[llvm] r224098 - A fix for PR21176.
Ekaterina Romanova
katya_romanova at playstation.sony.com
Thu Dec 11 21:11:48 PST 2014
Author: kromanova
Date: Thu Dec 11 23:11:47 2014
New Revision: 224098
URL: http://llvm.org/viewvc/llvm-project?rev=224098&view=rev
Log:
A fix for PR21176.
DW_OP_const <const> doesn't describe a constant value, but a value at a constant address.
The proper way to describe a constant value is DW_OP_constu <const>, DW_OP_stack_value.
Added DW_OP_stack_value to the stack.
Marked incorrect-variable-debugloc1.ll to xfail for PowerPC64, while the the failure (PR21881)
is being investigated.
Added:
llvm/trunk/test/DebugInfo/incorrect-variable-debugloc1.ll
Modified:
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=224098&r1=224097&r2=224098&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Thu Dec 11 23:11:47 2014
@@ -1722,6 +1722,18 @@ void DwarfDebug::emitDebugLocValue(ByteS
Streamer.EmitInt8(dwarf::DW_OP_constu, "DW_OP_constu");
Streamer.EmitULEB128(Value.getInt());
}
+ // The proper way to describe a constant value is
+ // DW_OP_constu <const>, DW_OP_stack_value.
+ // Unfortunately, DW_OP_stack_value was not available until DWARF-4,
+ // so we will continue to generate DW_OP_constu <const> for DWARF-2
+ // and DWARF-3. Technically, this is incorrect since DW_OP_const <const>
+ // actually describes a value at a constant addess, not a constant value.
+ // However, in the past there was no better way to describe a constant
+ // value, so the producers and consumers started to rely on heuristics
+ // to disambiguate the value vs. location status of the expression.
+ // See PR21176 for more details.
+ if (getDwarfVersion() >= 4)
+ Streamer.EmitInt8(dwarf::DW_OP_stack_value, "DW_OP_stack_value");
} else if (Value.isLocation()) {
MachineLocation Loc = Value.getLoc();
DIExpression Expr = Value.getExpression();
Added: llvm/trunk/test/DebugInfo/incorrect-variable-debugloc1.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/incorrect-variable-debugloc1.ll?rev=224098&view=auto
==============================================================================
--- llvm/trunk/test/DebugInfo/incorrect-variable-debugloc1.ll (added)
+++ llvm/trunk/test/DebugInfo/incorrect-variable-debugloc1.ll Thu Dec 11 23:11:47 2014
@@ -0,0 +1,77 @@
+; REQUIRES: object-emission
+; This test is failing for powerpc64, because a location list for the
+; variable 'c' is not generated at all. Temporary marking this test as XFAIL
+; for powerpc, until PR21881 is fixed.
+; XFAIL: powerpc64
+
+; RUN: %llc_dwarf -O2 -dwarf-version 2 -filetype=obj < %s | llvm-dwarfdump - | FileCheck %s --check-prefix=DWARF23
+; RUN: %llc_dwarf -O2 -dwarf-version 3 -filetype=obj < %s | llvm-dwarfdump - | FileCheck %s --check-prefix=DWARF23
+; RUN: %llc_dwarf -O2 -dwarf-version 4 -filetype=obj < %s | llvm-dwarfdump - | FileCheck %s --check-prefix=DWARF4
+
+; This is a test for PR21176.
+; DW_OP_const <const> doesn't describe a constant value, but a value at a constant address.
+; The proper way to describe a constant value is DW_OP_constu <const>, DW_OP_stack_value.
+
+; Generated with clang -S -emit-llvm -g -O2 test.cpp
+
+; extern int func();
+;
+; int main()
+; {
+; volatile int c = 13;
+; c = func();
+; return c;
+; }
+
+; DWARF23: Location description: 10 0d {{$}}
+; DWARF4: Location description: 10 0d 9f
+
+; Function Attrs: uwtable
+define i32 @main() #0 {
+entry:
+ %c = alloca i32, align 4
+ tail call void @llvm.dbg.value(metadata !15, i64 0, metadata !10, metadata !16), !dbg !17
+ store volatile i32 13, i32* %c, align 4, !dbg !18
+ %call = tail call i32 @_Z4funcv(), !dbg !19
+ tail call void @llvm.dbg.value(metadata !{i32 %call}, i64 0, metadata !10, metadata !16), !dbg !17
+ store volatile i32 %call, i32* %c, align 4, !dbg !19
+ tail call void @llvm.dbg.value(metadata !{i32* %c}, i64 0, metadata !10, metadata !16), !dbg !17
+ %c.0.c.0. = load volatile i32* %c, align 4, !dbg !20
+ ret i32 %c.0.c.0., !dbg !20
+}
+
+declare i32 @_Z4funcv() #1
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #2
+
+attributes #0 = { uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!12, !13}
+!llvm.ident = !{!14}
+
+!0 = metadata !{metadata !"0x11\004\00clang version 3.6.0 (trunk 223522)\001\00\000\00\001", metadata !1, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2} ; [ DW_TAG_compile_unit ] [/home/kromanova/ngh/ToT_latest/llvm/test/DebugInfo/test.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"test.cpp", metadata !"/home/kromanova/ngh/ToT_latest/llvm/test/DebugInfo"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4}
+!4 = metadata !{metadata !"0x2e\00main\00main\00\003\000\001\000\000\00256\001\004", metadata !1, metadata !5, metadata !6, null, i32 ()* @main, null, null, metadata !9} ; [ DW_TAG_subprogram ] [line 3] [def] [scope 4] [main]
+!5 = metadata !{metadata !"0x29", metadata !1} ; [ DW_TAG_file_type ] [/home/kromanova/ngh/ToT_latest/llvm/test/DebugInfo/test.cpp]
+!6 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", null, null, null, metadata !7, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{metadata !8}
+!8 = metadata !{metadata !"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]
+!9 = metadata !{metadata !10}
+!10 = metadata !{metadata !"0x100\00c\005\000", metadata !4, metadata !5, metadata !11} ; [ DW_TAG_auto_variable ] [c] [line 5]
+!11 = metadata !{metadata !"0x35\00\000\000\000\000\000", null, null, metadata !8} ; [ DW_TAG_volatile_type ] [line 0, size 0, align 0, offset 0] [from int]
+!12 = metadata !{i32 2, metadata !"Dwarf Version", i32 2}
+!13 = metadata !{i32 2, metadata !"Debug Info Version", i32 2}
+!14 = metadata !{metadata !"clang version 3.6.0 (trunk 223522)"}
+!15 = metadata !{i32 13}
+!16 = metadata !{metadata !"0x102"} ; [ DW_TAG_expression ]
+!17 = metadata !{i32 5, i32 16, metadata !4, null}
+!18 = metadata !{i32 5, i32 3, metadata !4, null}
+!19 = metadata !{i32 6, i32 7, metadata !4, null}
+!20 = metadata !{i32 7, i32 3, metadata !4, null}
+
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