[llvm-commits] [llvm] r83122 - in /llvm/trunk: include/llvm/Target/TargetSubtarget.h lib/CodeGen/LLVMTargetMachine.cpp lib/CodeGen/PostRASchedulerList.cpp lib/Target/ARM/ARM.td lib/Target/ARM/ARMSubtarget.cpp lib/Target/ARM/ARMSubtarget.h test/Co

[David Goodwin]

Well, now I've found something like this:

static cl::opt<cl::boolOrDefault> FlagEnableTailMerge("enable-tail- 
merge",
                               cl::init(cl::BOU_UNSET), cl::Hidden);

So I can use CPU type to set NEON-fp and post-ra sched defaults, and  
then this type of hidden flag to override. This one provides the "keep  
default" behavior that I need. That is what I will do unless I hear  
otherwise.

David


On Sep 30, 2009, at 12:49 PM, Sandeep Patel wrote:

> I'd actually prefer if there were a way to toggle codegen choices like
> neonfp from the llvm-gcc command line instead of using -mattr. Perhaps
> the fix here is to add -mattr to llvm-gcc.
>
> deep
>
> On Wed, Sep 30, 2009 at 4:58 PM, David Goodwin <david_goodwin at apple.com 
> > wrote:
>> I suppose I could set the default programmatically based on the CPU
>> string, and then have a hidden tri-state flag (keep default, force  
>> on,
>> force off) for overriding. Note that we have another attribute like
>> this that is used to indicate that NEON instructions should be used
>> for single-precision FP.
>>
>> David
>>
>> On Sep 30, 2009, at 8:40 AM, David Goodwin wrote:
>>
>>> I did add a subtarget hook to control post-ra scheduling. And by
>>> default it is off except for the one CPU that is ready for it
>>> (cortex-a8). But there needs to be a way to override the default (in
>>> either direction), as well as a way to set the default for a
>>> particular CPU. -mattr satisfies both of those requirements. Can I
>>> get the same behavior in a different way?
>>>
>>> Evan, all CPUs have an itinerary (even if it is an empty itinerary)
>>> so I don't think that can be used... and we would still need a way
>>> to override the default.
>>>
>>> David
>>>
>>> On Sep 30, 2009, at 12:43 AM, Evan Cheng wrote:
>>>
>>>>
>>>> On Sep 29, 2009, at 10:16 PM, Chris Lattner wrote:
>>>>
>>>>>
>>>>> On Sep 29, 2009, at 5:10 PM, David Goodwin wrote:
>>>>>
>>>>>> Author: david_goodwin
>>>>>> Date: Tue Sep 29 19:10:16 2009
>>>>>> New Revision: 83122
>>>>>>
>>>>>> URL: http://llvm.org/viewvc/llvm-project?rev=83122&view=rev
>>>>>> Log:
>>>>>> Remove -post-RA-schedule flag and add a TargetSubtarget method to
>>>>>> enable post-register-allocation scheduling. By default it is off.
>>>>>> For ARM, enable/disable with -mattr=+/-postrasched. Enable by
>>>>>> default for cortex-a8.
>>>>>
>>>>> Hi David,
>>>>>
>>>>> -mattr should be used for CPU attributes, not for optimization
>>>>> flags.
>>>>> Having a subtarget hook (or even TargetMachine hook) to indicate
>>>>> whether this should default to on or not makes sense to me, but
>>>>> should
>>>>> it really be controlled via -mattr?
>>>>
>>>> I think ARM target should run postalloc scheduling when scheduling
>>>> itinerary is available for the given cpu?
>>>>
>>>> Evan
>>>>
>>>>>
>>>>> -Chris
>>>>>
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>>>>
>>>
>>
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