[llvm-commits] [llvm] r64124 - in /llvm/trunk: include/llvm/Target/ lib/CodeGen/ lib/Target/ARM/ lib/Target/Alpha/ lib/Target/CellSPU/ lib/Target/Mips/ lib/Target/PowerPC/ lib/Target/X86/ lib/Target/XCore/

Evan Cheng evan.cheng at apple.com
Mon Feb 9 00:41:58 PST 2009

On Feb 8, 2009, at 11:20 PM, Chris Lattner wrote:

> On Feb 8, 2009, at 11:14 PM, Evan Cheng wrote:
>> Author: evancheng
>> Date: Mon Feb  9 01:14:22 2009
>> New Revision: 64124
>> URL: http://llvm.org/viewvc/llvm-project?rev=64124&view=rev
>> Log:
>> Turns out AnalyzeBranch can modify the mbb being analyzed. This is a
>> nasty
>> suprise to some callers, e.g. register coalescer. For now, add an
>> parameter
>> that tells AnalyzeBranch whether it's safe to modify the mbb. A  
>> better
>> solution is out there, but I don't have time to deal with it right
>> now.
> Whoa, that's really not cool.  *why* does analyze branch modify a
> mbb?  What breaks if that is disabled from all targets?

It's trimming instructions in a mbb after an unconditional branch. I  
don't know why that would happen but it does. I think it's branching  
folding's job to trim those instructions. But I don't have the energy  
to deal with that right now.


> -chris
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