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[libc] memmove optimizations (#70043)
1. Remove is_disjoint check for smaller sizes and reduce code bloat. inline_memmove may handle some small sizes as efficiently as inline_memcpy. For these sizes we may not do is_disjoint check. This both avoids additional code for the most frequent smaller sizes and removes code bloat (we don't need the memcpy logic for small sizes). Here we heavily rely on inlining and dead code elimination: from the first inline_memmove we should get only handling of small sizes, and from the second inline_memmove and inline_memcpy we should get only handling of larger sizes. 2. Use the memcpy thresholds for memmove. Memcpy thresholds were more carefully tuned. This becomes more important since we use memmove for all small sizes always now. 3. Fix boundary conditions for sizes = 16/32/64. See the added comment for explanations. Memmove function size drops from 885 to 715 bytes due to removed duplication. ``` │ baseline │ small-size │ │ sec/op │ sec/op vs base │ memmove/Google_A 3.208n ± 0% 2.911n ± 0% -9.25% (n=100) memmove/Google_B 4.113n ± 1% 3.428n ± 0% -16.65% (n=100) memmove/Google_D 5.838n ± 0% 4.158n ± 0% -28.78% (n=100) memmove/Google_S 4.712n ± 1% 3.899n ± 0% -17.25% (n=100) memmove/Google_U 3.609n ± 0% 3.247n ± 1% -10.02% (n=100) memmove/0 2.982n ± 0% 2.169n ± 0% -27.26% (n=50) memmove/1 3.253n ± 0% 2.168n ± 0% -33.34% (n=50) memmove/2 3.255n ± 0% 2.169n ± 0% -33.38% (n=50) memmove/3 3.259n ± 2% 2.175n ± 0% -33.27% (p=0.000 n=50) memmove/4 3.259n ± 0% 2.168n ± 5% -33.46% (p=0.000 n=50) memmove/5 2.488n ± 0% 1.926n ± 0% -22.57% (p=0.000 n=50) memmove/6 2.490n ± 0% 1.928n ± 0% -22.59% (p=0.000 n=50) memmove/7 2.492n ± 0% 1.927n ± 0% -22.65% (p=0.000 n=50) memmove/8 2.737n ± 0% 2.711n ± 0% -0.97% (p=0.000 n=50) memmove/9 2.736n ± 0% 2.711n ± 0% -0.94% (p=0.000 n=50) memmove/10 2.739n ± 0% 2.711n ± 0% -1.04% (p=0.000 n=50) memmove/11 2.740n ± 0% 2.711n ± 0% -1.07% (p=0.000 n=50) memmove/12 2.740n ± 0% 2.711n ± 0% -1.09% (p=0.000 n=50) memmove/13 2.744n ± 0% 2.711n ± 0% -1.22% (p=0.000 n=50) memmove/14 2.742n ± 0% 2.711n ± 0% -1.14% (p=0.000 n=50) memmove/15 2.742n ± 0% 2.711n ± 0% -1.15% (p=0.000 n=50) memmove/16 2.997n ± 0% 2.981n ± 0% -0.52% (p=0.000 n=50) memmove/17 2.998n ± 0% 2.981n ± 0% -0.55% (p=0.000 n=50) memmove/18 2.998n ± 0% 2.981n ± 0% -0.55% (p=0.000 n=50) memmove/19 2.999n ± 0% 2.982n ± 0% -0.59% (p=0.000 n=50) memmove/20 2.998n ± 0% 2.981n ± 0% -0.55% (p=0.000 n=50) memmove/21 3.000n ± 0% 2.981n ± 0% -0.61% (p=0.000 n=50) memmove/22 3.002n ± 0% 2.981n ± 0% -0.68% (p=0.000 