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tcg/riscv: Implement movcond 
Implement with and without Zicond.  Without Zicond, we were letting
the middle-end expand to a 5 insn sequence; better to use a branch
over a single insn.

Acked-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@rth7680
rth7680 committed May 25, 2023
1 parent f645369 commit a18d783
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Showing 3 changed files with 141 additions and 3 deletions.
1 change: 1 addition & 0 deletions tcg/riscv/tcg-target-con-set.h
View file
Expand Up @@ -18,4 +18,5 @@ C_O1_I2(r, r, rI)
C_O1_I2(r, r, rJ)
C_O1_I2(r, rZ, rN)
C_O1_I2(r, rZ, rZ)
C_O1_I4(r, r, rI, rM, rM)
C_O2_I4(r, r, rZ, rZ, rM, rM)
139 changes: 138 additions & 1 deletion tcg/riscv/tcg-target.c.inc
View file
Expand Up @@ -169,7 +169,7 @@ static bool tcg_target_const_match(int64_t val, TCGType type, int ct)
}
/*
* Sign extended from 12 bits, +/- matching: [-0x7ff, 0x7ff].
* Used by addsub2, which may need the negative operation,
* Used by addsub2 and movcond, which may need the negative value,
* and requires the modified constant to be representable.
*/
if ((ct & TCG_CT_CONST_M12) && val >= -0x7ff && val <= 0x7ff) {
Expand Down Expand Up @@ -936,6 +936,133 @@ static void tcg_out_setcond(TCGContext *s, TCGCond cond, TCGReg ret,
}
}

static void tcg_out_movcond_zicond(TCGContext *s, TCGReg ret, TCGReg test_ne,
int val1, bool c_val1,
int val2, bool c_val2)
{
if (val1 == 0) {
if (c_val2) {
tcg_out_movi(s, TCG_TYPE_REG, TCG_REG_TMP1, val2);
val2 = TCG_REG_TMP1;
}
tcg_out_opc_reg(s, OPC_CZERO_NEZ, ret, val2, test_ne);
return;
}

if (val2 == 0) {
if (c_val1) {
tcg_out_movi(s, TCG_TYPE_REG, TCG_REG_TMP1, val1);
val1 = TCG_REG_TMP1;
}
tcg_out_opc_reg(s, OPC_CZERO_EQZ, ret, val1, test_ne);
return;
}

if (c_val2) {
if (c_val1) {
tcg_out_movi(s, TCG_TYPE_REG, TCG_REG_TMP1, val1 - val2);
} else {
tcg_out_opc_imm(s, OPC_ADDI, TCG_REG_TMP1, val1, -val2);
}
tcg_out_opc_reg(s, OPC_CZERO_EQZ, ret, TCG_REG_TMP1, test_ne);
tcg_out_opc_imm(s, OPC_ADDI, ret, ret, val2);
return;
}

if (c_val1) {
tcg_out_opc_imm(s, OPC_ADDI, TCG_REG_TMP1, val2, -val1);
tcg_out_opc_reg(s, OPC_CZERO_NEZ, ret, TCG_REG_TMP1, test_ne);
tcg_out_opc_imm(s, OPC_ADDI, ret, ret, val1);
return;
}

tcg_out_opc_reg(s, OPC_CZERO_NEZ, TCG_REG_TMP1, val2, test_ne);
tcg_out_opc_reg(s, OPC_CZERO_EQZ, TCG_REG_TMP0, val1, test_ne);
tcg_out_opc_reg(s, OPC_OR, ret, TCG_REG_TMP0, TCG_REG_TMP1);
}

static void tcg_out_movcond_br1(TCGContext *s, TCGCond cond, TCGReg ret,
TCGReg cmp1, TCGReg cmp2,
int val, bool c_val)
{
RISCVInsn op;
int disp = 8;

tcg_debug_assert((unsigned)cond < ARRAY_SIZE(tcg_brcond_to_riscv));
op = tcg_brcond_to_riscv[cond].op;
tcg_debug_assert(op != 0);

if (tcg_brcond_to_riscv[cond].swap) {
tcg_out_opc_branch(s, op, cmp2, cmp1, disp);
} else {
tcg_out_opc_branch(s, op, cmp1, cmp2, disp);
}
if (c_val) {
tcg_out_opc_imm(s, OPC_ADDI, ret, TCG_REG_ZERO, val);
} else {
tcg_out_opc_imm(s, OPC_ADDI, ret, val, 0);
}
}

static void tcg_out_movcond_br2(TCGContext *s, TCGCond cond, TCGReg ret,
TCGReg cmp1, TCGReg cmp2,
int val1, bool c_val1,
int val2, bool c_val2)
{
TCGReg tmp;

