//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the Raul Herbster and is distributed under the
-// University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
#include "ARMJITInfo.h"
#include "ARMRelocations.h"
#include "ARMSubtarget.h"
+#include "llvm/Function.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
#include "llvm/Config/alloca.h"
+#include "llvm/Support/Streams.h"
+#include "llvm/System/Memory.h"
#include <cstdlib>
using namespace llvm;
/// compile a function lazily.
static TargetJITInfo::JITCompilerFn JITCompilerFunction;
+// Get the ASMPREFIX for the current host. This is often '_'.
+#ifndef __USER_LABEL_PREFIX__
+#define __USER_LABEL_PREFIX__
+#endif
+#define GETASMPREFIX2(X) #X
+#define GETASMPREFIX(X) GETASMPREFIX2(X)
+#define ASMPREFIX GETASMPREFIX(__USER_LABEL_PREFIX__)
+
// CompilationCallback stub - We can't use a C function with inline assembly in
-// it, because we the prolog/epilog inserted by GCC won't work for us. Instead,
-// write our own wrapper, which does things our way, so we have complete control
-// over register saving and restoring.
+// it, because we the prolog/epilog inserted by GCC won't work for us (we need
+// to preserve more context and manipulate the stack directly). Instead,
+// write our own wrapper, which does things our way, so we have complete
+// control over register saving and restoring.
extern "C" {
#if defined(__arm__)
void ARMCompilationCallback(void);
asm(
".text\n"
".align 2\n"
- ".globl ARMCompilationCallback\n"
- "ARMCompilationCallback:\n"
- // save main registers
- "mov ip, sp\n"
- "stmfd sp!, {fp, ip, lr, pc}\n"
- "sub fp, ip, #4\n"
- // arguments to Compilation Callback
- // r0 - our lr (address of the call instruction in stub plus 4)
- // r1 - stub's lr (address of instruction that called the stub plus 4)
- "mov r0, fp\n" // stub's frame
- "mov r1, lr\n" // stub's lr
- "bl ARMCompilationCallbackC\n"
- // restore main registers
- "ldmfd sp, {fp, sp, pc}\n");
-#else // Not an ARM host
+ ".globl " ASMPREFIX "ARMCompilationCallback\n"
+ ASMPREFIX "ARMCompilationCallback:\n"
+ // Save caller saved registers since they may contain stuff
+ // for the real target function right now. We have to act as if this
+ // whole compilation callback doesn't exist as far as the caller is
+ // concerned, so we can't just preserve the callee saved regs.
+ "push {r0, r1, r2, r3, lr}\n"
+ // The LR contains the address of the stub function on entry.
+ // pass it as the argument to the C part of the callback
+ "mov r0, lr\n"
+ "sub sp, sp, #4\n"
+ // Call the C portion of the callback
+ "bl " ASMPREFIX "ARMCompilationCallbackC\n"
+ "add sp, sp, #4\n"
+ // Restoring the LR to the return address of the function that invoked
+ // the stub and de-allocating the stack space for it requires us to
+ // swap the two saved LR values on the stack, as they're backwards
+ // for what we need since the pop instruction has a pre-determined
+ // order for the registers.
+ // +--------+
+ // 0 | LR | Original return address
+ // +--------+
+ // 1 | LR | Stub address (start of stub)
+ // 2-5 | R3..R0 | Saved registers (we need to preserve all regs)
+ // +--------+
+ //
+ // We need to exchange the values in slots 0 and 1 so we can
+ // return to the address in slot 1 with the address in slot 0
+ // restored to the LR.
+ "ldr r0, [sp,#20]\n"
+ "ldr r1, [sp,#16]\n"
+ "str r1, [sp,#20]\n"
+ "str r0, [sp,#16]\n"
+ // Return to the (newly modified) stub to invoke the real function.
+ // The above twiddling of the saved return addresses allows us to
+ // deallocate everything, including the LR the stub saved, all in one
+ // pop instruction.
+ "pop {r0, r1, r2, r3, lr, pc}\n"
+ );
+#else // Not an ARM host
void ARMCompilationCallback() {
assert(0 && "Cannot call ARMCompilationCallback() on a non-ARM arch!\n");
abort();
#endif
}
-/// ARMCompilationCallbackC - This is the target-specific function invoked by the
-/// function stub when we did not know the real target of a call. This function
-/// must locate the start of the stub or call site and pass it into the JIT
-/// compiler function.
