mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2025-01-31 20:51:52 +01:00
d952afa83a
Previously, _any_ store or load instruction was considered to be operating on a spill if it had a frameindex as an operand, and thus was fair game for optimisations such as "StackSlotColoring". This usually works, except on architectures where spills can be partially restored, for example on X86 where a spilt vector can have a single component loaded (zeroing the rest of the target register). This can be mis-interpreted and the zero extension unsoundly eliminated, see pr30821. To avoid this, this commit optionally provides the caller to isLoadFromStackSlot and isStoreToStackSlot with the number of bytes spilt/loaded by the given instruction. Optimisations can then determine that a full spill followed by a partial load (or vice versa), for example, cannot necessarily be commuted. Patch by Jeremy Morse! Differential Revision: https://reviews.llvm.org/D44782 llvm-svn: 330778