[llvm] [VPlan] First step towards VPlan cost modeling. (PR #92555)

[Alexander Kornienko via llvm-commits]

alexfh wrote:

I see another clang fatal error that is not fixed by the patches including 67f4968a57789fa07dcdb0c4421e4beeb725a0db. 

The error looks like this:
```
Invalid shufflevector operands!
  %.uncasted = shufflevector <4 x i16> %37, <4 x i16> %42, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>, !dbg !43223
Invalid shufflevector operands!
  %.uncasted21 = shufflevector <4 x i16> %47, <4 x i16> %52, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>, !dbg !43223
Both operands to a binary operator are not of the same type!
  %34 = fmul <4 x float> %33, <2 x float> <float 5.000000e-01, float 5.000000e-01>, !dbg !56204
Both operands to a binary operator are not of the same type!
  %36 = fmul <4 x float> %35, <2 x float> <float 5.000000e-01, float 5.000000e-01>, !dbg !56207
Both operands to a binary operator are not of the same type!
  %38 = fmul <4 x float> %37, <2 x float> <float 5.000000e-01, float 5.000000e-01>, !dbg !56210
Both operands to a binary operator are not of the same type!
  %40 = fmul <4 x float> %39, <2 x float> <float 5.000000e-01, float 5.000000e-01>, !dbg !56213
fatal error: error in backend: Broken module found, compilation aborted!
```

The issue reproduces in a ThinLTO compilation, which somewhat complicates extracting a test case.

https://github.com/llvm/llvm-project/pull/92555