n=50) memmove/23 3.002n ± 0% 2.981n ± 0% -0.67% (p=0.000 n=50) memmove/24 3.002n ± 0% 2.981n ± 0% -0.70% (n=50) memmove/25 3.002n ± 0% 2.981n ± 0% -0.68% (p=0.000 n=50) memmove/26 3.004n ± 0% 2.982n ± 0% -0.74% (p=0.000 n=50) memmove/27 3.005n ± 0% 2.981n ± 0% -0.79% (n=50) memmove/28 3.005n ± 0% 2.982n ± 0% -0.77% (n=50) memmove/29 3.009n ± 0% 2.981n ± 0% -0.92% (n=50) memmove/30 3.008n ± 0% 2.981n ± 0% -0.89% (n=50) memmove/31 3.007n ± 0% 2.982n ± 0% -0.86% (n=50) memmove/32 3.540n ± 0% 2.998n ± 0% -15.31% (p=0.000 n=50) memmove/33 3.544n ± 0% 2.997n ± 0% -15.44% (p=0.000 n=50) memmove/34 3.546n ± 0% 2.999n ± 0% -15.42% (n=50) memmove/35 3.545n ± 0% 2.999n ± 0% -15.40% (n=50) memmove/36 3.548n ± 0% 2.998n ± 0% -15.52% (p=0.000 n=50) memmove/37 3.546n ± 0% 3.000n ± 0% -15.41% (n=50) memmove/38 3.549n ± 0% 2.999n ± 0% -15.49% (p=0.000 n=50) memmove/39 3.549n ± 0% 2.999n ± 0% -15.48% (p=0.000 n=50) memmove/40 3.549n ± 0% 3.000n ± 0% -15.46% (p=0.000 n=50) memmove/41 3.550n ± 0% 3.001n ± 0% -15.47% (n=50) memmove/42 3.549n ± 0% 3.001n ± 0% -15.43% (n=50) memmove/43 3.552n ± 0% 3.001n ± 0% -15.52% (p=0.000 n=50) memmove/44 3.552n ± 0% 3.001n ± 0% -15.51% (n=50) memmove/45 3.552n ± 0% 3.002n ± 0% -15.48% (n=50) memmove/46 3.554n ± 0% 3.001n ± 0% -15.55% (p=0.000 n=50) memmove/47 3.556n ± 0% 3.002n ± 0% -15.58% (p=0.000 n=50) memmove/48 3.555n ± 0% 3.003n ± 0% -15.54% (n=50) memmove/49 3.557n ± 0% 3.002n ± 0% -15.59% (p=0.000 n=50) memmove/50 3.557n ± 0% 3.004n ± 0% -15.55% (p=0.000 n=50) memmove/51 3.556n ± 0% 3.004n ± 0% -15.53% (p=0.000 n=50) memmove/52 3.561n ± 0% 3.004n ± 0% -15.65% (p=0.000 n=50) memmove/53 3.558n ± 0% 3.004n ± 0% -15.57% (p=0.000 n=50) memmove/54 3.561n ± 0% 3.005n ± 0% -15.62% (n=50) memmove/55 3.560n ± 0% 3.006n ± 0% -15.57% (n=50) memmove/56 3.562n ± 0% 3.006n ± 0% -15.60% (p=0.000 n=50) memmove/57 3.563n ± 0% 3.006n ± 0% -15.64% (n=50) memmove/58 3.565n ± 0% 3.007n ± 0% -15.64% (p=0.000 n=50) memmove/59 3.564n ± 0% 3.006n ± 0% -15.66% (p=0.000 n=50) memmove/60 3.570n ± 0% 3.008n ± 0% -15.74% (p=0.000 n=50) memmove/61 3.566n ± 0% 3.009n ± 0% -15.63% (p=0.000 n=50) memmove/62 3.567n ± 0% 3.007n ± 0% -15.70% (p=0.000 n=50) memmove/63 3.568n ± 0% 3.008n ± 0% -15.71% (p=0.000 n=50) memmove/64 4.104n ± 0% 3.008n ± 0% -26.70% (p=0.000 n=50) memmove/65 4.126n ± 0% 3.662n ± 0% -11.26% (p=0.000 n=50) memmove/66 4.128n ± 0% 3.662n ± 0% -11.29% (n=50) memmove/67 4.129n ± 0% 3.662n ± 0% -11.31% (n=50) memmove/68 4.129n ± 0% 3.661n ± 0% -11.33% (p=0.000 n=50) memmove/69 4.130n ± 0% 3.662n ± 0% -11.34% (p=0.000 n=50) memmove/70 4.130n ± 0% 3.662n ± 0% -11.33% (n=50) memmove/71 