[llvm] [CodeGen] Port `StackProtector` to new pass manager (PR #75334)

[Matt Arsenault via llvm-commits]

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@@ -57,26 +109,14 @@ class StackProtector : public FunctionPass {
 
   /// The minimum size of buffers that will receive stack smashing
   /// protection when -fstack-protection is used.
-  unsigned SSPBufferSize = DefaultSSPBufferSize;
+  unsigned SSPBufferSize = SSPLayoutInfo::DefaultSSPBufferSize;
 
   // A prologue is generated.
   bool HasPrologue = false;
 
   // IR checking code is generated.
   bool HasIRCheck = false;
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arsenm wrote:

I don't follow this. If you moved them the old references should be deleted? Changing less code isn't preferable to leaving dead code 

https://github.com/llvm/llvm-project/pull/75334