source: webkit/trunk/JavaScriptCore/assembler/ARMAssembler.cpp@ 46247

/*
 * Copyright (C) 2009 University of Szeged
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY UNIVERSITY OF SZEGED ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL UNIVERSITY OF SZEGED OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"

#if ENABLE(ASSEMBLER) && PLATFORM(ARM)

#include "ARMAssembler.h"

namespace JSC {

// Patching helpers

ARMWord* ARMAssembler::getLdrImmAddress(ARMWord* insn, uint32_t* constPool)
{
    // Must be an ldr ..., [pc +/- imm]
    ASSERT((*insn & 0x0f7f0000) == 0x051f0000);

    if (constPool && (*insn & 0x1))
        return reinterpret_cast<ARMWord*>(constPool + ((*insn & SDT_OFFSET_MASK) >> 1));

    ARMWord addr = reinterpret_cast<ARMWord>(insn) + 2 * sizeof(ARMWord);
    if (*insn & DT_UP)
        return reinterpret_cast<ARMWord*>(addr + (*insn & SDT_OFFSET_MASK));
    else
        return reinterpret_cast<ARMWord*>(addr - (*insn & SDT_OFFSET_MASK));
}

void ARMAssembler::linkBranch(void* code, JmpSrc from, void* to)
{
    ARMWord* insn = reinterpret_cast<ARMWord*>(code) + (from.m_offset / sizeof(ARMWord));

    if (!from.m_latePatch) {
        int diff = reinterpret_cast<ARMWord*>(to) - reinterpret_cast<ARMWord*>(insn + 2);

        if ((diff <= BOFFSET_MAX && diff >= BOFFSET_MIN)) {
            *insn = B | getConditionalField(*insn) | (diff & BRANCH_MASK);
            ExecutableAllocator::cacheFlush(insn, sizeof(ARMWord));
            return;
        }
    }
    ARMWord* addr = getLdrImmAddress(insn);
    *addr = reinterpret_cast<ARMWord>(to);
    ExecutableAllocator::cacheFlush(addr, sizeof(ARMWord));
}

void ARMAssembler::patchConstantPoolLoad(void* loadAddr, void* constPoolAddr)
{
    ARMWord *ldr = reinterpret_cast<ARMWord*>(loadAddr);
    ARMWord diff = reinterpret_cast<ARMWord*>(constPoolAddr) - ldr;
    ARMWord index = (*ldr & 0xfff) >> 1;

    ASSERT(diff >= 1);
    if (diff >= 2 || index > 0) {
        diff = (diff + index - 2) * sizeof(ARMWord);
        ASSERT(diff <= 0xfff);
        *ldr = (*ldr & ~0xfff) | diff;
    } else
        *ldr = (*ldr & ~(0xfff | ARMAssembler::DT_UP)) | sizeof(ARMWord);
}

// Handle immediates

ARMWord ARMAssembler::getOp2(ARMWord imm)
{
    int rol;

    if (imm <= 0xff)
        return OP2_IMM | imm;

    if ((imm & 0xff000000) == 0) {
        imm <<= 8;
        rol = 8;
    }
    else {
        imm = (imm << 24) | (imm >> 8);
        rol = 0;
    }

    if ((imm & 0xff000000) == 0) {
        imm <<= 8;
        rol += 4;
    }

    if ((imm & 0xf0000000) == 0) {
        imm <<= 4;
        rol += 2;
    }

    if ((imm & 0xc0000000) == 0) {
        imm <<= 2;
        rol += 1;
    }

    if ((imm & 0x00ffffff) == 0)
        return OP2_IMM | (imm >> 24) | (rol << 8);

    return 0;
}

int ARMAssembler::genInt(int reg, ARMWord imm, bool positive)
{
    // Step1: Search a non-immediate part
    ARMWord mask;
    ARMWord imm1;
    ARMWord imm2;
    int rol;

    mask = 0xff000000;
    rol = 8;
    while(1) {
        if ((imm & mask) == 0) {
            imm = (imm << rol) | (imm >> (32 - rol));
            rol = 4 + (rol >> 1);
            break;
        }
        rol += 2;
        mask >>= 2;
        if (mask & 0x3) {
            // rol 8
            imm = (imm << 8) | (imm >> 24);
            mask = 0xff00;
            rol = 24;
            while (1) {
                if ((imm & mask) == 0) {
                    imm = (imm << rol) | (imm >> (32 - rol));
                    rol = (rol >> 1) - 8;
                    break;
                }
                rol += 2;
                mask >>= 2;
                if (mask & 0x3)
                    return 0;
            }
            break;
        }
    }

