[llvm] StructurizeCFG: Optimize phi insertion during ssa reconstruction (PR #101301)

[Yaxun Liu via llvm-commits]

yxsamliu wrote:

> > This PR seems to break HIP buildbot, causing Blender test to memfault:
> > https://lab.llvm.org/buildbot/#/builders/123/builds/3282
> 
> Thanks for the revert. @yxsamliu Is there any guide how to reproduce the Blender fail locally?

The test script of blender is at https://github.com/llvm/llvm-test-suite/blob/main/External/HIP/workload/blender/test_blender.sh.in . It can be renamed to .sh and executed. The dependent scripts can be found at https://github.com/llvm/llvm-test-suite/tree/main/External/HIP/utils and copied to the same directory.

I will add documentation about how to locally run HIP blender test to README of https://github.com/llvm/llvm-test-suite/tree/main/External/HIP

Since the issue is memfault, here is a simpler script to reproduce it:

```
export CCC_OVERRIDE_OPTIONS='x-ffast-math +-mcode-object-version=4 +-v'
export HIP_CLANG_PATH=/path/to/your/clang/bin
export HIPCC_VERBOSE=7
export HIP_USE_PERL_SCRIPTS=1

rm -rf ~/.cache/cycles/kernels/*
mkdir -p ~/.cache/cycles/kernels

/path/to/blender -b 290skydemo_release.blend -F PNG -o 290skydemo_release### -f 48 --debug-cycles -- --cycles-device HIP

```
The issue was found with Blender 4.1 (https://download.blender.org/release/Blender4.1/) on gfx908 + ubuntu 22.04 + ROCm 6.0.2 but may also be reproducible on other AMD GPU + ROCm 6.1 or 6.2. The blender scene file can be downloaded at https://cloud.blender.org/p/gallery/5f4d1791cc1d7c5e0e8832d4 . Thanks.

https://github.com/llvm/llvm-project/pull/101301