[libc-commits] [libc] [libc] Speed up memmove overlapping check (PR #70017)
Dmitry Vyukov via libc-commits
libc-commits at lists.llvm.org
Tue Oct 24 06:02:59 PDT 2023
https://github.com/dvyukov updated https://github.com/llvm/llvm-project/pull/70017
>From 81d8231c88878ecfa685eb4085ff2d2993764425 Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov at google.com>
Date: Tue, 24 Oct 2023 10:52:00 +0200
Subject: [PATCH] [libc] Speed up memmove overlapping check
MIME-Version: 1.0
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Use a check that requries fewer instructions and cheaper.
Current code:
1b704: 48 39 f7 cmp %rsi,%rdi
1b707: 48 89 f0 mov %rsi,%rax
1b70a: 48 0f 47 c7 cmova %rdi,%rax
1b70e: 48 89 f9 mov %rdi,%rcx
1b711: 48 0f 47 ce cmova %rsi,%rcx
1b715: 48 01 d1 add %rdx,%rcx
1b718: 48 39 c1 cmp %rax,%rcx
New code:
1b704: 48 89 f8 mov %rdi,%rax
1b707: 48 29 f0 sub %rsi,%rax
1b70a: 48 89 c1 mov %rax,%rcx
1b70d: 48 f7 d9 neg %rcx
1b710: 48 0f 48 c8 cmovs %rax,%rcx
1b714: 48 39 d1 cmp %rdx,%rcx
│ baseline │ disjoint │
│ sec/op │ sec/op vs base │
memmove/Google_A 3.910n ± 0% 3.861n ± 1% -1.26% (p=0.000 n=50)
│ baseline │ disjoint │
│ sec/op │ sec/op vs base │
memmove/1 2.724n ± 3% 2.441n ± 0% -10.37% (n=50)
memmove/2 2.878n ± 0% 2.713n ± 0% -5.73% (n=50)
memmove/3 2.835n ± 0% 2.593n ± 0% -8.54% (n=50)
memmove/4 3.032n ± 0% 2.776n ± 0% -8.45% (p=0.000 n=50)
memmove/5 2.833n ± 0% 2.600n ± 0% -8.20% (p=0.000 n=50)
memmove/6 2.758n ± 0% 2.744n ± 0% -0.52% (p=0.000 n=50)
memmove/7 2.762n ± 0% 2.744n ± 0% -0.63% (p=0.000 n=50)
memmove/8 2.763n ± 0% 2.750n ± 0% -0.46% (p=0.000 n=50)
memmove/9 3.182n ± 0% 3.269n ± 0% +2.75% (p=0.000 n=50)
memmove/10 3.185n ± 0% 3.270n ± 0% +2.64% (p=0.000 n=50)
memmove/11 3.188n ± 0% 3.277n ± 0% +2.79% (p=0.000 n=50)
memmove/12 3.190n ± 0% 3.279n ± 0% +2.82% (p=0.000 n=50)
memmove/13 3.194n ± 0% 3.281n ± 0% +2.73% (p=0.000 n=50)
memmove/14 3.197n ± 0% 3.285n ± 0% +2.77% (p=0.000 n=50)
memmove/15 3.198n ± 0% 3.282n ± 0% +2.62% (p=0.000 n=50)
memmove/16 3.201n ± 0% 3.284n ± 0% +2.61% (p=0.000 n=50)
memmove/17 3.564n ± 0% 3.320n ± 0% -6.86% (p=0.000 n=50)
memmove/18 3.572n ± 0% 3.313n ± 0% -7.25% (p=0.000 n=50)
memmove/19 3.572n ± 0% 3.325n ± 0% -6.94% (p=0.000 n=50)
memmove/20 3.575n ± 0% 3.319n ± 0% -7.15% (p=0.000 n=50)
memmove/21 3.578n ± 0% 3.327n ± 0% -7.03% (p=0.000 n=50)
memmove/22 3.581n ± 0% 3.330n ± 0% -7.01% (p=0.000 n=50)
memmove/23 3.582n ± 0% 3.354n ± 1% -6.37% (p=0.000 n=50)
memmove/24 3.587n ± 0% 3.347n ± 1% -6.71% (p=0.000 n=50)
