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tcg: Introduce tcg_out_movext3

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With x86_64 as host, we do not have any temporaries with which to
resolve cycles, but we do have xchg.   As a side bonus, the set of
graphs that can be made with 3 nodes and all nodes conflicting is
small: two.  We can solve the cycle with a single temp.

This is required for x86_64 to handle stores of i128: 1 address
register and 2 data registers.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2023-05-14 09:58:39 -07:00
parent 12fde9bcdb
commit 2462e30e99
1 changed files with 108 additions and 30 deletions
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138
tcg/tcg.c
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@ -532,6 +532,82 @@ static void tcg_out_movext2(TCGContext *s, const TCGMovExtend *i1,
tcg_out_movext1_new_src(s, i1, src1);
}
/**
* tcg_out_movext3 -- move and extend three pair
* @s: tcg context
* @i1: first move description
* @i2: second move description
* @i3: third move description
* @scratch: temporary register, or -1 for none
*
* As tcg_out_movext, for all of @i1, @i2 and @i3, caring for overlap
* between the sources and destinations.
*/
static void tcg_out_movext3(TCGContext *s, const TCGMovExtend *i1,
const TCGMovExtend *i2, const TCGMovExtend *i3,
int scratch)
{
TCGReg src1 = i1->src;
TCGReg src2 = i2->src;
TCGReg src3 = i3->src;
if (i1->dst != src2 && i1->dst != src3) {
tcg_out_movext1(s, i1);
tcg_out_movext2(s, i2, i3, scratch);
return;
}
if (i2->dst != src1 && i2->dst != src3) {
tcg_out_movext1(s, i2);
tcg_out_movext2(s, i1, i3, scratch);
return;
}
if (i3->dst != src1 && i3->dst != src2) {
tcg_out_movext1(s, i3);
tcg_out_movext2(s, i1, i2, scratch);
return;
}
/*
* There is a cycle. Since there are only 3 nodes, the cycle is
* either "clockwise" or "anti-clockwise", and can be solved with
* a single scratch or two xchg.
*/
if (i1->dst == src2 && i2->dst == src3 && i3->dst == src1) {
/* "Clockwise" */
if (tcg_out_xchg(s, MAX(i1->src_type, i2->src_type), src1, src2)) {
tcg_out_xchg(s, MAX(i2->src_type, i3->src_type), src2, src3);
/* The data is now in the correct registers, now extend. */
tcg_out_movext1_new_src(s, i1, i1->dst);
tcg_out_movext1_new_src(s, i2, i2->dst);
tcg_out_movext1_new_src(s, i3, i3->dst);
} else {
tcg_debug_assert(scratch >= 0);
tcg_out_mov(s, i1->src_type, scratch, src1);
tcg_out_movext1(s, i3);
tcg_out_movext1(s, i2);
tcg_out_movext1_new_src(s, i1, scratch);
}
} else if (i1->dst == src3 && i2->dst == src1 && i3->dst == src2) {
/* "Anti-clockwise" */
if (tcg_out_xchg(s, MAX(i2->src_type, i3->src_type), src2, src3)) {
tcg_out_xchg(s, MAX(i1->src_type, i2->src_type), src1, src2);
/* The data is now in the correct registers, now extend. */
tcg_out_movext1_new_src(s, i1, i1->dst);
tcg_out_movext1_new_src(s, i2, i2->dst);
tcg_out_movext1_new_src(s, i3, i3->dst);
} else {
tcg_debug_assert(scratch >= 0);
tcg_out_mov(s, i1->src_type, scratch, src1);
tcg_out_movext1(s, i2);
tcg_out_movext1(s, i3);
tcg_out_movext1_new_src(s, i1, scratch);
}
} else {
g_assert_not_reached();
}
}
#define C_PFX1(P, A) P##A
#define C_PFX2(P, A, B) P##A##_##B
#define C_PFX3(P, A, B, C) P##A##_##B##_##C
@ -5153,46 +5229,48 @@ static int tcg_out_helper_stk_ofs(TCGType type, unsigned slot)
static void tcg_out_helper_load_regs(TCGContext *s,
unsigned nmov, TCGMovExtend *mov,
unsigned ntmp, const int *tmp)
const TCGLdstHelperParam *parm)
{
TCGReg dst3;
switch (nmov) {
default:
case 4:
/* The backend must have provided enough temps for the worst case. */
tcg_debug_assert(ntmp + 1 >= nmov);
tcg_debug_assert(parm->ntmp >= 2);
for (unsigned i = nmov - 1; i >= 2; --i) {
TCGReg dst = mov[i].dst;
dst3 = mov[3].dst;
for (unsigned j = 0; j < 3; ++j) {
if (dst3 == mov[j].src) {
/*
* Conflict. Copy the source to a temporary, perform the
* remaining moves, then the extension from our scratch
* on the way out.
*/
TCGReg scratch = parm->tmp[1];
for (unsigned j = 0; j < i; ++j) {
if (dst == mov[j].src) {
/*
* Conflict.
* Copy the source to a temporary, recurse for the
* remaining moves, perform the extension from our
* scratch on the way out.
*/
TCGReg scratch = tmp[--ntmp];
tcg_out_mov(s, mov[i].src_type, scratch, mov[i].src);
mov[i].src = scratch;
tcg_out_helper_load_regs(s, i, mov, ntmp, tmp);
tcg_out_movext1(s, &mov[i]);
return;
}
tcg_out_mov(s, mov[3].src_type, scratch, mov[3].src);
tcg_out_movext3(s, mov, mov + 1, mov + 2, parm->tmp[0]);
tcg_out_movext1_new_src(s, &mov[3], scratch);
break;
}
/* No conflicts: perform this move and continue. */
tcg_out_movext1(s, &mov[i]);
}
/* fall through for the final two moves */
/* No conflicts: perform this move and continue. */
tcg_out_movext1(s, &mov[3]);
/* fall through */
case 3:
tcg_out_movext3(s, mov, mov + 1, mov + 2,
parm->ntmp ? parm->tmp[0] : -1);
break;
case 2:
tcg_out_movext2(s, mov, mov + 1, ntmp ? tmp[0] : -1);
return;
tcg_out_movext2(s, mov, mov + 1,
parm->ntmp ? parm->tmp[0] : -1);
break;
case 1:
tcg_out_movext1(s, mov);
return;
case 0:
break;
default:
g_assert_not_reached();
}
}
@ -5239,7 +5317,7 @@ static void tcg_out_helper_load_slots(TCGContext *s,
for (i = 0; i < nmov; ++i) {
mov[i].dst = tcg_target_call_iarg_regs[mov[i].dst];
}
tcg_out_helper_load_regs(s, nmov, mov, parm->ntmp, parm->tmp);
tcg_out_helper_load_regs(s, nmov, mov, parm);
}
static void tcg_out_helper_load_imm(TCGContext *s, unsigned slot,