[llvm-commits] [llvm] r64877 - in /llvm/trunk: lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp lib/Target/PowerPC/AsmPrinter/PPCAsmPrinter.cpp lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp test/CodeGen/X86/cstring.ll

[Evan Cheng]

On Feb 17, 2009, at 8:53 PM, Chris Lattner wrote:

>
> On Feb 17, 2009, at 8:52 PM, Evan Cheng wrote:
>
>>
>> On Feb 17, 2009, at 7:48 PM, Chris Lattner wrote:
>>
>>>
>>> On Feb 17, 2009, at 6:19 PM, Evan Cheng wrote:
>>>
>>>> Author: evancheng
>>>> Date: Tue Feb 17 20:19:52 2009
>>>> New Revision: 64877
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=64877&view=rev
>>>> Log:
>>>> GV with null value initializer shouldn't go to BSS if it's meant  
>>>> for
>>>> a mergeable strings section. Currently it only checks for Darwin.
>>>> Someone else please check if it should apply to other targets as  
>>>> well.
>>>
>>> Evan, this seems like the wrong fix.  What *requires* an empty  
>>> string
>>> to go into the cstring section?  If there is some semantics that
>>> require it, then whatever produces the llvm global should set the
>>> section of the global to the cstring section explicitly.
>>
>> I don't see why this is wrong/ Per revision 63142,target asm info  
>> has already decided this particular GV should go into cstring. But  
>> the asm printer then decided to put it in BSS (which means it  
>> cannot be coalesced) because the initializer is empty. This patch  
>> makes sure asm printer doesn't try to out smart itself.
>
> Why is this important?

rdar://6479858. It's a minor size win, but more importantly it avoids  
linker warning. That means fewer complaints about llvm-gcc (and it has  
been reported at least twice so far at Apple).

Evan


>
> -Chris
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