[clang] [llvm] [clang][SPIR-V] Implement -fspv-preserve-interface (PR #196404)

[Juan Manuel Martinez Caamaño via cfe-commits]

jmmartinez wrote:

> > > > @bogner thanks for the review. Would you be able to submit the PR for me? I don't have write access to the repo. Thanks.
> > > 
> > > 
> > > ~I'll do it.~
> > > After the rebase son hlsl tests failed. @dnovillo could you check this ?
> > > The windows failure look related to this PR.
> > 
> > 
> > Will do. Thanks for the heads up.
> 
> I looked at the failures but I could not find a relation to my PR:
> 
> 1. macOS has a failure in `OffloadTest-clang-mtl :: WaveOps/WaveReadLaneAt.index.test` that I can't see being caused by the flag:
> 
> ```
> Function: main: error: I8 can only be used as immediate value for intrinsic or as i8* via bitcast by lifetime intrinsics.
> note: at '%21 = getelementptr inbounds [3 x i8], [3 x i8]* @switch.table.main, i32 0, i32 %20' in block '#1' of function 'main'.
> Function: main: error: I8 can only be used as immediate value for intrinsic or as i8* via bitcast by lifetime intrinsics.
> note: at '%22 = load i8, i8* %21, align 1' in block '#1' of function 'main'.
> Function: main: error: I8 can only be used as immediate value for intrinsic or as i8* via bitcast by lifetime intrinsics.
> note: at '%23 = zext i8 %22 to i32' in block '#1' of function 'main'.
> Validation failed.
> clang-dxc: error: dxv command failed with exit code 1 (use -v to see invocation)
> ```
> 
> 2. The windows bot is getting an sccache timeout:
> 
> ```
> sccache: error: Timed out waiting for server startup
> sccache: error: Timed out waiting for server startup. Maybe the remote service is unreachable?
> Run with SCCACHE_LOG=debug SCCACHE_NO_DAEMON=1 to get more information
> Process completed with exit code 2.
> ```
> 
> Not sure how to deal with these failures.

No worries then. If you think it's not related I'll rebase and move on with the merge.

https://github.com/llvm/llvm-project/pull/196404