    ASSERT((imm & 0xff) == 0);

    if ((imm & 0xff000000) == 0) {
        imm1 = OP2_IMM | ((imm >> 16) & 0xff) | (((rol + 4) & 0xf) << 8);
        imm2 = OP2_IMM | ((imm >> 8) & 0xff) | (((rol + 8) & 0xf) << 8);
    } else if (imm & 0xc0000000) {
        imm1 = OP2_IMM | ((imm >> 24) & 0xff) | ((rol & 0xf) << 8);
        imm <<= 8;
        rol += 4;

        if ((imm & 0xff000000) == 0) {
            imm <<= 8;
            rol += 4;
        }

        if ((imm & 0xf0000000) == 0) {
            imm <<= 4;
            rol += 2;
        }

        if ((imm & 0xc0000000) == 0) {
            imm <<= 2;
            rol += 1;
        }

        if ((imm & 0x00ffffff) == 0)
            imm2 = OP2_IMM | (imm >> 24) | ((rol & 0xf) << 8);
        else
            return 0;
    } else {
        if ((imm & 0xf0000000) == 0) {
            imm <<= 4;
            rol += 2;
        }

        if ((imm & 0xc0000000) == 0) {
            imm <<= 2;
            rol += 1;
        }

        imm1 = OP2_IMM | ((imm >> 24) & 0xff) | ((rol & 0xf) << 8);
        imm <<= 8;
        rol += 4;

        if ((imm & 0xf0000000) == 0) {
            imm <<= 4;
            rol += 2;
        }

        if ((imm & 0xc0000000) == 0) {
            imm <<= 2;
            rol += 1;
        }

        if ((imm & 0x00ffffff) == 0)
            imm2 = OP2_IMM | (imm >> 24) | ((rol & 0xf) << 8);
        else
            return 0;
    }

    if (positive) {
        mov_r(reg, imm1);
        orr_r(reg, reg, imm2);
    } else {
        mvn_r(reg, imm1);
        bic_r(reg, reg, imm2);
    }

    return 1;
}

ARMWord ARMAssembler::getImm(ARMWord imm, int tmpReg, bool invert)
{
    ARMWord tmp;

    // Do it by 1 instruction
    tmp = getOp2(imm);
    if (tmp)
        return tmp;

    tmp = getOp2(~imm);
    if (tmp) {
        if (invert)
            return tmp | OP2_INV_IMM;
        mvn_r(tmpReg, tmp);
        return tmpReg;
    }

    // Do it by 2 instruction
    if (genInt(tmpReg, imm, true))
        return tmpReg;
    if (genInt(tmpReg, ~imm, false))
        return tmpReg;

    ldr_imm(tmpReg, imm);
    return tmpReg;
}

void ARMAssembler::moveImm(ARMWord imm, int dest)
{
    ARMWord tmp;

    // Do it by 1 instruction
    tmp = getOp2(imm);
    if (tmp) {
        mov_r(dest, tmp);
        return;
    }

    tmp = getOp2(~imm);
    if (tmp) {
        mvn_r(dest, tmp);
        return;
    }

    // Do it by 2 instruction
    if (genInt(dest, imm, true))
        return;
    if (genInt(dest, ~imm, false))
        return;

    ldr_imm(dest, imm);
}

// Memory load/store helpers

void ARMAssembler::dataTransfer32(bool isLoad, RegisterID srcDst, RegisterID base, int32_t offset)
{
    if (offset >= 0) {
        if (offset <= 0xfff)
            dtr_u(isLoad, srcDst, base, offset);
        else if (offset <= 0xfffff) {
            add_r(ARM::S0, base, OP2_IMM | (offset >> 12) | (10 << 8));
            dtr_u(isLoad, srcDst, ARM::S0, offset & 0xfff);
        } else {
            ARMWord reg = getImm(offset, ARM::S0);
            dtr_ur(isLoad, srcDst, base, reg);
        }
    } else {
        offset = -offset;
        if (offset <= 0xfff)
            dtr_d(isLoad, srcDst, base, offset);
        else if (offset <= 0xfffff) {
            sub_r(ARM::S0, base, OP2_IMM | (offset >> 12) | (10 << 8));
            dtr_d(isLoad, srcDst, ARM::S0, offset & 0xfff);
        } else {
            ARMWord reg = getImm(offset, ARM::S0);
            dtr_dr(isLoad, srcDst, base, reg);
        }
    }
}

void ARMAssembler::baseIndexTransfer32(bool isLoad, RegisterID srcDst, RegisterID base, RegisterID index, int scale, int32_t offset)
{
    ARMWord op2;

    ASSERT(scale >= 0 && scale <= 3);
    op2 = lsl(index, scale);

    if (offset >= 0 && offset <= 0xfff) {
        add_r(ARM::S0, base, op2);
        dtr_u(isLoad, srcDst, ARM::S0, offset);
        return;
    }
    if (offset <= 0 && offset >= -0xfff) {
        add_r(ARM::S0, base, op2);
        dtr_d(isLoad, srcDst, ARM::S0, -offset);
        return;
    }

    moveImm(offset, ARM::S0);
    add_r(ARM::S0, ARM::S0, op2);
    dtr_ur(isLoad, srcDst, base, ARM::S0);
}

void* ARMAssembler::executableCopy(ExecutablePool* allocator)
{
    char* data = reinterpret_cast<char*>(m_buffer.executableCopy(allocator));

    for (Jumps::Iterator iter = m_jumps.begin(); iter != m_jumps.end(); ++iter) {
        ARMWord* ldrAddr = reinterpret_cast<ARMWord*>(data + *iter);
        ARMWord* offset = getLdrImmAddress(ldrAddr);
        if (*offset != 0xffffffff)
            linkBranch(data, JmpSrc(*iter), data + *offset);
    }

    return data;
}

} // namespace JSC

#endif // ENABLE(ASSEMBLER) && PLATFORM(ARM)