qemu/target/riscv/insn_trans/trans_rvm.inc.c
Palmer Dabbelt f17e02cd37
target/riscv: Zero extend the inputs of divuw and remuw
While running the GCC test suite against 4.0.0-rc0, Kito found a
regression introduced by the decodetree conversion that caused divuw and
remuw to sign-extend their inputs.  The ISA manual says they are
supposed to be zero extended:

    DIVW and DIVUW instructions are only valid for RV64, and divide the
    lower 32 bits of rs1 by the lower 32 bits of rs2, treating them as
    signed and unsigned integers respectively, placing the 32-bit
    quotient in rd, sign-extended to 64 bits. REMW and REMUW
    instructions are only valid for RV64, and provide the corresponding
    signed and unsigned remainder operations respectively.  Both REMW
    and REMUW always sign-extend the 32-bit result to 64 bits, including
    on a divide by zero.

Here's Kito's reduced test case from the GCC test suite

    unsigned calc_mp(unsigned mod)
    {
         unsigned a,b,c;
         c=-1;
         a=c/mod;
         b=0-a*mod;
         if (b > mod) { a += 1; b-=mod; }
         return b;
    }

    int main(int argc, char *argv[])
    {
         unsigned x = 1234;
         unsigned y = calc_mp(x);

         if ((sizeof (y) == 4 && y != 680)
      || (sizeof (y) == 2 && y != 134))
    abort ();
         exit (0);
    }

I haven't done any other testing on this, but it does fix the test case.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2019-03-22 00:26:39 -07:00

121 lines
3.1 KiB
C

/*
* RISC-V translation routines for the RV64M Standard Extension.
*
* Copyright (c) 2016-2017 Sagar Karandikar, sagark@eecs.berkeley.edu
* Copyright (c) 2018 Peer Adelt, peer.adelt@hni.uni-paderborn.de
* Bastian Koppelmann, kbastian@mail.uni-paderborn.de
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2 or later, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
*/
static bool trans_mul(DisasContext *ctx, arg_mul *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith(ctx, a, &tcg_gen_mul_tl);
}
static bool trans_mulh(DisasContext *ctx, arg_mulh *a)
{
REQUIRE_EXT(ctx, RVM);
TCGv source1 = tcg_temp_new();
TCGv source2 = tcg_temp_new();
gen_get_gpr(source1, a->rs1);
gen_get_gpr(source2, a->rs2);
tcg_gen_muls2_tl(source2, source1, source1, source2);
gen_set_gpr(a->rd, source1);
tcg_temp_free(source1);
tcg_temp_free(source2);
return true;
}
static bool trans_mulhsu(DisasContext *ctx, arg_mulhsu *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith(ctx, a, &gen_mulhsu);
}
static bool trans_mulhu(DisasContext *ctx, arg_mulhu *a)
{
REQUIRE_EXT(ctx, RVM);
TCGv source1 = tcg_temp_new();
TCGv source2 = tcg_temp_new();
gen_get_gpr(source1, a->rs1);
gen_get_gpr(source2, a->rs2);
tcg_gen_mulu2_tl(source2, source1, source1, source2);
gen_set_gpr(a->rd, source1);
tcg_temp_free(source1);
tcg_temp_free(source2);
return true;
}
static bool trans_div(DisasContext *ctx, arg_div *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith(ctx, a, &gen_div);
}
static bool trans_divu(DisasContext *ctx, arg_divu *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith(ctx, a, &gen_divu);
}
static bool trans_rem(DisasContext *ctx, arg_rem *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith(ctx, a, &gen_rem);
}
static bool trans_remu(DisasContext *ctx, arg_remu *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith(ctx, a, &gen_remu);
}
#ifdef TARGET_RISCV64
static bool trans_mulw(DisasContext *ctx, arg_mulw *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith(ctx, a, &gen_mulw);
}
static bool trans_divw(DisasContext *ctx, arg_divw *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith_div_w(ctx, a, &gen_div);
}
static bool trans_divuw(DisasContext *ctx, arg_divuw *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith_div_uw(ctx, a, &gen_divu);
}
static bool trans_remw(DisasContext *ctx, arg_remw *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith_div_w(ctx, a, &gen_rem);
}
static bool trans_remuw(DisasContext *ctx, arg_remuw *a)
{
REQUIRE_EXT(ctx, RVM);
return gen_arith_div_uw(ctx, a, &gen_remu);
}
#endif