-extern "C" void ARMCompilationCallbackC(intptr_t *StackPtr, intptr_t RetAddr) {
- intptr_t *RetAddrLoc = &StackPtr[-1];
-
- assert(*RetAddrLoc == RetAddr &&
- "Could not find return address on the stack!");
-#if 0
- DOUT << "In callback! Addr=" << (void*)RetAddr
- << " FP=" << (void*)StackPtr
- << ": Resolving call to function: "
- << TheVM->getFunctionReferencedName((void*)RetAddr) << "\n";
-#endif
- intptr_t Addr = RetAddr - 4;
-
- intptr_t NewVal = (intptr_t)JITCompilerFunction((void*)Addr);
+/// ARMCompilationCallbackC - This is the target-specific function invoked
+/// by the function stub when we did not know the real target of a call.
+/// This function must locate the start of the stub or call site and pass
+/// it into the JIT compiler function.
+extern "C" void ARMCompilationCallbackC(intptr_t StubAddr) {
+ // Get the address of the compiled code for this function.
+ intptr_t NewVal = (intptr_t)JITCompilerFunction((void*)StubAddr);
// Rewrite the call target... so that we don't end up here every time we
- // execute the call.
- *(intptr_t *)Addr = NewVal;
-
- // Change the return address to reexecute the branch and link instruction...
- *RetAddrLoc -= 12;
+ // execute the call. We're replacing the first two instructions of the
+ // stub with:
+ // ldr pc, [pc,#-4]
+ // <addr>
+#if defined(__APPLE__)
+ bool ok = sys::Memory::setRangeWritable ((void*)StubAddr, 8);
+ if (!ok)
+ {
+ cerr << "ERROR: Unable to mark stub writable\n";
+ abort();
+ }
+#endif
+ *(intptr_t *)StubAddr = 0xe51ff004;
+ *(intptr_t *)(StubAddr+4) = NewVal;
+#if defined(__APPLE__)
+ ok = sys::Memory::setRangeExecutable ((void*)StubAddr, 8);
+ if (!ok)
+ {
+ cerr << "ERROR: Unable to mark stub executable\n";
+ abort();
+ }
+#endif
}
TargetJITInfo::LazyResolverFn
return ARMCompilationCallback;
}
-void *ARMJITInfo::emitFunctionStub(void *Fn, MachineCodeEmitter &MCE) {
+void *ARMJITInfo::emitFunctionStub(const Function* F, void *Fn,
+ MachineCodeEmitter &MCE) {
unsigned addr = (intptr_t)Fn;
// If this is just a call to an external function, emit a branch instead of a
// call. The code is the same except for one bit of the last instruction.
if (Fn != (void*)(intptr_t)ARMCompilationCallback) {
// branch to the corresponding function addr
// the stub is 8-byte size and 4-aligned
- MCE.startFunctionStub(8, 4);
- MCE.emitWordLE(0xE51FF004); // LDR PC, [PC,#-4]
+ MCE.startFunctionStub(F, 8, 4);
+ MCE.emitWordLE(0xe51ff004); // LDR PC, [PC,#-4]
MCE.emitWordLE(addr); // addr of function
} else {
- // branch and link to the corresponding function addr
- // the stub is 20-byte size and 4-aligned
- MCE.startFunctionStub(20, 4);
- MCE.emitWordLE(0xE92D4800); // STMFD SP!, [R11, LR]
- MCE.emitWordLE(0xE28FE004); // ADD LR, PC, #4
- MCE.emitWordLE(0xE51FF004); // LDR PC, [PC,#-4]
- MCE.emitWordLE(addr); // addr of function
- MCE.emitWordLE(0xE8BD8800); // LDMFD SP!, [R11, PC]
+ // The compilation callback will overwrite the first two words of this
+ // stub with indirect branch instructions targeting the compiled code.
+ // This stub sets the return address to restart the stub, so that
+ // the new branch will be invoked when we come back.
+ //
+ // branch and link to the compilation callback.
+ // the stub is 16-byte size and 4-byte aligned.
+ MCE.startFunctionStub(F, 16, 4);
+ // Save LR so the callback can determine which stub called it.
+ // The compilation callback is responsible for popping this prior
+ // to returning.
+ MCE.emitWordLE(0xe92d4000); // PUSH {lr}
+ // Set the return address to go back to the start of this stub
+ MCE.emitWordLE(0xe24fe00c); // SUB LR, PC, #12
+ // Invoke the compilation callback
+ MCE.emitWordLE(0xe51ff004); // LDR PC, [PC,#-4]
+ // The address of the compilation callback
+ MCE.emitWordLE((intptr_t)ARMCompilationCallback);
}
- return MCE.finishFunctionStub(0);
+ return MCE.finishFunctionStub(F);
}
/// relocate - Before the JIT can run a block of code that has been emitted,
projects / oota-llvm.git / blobdiff