[llvm] [WIP][Assume] Generic assume-based uniformity optimization (PR #160670)

[Sameer Sahasrabuddhe via llvm-commits]

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@@ -3540,6 +3540,79 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
       }
     }
 
+    // Basic assume equality optimization: assume(x == c) -> replace dominated uses of x with c
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ssahasra wrote:

```suggestion
    // Basic assume equality optimization: assume(x == c) -> replace uses of x with c
```
LLVM IR is SSA ... a value always dominates all its uses.

https://github.com/llvm/llvm-project/pull/160670