4.132n ± 0% 3.662n ± 0% -11.38% (p=0.000 n=50) memmove/72 4.131n ± 0% 3.661n ± 0% -11.39% (n=50) memmove/73 4.135n ± 0% 3.661n ± 0% -11.45% (p=0.000 n=50) memmove/74 4.137n ± 0% 3.662n ± 0% -11.49% (n=50) memmove/75 4.138n ± 0% 3.662n ± 0% -11.51% (p=0.000 n=50) memmove/76 4.139n ± 0% 3.661n ± 0% -11.56% (p=0.000 n=50) memmove/77 4.136n ± 0% 3.662n ± 0% -11.47% (p=0.000 n=50) memmove/78 4.143n ± 0% 3.661n ± 0% -11.62% (p=0.000 n=50) memmove/79 4.142n ± 0% 3.661n ± 0% -11.60% (n=50) memmove/80 4.142n ± 0% 3.661n ± 0% -11.62% (p=0.000 n=50) memmove/81 4.140n ± 0% 3.661n ± 0% -11.57% (n=50) memmove/82 4.146n ± 0% 3.661n ± 0% -11.69% (n=50) memmove/83 4.143n ± 0% 3.661n ± 0% -11.63% (p=0.000 n=50) memmove/84 4.143n ± 0% 3.661n ± 0% -11.63% (n=50) memmove/85 4.147n ± 0% 3.661n ± 0% -11.73% (p=0.000 n=50) memmove/86 4.142n ± 0% 3.661n ± 0% -11.62% (p=0.000 n=50) memmove/87 4.147n ± 0% 3.661n ± 0% -11.72% (p=0.000 n=50) memmove/88 4.148n ± 0% 3.661n ± 0% -11.74% (n=50) memmove/89 4.152n ± 0% 3.661n ± 0% -11.84% (n=50) memmove/90 4.151n ± 0% 3.661n ± 0% -11.81% (n=50) memmove/91 4.150n ± 0% 3.661n ± 0% -11.78% (n=50) memmove/92 4.153n ± 0% 3.661n ± 0% -11.86% (n=50) memmove/93 4.158n ± 0% 3.661n ± 0% -11.95% (n=50) memmove/94 4.157n ± 0% 3.661n ± 0% -11.95% (p=0.000 n=50) memmove/95 4.155n ± 0% 3.661n ± 0% -11.90% (p=0.000 n=50) memmove/96 4.149n ± 0% 3.660n ± 0% -11.79% (n=50) memmove/97 4.157n ± 0% 3.661n ± 0% -11.94% (n=50) memmove/98 4.157n ± 0% 3.661n ± 0% -11.94% (n=50) memmove/99 4.168n ± 0% 3.661n ± 0% -12.17% (p=0.000 n=50) memmove/100 4.159n ± 0% 3.660n ± 0% -12.00% (p=0.000 n=50) memmove/101 4.161n ± 0% 3.660n ± 0% -12.03% (p=0.000 n=50) memmove/102 4.165n ± 0% 3.660n ± 0% -12.12% (p=0.000 n=50) memmove/103 4.164n ± 0% 3.661n ± 0% -12.08% (n=50) memmove/104 4.164n ± 0% 3.660n ± 0% -12.11% (n=50) memmove/105 4.165n ± 0% 3.660n ± 0% -12.12% (p=0.000 n=50) memmove/106 4.166n ± 0% 3.660n ± 0% -12.15% (n=50) memmove/107 4.171n ± 0% 3.660n ± 1% -12.26% (p=0.000 n=50) memmove/108 4.173n ± 0% 3.660n ± 0% -12.30% (p=0.000 n=50) memmove/109 4.170n ± 0% 3.660n ± 0% -12.24% (n=50) memmove/110 4.174n ± 0% 3.660n ± 0% -12.31% (n=50) memmove/111 4.176n ± 0% 3.660n ± 0% -12.35% (p=0.000 n=50) memmove/112 4.174n ± 0% 3.659n ± 0% -12.34% (p=0.000 n=50) memmove/113 4.176n ± 0% 3.660n ± 0% -12.35% (n=50) memmove/114 4.182n ± 0% 3.660n ± 0% -12.49% (n=50) memmove/115 4.185n ± 0% 3.660n ± 0% -12.55% (n=50) memmove/116 4.184n ± 0% 3.659n ± 0% -12.54% (n=50) memmove/117 4.182n ± 0% 3.660n ± 0% -12.50% (n=50) memmove/118 4.188n ± 0% 3.660n ± 0% -12.61% (n=50) memmove/119 4.186n ± 0% 3.660n ± 0% -12.57% (p=0.000 n=50) memmove/120 4.189n ± 0% 3.659n ± 0% -12.63% (n=50) memmove/121 4.187n ± 0% 3.660n ± 0% -12.60% (n=50) memmove/122 4.186n ± 0% 3.660n ± 0% -12.58% (n=50) memmove/123 4.187n ± 0% 3.660n ± 0% -12.60% (n=50) memmove/124 4.189n ± 0% 3.659n ± 0% -12.65% (n=50) memmove/125 4.195n ± 0% 3.659n ± 0% -12.78% (n=50) memmove/126 4.197n ± 0% 3.659n ± 0% -12.81% (n=50) memmove/127 4.194n ± 0% 3.659n ± 0% -12.75% (n=50) memmove/128 5.035n ± 0% 3.659n ± 0% -27.32% (n=50) memmove/129 5.127n ± 0% 5.164n ± 0% +0.73% (p=0.000 n=50) memmove/130 5.130n ± 0% 5.176n ± 0% +0.88% (p=0.000 n=50) memmove/131 5.127n ± 0% 5.180n ± 0% +1.05% (p=0.000 n=50) memmove/132 5.131n ± 0% 5.169n ± 0% +0.75% (p=0.000 n=50) memmove/133 5.137n ± 0% 5.179n ± 0% +0.81% (p=0.000 n=50) memmove/134 5.140n ± 0% 5.178n ± 0% +0.74% (p=0.000 n=50) memmove/135 5.141n ± 0% 5.187n ± 0% +0.88% (p=0.000 n=50) memmove/136 5.133n ± 0% 5.184n ± 0% +0.99% (p=0.000 n=50) memmove/137 5.148n ± 0% 5.186n ± 0% +0.73% (p=0.000 n=50) memmove/138 5.143n ± 0% 5.189n ± 0% +0.88% (p=0.000 n=50) memmove/139 5.142n ± 0% 5.192n ± 0% +0.97% (p=0.000 n=50) memmove/140 5.141n ± 0% 5.192n ± 0% +1.01% (p=0.000 n=50) memmove/141 5.155n ± 0% 5.188n ± 0% +0.64% (p=0.000 n=50) memmove/142 5.146n ± 0% 5.192n ± 0% +0.90% (p=0.000 n=50) memmove/143 5.142n ± 0% 5.203n ± 0% +1.19% (p=0.000 n=50) memmove/144 5.146n ± 0% 5.197n ± 0% +0.99% (p=0.000 n=50) memmove/145 5.146n ± 0% 5.196n ± 0% +0.97% (p=0.000 n=50) memmove/146 5.151n ± 0% 5.207n ± 0% +1.10% (p=0.000 n=50) memmove/147 5.151n ± 0% 5.205n ± 0% +1.06% (p=0.000 n=50) memmove/148 5.156n ± 0% 5.190n ± 0% +0.66% (p=0.000 n=50) memmove/149 5.158n ± 0% 5.212n ± 0% +1.04% (p=0.000 n=50) memmove/150 5.160n ± 0% 5.203n ± 0% +0.84% (p=0.000 n=50) memmove/151 5.167n ± 0% 5.210n ± 0% +0.83% (p=0.000 n=50) memmove/152 5.157n ± 0% 5.206n ± 0% +0.94% (p=0.000 n=50) memmove/153 5.170n ± 0% 5.211n ± 0% +0.80% (p=0.000 n=50) memmove/154 5.169n ± 0% 5.222n ± 0% +1.02% (p=0.000 n=50) memmove/155 5.171n ± 0% 5.215n ± 0% +0.87% (p=0.000 n=50) memmove/156 5.174n ± 0% 5.214n ± 0% +0.78% (p=0.000 n=50) memmove/157 5.171n ± 0% 5.218n ± 0% +0.92% (p=0.000 n=50) memmove/158 5.168n ± 0% 5.224n ± 0% +1.09% (p=0.000 n=50) memmove/159 5.179n ± 0% 5.218n ± 0% +0.76% (p=0.000 n=50) memmove/160 5.170n ± 0% 5.219n ± 0% +0.95% (p=0.000 n=50) memmove/161 5.187n ± 0% 5.220n ± 0% +0.64% (p=0.000 n=50) memmove/162 5.189n ± 0% 5.234n ± 0% +0.86% (p=0.000 n=50) memmove/163 5.199n ± 0% 5.250n ± 0% +0.99% (p=0.000 n=50) memmove/164 5.205n ± 0% 5.260n ± 0% +1.04% (p=0.000 n=50) memmove/165 5.208n ± 0% 5.261n ± 0% +1.01% (p=0.000 n=50) memmove/166 5.227n ± 0% 5.275n ± 0% +0.91% (p=0.000 n=50) memmove/167 5.233n ± 0% 5.281n ± 0% +0.92% (p=0.000 n=50) memmove/168 5.236n ± 0% 5.295n ± 0% +1.12% (p=0.000 n=50) memmove/169 5.256n ± 0% 5.297n ± 0% +0.79% (p=0.000 n=50) memmove/170 5.259n ± 0% 5.302n ± 0% +0.80% (p=0.000 n=50) memmove/171 5.269n ± 0% 5.321n ± 0% +0.97% (p=0.000 n=50) memmove/172 5.266n ± 0% 5.318n ± 0% +0.98% (p=0.000 n=50) memmove/173 5.272n ± 0% 5.330n ± 0% +1.09% (p=0.000 n=50) memmove/174 5.284n ± 0% 5.331n ± 0% +0.89% (p=0.000 n=50) memmove/175 5.284n ± 0% 5.322n ± 0% +0.72% (p=0.000 n=50) memmove/176 5.298n ± 0% 5.337n ± 0% +0.74% (p=0.000 n=50) memmove/177 5.282n ± 0% 5.338n ± 0% +1.04% (p=0.000 n=50) memmove/178 5.299n ± 0% 5.337n ± 0% +0.71% (p=0.000 n=50) memmove/179 5.296n ± 0% 5.343n ± 0% +0.88% (p=0.000 n=50) memmove/180 5.292n ± 0% 5.343n ± 0% +0.97% (p=0.000 n=50) memmove/181 5.303n ± 0% 5.335n ± 0% +0.60% (p=0.000 n=50) memmove/182 5.305n ± 0% 5.338n ± 0% +0.62% (p=0.000 n=50) memmove/183 5.298n ± 0% 5.329n ± 0% +0.59% (p=0.000 n=50) memmove/184 5.299n ± 0% 5.333n ± 0% +0.64% (p=0.000 n=50) memmove/185 5.291n ± 0% 5.330n ± 0% +0.73% (p=0.000 n=50) memmove/186 5.296n ± 0% 5.332n ± 0% +0.68% (p=0.000 n=50) memmove/187 5.297n ± 0% 5.320n ± 0% +0.44% (p=0.000 n=50) memmove/188 5.286n ± 0% 5.314n ± 0% +0.53% (p=0.000 n=50) memmove/189 5.293n ± 0% 5.318n ± 0% +0.46% (p=0.000 n=50) memmove/190 5.294n ± 0% 5.318n ± 0% +0.45% (p=0.000 n=50) memmove/191 5.292n ± 0% 5.314n ± 0% +0.40% (p=0.032 n=50) memmove/192 5.272n ± 0% 5.304n ± 0% +0.60% (p=0.000 n=50) memmove/193 5.279n ± 0% 5.310n ± 0% +0.57% (p=0.000 n=50) memmove/194 5.294n ± 0% 5.308n ± 0% +0.26% (p=0.018 n=50) memmove/195 5.302n ± 0% 5.311n ± 0% +0.18% (p=0.010 n=50) memmove/196 5.301n ± 0% 5.316n ± 0% +0.28% (p=0.023 n=50) memmove/197 5.302n ± 0% 5.327n ± 0% +0.47% (p=0.000 n=50) memmove/198 5.310n ± 0% 5.326n ± 0% +0.30% (p=0.003 n=50) memmove/199 5.303n ± 0% 5.319n ± 0% +0.30% (p=0.009 n=50) memmove/200 5.312n ± 0% 5.330n ± 0% +0.35% (p=0.001 n=50) memmove/201 5.307n ± 0% 5.333n ± 0% +0.50% (p=0.000 n=50) memmove/202 5.311n ± 0% 5.334n ± 0% +0.44% (p=0.000 n=50) memmove/203 5.313n ± 0% 5.335n ± 0% +0.41% (p=0.006 n=50) memmove/204 5.312n ± 0% 5.332n ± 0% +0.36% (p=0.002 n=50) memmove/205 5.318n ± 0% 5.345n ± 0% +0.50% (p=0.000 n=50) memmove/206 5.311n ± 0% 5.333n ± 0% +0.42% (p=0.002 n=50) memmove/207 5.310n ± 0% 5.338n ± 0% +0.52% (p=0.000 n=50) memmove/208 5.319n ± 0% 5.341n ± 0% +0.40% (p=0.004 n=50) memmove/209 5.330n ± 0% 5.346n ± 0% +0.30% (p=0.004 n=50) memmove/210 5.329n ± 0% 5.349n ± 