memmove/25 3.591n ± 0% 3.320n ± 0% -7.55% (p=0.000 n=50)
memmove/26 3.593n ± 0% 3.348n ± 0% -6.82% (p=0.000 n=50)
memmove/27 3.596n ± 0% 3.346n ± 0% -6.94% (p=0.000 n=50)
memmove/28 3.597n ± 0% 3.357n ± 0% -6.67% (p=0.000 n=50)
memmove/29 3.601n ± 0% 3.340n ± 0% -7.23% (p=0.000 n=50)
memmove/30 3.602n ± 0% 3.345n ± 0% -7.12% (p=0.000 n=50)
memmove/31 3.608n ± 0% 3.357n ± 0% -6.94% (p=0.000 n=50)
memmove/32 3.605n ± 0% 3.352n ± 0% -7.01% (p=0.000 n=50)
memmove/33 4.128n ± 1% 3.829n ± 0% -7.23% (p=0.000 n=50)
memmove/34 4.149n ± 0% 3.836n ± 0% -7.54% (p=0.000 n=50)
memmove/35 4.134n ± 0% 3.839n ± 0% -7.15% (n=50)
memmove/36 4.151n ± 0% 3.842n ± 0% -7.45% (n=50)
memmove/37 4.152n ± 0% 3.841n ± 0% -7.49% (p=0.000 n=50)
memmove/38 4.159n ± 0% 3.844n ± 0% -7.58% (p=0.000 n=50)
memmove/39 4.165n ± 0% 3.841n ± 0% -7.78% (p=0.000 n=50)
memmove/40 4.162n ± 0% 3.837n ± 0% -7.81% (p=0.000 n=50)
memmove/41 4.161n ± 0% 3.845n ± 0% -7.58% (p=0.000 n=50)
memmove/42 4.164n ± 0% 3.851n ± 0% -7.53% (p=0.000 n=50)
memmove/43 4.165n ± 0% 3.843n ± 0% -7.74% (p=0.000 n=50)
memmove/44 4.175n ± 0% 3.847n ± 0% -7.83% (p=0.000 n=50)
memmove/45 4.170n ± 0% 3.849n ± 0% -7.70% (p=0.000 n=50)
memmove/46 4.175n ± 0% 3.850n ± 0% -7.79% (p=0.000 n=50)
memmove/47 4.180n ± 0% 3.851n ± 0% -7.87% (p=0.000 n=50)
memmove/48 4.178n ± 0% 3.852n ± 0% -7.81% (p=0.000 n=50)
memmove/49 4.175n ± 0% 3.851n ± 0% -7.76% (n=50)
memmove/50 4.178n ± 0% 3.855n ± 0% -7.73% (p=0.000 n=50)
memmove/51 4.190n ± 0% 3.859n ± 0% -7.91% (p=0.000 n=50)
memmove/52 4.188n ± 0% 3.859n ± 0% -7.84% (p=0.000 n=50)
memmove/53 4.191n ± 0% 3.863n ± 0% -7.82% (p=0.000 n=50)
memmove/54 4.192n ± 0% 3.860n ± 0% -7.91% (p=0.000 n=50)
memmove/55 4.192n ± 0% 3.869n ± 0% -7.70% (p=0.000 n=50)
memmove/56 4.204n ± 0% 3.866n ± 0% -8.05% (p=0.000 n=50)
memmove/57 4.198n ± 0% 3.864n ± 0% -7.95% (p=0.000 n=50)
memmove/58 4.202n ± 0% 3.865n ± 0% -8.02% (p=0.000 n=50)
memmove/59 4.208n ± 0% 3.868n ± 0% -8.09% (p=0.000 n=50)
memmove/60 4.205n ± 0% 3.873n ± 0% -7.89% (p=0.000 n=50)
memmove/61 4.212n ± 0% 3.872n ± 0% -8.08% (p=0.000 n=50)
memmove/62 4.214n ± 0% 3.870n ± 0% -8.16% (p=0.000 n=50)
memmove/63 4.215n ± 0% 3.877n ± 0% -8.02% (p=0.000 n=50)
memmove/64 4.217n ± 0% 3.881n ± 0% -7.99% (p=0.000 n=50)
memmove/65 4.990n ± 0% 4.683n ± 0% -6.15% (p=0.000 n=50)
memmove/66 5.022n ± 0% 4.719n ± 0% -6.03% (p=0.000 n=50)
memmove/67 5.030n ± 0% 4.725n ± 0% -6.07% (p=0.000 n=50)
memmove/68 5.035n ± 0% 4.724n ± 0% -6.18% (p=0.000 n=50)
