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llvm/lib/Target/X86/X86JITInfo.cpp
Dale Johannesen 6f83be0c61 When resolving a stub in x86-64 JIT, use a PC-relative branch 
rather than the absolute address if the target is within range.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54708 91177308-0d34-0410-b5e6-96231b3b80d8
2008-08-12 23:20:24 +00:00

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//===-- X86JITInfo.cpp - Implement the JIT interfaces for the X86 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 X86 target.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "jit"
#include "X86JITInfo.h"
#include "X86Relocations.h"
#include "X86Subtarget.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
#include "llvm/Config/alloca.h"
#include "llvm/Support/Compiler.h"
#include <cstdlib>
#include <cstring>
using namespace llvm;
// Determine the platform we're running on
#if defined (__x86_64__) || defined (_M_AMD64)
# define X86_64_JIT
#elif defined(__i386__) || defined(i386) || defined(_M_IX86)
# define X86_32_JIT
#endif
void X86JITInfo::replaceMachineCodeForFunction(void *Old, void *New) {
unsigned char *OldByte = (unsigned char *)Old;
*OldByte++ = 0xE9; // Emit JMP opcode.
unsigned *OldWord = (unsigned *)OldByte;
unsigned NewAddr = (intptr_t)New;
unsigned OldAddr = (intptr_t)OldWord;
*OldWord = NewAddr - OldAddr - 4; // Emit PC-relative addr of New code.
}
/// 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__)
// Check if building with -fPIC
#if defined(__PIC__) && __PIC__ && defined(__linux__)
#define ASMCALLSUFFIX "@PLT"
#else
#define ASMCALLSUFFIX
#endif
// Provide a convenient way for disabling usage of CFI directives.
// This is needed for old/broken assemblers (for example, gas on
// Darwin is pretty old and doesn't support these directives)
#if defined(__APPLE__)
# define CFI(x)
#else
// FIXME: Disable this until we really want to use it. Also, we will
// need to add some workarounds for compilers, which support
// only subset of these directives.
# define CFI(x)
#endif
// Provide a wrapper for X86CompilationCallback2 that saves non-traditional
// callee saved registers, for the fastcc calling convention.
extern "C" {
#if defined(X86_64_JIT)
# ifndef _MSC_VER
// No need to save EAX/EDX for X86-64.
void X86CompilationCallback(void);
asm(
".text\n"
".align 8\n"
".globl " ASMPREFIX "X86CompilationCallback\n"
ASMPREFIX "X86CompilationCallback:\n"
CFI(".cfi_startproc\n")
// Save RBP
"pushq %rbp\n"
CFI(".cfi_def_cfa_offset 16\n")
CFI(".cfi_offset %rbp, -16\n")
// Save RSP
"movq %rsp, %rbp\n"
CFI(".cfi_def_cfa_register %rbp\n")
// Save all int arg registers
"pushq %rdi\n"
CFI(".cfi_rel_offset %rdi, 0\n")
"pushq %rsi\n"
CFI(".cfi_rel_offset %rsi, 8\n")
"pushq %rdx\n"
CFI(".cfi_rel_offset %rdx, 16\n")
"pushq %rcx\n"
CFI(".cfi_rel_offset %rcx, 24\n")
"pushq %r8\n"
CFI(".cfi_rel_offset %r8, 32\n")
"pushq %r9\n"
CFI(".cfi_rel_offset %r9, 40\n")
// Align stack on 16-byte boundary. ESP might not be properly aligned
// (8 byte) if this is called from an indirect stub.
