Displaying 2 results from an estimated 2 matches for "a5z".
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a5
2017 Dec 14
3
[RFC] Add TargetTransformInfo::isAllocaPtrValueNonZero and let ValueTracking depend on TargetTransformInfo
...represented by data layout, e.g., the last component of the data layout of amdgcn---amdgiz target is -A5, which means alloca is in address space 5. How about adding a letter z to -A5 to indicate alloca may have zero value? i.e. -A5 means alloca is in address space 5 and always has non-zero value, -A5z means alloca is in address space 5 and may have zero value.
Then we can add function DataLayout::isAllocaPtrValueNonZero() to check whether alloca always has non-zero value.
Sam
From: Hal Finkel [mailto:hfinkel at anl.gov]
Sent: Thursday, December 14, 2017 4:06 PM
To: Liu, Yaxun (Sam) <Yaxun....
2017 Dec 14
2
[RFC] Add TargetTransformInfo::isAllocaPtrValueNonZero and let ValueTracking depend on TargetTransformInfo
Some optimizations depend on whether alloca instruction always has non-zero value. Currently, this checking is done by isKnownNonZero() in ValueTracking, and it assumes alloca in address space 0 always has non-zero value but alloca in non-zero address spaces does not always have non-zero value.
However, this assumption is incorrect for certain targets. For example, amdgcn---amdgiz target has