memmove/69 5.030n ± 0% 4.725n ± 0% -6.07% (p=0.000 n=50)
memmove/70 5.040n ± 0% 4.728n ± 0% -6.19% (p=0.000 n=50)
memmove/71 5.053n ± 0% 4.728n ± 0% -6.43% (p=0.000 n=50)
memmove/72 5.050n ± 0% 4.732n ± 0% -6.29% (p=0.000 n=50)
memmove/73 5.049n ± 0% 4.733n ± 0% -6.24% (p=0.000 n=50)
memmove/74 5.054n ± 0% 4.734n ± 0% -6.34% (p=0.000 n=50)
memmove/75 5.063n ± 0% 4.736n ± 0% -6.46% (p=0.000 n=50)
memmove/76 5.046n ± 0% 4.741n ± 0% -6.04% (p=0.000 n=50)
memmove/77 5.057n ± 0% 4.741n ± 0% -6.25% (p=0.000 n=50)
memmove/78 5.077n ± 0% 4.739n ± 0% -6.65% (p=0.000 n=50)
memmove/79 5.074n ± 0% 4.746n ± 0% -6.46% (p=0.000 n=50)
memmove/80 5.085n ± 0% 4.747n ± 0% -6.65% (p=0.000 n=50)
memmove/81 5.077n ± 0% 4.735n ± 0% -6.74% (p=0.000 n=50)
memmove/82 5.087n ± 0% 4.747n ± 0% -6.68% (p=0.000 n=50)
memmove/83 5.087n ± 0% 4.754n ± 0% -6.56% (p=0.000 n=50)
memmove/84 5.096n ± 0% 4.753n ± 0% -6.73% (p=0.000 n=50)
memmove/85 5.082n ± 0% 4.749n ± 0% -6.55% (p=0.000 n=50)
memmove/86 5.103n ± 0% 4.752n ± 0% -6.87% (p=0.000 n=50)
memmove/87 5.096n ± 0% 4.760n ± 0% -6.61% (p=0.000 n=50)
memmove/88 5.099n ± 0% 4.765n ± 0% -6.55% (p=0.000 n=50)
memmove/89 5.104n ± 0% 4.757n ± 0% -6.79% (p=0.000 n=50)
memmove/90 5.117n ± 0% 4.767n ± 0% -6.84% (p=0.000 n=50)
memmove/91 5.100n ± 0% 4.766n ± 0% -6.54% (p=0.000 n=50)
memmove/92 5.103n ± 0% 4.763n ± 0% -6.67% (p=0.000 n=50)
memmove/93 5.115n ± 0% 4.772n ± 0% -6.71% (p=0.000 n=50)
memmove/94 5.117n ± 0% 4.769n ± 0% -6.80% (p=0.000 n=50)
memmove/95 5.131n ± 0% 4.775n ± 0% -6.94% (p=0.000 n=50)
memmove/96 5.129n ± 0% 4.772n ± 0% -6.97% (p=0.000 n=50)
memmove/97 5.130n ± 0% 4.764n ± 0% -7.13% (p=0.000 n=50)
memmove/98 5.134n ± 0% 4.780n ± 0% -6.89% (p=0.000 n=50)
memmove/99 5.141n ± 0% 4.780n ± 0% -7.03% (p=0.000 n=50)
memmove/100 5.141n ± 0% 4.780n ± 0% -7.02% (p=0.000 n=50)
memmove/101 5.150n ± 0% 4.782n ± 0% -7.14% (p=0.000 n=50)
memmove/102 5.150n ± 0% 4.790n ± 0% -6.99% (p=0.000 n=50)
memmove/103 5.156n ± 0% 4.788n ± 0% -7.14% (n=50)
memmove/104 5.157n ± 0% 4.793n ± 0% -7.05% (p=0.000 n=50)
memmove/105 5.147n ± 0% 4.791n ± 0% -6.90% (p=0.000 n=50)
memmove/106 5.167n ± 0% 4.793n ± 0% -7.23% (p=0.000 n=50)
memmove/107 5.165n ± 0% 4.801n ± 0% -7.06% (p=0.000 n=50)
memmove/108 5.173n ± 0% 4.800n ± 0% -7.21% (p=0.000 n=50)
memmove/109 5.173n ± 0% 4.797n ± 0% -7.27% (p=0.000 n=50)
memmove/110 5.171n ± 0% 4.808n ± 0% -7.01% (p=0.000 n=50)
memmove/111 5.180n ± 0% 4.799n ± 0% -7.36% (p=0.000 n=50)
