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tcg/aarch64: Fix tcg_out_movi

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There were some patterns, like 0x0000_ffff_ffff_00ff, for which we
would select to begin a multi-insn sequence with MOVN, but would
fail to set the 0x0000 lane back from 0xffff.

Backports commit 50b468d42107a2c646b1c566ed17d9ec362c51c4 from qemu
This commit is contained in:
Richard Henderson 2018-03-01 09:15:31 -05:00 committed by Lioncash
parent a03666f2f2
commit 6820964e2f
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GPG key ID: 4E3C3CC1031BA9C7
1 changed files with 24 additions and 33 deletions
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57
qemu/tcg/aarch64/tcg-target.inc.c
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@ -585,11 +585,9 @@ static void tcg_out_logicali(TCGContext *s, AArch64Insn insn, TCGType ext,
static void tcg_out_movi(TCGContext *s, TCGType type, TCGReg rd,
tcg_target_long value)
{
AArch64Insn insn;
int i, wantinv, shift;
tcg_target_long svalue = value;
tcg_target_long ivalue = ~value;
tcg_target_long imask;
/* For 32-bit values, discard potential garbage in value. For 64-bit
values within [2**31, 2**32-1], we can create smaller sequences by
@ -635,42 +633,35 @@ static void tcg_out_movi(TCGContext *s, TCGType type, TCGReg rd,
/* Would it take fewer insns to begin with MOVN? For the value and its
inverse, count the number of 16-bit lanes that are 0. */
for (i = wantinv = imask = 0; i < 64; i += 16) {
for (i = wantinv = 0; i < 64; i += 16) {
tcg_target_long mask = 0xffffull << i;
if ((value & mask) == 0) {
wantinv -= 1;
}
if ((ivalue & mask) == 0) {
wantinv += 1;
imask |= mask;
}
wantinv -= ((value & mask) == 0);
wantinv += ((ivalue & mask) == 0);
}
/* If we had more 0xffff than 0x0000, invert VALUE and use MOVN. */
insn = I3405_MOVZ;
if (wantinv > 0) {
value = ivalue;
insn = I3405_MOVN;
}
/* Find the lowest lane that is not 0x0000. */
shift = ctz64(value) & (63 & -16);
tcg_out_insn_3405(s, insn, type, rd, value >> shift, shift);
if (wantinv > 0) {
/* Re-invert the value, so MOVK sees non-inverted bits. */
value = ~value;
/* Clear out all the 0xffff lanes. */
value ^= imask;
}
/* Clear out the lane that we just set. */
value &= ~(0xffffUL << shift);
/* Iterate until all lanes have been set, and thus cleared from VALUE. */
while (value) {
if (wantinv <= 0) {
/* Find the lowest lane that is not 0x0000. */
shift = ctz64(value) & (63 & -16);
tcg_out_insn(s, 3405, MOVK, type, rd, value >> shift, shift);
tcg_out_insn(s, 3405, MOVZ, type, rd, value >> shift, shift);
/* Clear out the lane that we just set. */
value &= ~(0xffffUL << shift);
/* Iterate until all non-zero lanes have been processed. */
while (value) {
shift = ctz64(value) & (63 & -16);
tcg_out_insn(s, 3405, MOVK, type, rd, value >> shift, shift);
value &= ~(0xffffUL << shift);
}
} else {
/* Like above, but with the inverted value and MOVN to start. */
shift = ctz64(ivalue) & (63 & -16);
tcg_out_insn(s, 3405, MOVN, type, rd, ivalue >> shift, shift);
ivalue &= ~(0xffffUL << shift);
while (ivalue) {
shift = ctz64(ivalue) & (63 & -16);
/* Provide MOVK with the non-inverted value. */
tcg_out_insn(s, 3405, MOVK, type, rd, ~(ivalue >> shift), shift);
ivalue &= ~(0xffffUL << shift);
}
}
}