[llvm] [InstCombine] Add assume-based optimizations for equality and AMDGPU ballot patterns (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
+    if (auto *ICmp = dyn_cast<ICmpInst>(IIOperand)) {
+      if (ICmp->getPredicate() == ICmpInst::ICMP_EQ) {
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ssahasra wrote:

Can the pattern match be used here at this point?

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