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tcg/loongarch64: Optimize immediate loading 

diff:
  Imm                 Before                  After
  0000000000000000    addi.w  rd, zero, 0     addi.w  rd, zero, 0
                      lu52i.d rd, zero, 0
  00000000fffff800    lu12i.w rd, -1          addi.w  rd, zero, -2048
                      ori     rd, rd, 2048    lu32i.d rd, 0
                      lu32i.d rd, 0

Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Rui Wang <wangrui@loongson.cn>
Message-Id: <20221107144713.845550-1-wangrui@loongson.cn>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Rui Wang 2022-11-07 22:47:13 +08:00 committed by Richard Henderson
parent 69c9a5cfbe
commit 3fe7e36b44
1 changed files with 12 additions and 23 deletions
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35
tcg/loongarch64/tcg-target.c.inc
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@ -274,16 +274,6 @@ static bool tcg_out_mov(TCGContext *s, TCGType type, TCGReg ret, TCGReg arg)
return true;
}
static bool imm_part_needs_loading(bool high_bits_are_ones,
tcg_target_long part)
{
if (high_bits_are_ones) {
return part != -1;
} else {
return part != 0;
}
}
/* Loads a 32-bit immediate into rd, sign-extended. */
static void tcg_out_movi_i32(TCGContext *s, TCGReg rd, int32_t val)
{
@ -291,16 +281,16 @@ static void tcg_out_movi_i32(TCGContext *s, TCGReg rd, int32_t val)
tcg_target_long hi12 = sextreg(val, 12, 20);
/* Single-instruction cases. */
if (lo == val) {
/* val fits in simm12: addi.w rd, zero, val */
tcg_out_opc_addi_w(s, rd, TCG_REG_ZERO, val);
return;
}
if (0x800 <= val && val <= 0xfff) {
if (hi12 == 0) {
/* val fits in uimm12: ori rd, zero, val */
tcg_out_opc_ori(s, rd, TCG_REG_ZERO, val);
return;
}
if (hi12 == sextreg(lo, 12, 20)) {
/* val fits in simm12: addi.w rd, zero, val */
tcg_out_opc_addi_w(s, rd, TCG_REG_ZERO, val);
return;
}
/* High bits must be set; load with lu12i.w + optional ori. */
tcg_out_opc_lu12i_w(s, rd, hi12);
@ -334,8 +324,7 @@ static void tcg_out_movi(TCGContext *s, TCGType type, TCGReg rd,
intptr_t pc_offset;
tcg_target_long val_lo, val_hi, pc_hi, offset_hi;
tcg_target_long hi32, hi52;
bool rd_high_bits_are_ones;
tcg_target_long hi12, hi32, hi52;
/* Value fits in signed i32. */
if (type == TCG_TYPE_I32 || val == (int32_t)val) {
@ -366,25 +355,25 @@ static void tcg_out_movi(TCGContext *s, TCGType type, TCGReg rd,
return;
}
hi12 = sextreg(val, 12, 20);
hi32 = sextreg(val, 32, 20);
hi52 = sextreg(val, 52, 12);
/* Single cu52i.d case. */
if (ctz64(val) >= 52) {
if ((hi52 != 0) && (ctz64(val) >= 52)) {
tcg_out_opc_cu52i_d(s, rd, TCG_REG_ZERO, hi52);
return;
}
/* Slow path. Initialize the low 32 bits, then concat high bits. */
tcg_out_movi_i32(s, rd, val);
rd_high_bits_are_ones = (int32_t)val < 0;
if (imm_part_needs_loading(rd_high_bits_are_ones, hi32)) {
/* Load hi32 and hi52 explicitly when they are unexpected values. */
if (hi32 != sextreg(hi12, 20, 20)) {
tcg_out_opc_cu32i_d(s, rd, hi32);
rd_high_bits_are_ones = hi32 < 0;
}
if (imm_part_needs_loading(rd_high_bits_are_ones, hi52)) {
if (hi52 != sextreg(hi32, 20, 12)) {
tcg_out_opc_cu52i_d(s, rd, rd, hi52);
}
}