| //===-- ARMJITInfo.cpp - Implement the JIT interfaces for the ARM target --===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the JIT interfaces for the ARM target. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "jit" |
| #include "ARMJITInfo.h" |
| #include "ARMInstrInfo.h" |
| #include "ARMConstantPoolValue.h" |
| #include "ARMRelocations.h" |
| #include "ARMSubtarget.h" |
| #include "llvm/Function.h" |
| #include "llvm/CodeGen/JITCodeEmitter.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/System/Memory.h" |
| #include <cstdlib> |
| using namespace llvm; |
| |
| void ARMJITInfo::replaceMachineCodeForFunction(void *Old, void *New) { |
| report_fatal_error("ARMJITInfo::replaceMachineCodeForFunction"); |
| } |
| |
| /// JITCompilerFunction - This contains the address of the JIT function used to |
| /// 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 (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(); |
| asm( |
| ".text\n" |
| ".align 2\n" |
| ".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. |
| "stmdb sp!, {r0, r1, r2, r3, lr}\n" |
| #if (defined(__VFP_FP__) && !defined(__SOFTFP__)) |
| "fstmfdd sp!, {d0, d1, d2, d3, d4, d5, d6, d7}\n" |
| #endif |
| // 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) |
| // 6-20 | D0..D7 | Saved VFP registers |
| // +--------+ |
| // |
| #if (defined(__VFP_FP__) && !defined(__SOFTFP__)) |
| // Restore VFP caller-saved registers. |
| "fldmfdd sp!, {d0, d1, d2, d3, d4, d5, d6, d7}\n" |
| #endif |
| // |
| // 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. |
| "ldmia sp!, {r0, r1, r2, r3, lr, pc}\n" |
| ); |
| #else // Not an ARM host |
| void ARMCompilationCallback() { |
| llvm_unreachable("Cannot call ARMCompilationCallback() on a non-ARM arch!"); |
| } |
| #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 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. We're replacing the first two instructions of the |
| // stub with: |
| // ldr pc, [pc,#-4] |
| // <addr> |
| if (!sys::Memory::setRangeWritable((void*)StubAddr, 8)) { |
| llvm_unreachable("ERROR: Unable to mark stub writable"); |
| } |
| *(intptr_t *)StubAddr = 0xe51ff004; // ldr pc, [pc, #-4] |
| *(intptr_t *)(StubAddr+4) = NewVal; |
| if (!sys::Memory::setRangeExecutable((void*)StubAddr, 8)) { |
| llvm_unreachable("ERROR: Unable to mark stub executable"); |
| } |
| } |
| |
| TargetJITInfo::LazyResolverFn |
| ARMJITInfo::getLazyResolverFunction(JITCompilerFn F) { |
| JITCompilerFunction = F; |
| return ARMCompilationCallback; |
| } |
| |
| void *ARMJITInfo::emitGlobalValueIndirectSym(const GlobalValue *GV, void *Ptr, |
| JITCodeEmitter &JCE) { |
| uint8_t Buffer[4]; |
| uint8_t *Cur = Buffer; |
| MachineCodeEmitter::emitWordLEInto(Cur, (intptr_t)Ptr); |
| void *PtrAddr = JCE.allocIndirectGV( |
| GV, Buffer, sizeof(Buffer), /*Alignment=*/4); |
| addIndirectSymAddr(Ptr, (intptr_t)PtrAddr); |
| return PtrAddr; |
| } |
| |
| TargetJITInfo::StubLayout ARMJITInfo::getStubLayout() { |
| // The stub contains up to 3 4-byte instructions, aligned at 4 bytes, and a |
| // 4-byte address. See emitFunctionStub for details. |
| StubLayout Result = {16, 4}; |
| return Result; |
| } |
| |
| void *ARMJITInfo::emitFunctionStub(const Function* F, void *Fn, |
