[llvm] r200422 - Turn on CU ranges if we've got multiple compile units in the same

[Eric Christopher]

On Wed, Jan 29, 2014 at 2:23 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
>
> On Wed, Jan 29, 2014 at 2:06 PM, Eric Christopher <echristo at gmail.com>
> wrote:
>>
>> Author: echristo
>> Date: Wed Jan 29 16:06:27 2014
>> New Revision: 200422
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=200422&view=rev
>> Log:
>> Turn on CU ranges if we've got multiple compile units in the same
>> module since there's no range guarantee that we could make given
>> output order. This also fixes up the testcases that have multiple
>> CUs to have the correct range offset.
>
>
> What if LTO together a debug and non-debug module together? We'll still have
> one CU, but we'll have functions that aren't in that CU - and incorrectly
> describe that using an "all text" range?
>

... Short of saying "always use DW_AT_ranges" I don't have a good
solution for this. I'm somewhat down with that, but...

-eric

>>
>>
>> Modified:
>>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>     llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
>>
>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=200422&r1=200421&r2=200422&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Wed Jan 29 16:06:27
>> 2014
>> @@ -1119,10 +1119,12 @@ void DwarfDebug::endSections() {
>>    }
>>
>>    // For now only turn on CU ranges if we've explicitly asked for it,
>> -  // we have -ffunction-sections enabled, or we've emitted a function
>> -  // into a unique section. At this point all sections should be
>> finalized
>> -  // except for dwarf sections.
>> -  HasCURanges = DwarfCURanges || UsedNonDefaultText ||
>> +  // we have -ffunction-sections enabled, we've emitted a function
>> +  // into a unique section, or we're using LTO. If we're using LTO then
>> +  // we can't know that any particular function in the module is
>> correlated
>> +  // to a particular CU and so we need to be conservative. At this point
>> all
>> +  // sections should be finalized except for dwarf sections.
>> +  HasCURanges = DwarfCURanges || UsedNonDefaultText || (CUMap.size() > 1)
>> ||
>>                  TargetMachine::getFunctionSections();
>>  }
>>
>>
>> Modified:
>> llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll?rev=200422&r1=200421&r2=200422&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
>> (original)
>> +++ llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll Wed
>> Jan 29 16:06:27 2014
>> @@ -8,11 +8,11 @@
>>  ; CHECK: .debug_info contents:
>>  ; CHECK: DW_TAG_compile_unit
>>  ; CHECK: DW_AT_stmt_list [DW_FORM_sec_offset]   (0x00000000)
>> -; CHECK: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
>> +; CHECK: DW_AT_ranges [DW_FORM_sec_offset]      (0x00000000)
>>
>>  ; CHECK: DW_TAG_compile_unit
>>  ; CHECK: DW_AT_stmt_list [DW_FORM_sec_offset]   (0x0000003c)
>> -; CHECK: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
>> +; CHECK: DW_AT_ranges [DW_FORM_sec_offset]      (0x00000020)
>>
>>  ; CHECK: .debug_line contents:
>>  ; CHECK-NEXT: Line table prologue:
>> @@ -25,12 +25,12 @@
>>
>>  ; DWARF3: .debug_info contents:
>>  ; DWARF3: DW_TAG_compile_unit
>> -; DWARF3: DW_AT_stmt_list [DW_FORM_data4]   (0x00000000)
>> -; DWARF3: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
>> +; DWARF3: DW_AT_stmt_list [DW_FORM_data4]    (0x00000000)
>> +; DWARF3: DW_AT_ranges [DW_FORM_data4]       (0x00000000)
>>
>>  ; DWARF3: DW_TAG_compile_unit
>>  ; DWARF3: DW_AT_stmt_list [DW_FORM_data4]   (0x0000003c)
>> -; DWARF3: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
>> +; DWARF3: DW_AT_ranges [DW_FORM_data4]      (0x00000020)
>>
>>  ; DWARF3: .debug_line contents:
>>  ; DWARF3-NEXT: Line table prologue:
>>
>>
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>
>