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

[Joe Abbey]

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;
+  }

Gripe:  This pattern is probably super fast and has precedence… but the code is non-obvious:

SubclassOptionalData =
	(SubclassOptionalData & ~BitToSet) | (B * BitToSet);

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>
>>>>>> 
>>>>>> _______________________________________________
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>>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>> 
>>>> 
>>> 
>> 
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> 

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