[llvm-commits] [llvm] r82485 - in /llvm/trunk: lib/CodeGen/SimpleRegisterCoalescing.cpp lib/CodeGen/SimpleRegisterCoalescing.h test/CodeGen/ARM/2008-11-19-ScavengerAssert.ll test/CodeGen/ARM/remat.ll test/CodeGen/X86/2008-02-22-ReMatBug.ll test/CodeGen/X86/2008-07-11-SpillerBug.ll test/CodeGen/X86/2009-04-20-LinearScanOpt.ll test/CodeGen/X86/2009-09-21-NoSpillLoopCount.ll test/CodeGen/X86/stack-color-with-reg.ll

Bill Wendling wendling at apple.com
Mon Sep 21 19:47:55 CDT 2009


On Sep 21, 2009, at 5:07 PM, Evan Cheng wrote:

> On Sep 21, 2009, at 3:34 PM, Bill Wendling wrote:
>
>> On Sep 21, 2009, at 2:39 PM, Evan Cheng wrote:
>>
>>>
>>> On Sep 21, 2009, at 2:19 PM, Bill Wendling wrote:
>>>
>>>>>
>>>> This loop is dead is "HasDef" and "HasUse" are both true. :-)
>>>
>>> That's not possible. isDef() the opposite of isUse().
>>>
>> Yes, but the only affect of the "|=" operator on a boolean is to  
>> turn it from a "false" to a "true". If HasDef and HasUse are  
>> already true after their initializations, then the loop will can't  
>> turn them "false". :-)
>
> I don't understand your point. Before the loop, HasDef and HasUse  
> cannot both be true. The only possible simplification here is an  
> early exit out of the loop if both HasDef and HasUse have become true.
>
Ah. I see what you mean. Never mind. :)

-bw




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