[PATCH] D40633: [PCG] Poor shuffle lane tracking (PR35454 )
Sanjay Patel via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 30 12:54:56 PST 2017
spatel added inline comments.
================
Comment at: lib/Transforms/InstCombine/InstructionCombining.cpp:1465-1466
+ // recompute the shuffle instruction mask has very limited usage because, we
+ // can recompute the shuffle mask only in a case when the shuffle mask is a
+ // constant value, and secondly we can do this only in a situation when we
+ // need to change a shuffle instruction vector type from <4 x i32> to <16 x
----------------
The shuffle mask is always a constant:
"The shuffle mask operand is required to be a constant vector with either constant integer or undef values."
http://llvm.org/docs/LangRef.html#shufflevector-instruction
https://reviews.llvm.org/D40633
More information about the llvm-commits
mailing list