0% +0.38% (p=0.002 n=50) memmove/211 5.318n ± 0% 5.340n ± 0% +0.41% (p=0.000 n=50) memmove/212 5.339n ± 0% 5.343n ± 0% ~ (p=0.396 n=50) memmove/213 5.329n ± 0% 5.343n ± 0% +0.25% (p=0.017 n=50) memmove/214 5.339n ± 0% 5.358n ± 0% +0.35% (p=0.035 n=50) memmove/215 5.342n ± 0% 5.346n ± 0% ~ (p=0.063 n=50) memmove/216 5.338n ± 0% 5.359n ± 0% +0.39% (p=0.002 n=50) memmove/217 5.341n ± 0% 5.362n ± 0% +0.39% (p=0.015 n=50) memmove/218 5.354n ± 0% 5.373n ± 0% +0.36% (p=0.041 n=50) memmove/219 5.352n ± 0% 5.362n ± 0% ~ (p=0.143 n=50) memmove/220 5.344n ± 0% 5.370n ± 0% +0.50% (p=0.001 n=50) memmove/221 5.345n ± 0% 5.373n ± 0% +0.53% (p=0.000 n=50) memmove/222 5.348n ± 0% 5.360n ± 0% +0.23% (p=0.014 n=50) memmove/223 5.354n ± 0% 5.377n ± 0% +0.43% (p=0.024 n=50) memmove/224 5.352n ± 0% 5.363n ± 0% ~ (p=0.052 n=50) memmove/225 5.372n ± 0% 5.380n ± 0% ~ (p=0.481 n=50) memmove/226 5.368n ± 0% 5.386n ± 0% +0.34% (p=0.004 n=50) memmove/227 5.386n ± 0% 5.402n ± 0% +0.29% (p=0.028 n=50) memmove/228 5.400n ± 0% 5.408n ± 0% ~ (p=0.174 n=50) memmove/229 5.423n ± 0% 5.427n ± 0% ~ (p=0.444 n=50) memmove/230 5.411n ± 0% 5.429n ± 0% +0.33% (p=0.020 n=50) memmove/231 5.420n ± 0% 5.433n ± 0% +0.24% (p=0.034 n=50) memmove/232 5.435n ± 0% 5.441n ± 0% ~ (p=0.235 n=50) memmove/233 5.446n ± 0% 5.462n ± 0% ~ (p=0.590 n=50) memmove/234 5.467n ± 0% 5.461n ± 0% ~ (p=0.921 n=50) memmove/235 5.472n ± 0% 5.478n ± 0% ~ (p=0.883 n=50) memmove/236 5.466n ± 0% 5.478n ± 0% ~ (p=0.324 n=50) memmove/237 5.471n ± 0% 5.489n ± 0% ~ (p=0.132 n=50) memmove/238 5.485n ± 0% 5.489n ± 0% ~ (p=0.460 n=50) memmove/239 5.484n ± 0% 5.488n ± 0% ~ (p=0.833 n=50) memmove/240 5.483n ± 0% 5.495n ± 0% ~ (p=0.095 n=50) memmove/241 5.498n ± 0% 5.514n ± 0% ~ (p=0.077 n=50) memmove/242 5.518n ± 0% 5.517n ± 0% ~ (p=0.481 n=50) memmove/243 5.514n ± 0% 5.511n ± 0% ~ (p=0.503 n=50) memmove/244 5.510n ± 0% 5.497n ± 0% -0.24% (p=0.038 n=50) memmove/245 5.516n ± 0% 5.505n ± 0% ~ (p=0.317 n=50) memmove/246 5.513n ± 1% 5.494n ± 0% ~ (p=0.147 n=50) memmove/247 5.518n ± 0% 5.499n ± 0% -0.36% (p=0.011 n=50) memmove/248 5.503n ± 0% 5.492n ± 0% ~ (p=0.267 n=50) memmove/249 5.498n ± 0% 5.497n ± 0% ~ (p=0.765 n=50) memmove/250 5.485n ± 0% 5.493n ± 0% ~ (p=0.348 n=50) memmove/251 5.503n ± 0% 5.482n ± 0% -0.37% (p=0.013 n=50) memmove/252 5.497n ± 0% 5.485n ± 0% ~ (p=0.077 n=50) memmove/253 5.489n ± 0% 5.496n ± 0% ~ (p=0.850 n=50) memmove/254 5.497n ± 0% 5.491n ± 0% ~ (p=0.548 n=50) memmove/255 5.484n ± 1% 5.494n ± 0% ~ (p=0.888 n=50) memmove/256 6.952n ± 0% 7.676n ± 0% +10.41% (p=0.000 n=50) geomean 4.406n 4.127n -6.33% ```
1 parent 16fbc45 commit 0e110fb

