[PATCH] D28135: SelectionDAG: Fix in legalization of UMAX/SMAX/UMIN/SMIN. Solves PR31486.

[Mikael Holmén via Phabricator via llvm-commits]

uabelho added inline comments.


================
Comment at: test/CodeGen/AMDGPU/legalize-umax-bug.mir:1-2
+# RUN: llc -march=r600 -mcpu=cypress -start-after safe-stack %s -o /dev/null
+
+# Don't crash
----------------
uabelho wrote:
> arsenm wrote:
> > Having a MIR test for a SelectionDAG bug doesn't really make sense. This should be a regular IR test.
> > 
> > Also can you run opt -instnamer on it?
> I agree, and on my out-of-tree target I get the crash from an ll-file. However, running that on -march=r600 -mcpu=cypress Early CSE kicks in and simplifies the test case so the crash doesn't appear anymore, and I can't find any flag to turn off Early CSE while still running later optimizations on the DAG?
> 
> So using the mir file (without any mir in it) was just a way to be able to start compilation after Early CSE, so it wouldn't mess up things for me.
> 
> Someone with better knowledge of the different in-tree target can probably reproduce the crash from an ll file but I fail.
> 
> I don't know what opt -instnamer is but I'll look into it.
And, looking in my inbox I saw that I already had a better (ll) reproducer sent to me from Jan Vesely. Thanks! I'll update the patch!

(Also I learned that I can use -start-after also on ll files. For some reason I thought that didn't work...)


https://reviews.llvm.org/D28135