/// getFunctionStub - This returns a pointer to a function stub, creating
/// one on demand as needed. If empty is true, create a function stub
/// pointing at address 0, to be filled in later.
- void *getFunctionStub(Function *F, bool empty = false);
+ void *getFunctionStub(Function *F);
/// getExternalFunctionStub - Return a stub for the function at the
/// specified address, created lazily on demand.
/// getFunctionStub - This returns a pointer to a function stub, creating
/// one on demand as needed.
-void *JITResolver::getFunctionStub(Function *F, bool empty) {
+void *JITResolver::getFunctionStub(Function *F) {
MutexGuard locked(TheJIT->lock);
// If we already have a stub for this function, recycle it.
void *&Stub = state.getFunctionToStubMap(locked)[F];
if (Stub) return Stub;
- // Call the lazy resolver function unless we already KNOW it is an external
- // function, in which case we just skip the lazy resolution step.
- void *Actual = empty ? (void*)0 : (void*)(intptr_t)LazyResolverFn;
+ // Call the lazy resolver function unless we are JIT'ing non-lazily, in which
+ // case we must resolve the symbol now.
+ void *Actual = TheJIT->isLazyCompilationDisabled()
+ ? (void *)0 : (void *)(intptr_t)LazyResolverFn;
+
+ // If this is an external declaration, attempt to resolve the address now
+ // to place in the stub.
if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode()) {
Actual = TheJIT->getPointerToFunction(F);
// If we resolved the symbol to a null address (eg. a weak external)
- // don't emit a stub. Return a null pointer to the application.
- if (!Actual) return 0;
+ // don't emit a stub. Return a null pointer to the application. If dlsym
+ // stubs are enabled, not being able to resolve the address is not
+ // meaningful.
+ if (!Actual && !TheJIT->areDlsymStubsEnabled()) return 0;
}
- // Otherwise, codegen a new stub. For now, the stub will call the lazy
- // resolver function.
+ // Codegen a new stub, calling the lazy resolver or the actual address of the
+ // external function, if it was resolved.
Stub = TheJIT->getJITInfo().emitFunctionStub(F, Actual,
*TheJIT->getCodeEmitter());
// JITCompilerFn knows which function to compile!
state.getStubToFunctionMap(locked)[Stub] = F;
- // If this is an "empty" stub, then inform the JIT that it will need to
- // JIT the function so an address can be provided.
- if (empty)
- TheJIT->addPendingFunction(F);
+ // If we are JIT'ing non-lazily but need to call a function that does not
+ // exist yet, add it to the JIT's work list so that we can fill in the stub
+ // address later.
+ if (!Actual && TheJIT->isLazyCompilationDisabled())
+ if (!F->isDeclaration() || F->hasNotBeenReadFromBitcode())
+ TheJIT->addPendingFunction(F);
return Stub;
}
if (ResultPtr) return ResultPtr;
// If this is an external function pointer, we can force the JIT to
- // 'compile' it, which really just adds it to the map.
- if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode() && DoesntNeedStub)
+ // 'compile' it, which really just adds it to the map. In dlsym mode,
+ // external functions are forced through a stub, regardless of reloc type.
+ if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode() &&
+ DoesntNeedStub && !TheJIT->areDlsymStubsEnabled())
return TheJIT->getPointerToFunction(F);
- // If we are jitting non-lazily but encounter a function that has not been
- // jitted yet, we need to allocate a blank stub to call the function
- // once we JIT it and its address is known.
- if (TheJIT->isLazyCompilationDisabled())
- if (!F->isDeclaration() || F->hasNotBeenReadFromBitcode())
- return Resolver.getFunctionStub(F, true);
-
// Okay, the function has not been compiled yet, if the target callback
// mechanism is capable of rewriting the instruction directly, prefer to do
- // that instead of emitting a stub.
- if (DoesntNeedStub)
+ // that instead of emitting a stub. This uses the lazy resolver, so is not
+ // legal if lazy compilation is disabled.
+ if (DoesntNeedStub && !TheJIT->isLazyCompilationDisabled())
return Resolver.AddCallbackAtLocation(F, Reference);
- // Otherwise, we have to emit a lazy resolving stub.
+ // Otherwise, we have to emit a stub.
void *StubAddr = Resolver.getFunctionStub(F);
// Add the stub to the current function's list of referenced stubs, so we can
- // deallocate them if the current function is ever freed.
- AddStubToCurrentFunction(StubAddr);
-
+ // deallocate them if the current function is ever freed. It's possible to
+ // return null from getFunctionStub in the case of a weak extern that fails
+ // to resolve.
+ if (StubAddr)
+ AddStubToCurrentFunction(StubAddr);
+
return StubAddr;
}
// in the JITResolver. Were there a memory manager deallocateStub routine,
// we could call that at this point too.
if (FnRefs.empty()) {
- Resolver.invalidateStub(Stub);
+ DOUT << "\nJIT: Invalidated Stub at [" << Stub << "]\n";
+ GlobalValue *GV = Resolver.invalidateStub(Stub);
+ TheJIT->updateGlobalMapping(GV, 0);
StubFnRefs.erase(F);
}
}