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3 files changed

+114
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lines changed

libc/src/string/memmove.cpp

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -15,10 +15,16 @@ namespace LIBC_NAMESPACE {
1515

1616
LLVM_LIBC_FUNCTION(void *, memmove,
1717
(void *dst, const void *src, size_t count)) {
18+
// Memmove may handle some small sizes as efficiently as inline_memcpy.
19+
// For these sizes we may not do is_disjoint check.
20+
// This both avoids additional code for the most frequent smaller sizes
21+
// and removes code bloat (we don't need the memcpy logic for small sizes).
22+
if (inline_memmove_small_size(dst, src, count))
23+
return dst;
1824
if (is_disjoint(dst, src, count))
1925
inline_memcpy(dst, src, count);
2026
else
21-
inline_memmove(dst, src, count);
27+
inline_memmove_follow_up(dst, src, count);
2228
return dst;
2329
}
2430

libc/src/string/memory_utils/inline_memmove.h

Lines changed: 37 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -13,28 +13,58 @@
1313

1414
#if defined(LIBC_TARGET_ARCH_IS_X86)
1515
#include "src/string/memory_utils/x86_64/inline_memmove.h"
16-
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE inline_memmove_x86
16+
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_SMALL_SIZE \
17+
inline_memmove_small_size_x86
18+
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_FOLLOW_UP \
19+
inline_memmove_follow_up_x86
1720
#elif defined(LIBC_TARGET_ARCH_IS_AARCH64)
1821
#include "src/string/memory_utils/aarch64/inline_memmove.h"
19-
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE inline_memmove_aarch64
22+
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_SMALL_SIZE \
23+
inline_memmove_no_small_size
24+
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_FOLLOW_UP inline_memmove_aarch64
2025
#elif defined(LIBC_TARGET_ARCH_IS_ANY_RISCV)
2126
#include "src/string/memory_utils/riscv/inline_memmove.h"
22-
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE inline_memmove_riscv
27+
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_SMALL_SIZE \
28+
inline_memmove_no_small_size
29+
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_FOLLOW_UP inline_memmove_riscv
2330
#elif defined(LIBC_TARGET_ARCH_IS_ARM)
2431
#include "src/string/memory_utils/generic/byte_per_byte.h"
25-
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE inline_memmove_byte_per_byte
32+
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_SMALL_SIZE \
33+
inline_memmove_no_small_size
34+
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_FOLLOW_UP \
35+
inline_memmove_byte_per_byte
2636
#elif defined(LIBC_TARGET_ARCH_IS_GPU)
2737
#include "src/string/memory_utils/generic/builtin.h"
28-
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE inline_memmove_builtin
38+
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_SMALL_SIZE \
39+
inline_memmove_no_small_size
40+
#define LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_FOLLOW_UP inline_memmove_builtin
2941
#else
3042
#error "Unsupported architecture"
3143
#endif
3244

3345
namespace LIBC_NAMESPACE {
3446

47+
LIBC_INLINE constexpr bool inline_memmove_no_small_size(void *, const void *,
48+
size_t) {
49+
return false;
50+
}
51+
52+
LIBC_INLINE bool inline_memmove_small_size(void *dst, const void *src,
53+
size_t count) {
54+
return LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_SMALL_SIZE(
55+
reinterpret_cast<Ptr>(dst), reinterpret_cast<CPtr>(src), count);
56+
}
57+
58+
LIBC_INLINE void inline_memmove_follow_up(void *dst, const void *src,
59+
size_t count) {
60+
LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_FOLLOW_UP(
61+
reinterpret_cast<Ptr>(dst), reinterpret_cast<CPtr>(src), count);
62+
}
63+
3564
LIBC_INLINE void inline_memmove(void *dst, const void *src, size_t count) {
36-
LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE(reinterpret_cast<Ptr>(dst),
37-
reinterpret_cast<CPtr>(src), count);
65+
if (inline_memmove_small_size(dst, src, count))
66+
return;
67+
inline_memmove_follow_up(dst, src, count);
3868
}
3969

4070
} // namespace LIBC_NAMESPACE

libc/src/string/memory_utils/x86_64/inline_memmove.h

Lines changed: 70 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -18,40 +18,94 @@
1818

