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view ir/irlandingpad.h @ 1117:4c20fcc4252b
Fun with parameter attributes: For several of the "synthetic" parameters added
to D functions, we can apply noalias and nocapture. They are sret parameters,
'nest' pointers passed to nested functions, and _argptr:
Nocapture:
- Sret and nest are nocapture because they don't represent D-level variables,
and thus the callee can't (validly) obtain a pointer to them, let alone keep
it around after it returns.
- _argptr is nocapture because although the callee has access to it as a
pointer, that pointer is invalidated when it returns.
All three are noalias because they're function-local variables
- Sret and _argptr are noalias because they're freshly alloca'd memory only
used for a single function call that's not allowed to keep an aliasing
pointer to it around (since the parameter is nocapture).
- 'Nest' is noalias because the callee only ever has access to one such pointer
per parent function, and every parent function has a different one.
This commit also ensures attributes set on sret, _arguments and _argptr are
propagated to calls to such functions.
It also adds one exception to the general rule that attributes on function types
should propagate to calls: the type of a delegate's function pointer has a
'nest' parameter, but this can either be a true 'nest' (for delegates to nested
functions) or a 'this' (for delegates to member functions). Since 'this' is
neither noalias nor nocapture, and there's generally no way to tell which one it
is, we remove these attributes at the call site if the callee is a delegate.
author | Frits van Bommel <fvbommel wxs.nl> |
---|---|
date | Sat, 14 Mar 2009 22:15:31 +0100 |
parents | dc608dc33081 |
children |
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#ifndef LDC_IR_IRLANDINGPADINFO_H #define LDC_IR_IRLANDINGPADINFO_H #include "ir/ir.h" #include "statement.h" #include <deque> #include <stack> namespace llvm { class Type; class Value; class BasicBlock; class Function; } // only to be used within IRLandingPad // holds information about a single catch or finally struct IRLandingPadInfo { // default constructor for being able to store in a vector IRLandingPadInfo() : target(NULL), finallyBody(NULL), catchType(NULL) {} // constructor for catch IRLandingPadInfo(Catch* catchstmt, llvm::BasicBlock* end); // constructor for finally IRLandingPadInfo(Statement* finallystmt); // the target catch bb if this is a catch // or the target finally bb if this is a finally llvm::BasicBlock* target; // nonzero if this is a finally Statement* finallyBody; // nonzero if this is a catch ClassDeclaration* catchType; }; // holds information about all possible catch and finally actions // and can emit landing pads to be called from the unwind runtime struct IRLandingPad { IRLandingPad() : catch_var(NULL) {} // builds a new landing pad according to given infos // and the ones on the stack. also stores it as invoke target void push(llvm::BasicBlock* inBB); // add catch information, will be used in next call to push void addCatch(Catch* catchstmt, llvm::BasicBlock* end); // add finally information, will be used in next call to push void addFinally(Statement* finallystmt); // pops the most recently constructed landing pad bb // and its infos void pop(); // gets the current landing pad llvm::BasicBlock* get(); // creates or gets storage for exception object llvm::Value* getExceptionStorage(); private: // constructs the landing pad from infos void constructLandingPad(llvm::BasicBlock* inBB); // information needed to create landing pads std::deque<IRLandingPadInfo> infos; std::deque<IRLandingPadInfo> unpushed_infos; // the number of infos we had before the push std::stack<size_t> nInfos; // the target for invokes std::stack<llvm::BasicBlock*> padBBs; // associate increasing ints with each unique classdecl encountered std::map<ClassDeclaration*, int> catchToInt; // storage for the catch variable llvm::Value* catch_var; }; #endif