[clang] [PAC] Implement function pointer re-signing (PR #98847)

[Anatoly Trosinenko via cfe-commits]

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@@ -165,6 +166,88 @@ CGPointerAuthInfo CodeGenModule::getPointerAuthInfoForType(QualType T) {
   return ::getPointerAuthInfoForType(*this, T);
 }
 
+static bool isZeroConstant(llvm::Value *value) {
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atrosinenko wrote:

The existing code in `CGPointerAuth.cpp` seems to use the traditional naming style for function arguments and local variables, so this patch should be consistent, I guess (`s/value/Value/`, `s/ci/CI/`, etc.). The existing functions' names are not as consistent, though: some start with lower case letter and some with upper case one...

https://github.com/llvm/llvm-project/pull/98847