[llvm] r203187 - DebugInfo: Emit DW_TAG_subprogram's DW_AT_high_pc as an offset from the low_pc

David Blaikie dblaikie at gmail.com
Fri Mar 7 14:17:08 PST 2014


On Fri, Mar 7, 2014 at 2:09 PM, Adrian Prantl <aprantl at apple.com> wrote:
> This was actually Greg's idea :-)
> Ideally they would all be relative to the low_pc of the subprogram, I think.

Yeah, I was discussing similar ideas with Eric yesterday too (I guess
low_pc could be relative to the nearest enclosing low_pc (or at least
just the subprogram - and even a subprogram's low_pc could, arguably,
be relative to the CU's low_pc if it's using one))

>
> -- adrian
>
> On Mar 7, 2014, at 14:08, David Blaikie <dblaikie at gmail.com> wrote:
>
>> On Fri, Mar 7, 2014 at 10:41 AM, Adrian Prantl <aprantl at apple.com> wrote:
>>> Hi David,
>>>
>>> would it make sense to implement a similar change for high/low_pc of TAG_lexical_block, too?
>>
>> Oh... good point. I've done this for inlined subprograms in r203295
>> since there was already a test case covering that (with a little
>> improvement, anyway) - lexical blocks coming soon once I work up a
>> test case.
>>
>>>
>>> -- adrian
>>>
>>>
>>> On Mar 6, 2014, at 17:30, David Blaikie <dblaikie at gmail.com> wrote:
>>>
>>>> Author: dblaikie
>>>> Date: Thu Mar  6 19:30:55 2014
>>>> New Revision: 203187
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=203187&view=rev
>>>> Log:
>>>> DebugInfo: Emit DW_TAG_subprogram's DW_AT_high_pc as an offset from the low_pc
>>>>
>>>> This removes a relocation from each subprogram, reducing link times,
>>>> etc.
>>>>
>>>> Modified:
>>>>   llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>>>   llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
>>>>   llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.h
>>>>   llvm/trunk/test/DebugInfo/AArch64/dwarfdump.ll
>>>>   llvm/trunk/test/DebugInfo/X86/dbg-value-location.ll
>>>>
>>>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=203187&r1=203186&r2=203187&view=diff
>>>> ==============================================================================
>>>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
>>>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Thu Mar  6 19:30:55 2014
>>>> @@ -413,7 +413,8 @@ DIE *DwarfDebug::updateSubprogramScopeDI
>>>>  }
>>>>
>>>>  SPCU->addLabelAddress(SPDie, dwarf::DW_AT_low_pc, FunctionBeginSym);
>>>> -  SPCU->addLabelAddress(SPDie, dwarf::DW_AT_high_pc, FunctionEndSym);
>>>> +  SPCU->addLabelDelta(SPDie, dwarf::DW_AT_high_pc, FunctionEndSym,
>>>> +                      FunctionBeginSym);
>>>>
>>>>  const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
>>>>  MachineLocation Location(RI->getFrameRegister(*Asm->MF));
>>>>
>>>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp?rev=203187&r1=203186&r2=203187&view=diff
>>>> ==============================================================================
>>>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
>>>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Thu Mar  6 19:30:55 2014
>>>> @@ -320,6 +320,12 @@ void DwarfUnit::addSectionDelta(DIE *Die
>>>>    Die->addValue(Attribute, dwarf::DW_FORM_data4, Value);
>>>> }
>>>>
>>>> +void DwarfUnit::addLabelDelta(DIE *Die, dwarf::Attribute Attribute,
>>>> +                              const MCSymbol *Hi, const MCSymbol *Lo) {
>>>> +  DIEValue *Value = new (DIEValueAllocator) DIEDelta(Hi, Lo);
>>>> +  Die->addValue(Attribute, dwarf::DW_FORM_data4, Value);
>>>> +}
>>>> +
>>>> /// addDIEEntry - Add a DIE attribute data and value.
>>>> ///
>>>> void DwarfUnit::addDIEEntry(DIE *Die, dwarf::Attribute Attribute, DIE *Entry) {
>>>>
>>>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.h
>>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.h?rev=203187&r1=203186&r2=203187&view=diff
>>>> ==============================================================================
>>>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.h (original)
>>>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.h Thu Mar  6 19:30:55 2014
>>>> @@ -359,6 +359,10 @@ public:
>>>>  void addSectionDelta(DIE *Die, dwarf::Attribute Attribute, const MCSymbol *Hi,
>>>>                       const MCSymbol *Lo);
>>>>
>>>> +  /// addLabelDelta - Add a label delta attribute data and value.
>>>> +  void addLabelDelta(DIE *Die, dwarf::Attribute Attribute, const MCSymbol *Hi,
>>>> +                     const MCSymbol *Lo);
>>>> +
>>>>  /// addDIEEntry - Add a DIE attribute data and value.
>>>>  void addDIEEntry(DIE *Die, dwarf::Attribute Attribute, DIE *Entry);
>>>>
>>>>
>>>> Modified: llvm/trunk/test/DebugInfo/AArch64/dwarfdump.ll
>>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/AArch64/dwarfdump.ll?rev=203187&r1=203186&r2=203187&view=diff
>>>> ==============================================================================
>>>> --- llvm/trunk/test/DebugInfo/AArch64/dwarfdump.ll (original)
>>>> +++ llvm/trunk/test/DebugInfo/AArch64/dwarfdump.ll Thu Mar  6 19:30:55 2014
>>>> @@ -12,7 +12,7 @@
>>>> ; A couple of ABS64s similarly:
>>>>
>>>> ; CHECK: DW_AT_low_pc [DW_FORM_addr] (0x0000000000000000)
>>>> -; CHECK: DW_AT_high_pc [DW_FORM_addr] (0x0000000000000008)
>>>> +; CHECK: DW_AT_high_pc [DW_FORM_data4] (0x00000008)
>>>>
>>>> define i32 @main() nounwind {
>>>>  ret i32 0, !dbg !8
>>>>
>>>> Modified: llvm/trunk/test/DebugInfo/X86/dbg-value-location.ll
>>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dbg-value-location.ll?rev=203187&r1=203186&r2=203187&view=diff
>>>> ==============================================================================
>>>> --- llvm/trunk/test/DebugInfo/X86/dbg-value-location.ll (original)
>>>> +++ llvm/trunk/test/DebugInfo/X86/dbg-value-location.ll Thu Mar  6 19:30:55 2014
>>>> @@ -4,7 +4,7 @@ target datalayout = "e-p:64:64:64-i1:8:8
>>>> target triple = "x86_64-apple-darwin10.0.0"
>>>> ;Radar 8950491
>>>>
>>>> -;CHECK: .long Lset5
>>>> +;CHECK: .long Lset6
>>>> ;CHECK-NEXT:        ## DW_AT_decl_file
>>>> ;CHECK-NEXT:        ## DW_AT_decl_line
>>>> ;CHECK-NEXT:        ## DW_AT_type
>>>>
>>>>
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>>>
>



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