[llvm] [SandboxIR] Implement missing PHINode functions (PR #101734)

[via llvm-commits]

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@@ -1150,6 +1150,22 @@ Value *PHINode::hasConstantValue() const {
   llvm::Value *LLVMV = cast<llvm::PHINode>(Val)->hasConstantValue();
   return LLVMV != nullptr ? Ctx.getValue(LLVMV) : nullptr;
 }
+void PHINode::replaceIncomingBlockWith (const BasicBlock *Old, BasicBlock *New) {
+  assert(New && Old && "Sandbox IR PHI node got a null basic block!");
+  for (unsigned Op = 0,
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vporpo wrote:

nit: `Op` usually refers to a `Value *`, but in this case this is an index, so I would prefer something like `OpIdx` or `OpNum`.

https://github.com/llvm/llvm-project/pull/101734