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tcg/ppc: Implement negsetcond_* 
In the general case we simply negate.  However with isel we
may load -1 instead of 1 with no extra effort.

Consolidate EQ0 and NE0 logic.  Replace the NE0 zero-extension
with inversion+negation of EQ0, which is never worse and may
eliminate one insn.  Provide a special case for -EQ0.

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@rth7680
rth7680 committed Aug 24, 2023
1 parent b0a433b commit cba10bb
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Showing 2 changed files with 82 additions and 49 deletions.
127 changes: 80 additions & 47 deletions tcg/ppc/tcg-target.c.inc
View file
Expand Up @@ -1548,27 +1548,49 @@ static void tcg_out_cmp(TCGContext *s, int cond, TCGArg arg1, TCGArg arg2,
}

static void tcg_out_setcond_eq0(TCGContext *s, TCGType type,
TCGReg dst, TCGReg src)
TCGReg dst, TCGReg src, bool neg)
{
if (neg && (TCG_TARGET_REG_BITS == 32 || type == TCG_TYPE_I64)) {
/*
* X != 0 implies X + -1 generates a carry.
* RT = (~X + X) + CA
* = -1 + CA
* = CA ? 0 : -1
*/
tcg_out32(s, ADDIC | TAI(TCG_REG_R0, src, -1));
tcg_out32(s, SUBFE | TAB(dst, src, src));
return;
}

if (type == TCG_TYPE_I32) {
tcg_out32(s, CNTLZW | RS(src) | RA(dst));
tcg_out_shri32(s, dst, dst, 5);
} else {
tcg_out32(s, CNTLZD | RS(src) | RA(dst));
tcg_out_shri64(s, dst, dst, 6);
}
if (neg) {
tcg_out32(s, NEG | RT(dst) | RA(dst));
}
}

static void tcg_out_setcond_ne0(TCGContext *s, TCGReg dst, TCGReg src)
static void tcg_out_setcond_ne0(TCGContext *s, TCGType type,
TCGReg dst, TCGReg src, bool neg)
{
/* X != 0 implies X + -1 generates a carry. Extra addition
trickery means: R = X-1 + ~X + C = X-1 + (-X+1) + C = C. */
if (dst != src) {
tcg_out32(s, ADDIC | TAI(dst, src, -1));
tcg_out32(s, SUBFE | TAB(dst, dst, src));
} else {
if (!neg && (TCG_TARGET_REG_BITS == 32 || type == TCG_TYPE_I64)) {
/*
* X != 0 implies X + -1 generates a carry. Extra addition
* trickery means: R = X-1 + ~X + C = X-1 + (-X+1) + C = C.
*/
tcg_out32(s, ADDIC | TAI(TCG_REG_R0, src, -1));
tcg_out32(s, SUBFE | TAB(dst, TCG_REG_R0, src));
return;
}
tcg_out_setcond_eq0(s, type, dst, src, false);
if (neg) {
tcg_out32(s, ADDI | TAI(dst, dst, -1));
} else {
tcg_out_xori32(s, dst, dst, 1);
}
}

Expand All @@ -1590,9 +1612,10 @@ static TCGReg tcg_gen_setcond_xor(TCGContext *s, TCGReg arg1, TCGArg arg2,

static void tcg_out_setcond(TCGContext *s, TCGType type, TCGCond cond,
TCGArg arg0, TCGArg arg1, TCGArg arg2,
int const_arg2)
int const_arg2, bool neg)
{
int crop, sh;
int sh;
bool inv;

tcg_debug_assert(TCG_TARGET_REG_BITS == 64 || type == TCG_TYPE_I32);

Expand All @@ -1605,14 +1628,10 @@ static void tcg_out_setcond(TCGContext *s, TCGType type, TCGCond cond,
if (arg2 == 0) {
switch (cond) {
case TCG_COND_EQ:
tcg_out_setcond_eq0(s, type, arg0, arg1);
tcg_out_setcond_eq0(s, type, arg0, arg1, neg);
return;
case TCG_COND_NE:
if (TCG_TARGET_REG_BITS == 64 && type == TCG_TYPE_I32) {
tcg_out_ext32u(s, TCG_REG_R0, arg1);
arg1 = TCG_REG_R0;
}
tcg_out_setcond_ne0(s, arg0, arg1);
tcg_out_setcond_ne0(s, type, arg0, arg1, neg);
return;
case TCG_COND_GE:
tcg_out32(s, NOR | SAB(arg1, arg0, arg1));
Expand All @@ -1621,9 +1640,17 @@ static void tcg_out_setcond(TCGContext *s, TCGType type, TCGCond cond,
case TCG_COND_LT:
/* Extract the sign bit. */
if (type == TCG_TYPE_I32) {
tcg_out_shri32(s, arg0, arg1, 31);
if (neg) {
tcg_out_sari32(s, arg0, arg1, 31);
} else {
tcg_out_shri32(s, arg0, arg1, 31);
}
} else {
tcg_out_shri64(s, arg0, arg1, 63);
if (neg) {
tcg_out_sari64(s, arg0, arg1, 63);
} else {
tcg_out_shri64(s, arg0, arg1, 63);
}
}
return;
default:
Expand All @@ -1641,7 +1668,7 @@ static void tcg_out_setcond(TCGContext *s, TCGType type, TCGCond cond,

isel = tcg_to_isel[cond];

tcg_out_movi(s, type, arg0, 1);
tcg_out_movi(s, type, arg0, neg ? -1 : 1);
if (isel & 1) {
/* arg0 = (bc ? 0 : 1) */
tab = TAB(arg0, 0, arg0);
Expand All @@ -1655,51 +1682,47 @@ static void tcg_out_setcond(TCGContext *s, TCGType type, TCGCond cond,
return;
}

