[DebugInfo] Add DW_ATE_complex_float case to assert in isUnsignedDIType

[Orlando]

Summary

Without this patch a DW_ATE_complex_float encoding trips an assertion in DebugHandlerBase::isUnsignedDIType. The assertion message "Unsupported encoding" possibly indicates that either the encoding either truly isn't supported or hasn't yet had support added.

By adding a case to the assert for DW_ATE_complex_float it becomes supported, behaving in the same way as the already supported DW_ATE_float type (return false), which I think makes sense.

That resolves this issue mentioned in D146987.

Note: For the reported reproducer:

#include <complex.h>
int main() {
  long double complex r1;
}

The assertion isn't tripped without assignment tracking because instcombine deletes everything, including the dbg.declare, without recovering any location information. Whereas with assignment tracking we track a zeroing memset that is emitted by clang.

[MaskRay]

llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp

226

Whether are the other Encoding == xxx tested? Is it possible to group the DW_ATE_complex_float test with those test files?

llvm/test/DebugInfo/X86/DW_ATE_complex_float.ll

1

-filetype=asm is the default action and usually omitted.

[Orlando]

+ address review comments

Thanks for the review

llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp

226

Omitting some types from the assertion and running the tests, among other failures I found float_const.ll, dbg-i128-const.ll and dbg-const-int.ll in llvm/test/DebugInfo/X86 (same directory as the new test) which look to be testing this behaviour. Not conclusive but it looks like there's a precedent for using this directory.

[Orlando]

ping

[probinson]

llvm/test/DebugInfo/X86/DW_ATE_complex_float.ll

12

This shows we have a const_value, but not what it's part of. More context for the check would be good.

[Orlando]

+ Added more CHECK lines to the test

[probinson]

LGTM

llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp

226

I suspect we could improve testing efficiency by combining some of these into a single test file, but as they are already split across files I don't think it's appropriate to insist that you do anything different here.

[MaskRay]

llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp

226

I agree. It'd be worth thinking about grouping tests if @Orlando or others have extra energy on the work:)

llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp

bool DebugHandlerBase::isUnsignedDIType(const DIType *Ty) {
   auto *BTy = cast<DIBasicType>(Ty);
   unsigned Encoding = BTy->getEncoding();
   assert((Encoding == dwarf::DW_ATE_unsigned ||
           Encoding == dwarf::DW_ATE_unsigned_char ||
           Encoding == dwarf::DW_ATE_signed ||
           Encoding == dwarf::DW_ATE_signed_char ||
           Encoding == dwarf::DW_ATE_float || Encoding == dwarf::DW_ATE_UTF ||
           Encoding == dwarf::DW_ATE_boolean ||
+          Encoding == dwarf::DW_ATE_complex_float ||
           (Ty->getTag() == dwarf::DW_TAG_unspecified_type &&
            Ty->getName() == "decltype(nullptr)")) &&
          "Unsupported encoding");
   return Encoding == dwarf::DW_ATE_unsigned ||
          Encoding == dwarf::DW_ATE_unsigned_char ||
          Encoding == dwarf::DW_ATE_UTF || Encoding == dwarf::DW_ATE_boolean ||
          Ty->getTag() == dwarf::DW_TAG_unspecified_type;
 }

llvm/test/DebugInfo/X86/DW_ATE_complex_float.ll

+; RUN: llc %s -filetype=asm -o - | FileCheck %s
+
+;; Check a single location variable of type DW_ATE_complex_float with a
+;; constant value is emitted with a DW_AT_const_value attribute.
+
+; CHECK: .Ldebug_info_start0:
+; CHECK: .byte 0 # DW_AT_const_value
+
+target triple = "x86_64-unknown-linux-gnu"
+
+define dso_local void @f() local_unnamed_addr !dbg !10 {
+entry:
+  call void @llvm.dbg.value(metadata i8 0, metadata !14, metadata !DIExpression()), !dbg !17
+  ret void, !dbg !19
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 17.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{!"clang version 17.0.0"}
+!10 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 2, type: !11, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !13)
+!11 = !DISubroutineType(types: !12)
+!12 = !{null}
+!13 = !{!14}
+!14 = !DILocalVariable(name: "r1", scope: !10, file: !1, line: 3, type: !15)
+!15 = !DIBasicType(name: "complex", size: 128, encoding: DW_ATE_complex_float)
+!17 = !DILocation(line: 0, scope: !10)
+!19 = !DILocation(line: 4, column: 1, scope: !10)