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Remove the user-count threshold when analyzing read attributes

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Summary:
This threshold limited FunctionAttrs ability to prove arguments to be read-only. 
In NVPTX, a specialized instruction ld.global.nc can be used to load memory
with non-coherent texture cache. We notice that in SHOC [1] benchmark, some
function arguments are not marked with readonly because FunctionAttrs reaches
a hardcoded threshold when analysis uses.

Removing this threshold won't cause significant regression in compilation time, because the worst-case time complexity of the algorithm is still O(# of instructions) for each parameter.

Patched by Xuetian Weng.  

[1] https://github.com/vetter/shoc

Reviewers: nlewycky, jingyue, nicholas

Subscribers: nicholas, test, llvm-commits

Differential Revision: http://reviews.llvm.org/D11311

llvm-svn: 243141
This commit is contained in:
Jingyue Wu 2015-07-24 19:05:53 +00:00
parent 48be953065
commit 344082ead8
1 changed files with 0 additions and 3 deletions
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3
lib/Transforms/IPO/FunctionAttrs.cpp
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@ -425,9 +425,6 @@ determinePointerReadAttrs(Argument *A,
// We don't need to track IsWritten. If A is written to, return immediately.
for (Use &U : A->uses()) {
if (Count++ >= 20)
return Attribute::None;
Visited.insert(&U);
Worklist.push_back(&U);
}