tcg-aarch64: Use MOVN in tcg_out_movi
When profitable, initialize the register with MOVN instead of MOVZ, before setting the remaining lanes with MOVK. Reviewed-by: Claudio Fontana <claudio.fontana@huawei.com> Signed-off-by: Richard Henderson <rth@twiddle.net>
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@ -531,24 +531,61 @@ static void tcg_out_movi(TCGContext *s, TCGType type, TCGReg rd,
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tcg_target_long value)
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{
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AArch64Insn insn;
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int i, wantinv, shift;
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tcg_target_long svalue = value;
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tcg_target_long ivalue = ~value;
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tcg_target_long imask;
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if (type == TCG_TYPE_I32) {
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/* For 32-bit values, discard potential garbage in value. For 64-bit
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values within [2**31, 2**32-1], we can create smaller sequences by
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interpreting this as a negative 32-bit number, while ensuring that
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the high 32 bits are cleared by setting SF=0. */
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if (type == TCG_TYPE_I32 || (value & ~0xffffffffull) == 0) {
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svalue = (int32_t)value;
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value = (uint32_t)value;
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ivalue = (uint32_t)ivalue;
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type = TCG_TYPE_I32;
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}
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/* count trailing zeros in 16 bit steps, mapping 64 to 0. Emit the
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first MOVZ with the half-word immediate skipping the zeros, with a shift
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(LSL) equal to this number. Then all next instructions use MOVKs.
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Zero the processed half-word in the value, continue until empty.
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We build the final result 16bits at a time with up to 4 instructions,
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but do not emit instructions for 16bit zero holes. */
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/* Would it take fewer insns to begin with MOVN? For the value and its
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inverse, count the number of 16-bit lanes that are 0. */
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for (i = wantinv = imask = 0; i < 64; i += 16) {
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tcg_target_long mask = 0xffffull << i;
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if ((value & mask) == 0) {
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wantinv -= 1;
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}
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if ((ivalue & mask) == 0) {
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wantinv += 1;
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imask |= mask;
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}
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}
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/* If we had more 0xffff than 0x0000, invert VALUE and use MOVN. */
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insn = I3405_MOVZ;
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do {
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unsigned shift = ctz64(value) & (63 & -16);
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tcg_out_insn_3405(s, insn, shift >= 32, rd, value >> shift, shift);
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if (wantinv > 0) {
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value = ivalue;
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insn = I3405_MOVN;
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}
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/* Find the lowest lane that is not 0x0000. */
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shift = ctz64(value) & (63 & -16);
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tcg_out_insn_3405(s, insn, type, rd, value >> shift, shift);
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if (wantinv > 0) {
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/* Re-invert the value, so MOVK sees non-inverted bits. */
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value = ~value;
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/* Clear out all the 0xffff lanes. */
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value ^= imask;
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}
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/* Clear out the lane that we just set. */
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value &= ~(0xffffUL << shift);
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insn = I3405_MOVK;
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} while (value);
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/* Iterate until all lanes have been set, and thus cleared from VALUE. */
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while (value) {
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shift = ctz64(value) & (63 & -16);
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tcg_out_insn(s, 3405, MOVK, type, rd, value >> shift, shift);
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value &= ~(0xffffUL << shift);
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}
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}
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static inline void tcg_out_ldst_r(TCGContext *s,
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