"andq $-16, %rsp\n"
// Save all XMM arg registers
"subq $128, %rsp\n"
"movaps %xmm0, (%rsp)\n"
"movaps %xmm1, 16(%rsp)\n"
"movaps %xmm2, 32(%rsp)\n"
"movaps %xmm3, 48(%rsp)\n"
"movaps %xmm4, 64(%rsp)\n"
"movaps %xmm5, 80(%rsp)\n"
"movaps %xmm6, 96(%rsp)\n"
"movaps %xmm7, 112(%rsp)\n"
// JIT callee
"movq %rbp, %rdi\n" // Pass prev frame and return address
"movq 8(%rbp), %rsi\n"
"call " ASMPREFIX "X86CompilationCallback2" ASMCALLSUFFIX "\n"
// Restore all XMM arg registers
"movaps 112(%rsp), %xmm7\n"
"movaps 96(%rsp), %xmm6\n"
"movaps 80(%rsp), %xmm5\n"
"movaps 64(%rsp), %xmm4\n"
"movaps 48(%rsp), %xmm3\n"
"movaps 32(%rsp), %xmm2\n"
"movaps 16(%rsp), %xmm1\n"
"movaps (%rsp), %xmm0\n"
// Restore RSP
"movq %rbp, %rsp\n"
CFI(".cfi_def_cfa_register %rsp\n")
// Restore all int arg registers
"subq $48, %rsp\n"
CFI(".cfi_adjust_cfa_offset 48\n")
"popq %r9\n"
CFI(".cfi_adjust_cfa_offset -8\n")
CFI(".cfi_restore %r9\n")
"popq %r8\n"
CFI(".cfi_adjust_cfa_offset -8\n")
CFI(".cfi_restore %r8\n")
"popq %rcx\n"
CFI(".cfi_adjust_cfa_offset -8\n")
CFI(".cfi_restore %rcx\n")
"popq %rdx\n"
CFI(".cfi_adjust_cfa_offset -8\n")
CFI(".cfi_restore %rdx\n")
"popq %rsi\n"
CFI(".cfi_adjust_cfa_offset -8\n")
CFI(".cfi_restore %rsi\n")
"popq %rdi\n"
CFI(".cfi_adjust_cfa_offset -8\n")
CFI(".cfi_restore %rdi\n")
// Restore RBP
"popq %rbp\n"
CFI(".cfi_adjust_cfa_offset -8\n")
CFI(".cfi_restore %rbp\n")
"ret\n"
CFI(".cfi_endproc\n")
);
# else
// No inline assembler support on this platform. The routine is in external
// file.
void X86CompilationCallback();
# endif
#elif defined (X86_32_JIT)
# ifndef _MSC_VER
void X86CompilationCallback(void);
asm(
".text\n"
".align 8\n"
".globl " ASMPREFIX "X86CompilationCallback\n"
ASMPREFIX "X86CompilationCallback:\n"
CFI(".cfi_startproc\n")
"pushl %ebp\n"
CFI(".cfi_def_cfa_offset 8\n")
CFI(".cfi_offset %ebp, -8\n")
"movl %esp, %ebp\n" // Standard prologue
CFI(".cfi_def_cfa_register %ebp\n")
"pushl %eax\n"
CFI(".cfi_rel_offset %eax, 0\n")
"pushl %edx\n" // Save EAX/EDX/ECX
CFI(".cfi_rel_offset %edx, 4\n")
"pushl %ecx\n"
CFI(".cfi_rel_offset %ecx, 8\n")
# if defined(__APPLE__)
"andl $-16, %esp\n" // Align ESP on 16-byte boundary
# endif
"subl $16, %esp\n"
"movl 4(%ebp), %eax\n" // Pass prev frame and return address
"movl %eax, 4(%esp)\n"
"movl %ebp, (%esp)\n"
"call " ASMPREFIX "X86CompilationCallback2" ASMCALLSUFFIX "\n"
"movl %ebp, %esp\n" // Restore ESP
CFI(".cfi_def_cfa_register %esp\n")
"subl $12, %esp\n"
CFI(".cfi_adjust_cfa_offset 12\n")
"popl %ecx\n"
CFI(".cfi_adjust_cfa_offset -4\n")
CFI(".cfi_restore %ecx\n")
"popl %edx\n"
CFI(".cfi_adjust_cfa_offset -4\n")
CFI(".cfi_restore %edx\n")
"popl %eax\n"
CFI(".cfi_adjust_cfa_offset -4\n")
CFI(".cfi_restore %eax\n")
"popl %ebp\n"
CFI(".cfi_adjust_cfa_offset -4\n")
CFI(".cfi_restore %ebp\n")
"ret\n"
CFI(".cfi_endproc\n")
);
// Same as X86CompilationCallback but also saves XMM argument registers.
