[llvm-commits] [llvm] r66366 - in /llvm/trunk: lib/Transforms/Scalar/ScalarReplAggregates.cpp test/Transforms/ScalarRepl/2008-06-22-LargeArray.ll test/Transforms/ScalarRepl/vector_memcpy.ll

[Eli Friedman]

On Sun, Mar 8, 2009 at 10:41 AM, Chris Lattner <clattner at apple.com> wrote:
> On Mar 8, 2009, at 3:36 AM, Duncan Sands wrote:
>> Hi Chris,
>>
>>> +    // If this is a memcpy or memmove into or out of the whole
>>> allocation, we
>>> +    // can handle it like a load or store of the scalar type.
>>
>> a load+store of a floating point type might trap, while a memcpy/
>> memmove would
>> not.
>
> How so?  Load of double works on any bit pattern, so long as the
> address is correct and the alignment is right etc.

That's not true for x87 FP: SNaNs either crash or get silently changed
into QNaNs, depending on the control word.  I haven't read the code
carefully enough to see whether that applies here, though.

-Eli