From 552672d28516f71344d7ce5ae3edd8a251cefc42 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sat, 25 Apr 2009 22:10:06 +0000 Subject: [PATCH] improve documentation around memory lifetimes, patch by Jeffrey Yasskin! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70083 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../llvm/ExecutionEngine/ExecutionEngine.h | 22 ++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/include/llvm/ExecutionEngine/ExecutionEngine.h b/include/llvm/ExecutionEngine/ExecutionEngine.h index 0c53a53e758..39ed071dba1 100644 --- a/include/llvm/ExecutionEngine/ExecutionEngine.h +++ b/include/llvm/ExecutionEngine/ExecutionEngine.h @@ -186,7 +186,8 @@ public: /// at the specified location. This is used internally as functions are JIT'd /// and as global variables are laid out in memory. It can and should also be /// used by clients of the EE that want to have an LLVM global overlay - /// existing data in memory. + /// existing data in memory. After adding a mapping for GV, you must not + /// destroy it until you've removed the mapping. void addGlobalMapping(const GlobalValue *GV, void *Addr); /// clearAllGlobalMappings - Clear all global mappings and start over again @@ -210,19 +211,29 @@ public: void *getPointerToGlobalIfAvailable(const GlobalValue *GV); /// getPointerToGlobal - This returns the address of the specified global - /// value. This may involve code generation if it's a function. + /// value. This may involve code generation if it's a function. After + /// getting a pointer to GV, it and all globals it transitively refers to have + /// been passed to addGlobalMapping. You must clear the mapping for each + /// referred-to global before destroying it. If a referred-to global RTG is a + /// function and this ExecutionEngine is a JIT compiler, calling + /// updateGlobalMapping(RTG, 0) will leak the function's machine code, so you + /// should call freeMachineCodeForFunction(RTG) instead. Note that + /// optimizations can move and delete non-external GlobalValues without + /// notifying the ExecutionEngine. /// void *getPointerToGlobal(const GlobalValue *GV); /// getPointerToFunction - The different EE's represent function bodies in /// different ways. They should each implement this to say what a function - /// pointer should look like. + /// pointer should look like. See getPointerToGlobal for the requirements on + /// destroying F and any GlobalValues it refers to. /// virtual void *getPointerToFunction(Function *F) = 0; /// getPointerToFunctionOrStub - If the specified function has been /// code-gen'd, return a pointer to the function. If not, compile it, or use - /// a stub to implement lazy compilation if available. + /// a stub to implement lazy compilation if available. See getPointerToGlobal + /// for the requirements on destroying F and any GlobalValues it refers to. /// virtual void *getPointerToFunctionOrStub(Function *F) { // Default implementation, just codegen the function. @@ -255,7 +266,8 @@ public: /// getOrEmitGlobalVariable - Return the address of the specified global /// variable, possibly emitting it to memory if needed. This is used by the - /// Emitter. + /// Emitter. See getPointerToGlobal for the requirements on destroying GV and + /// any GlobalValues it refers to. virtual void *getOrEmitGlobalVariable(const GlobalVariable *GV) { return getPointerToGlobal((GlobalValue*)GV); } -- 2.34.1