void X86CompilationCallback_SSE(void);
asm(
".text\n"
".align 8\n"
".globl " ASMPREFIX "X86CompilationCallback_SSE\n"
ASMPREFIX "X86CompilationCallback_SSE:\n"
CFI(".cfi_startproc\n")
"pushl %ebp\n"
CFI(".cfi_def_cfa_offset 8\n")
CFI(".cfi_offset %ebp, -8\n")
"movl %esp, %ebp\n" // Standard prologue
CFI(".cfi_def_cfa_register %ebp\n")
"pushl %eax\n"
CFI(".cfi_rel_offset %eax, 0\n")
"pushl %edx\n" // Save EAX/EDX/ECX
CFI(".cfi_rel_offset %edx, 4\n")
"pushl %ecx\n"
CFI(".cfi_rel_offset %ecx, 8\n")
"andl $-16, %esp\n" // Align ESP on 16-byte boundary
// Save all XMM arg registers
"subl $64, %esp\n"
// FIXME: provide frame move information for xmm registers.
// This can be tricky, because CFA register is ebp (unaligned)
// and we need to produce offsets relative to it.
"movaps %xmm0, (%esp)\n"
"movaps %xmm1, 16(%esp)\n"
"movaps %xmm2, 32(%esp)\n"
"movaps %xmm3, 48(%esp)\n"
"subl $16, %esp\n"
"movl 4(%ebp), %eax\n" // Pass prev frame and return address
"movl %eax, 4(%esp)\n"
"movl %ebp, (%esp)\n"
"call " ASMPREFIX "X86CompilationCallback2" ASMCALLSUFFIX "\n"
"addl $16, %esp\n"
"movaps 48(%esp), %xmm3\n"
CFI(".cfi_restore %xmm3\n")
"movaps 32(%esp), %xmm2\n"
CFI(".cfi_restore %xmm2\n")
"movaps 16(%esp), %xmm1\n"
CFI(".cfi_restore %xmm1\n")
"movaps (%esp), %xmm0\n"
CFI(".cfi_restore %xmm0\n")
"movl %ebp, %esp\n" // Restore ESP
CFI(".cfi_def_cfa_register esp\n")
"subl $12, %esp\n"
CFI(".cfi_adjust_cfa_offset 12\n")
"popl %ecx\n"
CFI(".cfi_adjust_cfa_offset -4\n")
CFI(".cfi_restore %ecx\n")
"popl %edx\n"
CFI(".cfi_adjust_cfa_offset -4\n")
CFI(".cfi_restore %edx\n")
"popl %eax\n"
CFI(".cfi_adjust_cfa_offset -4\n")
CFI(".cfi_restore %eax\n")
"popl %ebp\n"
CFI(".cfi_adjust_cfa_offset -4\n")
CFI(".cfi_restore %ebp\n")
"ret\n"
CFI(".cfi_endproc\n")
);
# else
void X86CompilationCallback2(intptr_t *StackPtr, intptr_t RetAddr);
_declspec(naked) void X86CompilationCallback(void) {
__asm {
push ebp
mov ebp, esp
push eax
push edx
push ecx
and esp, -16
mov eax, dword ptr [ebp+4]
mov dword ptr [esp+4], eax
mov dword ptr [esp], ebp
call X86CompilationCallback2
mov esp, ebp
sub esp, 12
pop ecx
pop edx
pop eax
pop ebp
ret
}
}
# endif // _MSC_VER
#else // Not an i386 host
void X86CompilationCallback() {
assert(0 && "Cannot call X86CompilationCallback() on a non-x86 arch!\n");
abort();
}
#endif
}
/// X86CompilationCallback - 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 ATTRIBUTE_USED
X86CompilationCallback2(intptr_t *StackPtr, intptr_t RetAddr) {
intptr_t *RetAddrLoc = &StackPtr[1];
assert(*RetAddrLoc == RetAddr &&
"Could not find return address on the stack!");
// It's a stub if there is an interrupt marker after the call.
bool isStub = ((unsigned char*)RetAddr)[0] == 0xCD;
// The call instruction should have pushed the return value onto the stack...
