[PATCH] D77982: [Windows SEH] Fix the frame-ptr of a nested-filter within a _finally

[Ten Tzen via Phabricator via cfe-commits]

tentzen added a comment.

In D77982#1981505 <https://reviews.llvm.org/D77982#1981505>, @efriedma wrote:

> Searching LocalDeclMap is less problematic, I guess... but still, it should be possible to something more straightforward.  Maybe make startOutlinedSEHHelper store the actual ImplicitParamDecl, or something like that.


I respectfully disagree.  Two reasons:
(1)	Nested filter within a _finally is a rare case.  Scanning CGF.LocalDeclMap is not much different from retrieving it from CGF.FuncletFramePointerAddr.  Why do we want to store a redundant information in CGF for a rare case of one specific target?
(2)	The code a paremeter’s home address is allocated today is in EmitParmDecl() which (and two its callers in call-stack) are all target agnostic functions. See code and call-stack below.  To store DeclPtr in CGF for SEH filter only would require some target-specific code in those functions.  Do you really think it’s what you want? I thought one implementation philosophy is to avoid target-specific code in target-independent functions.

        // Otherwise, create a temporary to hold the value.
        DeclPtr = CreateMemTemp(Ty, getContext().getDeclAlign(&D), D.getName() + ".addr");
  
  	clang-cl.exe!clang::CodeGen::CodeGenFunction::EmitParmDecl(const clang::VarDecl & D, clang::CodeGen::CodeGenFunction::ParamValue Arg, unsigned int ArgNo) Line 2434	C++
   	clang-cl.exe!clang::CodeGen::CodeGenFunction::EmitFunctionProlog(const clang::CodeGen::CGFunctionInfo & FI, llvm::Function * Fn, const clang::CodeGen::FunctionArgList & Args) Line 2631	C++
   	clang-cl.exe!clang::CodeGen::CodeGenFunction::StartFunction(clang::GlobalDecl GD, clang::QualType RetTy, llvm::Function * Fn, const clang::CodeGen::CGFunctionInfo & FnInfo, const clang::CodeGen::FunctionArgList & Args, clang::SourceLocation Loc, clang::SourceLocation StartLoc) Line 1065	C++
   	clang-cl.exe!clang::CodeGen::CodeGenFunction::startOutlinedSEHHelper(clang::CodeGen::CodeGenFunction & ParentCGF, bool IsFilter, const clang::Stmt * OutlinedStmt) Line 2157	C++
   	clang-cl.exe!clang::CodeGen::CodeGenFunction::GenerateSEHFinallyFunction(clang::CodeGen::CodeGenFunction & ParentCGF, const clang::SEHFinallyStmt & Finally) Line 2190	C++
   	clang-cl.exe!clang::CodeGen::CodeGenFunction::EnterSEHTryStmt(const clang::SEHTryStmt & S) Line 2315	C++
   	clang-cl.exe!clang::CodeGen::CodeGenFunction::EmitSEHTryStmt(const clang::SEHTryStmt & S) Line 1622	C++
   	clang-cl.exe!clang::CodeGen::CodeGenFunction::EmitStmt(const clang::Stmt * S, llvm::ArrayRef<clang::Attr const *> Attrs) Line 191	C++
   	clang-cl.exe!clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(const clang::CompoundStmt & S, bool GetLast, clang::CodeGen::AggValueSlot AggSlot) Line 446	C++
   	clang-cl.exe!clang::CodeGen::CodeGenFunction::EmitFunctionBody(const clang::Stmt * Body) Line 1159	C++
   	clang-cl.exe!clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl GD, llvm::Function * Fn, const clang::CodeGen::CGFunctionInfo & FnInfo) Line 1325	C++




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