[llvm-commits] CVS: llvm/tools/lli/JIT/Intercept.cpp VM.cpp

[Chris Lattner]

Changes in directory llvm/tools/lli/JIT:

Intercept.cpp added (r1.1)
VM.cpp updated: 1.4 -> 1.5

---
Log message:

Add a framework for intercepting system calls


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Diffs of the changes:

Index: llvm/tools/lli/JIT/Intercept.cpp
diff -c /dev/null llvm/tools/lli/JIT/Intercept.cpp:1.1
*** /dev/null	Wed May 14 08:26:57 2003
--- llvm/tools/lli/JIT/Intercept.cpp	Wed May 14 08:26:47 2003
***************
*** 0 ****
--- 1,52 ----
+ //===-- Intercept.cpp - System function interception routines -------------===//
+ //
+ // If a function call occurs to an external function, the JIT is designed to use
+ // dlsym on the current process to find a function to call.  This is useful for
+ // calling system calls and library functions that are not available in LLVM.
+ // Some system calls, however, need to be handled specially.  For this reason,
+ // we intercept some of them here and use our own stubs to handle them.
+ //
+ //===----------------------------------------------------------------------===//
+ 
+ #include "VM.h"
+ #include <dlfcn.h>    // dlsym access
+ 
+ //===----------------------------------------------------------------------===//
+ // Function stubs that are invoked instead of raw system calls
+ //===----------------------------------------------------------------------===//
+ 
+ // NoopFn - Used if we have nothing else to call...
+ static void NoopFn() {}
+ 
+ // jit_exit - Used to intercept the "exit" system call.
+ static void jit_exit(int Status) {
+   exit(Status);  // Do nothing for now.
+ }
+ 
+ // jit_atexit - Used to intercept the "at_exit" system call.
+ static int jit_atexit(void (*Fn)(void)) {
+   atexit(Fn);    // Do nothing for now.
+ }
+ 
+ //===----------------------------------------------------------------------===//
+ // 
+ /// getPointerToNamedFunction - This method returns the address of the specified
+ /// function by using the dlsym function call.  As such it is only useful for
+ /// resolving library symbols, not code generated symbols.
+ ///
+ void *VM::getPointerToNamedFunction(const std::string &Name) {
+   // Check to see if this is one of the functions we want to intercept...
+   if (Name == "exit") return jit_exit;
+   if (Name == "at_exit") return jit_atexit;
+ 
+   // If it's an external function, look it up in the process image...
+   void *Ptr = dlsym(0, Name.c_str());
+   if (Ptr == 0) {
+     std::cerr << "WARNING: Cannot resolve fn '" << Name
+ 	      << "' using a dummy noop function instead!\n";
+     Ptr = (void*)NoopFn;
+   }
+   
+   return Ptr;
+ }
+ 


Index: llvm/tools/lli/JIT/VM.cpp
diff -u llvm/tools/lli/JIT/VM.cpp:1.4 llvm/tools/lli/JIT/VM.cpp:1.5
--- llvm/tools/lli/JIT/VM.cpp:1.4	Thu May  8 22:30:07 2003
+++ llvm/tools/lli/JIT/VM.cpp	Wed May 14 08:26:47 2003
@@ -1,4 +1,4 @@
-//===-- jello.cpp - LLVM Just in Time Compiler ----------------------------===//
+//===-- VM.cpp - LLVM Just in Time Compiler -------------------------------===//
 //
 // This tool implements a just-in-time compiler for LLVM, allowing direct
 // execution of LLVM bytecode in an efficient manner.
@@ -9,8 +9,6 @@
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/CodeGen/MachineCodeEmitter.h"
 #include "llvm/Function.h"
-#include <dlfcn.h>    // dlsym access
-
 
 VM::~VM() {
   delete MCE;
@@ -50,25 +48,8 @@
 }
 
 const std::string &VM::getFunctionReferencedName(void *RefAddr) {
+  assert(FunctionRefs[RefAddr] && "Function address unknown!");
   return FunctionRefs[RefAddr]->getName();
-}
-
-static void NoopFn() {}
-
-/// getPointerToNamedFunction - This method returns the address of the specified
-/// function by using the dlsym function call.  As such it is only useful for
-/// resolving library symbols, not code generated symbols.
-///
-void *VM::getPointerToNamedFunction(const std::string &Name) {
-  // If it's an external function, look it up in the process image...
-  void *Ptr = dlsym(0, Name.c_str());
-  if (Ptr == 0) {
-    std::cerr << "WARNING: Cannot resolve fn '" << Name
-	      << "' using a dummy noop function instead!\n";
-    Ptr = (void*)NoopFn;
-  }
-  
-  return Ptr;
 }
 
 /// getPointerToFunction - This method is used to get the address of the