[PATCH] D69891: [VP,Integer,#1] Vector-predicated integer intrinsics
Hanna Kruppe via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 19 11:27:21 PDT 2020
rkruppe added a comment.
In D69891#1931607 <https://reviews.llvm.org/D69891#1931607>, @reames wrote:
> Reading through the LangRef change post commit I was struck by this wording: "The VP intrinsic has undefined behavior if ``%evl > W``."
>
> This is a very strong interpretation and doesn't match what we do for arithmetic. One consequence of that difference is that hoisting a vp intrinsic out of a loop will not be legal unless we can prove the EVL is in bounds. You probably want some variant of a poison semantic propagation instead. Unless of course, real hardware happens to fault on out of bounds EVL in which case the current semantic is what you want. :)
>
> Otherwise, nice work.
I brought this up in D57504 <https://reviews.llvm.org/D57504> earlier, and @simoll said that some real hardware indeed faults in this case:
> The VE target strictly requires VL <= MVL or you'll get a hardware exception.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D69891/new/
https://reviews.llvm.org/D69891
More information about the llvm-commits
mailing list