2e712a28767c2f7fe50c90bae7255f5) (/data/src/llvm 5ba8dcca7470b5da405bc92b9681b1f36e5d6772)"}