[BACKEND] Update LLVM version to https://github.com/llvm/llvm-project/commit/3e77871c220e4d4c91956060b15ff28e27b2b764

[Moerafaat]

No description provided.

[Moerafaat]

@ThomasRaoux from what I understand the last LLVM update was causing a regression. Not sure if you have a reproducer yet, but this is a newer version. Not sure if it fixes the regression you have so can we check if this one is OK?

[ThomasRaoux]

Thanks @Moerafaat! I started debugging the perf regression but didn't get to the bottom of it (it happens either in codegen prepare or isel). I'll try this llvm version and if it is still there share a public reproducer.

[gflegar]

@Moerafaat do the tests start passing again after rebasing beyond #3147? @jlebar says that they are seeing something different than what we are seeing internally, so it could be that the patch is not doing what we thought it did, or maybe something changed in the newer LLVM version, and we need both that patch, and this PR to reproduce what we have internally.

[Moerafaat]

@Moerafaat do the tests start passing again after rebasing beyond #3147? @jlebar says that they are seeing something different than what we are seeing internally, so it could be that the patch is not doing what we thought it did, or maybe something changed in the newer LLVM version, and we need both that patch, and this PR to reproduce what we have internally.

I see that the checks are now passing so I assume the rebase did the trick.

[Moerafaat]

Thanks @Moerafaat! I started debugging the perf regression but didn't get to the bottom of it (it happens either in codegen prepare or isel). I'll try this llvm version and if it is still there share a public reproducer.

@ThomasRaoux following up if there are any updates here?

[ThomasRaoux]

Thanks @Moerafaat! I started debugging the perf regression but didn't get to the bottom of it (it happens either in codegen prepare or isel). I'll try this llvm version and if it is still there share a public reproducer.

@ThomasRaoux following up if there are any updates here?

unfortunately I still see the performance regression. I'll try to bisect

[ThomasRaoux]

Bisect is pointing to this PR as the reason for the perf slowdown:
llvm/llvm-project#80281

not clear exactly why, I'll have to debug more.