memmove/112 5.185n ± 0% 4.812n ± 0% -7.19% (p=0.000 n=50)
memmove/113 5.187n ± 0% 4.797n ± 0% -7.53% (p=0.000 n=50)
memmove/114 5.183n ± 0% 4.809n ± 0% -7.21% (n=50)
memmove/115 5.193n ± 0% 4.811n ± 0% -7.36% (p=0.000 n=50)
memmove/116 5.196n ± 0% 4.815n ± 0% -7.32% (p=0.000 n=50)
memmove/117 5.199n ± 0% 4.816n ± 0% -7.37% (p=0.000 n=50)
memmove/118 5.198n ± 0% 4.811n ± 0% -7.45% (p=0.000 n=50)
memmove/119 5.203n ± 0% 4.818n ± 0% -7.40% (p=0.000 n=50)
memmove/120 5.195n ± 0% 4.823n ± 0% -7.16% (p=0.000 n=50)
memmove/121 5.203n ± 0% 4.812n ± 0% -7.51% (p=0.000 n=50)
memmove/122 5.204n ± 0% 4.818n ± 0% -7.42% (n=50)
memmove/123 5.202n ± 0% 4.822n ± 0% -7.31% (p=0.000 n=50)
memmove/124 5.216n ± 0% 4.823n ± 0% -7.54% (p=0.000 n=50)
memmove/125 5.227n ± 0% 4.823n ± 0% -7.72% (p=0.000 n=50)
memmove/126 5.235n ± 0% 4.830n ± 0% -7.74% (p=0.000 n=50)
memmove/127 5.237n ± 0% 4.833n ± 0% -7.72% (p=0.000 n=50)
memmove/128 5.241n ± 0% 4.832n ± 0% -7.81% (p=0.000 n=50)
memmove/129 6.460n ± 0% 5.858n ± 0% -9.31% (p=0.000 n=50)
memmove/130 7.539n ± 0% 6.634n ± 0% -12.00% (p=0.000 n=50)
memmove/131 7.542n ± 0% 6.623n ± 0% -12.18% (p=0.000 n=50)
memmove/132 7.527n ± 0% 6.667n ± 1% -11.43% (p=0.000 n=50)
memmove/133 7.521n ± 0% 6.631n ± 0% -11.83% (p=0.000 n=50)
memmove/134 7.531n ± 0% 6.642n ± 0% -11.81% (p=0.000 n=50)
memmove/135 7.541n ± 0% 6.692n ± 1% -11.25% (p=0.000 n=50)
memmove/136 7.549n ± 0% 6.657n ± 0% -11.81% (p=0.000 n=50)
memmove/137 7.544n ± 0% 6.646n ± 0% -11.90% (p=0.000 n=50)
memmove/138 7.557n ± 0% 6.673n ± 1% -11.70% (p=0.000 n=50)
memmove/139 7.545n ± 0% 6.654n ± 0% -11.81% (n=50)
memmove/140 7.559n ± 0% 6.680n ± 1% -11.63% (p=0.000 n=50)
memmove/141 7.560n ± 0% 6.664n ± 0% -11.85% (p=0.000 n=50)
memmove/142 7.556n ± 0% 6.679n ± 0% -11.62% (p=0.000 n=50)
memmove/143 7.570n ± 0% 6.683n ± 1% -11.71% (p=0.000 n=50)
memmove/144 7.586n ± 0% 6.683n ± 0% -11.91% (p=0.000 n=50)
memmove/145 7.593n ± 0% 6.665n ± 0% -12.22% (p=0.000 n=50)
memmove/146 7.591n ± 0% 6.665n ± 0% -12.20% (p=0.000 n=50)
memmove/147 7.598n ± 0% 6.665n ± 0% -12.27% (p=0.000 n=50)
memmove/148 7.598n ± 0% 6.670n ± 0% -12.21% (p=0.000 n=50)
memmove/149 7.593n ± 0% 6.691n ± 0% -11.88% (p=0.000 n=50)
memmove/150 7.625n ± 0% 6.713n ± 1% -11.97% (p=0.000 n=50)
memmove/151 7.603n ± 0% 6.710n ± 1% -11.74% (p=0.000 n=50)
memmove/152 7.613n ± 0% 6.701n ± 1% -11.97% (p=0.000 n=50)
memmove/153 7.595n ± 0% 6.710n ± 0% -11.65% (p=0.000 n=50)
memmove/154 7.614n ± 0% 6.721n ± 0% -11.74% (p=0.000 n=50)