1919
namespace LIBC_NAMESPACE {
2020

21-
LIBC_INLINE void inline_memmove_x86(Ptr dst, CPtr src, size_t count) {
21+
LIBC_INLINE bool inline_memmove_small_size_x86(Ptr dst, CPtr src,
22+
size_t count) {
2223
#if defined(__AVX512F__)
24+
constexpr size_t vector_size = 64;
2325
using uint128_t = generic_v128;
2426
using uint256_t = generic_v256;
2527
using uint512_t = generic_v512;
2628
#elif defined(__AVX__)
29+
constexpr size_t vector_size = 32;
2730
using uint128_t = generic_v128;
2831
using uint256_t = generic_v256;
2932
using uint512_t = cpp::array<generic_v256, 2>;
3033
#elif defined(__SSE2__)
34+
constexpr size_t vector_size = 16;
3135
using uint128_t = generic_v128;
3236
using uint256_t = cpp::array<generic_v128, 2>;
3337
using uint512_t = cpp::array<generic_v128, 4>;
3438
#else
39+
constexpr size_t vector_size = 8;
3540
using uint128_t = cpp::array<uint64_t, 2>;
3641
using uint256_t = cpp::array<uint64_t, 4>;
3742
using uint512_t = cpp::array<uint64_t, 8>;
3843
#endif
44+
(void)vector_size;
3945
if (count == 0)
40-
return;
41-
if (count == 1)
42-
return generic::Memmove<uint8_t>::block(dst, src);
43-
if (count <= 4)
44-
return generic::Memmove<uint16_t>::head_tail(dst, src, count);
45-
if (count <= 8)
46-
return generic::Memmove<uint32_t>::head_tail(dst, src, count);
47-
if (count <= 16)
48-
return generic::Memmove<uint64_t>::head_tail(dst, src, count);
49-
if (count <= 32)
50-
return generic::Memmove<uint128_t>::head_tail(dst, src, count);
51-
if (count <= 64)
52-
return generic::Memmove<uint256_t>::head_tail(dst, src, count);
53-
if (count <= 128)
54-
return generic::Memmove<uint512_t>::head_tail(dst, src, count);
46+
return true;
47+
if (count == 1) {
48+
generic::Memmove<uint8_t>::block(dst, src);
49+
return true;
50+
}
51+
if (count == 2) {
52+
generic::Memmove<uint16_t>::block(dst, src);
53+
return true;
54+
}
55+
if (count == 3) {
56+
generic::Memmove<cpp::array<uint8_t, 3>>::block(dst, src);
57+
return true;
58+
}
59+
if (count == 4) {
60+
generic::Memmove<uint32_t>::block(dst, src);
61+
return true;
62+
}
63+
if (count < 8) {
64+
generic::Memmove<uint32_t>::head_tail(dst, src, count);
65+
return true;
66+
}
67+
// If count is equal to a power of 2, we can handle it as head-tail
68+
// of both smaller size and larger size (head-tail are either
69+
// non-overlapping for smaller size, or completely collapsed
70+
// for larger size). It seems to be more profitable to do the copy
71+
// with the larger size, if it's natively supported (e.g. doing
72+
// 2 collapsed 32-byte moves for count=64 if AVX2 is supported).
73+
// But it's not profitable to use larger size if it's not natively
74+
// supported: we will both use more instructions and handle fewer
75+
// sizes in earlier branches.
76+
if (vector_size >= 16 ? count < 16 : count <= 16) {
77+
generic::Memmove<uint64_t>::head_tail(dst, src, count);
78+
return true;
79+
}
80+
if (vector_size >= 32 ? count < 32 : count <= 32) {
81+
generic::Memmove<uint128_t>::head_tail(dst, src, count);
82+
return true;
83+
}
84+
if (vector_size >= 64 ? count < 64 : count <= 64) {
85+
generic::Memmove<uint256_t>::head_tail(dst, src, count);
86+
return true;
87+
}
88+
if (count <= 128) {
89+
generic::Memmove<uint512_t>::head_tail(dst, src, count);
90+
return true;
91+
}
92+
return false;
93+
}
94+
95+
LIBC_INLINE void inline_memmove_follow_up_x86(Ptr dst, CPtr src, size_t count) {
96+
#if defined(__AVX512F__)
97+
using uint256_t = generic_v256;
98+
using uint512_t = generic_v512;
99+
#elif defined(__AVX__)
100+
using uint256_t = generic_v256;
101+
using uint512_t = cpp::array<generic_v256, 2>;
102+
#elif defined(__SSE2__)
103+
using uint256_t = cpp::array<generic_v128, 2>;
104+
using uint512_t = cpp::array<generic_v128, 4>;
105+
#else
106+
using uint256_t = cpp::array<uint64_t, 4>;
107+
using uint512_t = cpp::array<uint64_t, 8>;
108+
#endif
55109
if (dst < src) {
56110
generic::Memmove<uint256_t>::align_forward<Arg::Src>(dst, src, count);
57111
return generic::Memmove<uint512_t>::loop_and_tail_forward(dst, src, count);

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