| JITCodeEmitter &JCE) { |
| void *Addr; |
| // 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. |
| if (IsPIC) { |
| // The stub is 16-byte size and 4-aligned. |
| intptr_t LazyPtr = getIndirectSymAddr(Fn); |
| if (!LazyPtr) { |
| // In PIC mode, the function stub is loading a lazy-ptr. |
| LazyPtr= (intptr_t)emitGlobalValueIndirectSym((GlobalValue*)F, Fn, JCE); |
| DEBUG(if (F) |
| errs() << "JIT: Indirect symbol emitted at [" << LazyPtr |
| << "] for GV '" << F->getName() << "'\n"; |
| else |
| errs() << "JIT: Stub emitted at [" << LazyPtr |
| << "] for external function at '" << Fn << "'\n"); |
| } |
| JCE.emitAlignment(4); |
| Addr = (void*)JCE.getCurrentPCValue(); |
| if (!sys::Memory::setRangeWritable(Addr, 16)) { |
| llvm_unreachable("ERROR: Unable to mark stub writable"); |
| } |
| JCE.emitWordLE(0xe59fc004); // ldr ip, [pc, #+4] |
| JCE.emitWordLE(0xe08fc00c); // L_func$scv: add ip, pc, ip |
| JCE.emitWordLE(0xe59cf000); // ldr pc, [ip] |
| JCE.emitWordLE(LazyPtr - (intptr_t(Addr)+4+8)); // func - (L_func$scv+8) |
| sys::Memory::InvalidateInstructionCache(Addr, 16); |
| if (!sys::Memory::setRangeExecutable(Addr, 16)) { |
| llvm_unreachable("ERROR: Unable to mark stub executable"); |
| } |
| } else { |
| // The stub is 8-byte size and 4-aligned. |
| JCE.emitAlignment(4); |
| Addr = (void*)JCE.getCurrentPCValue(); |
| if (!sys::Memory::setRangeWritable(Addr, 8)) { |
| llvm_unreachable("ERROR: Unable to mark stub writable"); |
| } |
| JCE.emitWordLE(0xe51ff004); // ldr pc, [pc, #-4] |
| JCE.emitWordLE((intptr_t)Fn); // addr of function |
| sys::Memory::InvalidateInstructionCache(Addr, 8); |
| if (!sys::Memory::setRangeExecutable(Addr, 8)) { |
| llvm_unreachable("ERROR: Unable to mark stub executable"); |
| } |
| } |
| } else { |
| // 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. |
| JCE.emitAlignment(4); |
| Addr = (void*)JCE.getCurrentPCValue(); |
| if (!sys::Memory::setRangeWritable(Addr, 16)) { |
| llvm_unreachable("ERROR: Unable to mark stub writable"); |
| } |
| // Save LR so the callback can determine which stub called it. |
| // The compilation callback is responsible for popping this prior |
| // to returning. |
| JCE.emitWordLE(0xe92d4000); // push {lr} |
| // Set the return address to go back to the start of this stub. |
| JCE.emitWordLE(0xe24fe00c); // sub lr, pc, #12 |
| // Invoke the compilation callback. |
| JCE.emitWordLE(0xe51ff004); // ldr pc, [pc, #-4] |
| // The address of the compilation callback. |
| JCE.emitWordLE((intptr_t)ARMCompilationCallback); |
| sys::Memory::InvalidateInstructionCache(Addr, 16); |
| if (!sys::Memory::setRangeExecutable(Addr, 16)) { |
| llvm_unreachable("ERROR: Unable to mark stub executable"); |
| } |
| } |
| |
| return Addr; |
| } |
| |
| intptr_t ARMJITInfo::resolveRelocDestAddr(MachineRelocation *MR) const { |
| ARM::RelocationType RT = (ARM::RelocationType)MR->getRelocationType(); |
| switch (RT) { |
| default: |
| return (intptr_t)(MR->getResultPointer()); |
| case ARM::reloc_arm_pic_jt: |
| // Destination address - jump table base. |
| return (intptr_t)(MR->getResultPointer()) - MR->getConstantVal(); |
| case ARM::reloc_arm_jt_base: |
| // Jump table base address. |