/* TCG optimizer reorders to prefer ret matching val2. */
if (!c_val2 && ret == val2) {
cond = tcg_invert_cond(cond);
tcg_out_movcond_br1(s, cond, ret, cmp1, cmp2, val1, c_val1);
return;
}

if (!c_val1 && ret == val1) {
tcg_out_movcond_br1(s, cond, ret, cmp1, cmp2, val2, c_val2);
return;
}

tmp = (ret == cmp1 || ret == cmp2 ? TCG_REG_TMP1 : ret);
if (c_val1) {
tcg_out_movi(s, TCG_TYPE_REG, tmp, val1);
} else {
tcg_out_mov(s, TCG_TYPE_REG, tmp, val1);
}
tcg_out_movcond_br1(s, cond, tmp, cmp1, cmp2, val2, c_val2);
tcg_out_mov(s, TCG_TYPE_REG, ret, tmp);
}

static void tcg_out_movcond(TCGContext *s, TCGCond cond, TCGReg ret,
TCGReg cmp1, int cmp2, bool c_cmp2,
TCGReg val1, bool c_val1,
TCGReg val2, bool c_val2)
{
int tmpflags;
TCGReg t;

if (!have_zicond && (!c_cmp2 || cmp2 == 0)) {
tcg_out_movcond_br2(s, cond, ret, cmp1, cmp2,
val1, c_val1, val2, c_val2);
return;
}

tmpflags = tcg_out_setcond_int(s, cond, TCG_REG_TMP0, cmp1, cmp2, c_cmp2);
t = tmpflags & ~SETCOND_FLAGS;

if (have_zicond) {
if (tmpflags & SETCOND_INV) {
tcg_out_movcond_zicond(s, ret, t, val2, c_val2, val1, c_val1);
} else {
tcg_out_movcond_zicond(s, ret, t, val1, c_val1, val2, c_val2);
}
} else {
cond = tmpflags & SETCOND_INV ? TCG_COND_EQ : TCG_COND_NE;
tcg_out_movcond_br2(s, cond, ret, t, TCG_REG_ZERO,
val1, c_val1, val2, c_val2);
}
}

static void tcg_out_call_int(TCGContext *s, const tcg_insn_unit *arg, bool tail)
{
TCGReg link = tail ? TCG_REG_ZERO : TCG_REG_RA;
Expand Down Expand Up @@ -1623,6 +1750,12 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc,
tcg_out_setcond(s, args[3], a0, a1, a2, c2);
break;

case INDEX_op_movcond_i32:
case INDEX_op_movcond_i64:
tcg_out_movcond(s, args[5], a0, a1, a2, c2,
args[3], const_args[3], args[4], const_args[4]);
break;

case INDEX_op_qemu_ld_a32_i32:
case INDEX_op_qemu_ld_a64_i32:
tcg_out_qemu_ld(s, a0, a1, a2, TCG_TYPE_I32);
Expand Down Expand Up @@ -1791,6 +1924,10 @@ static TCGConstraintSetIndex tcg_target_op_def(TCGOpcode op)
case INDEX_op_brcond_i64:
return C_O0_I2(rZ, rZ);

case INDEX_op_movcond_i32:
case INDEX_op_movcond_i64:
return C_O1_I4(r, r, rI, rM, rM);

case INDEX_op_add2_i32:
case INDEX_op_add2_i64:
case INDEX_op_sub2_i32:
Expand Down
4 changes: 2 additions & 2 deletions tcg/riscv/tcg-target.h
View file
Expand Up @@ -97,7 +97,7 @@ extern bool have_zbb;
#endif

/* optional instructions */
#define TCG_TARGET_HAS_movcond_i32 0
#define TCG_TARGET_HAS_movcond_i32 1
#define TCG_TARGET_HAS_div_i32 1
#define TCG_TARGET_HAS_rem_i32 1
#define TCG_TARGET_HAS_div2_i32 0
Expand Down Expand Up @@ -132,7 +132,7 @@ extern bool have_zbb;
#define TCG_TARGET_HAS_setcond2 1
#define TCG_TARGET_HAS_qemu_st8_i32 0

#define TCG_TARGET_HAS_movcond_i64 0
#define TCG_TARGET_HAS_movcond_i64 1
#define TCG_TARGET_HAS_div_i64 1
#define TCG_TARGET_HAS_rem_i64 1
#define TCG_TARGET_HAS_div2_i64 0
Expand Down

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