Debug Info: Relax assertion in isUnsignedDIType() to allow floats to be

described by integer constants. This is a bit ugly, but if the source
language allows arbitrary type casting, the debug info must follow suit.

For example:
  void foo() {
    float a;
    *(int *)&a = 0;
  }
For the curious: SROA replaces the float alloca with an i32 alloca, which
is then optimized away and described via dbg.value(i32 0, ...).

llvm-svn: 227827

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -606,6 +606,7 @@ static bool isUnsignedDIType(DwarfDebug *DD, DIType Ty) {
           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 ||
           (Ty.getTag() == dwarf::DW_TAG_unspecified_type &&
            Ty.getName() == "decltype(nullptr)")) &&

llvm/test/DebugInfo/X86/float_const.ll

@@ -0,0 +1,55 @@
+; RUN: llc < %s -filetype=obj | llvm-dwarfdump -debug-dump=info - | FileCheck %s
+; from (at -Os):
+; void foo() {
+;   float a = 3.14;
+;   *(int *)&a = 0;
+; }
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.10.0"
+
+; Function Attrs: nounwind optsize readnone uwtable
+define void @foo() #0 {
+entry:
+  tail call void @llvm.dbg.declare(metadata float* undef, metadata !13, metadata !19), !dbg !20
+  tail call void @llvm.dbg.value(metadata i32 1078523331, i64 0, metadata !13, metadata !19), !dbg !20
+  tail call void @llvm.dbg.value(metadata i32 0, i64 0, metadata !13, metadata !19), !dbg !20
+; CHECK:  DW_AT_const_value [DW_FORM_sdata]    (0)
+; CHECK-NEXT: DW_AT_name {{.*}}"a"
+  ret void, !dbg !21
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1
+
+attributes #0 = { nounwind optsize readnone uwtable }
+attributes #1 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!15, !16, !17}
+!llvm.ident = !{!18}
+
+!0 = !{!"0x11\0012\00clang version 3.7.0 (trunk 227686)\001\00\000\00\001", !1, !2, !3, !6, !2, !2} ; [ DW_TAG_compile_unit ] [foo.c] [DW_LANG_C99]
+!1 = !{!"foo.c", !""}
+!2 = !{}
+!3 = !{!4}
+!4 = !{!"0xf\00\000\0064\0064\000\000", null, null, !5} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from int]
+!5 = !{!"0x24\00int\000\0032\0032\000\000\005", null, null} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!6 = !{!7}
+!7 = !{!"0x2e\00foo\00foo\00\001\000\001\000\000\000\001\001", !8, !9, !10, null, void ()* @foo, null, null, !12} ; [ DW_TAG_subprogram ] [line 1] [def] [foo]
+!8 = !{!"foo.c", !""}
+!9 = !{!"0x29", !8}                               ; [ DW_TAG_file_type ]
+!10 = !{!"0x15\00\000\000\000\000\000\000", null, null, null, !11, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!11 = !{null}
+!12 = !{!13}
+!13 = !{!"0x100\00a\002\000", !7, !9, !14}        ; [ DW_TAG_auto_variable ] [a] [line 2]
+!14 = !{!"0x24\00float\000\0032\0032\000\000\004", null, null} ; [ DW_TAG_base_type ] [float] [line 0, size 32, align 32, offset 0, enc DW_ATE_float]
+!15 = !{i32 2, !"Dwarf Version", i32 2}
+!16 = !{i32 2, !"Debug Info Version", i32 2}
+!17 = !{i32 1, !"PIC Level", i32 2}
+!18 = !{!"clang version 3.7.0 (trunk 227686)"}
+!19 = !{!"0x102"}                                 ; [ DW_TAG_expression ]
+!20 = !MDLocation(line: 2, column: 9, scope: !7)
+!21 = !MDLocation(line: 4, column: 1, scope: !7)