| return getJumpTableBaseAddr(MR->getJumpTableIndex()); |
| case ARM::reloc_arm_cp_entry: |
| case ARM::reloc_arm_vfp_cp_entry: |
| // Constant pool entry address. |
| return getConstantPoolEntryAddr(MR->getConstantPoolIndex()); |
| case ARM::reloc_arm_machine_cp_entry: { |
| ARMConstantPoolValue *ACPV = (ARMConstantPoolValue*)MR->getConstantVal(); |
| assert((!ACPV->hasModifier() && !ACPV->mustAddCurrentAddress()) && |
| "Can't handle this machine constant pool entry yet!"); |
| intptr_t Addr = (intptr_t)(MR->getResultPointer()); |
| Addr -= getPCLabelAddr(ACPV->getLabelId()) + ACPV->getPCAdjustment(); |
| return Addr; |
| } |
| } |
| } |
| |
| /// relocate - Before the JIT can run a block of code that has been emitted, |
| /// it must rewrite the code to contain the actual addresses of any |
| /// referenced global symbols. |
| void ARMJITInfo::relocate(void *Function, MachineRelocation *MR, |
| unsigned NumRelocs, unsigned char* GOTBase) { |
| for (unsigned i = 0; i != NumRelocs; ++i, ++MR) { |
| void *RelocPos = (char*)Function + MR->getMachineCodeOffset(); |
| intptr_t ResultPtr = resolveRelocDestAddr(MR); |
| switch ((ARM::RelocationType)MR->getRelocationType()) { |
| case ARM::reloc_arm_cp_entry: |
| case ARM::reloc_arm_vfp_cp_entry: |
| case ARM::reloc_arm_relative: { |
| // It is necessary to calculate the correct PC relative value. We |
| // subtract the base addr from the target addr to form a byte offset. |
| ResultPtr = ResultPtr - (intptr_t)RelocPos - 8; |
| // If the result is positive, set bit U(23) to 1. |
| if (ResultPtr >= 0) |
| *((intptr_t*)RelocPos) |= 1 << ARMII::U_BitShift; |
| else { |
| // Otherwise, obtain the absolute value and set bit U(23) to 0. |
| *((intptr_t*)RelocPos) &= ~(1 << ARMII::U_BitShift); |
| ResultPtr = - ResultPtr; |
| } |
| // Set the immed value calculated. |
| // VFP immediate offset is multiplied by 4. |
| if (MR->getRelocationType() == ARM::reloc_arm_vfp_cp_entry) |
| ResultPtr = ResultPtr >> 2; |
| *((intptr_t*)RelocPos) |= ResultPtr; |
| // Set register Rn to PC. |
| *((intptr_t*)RelocPos) |= |
| ARMRegisterInfo::getRegisterNumbering(ARM::PC) << ARMII::RegRnShift; |
| break; |
| } |
| case ARM::reloc_arm_pic_jt: |
| case ARM::reloc_arm_machine_cp_entry: |
| case ARM::reloc_arm_absolute: { |
| // These addresses have already been resolved. |
| *((intptr_t*)RelocPos) |= (intptr_t)ResultPtr; |
| break; |
| } |
| case ARM::reloc_arm_branch: { |
| // It is necessary to calculate the correct value of signed_immed_24 |
| // field. We subtract the base addr from the target addr to form a |
| // byte offset, which must be inside the range -33554432 and +33554428. |
| // Then, we set the signed_immed_24 field of the instruction to bits |
| // [25:2] of the byte offset. More details ARM-ARM p. A4-11. |
| ResultPtr = ResultPtr - (intptr_t)RelocPos - 8; |
| ResultPtr = (ResultPtr & 0x03FFFFFC) >> 2; |
| assert(ResultPtr >= -33554432 && ResultPtr <= 33554428); |
| *((intptr_t*)RelocPos) |= ResultPtr; |
| break; |
| } |
| case ARM::reloc_arm_jt_base: { |
| // JT base - (instruction addr + 8) |
| ResultPtr = ResultPtr - (intptr_t)RelocPos - 8; |
| *((intptr_t*)RelocPos) |= ResultPtr; |
| break; |
| } |
| } |
| } |
| } |