memmove/155 7.615n ± 0% 6.709n ± 0% -11.89% (p=0.000 n=50)
memmove/156 7.613n ± 0% 6.693n ± 0% -12.08% (p=0.000 n=50)
memmove/157 7.628n ± 0% 6.708n ± 0% -12.05% (p=0.000 n=50)
memmove/158 7.629n ± 0% 6.706n ± 0% -12.10% (p=0.000 n=50)
memmove/159 7.639n ± 0% 6.724n ± 0% -11.98% (p=0.000 n=50)
memmove/160 7.619n ± 0% 6.702n ± 0% -12.04% (p=0.000 n=50)
memmove/161 7.653n ± 0% 6.698n ± 0% -12.49% (p=0.000 n=50)
memmove/162 8.104n ± 0% 7.140n ± 1% -11.89% (p=0.000 n=50)
memmove/163 8.141n ± 0% 7.187n ± 1% -11.72% (p=0.000 n=50)
memmove/164 8.154n ± 0% 7.107n ± 0% -12.84% (p=0.000 n=50)
memmove/165 8.143n ± 0% 7.117n ± 0% -12.59% (p=0.000 n=50)
memmove/166 8.176n ± 0% 7.110n ± 0% -13.04% (p=0.000 n=50)
memmove/167 8.194n ± 0% 7.168n ± 1% -12.52% (p=0.000 n=50)
memmove/168 8.214n ± 0% 7.188n ± 1% -12.50% (p=0.000 n=50)
memmove/169 8.220n ± 0% 7.242n ± 1% -11.90% (p=0.000 n=50)
memmove/170 8.228n ± 0% 7.244n ± 1% -11.96% (p=0.000 n=50)
memmove/171 8.263n ± 0% 7.184n ± 0% -13.06% (p=0.000 n=50)
memmove/172 8.259n ± 0% 7.325n ± 1% -11.31% (p=0.000 n=50)
memmove/173 8.271n ± 0% 7.225n ± 0% -12.65% (p=0.000 n=50)
memmove/174 8.284n ± 0% 7.287n ± 1% -12.04% (p=0.000 n=50)
memmove/175 8.289n ± 0% 7.282n ± 1% -12.15% (p=0.000 n=50)
memmove/176 8.309n ± 0% 7.328n ± 1% -11.81% (p=0.000 n=50)
memmove/177 8.317n ± 0% 7.264n ± 1% -12.67% (p=0.000 n=50)
memmove/178 8.302n ± 0% 7.342n ± 1% -11.57% (p=0.000 n=50)
memmove/179 8.309n ± 0% 7.357n ± 1% -11.45% (p=0.000 n=50)
memmove/180 8.304n ± 0% 7.318n ± 1% -11.87% (p=0.000 n=50)
memmove/181 8.312n ± 0% 7.363n ± 1% -11.42% (p=0.000 n=50)
memmove/182 8.315n ± 0% 7.320n ± 1% -11.96% (p=0.000 n=50)
memmove/183 8.330n ± 0% 7.286n ± 1% -12.53% (p=0.000 n=50)
memmove/184 8.310n ± 0% 7.324n ± 1% -11.86% (p=0.000 n=50)
memmove/185 8.303n ± 0% 7.267n ± 1% -12.47% (p=0.000 n=50)
memmove/186 8.287n ± 0% 7.312n ± 1% -11.76% (p=0.000 n=50)
memmove/187 8.298n ± 0% 7.395n ± 2% -10.88% (p=0.000 n=50)
memmove/188 8.296n ± 0% 7.339n ± 1% -11.54% (p=0.000 n=50)
memmove/189 8.306n ± 0% 7.299n ± 1% -12.12% (p=0.000 n=50)
memmove/190 8.281n ± 0% 7.309n ± 1% -11.74% (p=0.000 n=50)
memmove/191 8.299n ± 0% 7.282n ± 1% -12.26% (p=0.000 n=50)
memmove/192 8.281n ± 0% 7.335n ± 1% -11.41% (p=0.000 n=50)
memmove/193 8.299n ± 0% 7.325n ± 1% -11.74% (p=0.000 n=50)
memmove/194 8.641n ± 0% 8.034n ± 0% -7.02% (p=0.000 n=50)
memmove/195 8.667n ± 0% 8.073n ± 0% -6.85% (p=0.000 n=50)
memmove/196 8.666n ± 0% 8.030n ± 0% -7.34% (p=0.000 n=50)
memmove/197 8.660n ± 0% 8.096n ± 1% -6.51% (p=0.000 n=50)
