[llvm] Port Swift's merge function pass to llvm: merging functions that differ in constants (PR #68235)

[Florian Hahn via llvm-commits]

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@@ -0,0 +1,532 @@
+; RUN: opt -S -mergefunc-ignoringconst-threshold=4 -passes=mergefunc-ignoring-const %s | FileCheck %s
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fhahn wrote:

Also have tests without `-mergefunc-ignoringconst-threshold=4`?

https://github.com/llvm/llvm-project/pull/68235