#if defined (X86_64_JIT)
RetAddr--; // Backtrack to the reference itself...
#else
RetAddr -= 4; // Backtrack to the reference itself...
#endif
#if 0
DOUT << "In callback! Addr=" << (void*)RetAddr
<< " ESP=" << (void*)StackPtr
<< ": Resolving call to function: "
<< TheVM->getFunctionReferencedName((void*)RetAddr) << "\n";
#endif
// Sanity check to make sure this really is a call instruction.
#if defined (X86_64_JIT)
assert(((unsigned char*)RetAddr)[-2] == 0x41 &&"Not a call instr!");
assert(((unsigned char*)RetAddr)[-1] == 0xFF &&"Not a call instr!");
#else
assert(((unsigned char*)RetAddr)[-1] == 0xE8 &&"Not a call instr!");
#endif
intptr_t NewVal = (intptr_t)JITCompilerFunction((void*)RetAddr);
// Rewrite the call target... so that we don't end up here every time we
// execute the call.
#if defined (X86_64_JIT)
if (!isStub)
*(intptr_t *)(RetAddr - 0xa) = NewVal;
#else
*(intptr_t *)RetAddr = (intptr_t)(NewVal-RetAddr-4);
#endif
if (isStub) {
// If this is a stub, rewrite the call into an unconditional branch
// instruction so that two return addresses are not pushed onto the stack
// when the requested function finally gets called. This also makes the
// 0xCD byte (interrupt) dead, so the marker doesn't effect anything.
#if defined (X86_64_JIT)
// If the target address is within 32-bit range of the stub, use a
// PC-relative branch instead of loading the actual address. (This is
// considerably shorter than the 64-bit immediate load already there.)
// We assume here intptr_t is 64 bits.
intptr_t diff = NewVal-RetAddr+7;
if (diff >= -2147483648LL && diff <= 2147483647LL) {
*(unsigned char*)(RetAddr-0xc) = 0xE9;
*(intptr_t *)(RetAddr-0xb) = diff & 0xffffffff;
} else {
*(intptr_t *)(RetAddr - 0xa) = NewVal;
((unsigned char*)RetAddr)[0] = (2 | (4 << 3) | (3 << 6));
}
#else
((unsigned char*)RetAddr)[-1] = 0xE9;
#endif
}
// Change the return address to reexecute the call instruction...
#if defined (X86_64_JIT)
*RetAddrLoc -= 0xd;
#else
*RetAddrLoc -= 5;
#endif
}
TargetJITInfo::LazyResolverFn
X86JITInfo::getLazyResolverFunction(JITCompilerFn F) {
JITCompilerFunction = F;
#if defined (X86_32_JIT) && !defined (_MSC_VER)
unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
union {
unsigned u[3];
char c[12];
} text;
if (!X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1)) {
// FIXME: support for AMD family of processors.
if (memcmp(text.c, "GenuineIntel", 12) == 0) {
X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX);
if ((EDX >> 25) & 0x1)
return X86CompilationCallback_SSE;
}
}
#endif
return X86CompilationCallback;
}
void *X86JITInfo::emitGlobalValueLazyPtr(const GlobalValue* GV, void *ptr,
MachineCodeEmitter &MCE) {
#if defined (X86_64_JIT)
MCE.startFunctionStub(GV, 8, 8);
MCE.emitWordLE((unsigned)(intptr_t)ptr);
MCE.emitWordLE((unsigned)(((intptr_t)ptr) >> 32));
#else
MCE.startFunctionStub(GV, 4, 4);
MCE.emitWordLE((intptr_t)ptr);
#endif
return MCE.finishFunctionStub(GV);
}
void *X86JITInfo::emitFunctionStub(const Function* F, void *Fn,
MachineCodeEmitter &MCE) {
// Note, we cast to intptr_t here to silence a -pedantic warning that
// complains about casting a function pointer to a normal pointer.
