md.cpp

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/* src/vm/jit/sparc64/md.cpp - machine dependent SPARC64 functions

   Copyright (C) 1996-2013
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO

   This file is part of CACAO.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

*/


#include "config.h"

#include <cassert>
#include <stdint.h>

#include "vm/types.hpp"

#include "vm/jit/sparc64/md-abi.hpp"

#include "vm/jit/asmpart.hpp"
#include "vm/jit/codegen-common.hpp"
#include "vm/jit/jit.hpp"


/* assembler function prototypes **********************************************/
void asm_store_fp_state_reg(u8 *mem);
void asm_load_fp_state_reg(u8 *mem);


/* NOP is defined as a SETHI instruction with rd and imm. set to zero */
/* therefore we check if the 22-bit immediate is zero */
#define IS_SETHI(instr) \
    (((instr & 0xc1c00000)  == 0x01000000) \
    && ((instr & 0x3fffff) != 0x0))
    
#define IS_LDX_IMM(instr) \
    (((instr >> 13) & 0x60fc1) == 0x602c1)
    
#define IS_SUB(instr) \
    (((instr >> 13) & 0x60fc0) == 0x40100)

inline s2 decode_13bit_imm(u4 instr) {
    s2 imm;

    /* mask everything else in the instruction */
    imm = instr & 0x00001fff;

    /* sign extend 13-bit to 16-bit */
    imm <<= 3;
    imm >>= 3;

    return imm;
}

/* md_init *********************************************************************

   Do some machine dependent initialization.

*******************************************************************************/

void md_init(void)
{
    /* do nothing */
}


/* md_jit_method_patch_address *************************************************

   Gets the patch address of the currently compiled method. The offset
   is extracted from the load instruction(s) before the jump and added
   to the right base address (PV or REG_METHODPTR).

   INVOKESTATIC/SPECIAL:

   ????????    ldx      [i5 - 72],o5
   ????????    jmp      o5             <-- ra
   ????????    nop

   w/ sethi (mptr in dseg out of 13-bit simm range)

   ????????    sethi    hi(0x2000),o5
   ????????    sub      i5,o5,o5
   ????????    ldx      [o5 - 72],o5
   ????????    jmp      o5             <-- ra
   ????????    nop

   INVOKEVIRTUAL:

   ????????    ldx      [o0 + 0},g2
   ????????    ldx      [g2 + 0],o5
   ????????    jmp      o5             <-- ra
   ????????    nop

   INVOKEINTERFACE:

   ????????    ldx      [o0 + 0},g2
   ????????    ldx      [g2 - 112],g2
   ????????    ldx      [g2 + 24],o5
   ????????    jmp      o5             <-- ra
   ????????    nop

*******************************************************************************/

void *md_jit_method_patch_address(void *pv, void *ra, void *mptr)
{
    uint32_t *pc;
    uint32_t  mcode, mcode_sethi, mcode_masked;
    int32_t   disp;
    uint8_t  *iptr;
    void     *pa;

    /* Go back to the location of a possible sethi (3 instruction
       before jump). */

    pc = ((uint32_t *) ra) - 3;

    /* note: ra is the address of the jump instruction on SPARC */

    mcode_sethi = pc[0];

    /* check for sethi instruction */

    if (IS_SETHI(mcode_sethi)) {
        u4 mcode_sub, mcode_ldx;

        mcode_sub = pc[1];
        mcode_ldx = pc[2];

        /* make sure the sequence of instructions is a loadhi */
        if ((IS_SUB(mcode_sub)) && (IS_LDX_IMM(mcode_ldx)))
        {


        /* get 22-bit immediate of sethi instruction */

        disp = (int32_t) (mcode_sethi & 0x3fffff);
        disp = disp << 10;
        
        /* goto next instruction */
        
        /* make sure it's a sub instruction (pv - big_disp) */
        assert(IS_SUB(mcode_sub));
        disp = -disp;

        /* get displacement of load instruction */

        assert(IS_LDX_IMM(mcode_ldx));

        disp += decode_13bit_imm(mcode_ldx);
        
        pa = ((uint8_t *) pv) + disp;

        return pa;
        }
    }

    /* we didn't find a sethi, or it didn't belong to a loadhi */
    /* check for simple (one-instruction) load */

    mcode = pc[2];

    /* shift and mask rd */

    mcode_masked = (mcode >> 13) & 0x060fff;
    
    /* get the offset from the instruction */

    disp = decode_13bit_imm(mcode);

    /* check for call with rs1 == REG_METHODPTR: ldx [g2+x],pv_caller */

    if (mcode_masked == 0x0602c5) {
        /* in this case we use the passed method pointer */

        /* return NULL if no mptr was specified (used for replacement) */

        if (mptr == NULL)
            return NULL;

        pa = ((uint8_t *) mptr) + disp;

    } else {
        /* in the normal case we check for a `ldx [i5+x],pv_caller' instruction */

        assert(mcode_masked  == 0x0602fb);

        /* and get the final data segment address */

        pa = ((uint8_t *) pv) + disp;
    }

    return pa;
}


/* md_patch_replacement_point **************************************************

   Patch the given replacement point.

*******************************************************************************/

#if defined(ENABLE_REPLACEMENT)
void md_patch_replacement_point(u1 *pc, u1 *savedmcode, bool revert)
{
    u4 mcode;

    if (revert) {
        /* restore the patched-over instruction */
        *(u4*)(pc) = *(u4*)(savedmcode);
    }
    else {
        /* save the current machine code */
        *(u4*)(savedmcode) = *(u4*)(pc);

        /* build the machine code for the patch */
        assert(0); /* XXX build trap instruction below */
        mcode = 0;

        /* write the new machine code */
        *(u4*)(pc) = (u4) mcode;
    }

    /* flush instruction cache */
    /* md_icacheflush(pc,4); */
}
#endif /* defined(ENABLE_REPLACEMENT) */

/*
 * These are local overrides for various environment variables in Emacs.
 * Please do not remove this and leave it at the end of the file, where
 * Emacs will automagically detect them.
 * ---------------------------------------------------------------------
 * Local variables:
 * mode: c++
 * indent-tabs-mode: t
 * c-basic-offset: 4
 * tab-width: 4
 * End:
 * vim:noexpandtab:sw=4:ts=4:
 */