[LLVMdev] [llvm-commits] [PATCH] fast-math patches!

Michael Ilseman milseman at apple.com
Thu Nov 15 18:54:22 PST 2012 

Another round of improved patches, and a patch for documentation changes to LangRef.
 * Make comments more up to date
 * Use 'arcp' instead of 'ar'
 * Use logical ||

Still based off of r168110










On Nov 15, 2012, at 3:31 PM, Michael Ilseman <milseman at apple.com> wrote:

> 
> On Nov 15, 2012, at 3:23 PM, Joe Abbey <joe.abbey at gmail.com> wrote:
> 
>> Though semantically equivalent in this case, however I think you should use logical ors here not bitwise.
>> 
>> +  bool any() {
>> +    return UnsafeAlgebra | NoNaNs | NoInfs | NoSignedZeros |
>> +      AllowReciprocal;
>> +  }
>> 
> 
> Will do.
> 
>> Gripe:  This pattern is probably super fast and has precedence… but the code is non-obvious:
>> 
>> SubclassOptionalData =
>> 	(SubclassOptionalData & ~BitToSet) | (B * BitToSet);
>> 
> 
> This is an existing pattern that's used elsewhere in the file, so I had assumed it was well understood and preferred.
> 
>> This is likely one iota slower.. but it sure is easier to get the intent.
>> 
>> B ? SubclassOptionalData |=  BitToSet : 
>>     SubclassOptionalData &= ~BitToSet;
>> 
>> Otherwise looks good to me.
>> 
>> Joe
>> 
>> On Nov 15, 2012, at 5:50 PM, Joe Abbey <joe.abbey at gmail.com> wrote:
>> 
>>> Trying to apply patches..
>>> 
>>> What's your base revision?
>>> 
>>> Joe
>>> 
>>> On Nov 15, 2012, at 5:44 PM, Michael Ilseman <milseman at apple.com> wrote:
>>> 
>>>> New patches with review feedback incorporated:
>>>> * Changed single letter flags to short abbreviations ('S' ==> 'nsz')
>>>> * Indentation fixes
>>>> * Comments don't state function names
>>>> 
>>>> <0002-Fast-math-flags-added-to-FPMathOperator.patch>
>>>> <0003-Fast-math-interfaces-for-Instructions.patch>
>>>> <0004-Fast-math-flags-for-LLVM-IR-parsing-and-printing.patch>
>>>> <0005-Fast-math-flags-for-the-bitcode.patch>
>>>> <0006-Fast-math-test-case-for-bitcode-and-textual-reading-.patch>
>>>> <0007-Fast-math-optimization-fold-multiply-by-zero.patch>
>>>> <0008-Fast-math-test-for-SimplifyInstruction-fold-multiply.patch>
>>>> 
>>>> On Nov 15, 2012, at 10:51 AM, Evan Cheng <evan.cheng at apple.com> wrote:
>>>> 
>>>>> 
>>>>> On Nov 15, 2012, at 10:51 AM, Michael Ilseman <milseman at apple.com> wrote:
>>>>> 
>>>>>> 
>>>>>> On Nov 15, 2012, at 10:38 AM, Evan Cheng <evan.cheng at apple.com> wrote:
>>>>>> 
>>>>>>> Hi Michael,
>>>>>>> 
>>>>>>> The patch looks good in general. But I'm a bit concerned about the textural representation about these flags. 'N', 'I', 'S', 'R', 'A' seem cryptic to me. Does it make sense to expand them a bit 'nnan', 'inf', etc.? They definitely need to be documented.
>>>>>>> 
>>>>>> 
>>>>>> I think it does make sense to expand them to be more readable. Also, the textual representation doesn't have to precisely follow the internal names. What about:
>>>>>> nnan : no nans
>>>>>> ninf : no infs
>>>>>> nsz : no signed zeros
>>>>>> ar: allow reciprocal
>>>>>> fast : unsafe algebra (and implicitly all the others)
>>>>> 
>>>>> These seem reasonable to me. Thanks!
>>>>> 
>>>>> Evan
>>>>> 
>>>>>> 
>>>>>> I'll get started on documentation.
>>>>>> 
>>>>>>> Evan
>>>>>>> 
>>>>>>> On Nov 15, 2012, at 10:17 AM, Michael Ilseman <milseman at apple.com> wrote:
>>>>>>> 
>>>>>>>> Attached are some patches for adding in an IR-level mechanism for representing fast-math flags, as discussed in my prior RFC. Patches include infrastructure, API support, textual and bitcode reader/writer support, example optimization, and test cases.
>>>>>>>> 
>>>>>>>> <0002-Fast-math-flags-added-to-FPMathOperator.patch>
>>>>>>>> <0003-Fast-math-interfaces-for-Instructions.patch>
>>>>>>>> <0004-Fast-math-flags-for-LLVM-IR-parsing-and-printing.patch>
>>>>>>>> <0005-Fast-math-flags-for-the-bitcode.patch>
>>>>>>>> <0006-Fast-math-test-case-for-bitcode-and-textual-reading-.patch>
>>>>>>>> <0007-Fast-math-optimization-fold-multiply-by-zero.patch>
>>>>>>>> <0008-Fast-math-test-for-SimplifyInstruction-fold-multiply.patch>
>>>>>>>> 
>>>>>>>> _______________________________________________
>>>>>>>> LLVM Developers mailing list
>>>>>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>>>> 
>>>>>> 
>>>>> 
>>>> 
>>>> _______________________________________________
>>>> llvm-commits mailing list
>>>> llvm-commits at cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>> 
>> 
> 
> _______________________________________________
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