#if defined (X86_32_JIT) && !defined (_MSC_VER)
bool NotCC = (Fn != (void*)(intptr_t)X86CompilationCallback &&
Fn != (void*)(intptr_t)X86CompilationCallback_SSE);
#else
bool NotCC = Fn != (void*)(intptr_t)X86CompilationCallback;
#endif
if (NotCC) {
#if defined (X86_64_JIT)
MCE.startFunctionStub(F, 13, 4);
MCE.emitByte(0x49); // REX prefix
MCE.emitByte(0xB8+2); // movabsq r10
MCE.emitWordLE((unsigned)(intptr_t)Fn);
MCE.emitWordLE((unsigned)(((intptr_t)Fn) >> 32));
MCE.emitByte(0x41); // REX prefix
MCE.emitByte(0xFF); // jmpq *r10
MCE.emitByte(2 | (4 << 3) | (3 << 6));
#else
MCE.startFunctionStub(F, 5, 4);
MCE.emitByte(0xE9);
MCE.emitWordLE((intptr_t)Fn-MCE.getCurrentPCValue()-4);
#endif
return MCE.finishFunctionStub(F);
}
#if defined (X86_64_JIT)
MCE.startFunctionStub(F, 14, 4);
MCE.emitByte(0x49); // REX prefix
MCE.emitByte(0xB8+2); // movabsq r10
MCE.emitWordLE((unsigned)(intptr_t)Fn);
MCE.emitWordLE((unsigned)(((intptr_t)Fn) >> 32));
MCE.emitByte(0x41); // REX prefix
MCE.emitByte(0xFF); // callq *r10
MCE.emitByte(2 | (2 << 3) | (3 << 6));
#else
MCE.startFunctionStub(F, 6, 4);
MCE.emitByte(0xE8); // Call with 32 bit pc-rel destination...
MCE.emitWordLE((intptr_t)Fn-MCE.getCurrentPCValue()-4);
#endif
MCE.emitByte(0xCD); // Interrupt - Just a marker identifying the stub!
return MCE.finishFunctionStub(F);
}
/// getPICJumpTableEntry - Returns the value of the jumptable entry for the
/// specific basic block.
intptr_t X86JITInfo::getPICJumpTableEntry(intptr_t BB, intptr_t Entry) {
#if defined(X86_64_JIT)
return BB - Entry;
#else
return BB - PICBase;
#endif
}
/// 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 X86JITInfo::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 = (intptr_t)MR->getResultPointer();
switch ((X86::RelocationType)MR->getRelocationType()) {
case X86::reloc_pcrel_word: {
// PC relative relocation, add the relocated value to the value already in
// memory, after we adjust it for where the PC is.
ResultPtr = ResultPtr -(intptr_t)RelocPos - 4 - MR->getConstantVal();
*((unsigned*)RelocPos) += (unsigned)ResultPtr;
break;
}
case X86::reloc_picrel_word: {
// PIC base relative relocation, add the relocated value to the value
// already in memory, after we adjust it for where the PIC base is.
ResultPtr = ResultPtr - ((intptr_t)Function + MR->getConstantVal());
*((unsigned*)RelocPos) += (unsigned)ResultPtr;
break;
}
case X86::reloc_absolute_word:
// Absolute relocation, just add the relocated value to the value already
// in memory.
*((unsigned*)RelocPos) += (unsigned)ResultPtr;
break;
case X86::reloc_absolute_dword:
*((intptr_t*)RelocPos) += ResultPtr;
break;
}
}
}
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