[llvm] [SROA] Unfold gep of index phi (round 2) (PR #83494)

[Lei Wang via llvm-commits]

wlei-llvm wrote:

Hi, 
This breaks one of our assertion build:

```
Instruction does not dominate all uses!
  %3 = alloca i8, i64 %conv17169, align 16, !dbg !15551
  %__cs.0.sroa.gep = getelementptr inbounds i8, ptr %3, i64 1, !dbg !15533
Instruction does not dominate all uses!
  %4 = alloca i8, i64 %conv17, align 16, !dbg !15551
  %__cs.0.sroa.gep173 = getelementptr inbounds i8, ptr %4, i64 1, !dbg !15533
Instruction does not dominate all uses!
  %3 = alloca i8, i64 %conv17169, align 16, !dbg !15551
  %__cs.0.sroa.gep177 = getelementptr inbounds i8, ptr %3, i64 2, !dbg !15533
Instruction does not dominate all uses!
  %4 = alloca i8, i64 %conv17, align 16, !dbg !15551
  %__cs.0.sroa.gep178 = getelementptr inbounds i8, ptr %4, i64 2, !dbg !15533
Instruction does not dominate all uses!
  %3 = alloca i8, i64 %conv17145, align 16, !dbg !15820
  %__cs.0.sroa.gep = getelementptr inbounds i8, ptr %3, i64 1, !dbg !15803
Instruction does not dominate all uses!
  %4 = alloca i8, i64 %conv17, align 16, !dbg !15820
  %__cs.0.sroa.gep149 = getelementptr inbounds i8, ptr %4, i64 1, !dbg !15803
Instruction does not dominate all uses!
  %3 = alloca i8, i64 %conv17145, align 16, !dbg !15820
  %__cs.0.sroa.gep153 = getelementptr inbounds i8, ptr %3, i64 2, !dbg !15803
Instruction does not dominate all uses!
  %4 = alloca i8, i64 %conv17, align 16, !dbg !15820
  %__cs.0.sroa.gep154 = getelementptr inbounds i8, ptr %4, i64 2, !dbg !15803
fatal error: error in backend: Broken module found, compilation aborted!
```
Please take a look, thanks! I will try to get a reduced reproducer but posted just in case something obvious to fix.





https://github.com/llvm/llvm-project/pull/83494