inv = false;
switch (cond) {
case TCG_COND_EQ:
arg1 = tcg_gen_setcond_xor(s, arg1, arg2, const_arg2);
tcg_out_setcond_eq0(s, type, arg0, arg1);
return;
tcg_out_setcond_eq0(s, type, arg0, arg1, neg);
break;

case TCG_COND_NE:
arg1 = tcg_gen_setcond_xor(s, arg1, arg2, const_arg2);
/* Discard the high bits only once, rather than both inputs. */
if (TCG_TARGET_REG_BITS == 64 && type == TCG_TYPE_I32) {
tcg_out_ext32u(s, TCG_REG_R0, arg1);
arg1 = TCG_REG_R0;
}
tcg_out_setcond_ne0(s, arg0, arg1);
return;
tcg_out_setcond_ne0(s, type, arg0, arg1, neg);
break;

case TCG_COND_LE:
case TCG_COND_LEU:
inv = true;
/* fall through */
case TCG_COND_GT:
case TCG_COND_GTU:
sh = 30;
crop = 0;
goto crtest;

case TCG_COND_LT:
case TCG_COND_LTU:
sh = 29;
crop = 0;
sh = 30; /* CR7 CR_GT */
goto crtest;

case TCG_COND_GE:
case TCG_COND_GEU:
sh = 31;
crop = CRNOR | BT(7, CR_EQ) | BA(7, CR_LT) | BB(7, CR_LT);
inv = true;
/* fall through */
case TCG_COND_LT:
case TCG_COND_LTU:
sh = 29; /* CR7 CR_LT */
goto crtest;

case TCG_COND_LE:
case TCG_COND_LEU:
sh = 31;
crop = CRNOR | BT(7, CR_EQ) | BA(7, CR_GT) | BB(7, CR_GT);
crtest:
tcg_out_cmp(s, cond, arg1, arg2, const_arg2, 7, type);
if (crop) {
tcg_out32(s, crop);
}
tcg_out32(s, MFOCRF | RT(TCG_REG_R0) | FXM(7));
tcg_out_rlw(s, RLWINM, arg0, TCG_REG_R0, sh, 31, 31);
if (neg && inv) {
tcg_out32(s, ADDI | TAI(arg0, arg0, -1));
} else if (neg) {
tcg_out32(s, NEG | RT(arg0) | RA(arg0));
} else if (inv) {
tcg_out_xori32(s, arg0, arg0, 1);
}
break;

default:
Expand Down Expand Up @@ -2982,11 +3005,19 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc,

case INDEX_op_setcond_i32:
tcg_out_setcond(s, TCG_TYPE_I32, args[3], args[0], args[1], args[2],
const_args[2]);
const_args[2], false);
break;
case INDEX_op_setcond_i64:
tcg_out_setcond(s, TCG_TYPE_I64, args[3], args[0], args[1], args[2],
const_args[2]);
const_args[2], false);
break;
case INDEX_op_negsetcond_i32:
tcg_out_setcond(s, TCG_TYPE_I32, args[3], args[0], args[1], args[2],
const_args[2], true);
break;
case INDEX_op_negsetcond_i64:
tcg_out_setcond(s, TCG_TYPE_I64, args[3], args[0], args[1], args[2],
const_args[2], true);
break;
case INDEX_op_setcond2_i32:
tcg_out_setcond2(s, args, const_args);
Expand Down Expand Up @@ -3724,6 +3755,7 @@ static TCGConstraintSetIndex tcg_target_op_def(TCGOpcode op)
case INDEX_op_rotl_i32:
case INDEX_op_rotr_i32:
case INDEX_op_setcond_i32:
case INDEX_op_negsetcond_i32:
case INDEX_op_and_i64:
case INDEX_op_andc_i64:
case INDEX_op_shl_i64:
Expand All @@ -3732,6 +3764,7 @@ static TCGConstraintSetIndex tcg_target_op_def(TCGOpcode op)
case INDEX_op_rotl_i64:
case INDEX_op_rotr_i64:
case INDEX_op_setcond_i64:
case INDEX_op_negsetcond_i64:
return C_O1_I2(r, r, ri);

case INDEX_op_mul_i32:
Expand Down
4 changes: 2 additions & 2 deletions tcg/ppc/tcg-target.h
View file
Expand Up @@ -97,7 +97,7 @@ typedef enum {
#define TCG_TARGET_HAS_sextract_i32 0
#define TCG_TARGET_HAS_extract2_i32 0
#define TCG_TARGET_HAS_movcond_i32 1
#define TCG_TARGET_HAS_negsetcond_i32 0
#define TCG_TARGET_HAS_negsetcond_i32 1
#define TCG_TARGET_HAS_mulu2_i32 0
#define TCG_TARGET_HAS_muls2_i32 0
#define TCG_TARGET_HAS_muluh_i32 1
Expand Down Expand Up @@ -135,7 +135,7 @@ typedef enum {
#define TCG_TARGET_HAS_sextract_i64 0
#define TCG_TARGET_HAS_extract2_i64 0
#define TCG_TARGET_HAS_movcond_i64 1
#define TCG_TARGET_HAS_negsetcond_i64 0
#define TCG_TARGET_HAS_negsetcond_i64 1
#define TCG_TARGET_HAS_add2_i64 1
#define TCG_TARGET_HAS_sub2_i64 1
#define TCG_TARGET_HAS_mulu2_i64 0
Expand Down

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