memmove/198 8.688n ± 0% 8.047n ± 0% -7.39% (p=0.000 n=50)
memmove/199 8.678n ± 0% 8.061n ± 0% -7.11% (p=0.000 n=50)
memmove/200 8.669n ± 0% 8.034n ± 0% -7.32% (p=0.000 n=50)
memmove/201 8.692n ± 0% 8.061n ± 0% -7.26% (p=0.000 n=50)
memmove/202 8.668n ± 0% 8.060n ± 0% -7.02% (p=0.000 n=50)
memmove/203 8.687n ± 0% 8.066n ± 0% -7.15% (p=0.000 n=50)
memmove/204 8.699n ± 0% 8.076n ± 0% -7.16% (p=0.000 n=50)
memmove/205 8.676n ± 0% 8.085n ± 0% -6.82% (p=0.000 n=50)
memmove/206 8.684n ± 0% 8.101n ± 1% -6.71% (p=0.000 n=50)
memmove/207 8.725n ± 0% 8.099n ± 0% -7.18% (p=0.000 n=50)
memmove/208 8.674n ± 0% 8.073n ± 0% -6.92% (p=0.000 n=50)
memmove/209 8.697n ± 0% 8.088n ± 0% -7.01% (p=0.000 n=50)
memmove/210 8.733n ± 0% 8.076n ± 0% -7.53% (p=0.000 n=50)
memmove/211 8.732n ± 0% 8.104n ± 0% -7.19% (p=0.000 n=50)
memmove/212 8.730n ± 0% 8.091n ± 0% -7.32% (p=0.000 n=50)
memmove/213 8.728n ± 0% 8.100n ± 0% -7.19% (p=0.000 n=50)
memmove/214 8.744n ± 1% 8.081n ± 1% -7.57% (p=0.000 n=50)
memmove/215 8.734n ± 0% 8.150n ± 0% -6.68% (p=0.000 n=50)
memmove/216 8.748n ± 0% 8.116n ± 0% -7.23% (p=0.000 n=50)
memmove/217 8.751n ± 0% 8.129n ± 1% -7.11% (p=0.000 n=50)
memmove/218 8.747n ± 0% 8.114n ± 0% -7.23% (p=0.000 n=50)
memmove/219 8.733n ± 0% 8.159n ± 0% -6.57% (p=0.000 n=50)
memmove/220 8.764n ± 0% 8.145n ± 0% -7.06% (p=0.000 n=50)
memmove/221 8.764n ± 0% 8.142n ± 0% -7.10% (p=0.000 n=50)
memmove/222 8.775n ± 0% 8.152n ± 0% -7.10% (p=0.000 n=50)
memmove/223 8.771n ± 0% 8.143n ± 0% -7.16% (p=0.000 n=50)
memmove/224 8.778n ± 0% 8.175n ± 1% -6.87% (p=0.000 n=50)
memmove/225 8.794n ± 0% 8.138n ± 0% -7.45% (p=0.000 n=50)
memmove/226 10.13n ± 0% 10.06n ± 0% -0.71% (p=0.000 n=50)
memmove/227 10.14n ± 0% 10.08n ± 0% -0.53% (p=0.000 n=50)
memmove/228 10.13n ± 0% 10.08n ± 0% -0.56% (p=0.000 n=50)
memmove/229 10.17n ± 0% 10.11n ± 0% -0.56% (p=0.000 n=50)
memmove/230 10.17n ± 0% 10.13n ± 0% -0.38% (p=0.003 n=50)
memmove/231 10.16n ± 0% 10.12n ± 0% -0.41% (p=0.001 n=50)
memmove/232 10.19n ± 0% 10.12n ± 0% -0.67% (p=0.000 n=50)
memmove/233 10.21n ± 0% 10.14n ± 0% -0.71% (p=0.000 n=50)
memmove/234 10.24n ± 0% 10.16n ± 0% -0.79% (p=0.000 n=50)
memmove/235 10.24n ± 0% 10.16n ± 0% -0.76% (p=0.000 n=50)
memmove/236 10.25n ± 0% 10.16n ± 0% -0.81% (p=0.000 n=50)
memmove/237 10.24n ± 0% 10.17n ± 0% -0.69% (p=0.000 n=50)
memmove/238 10.27n ± 0% 10.19n ± 0% -0.79% (p=0.000 n=50)
memmove/239 10.29n ± 0% 10.19n ± 0% -0.90% (p=0.000 n=50)
memmove/240 10.30n ± 0% 10.20n ± 0% -0.95% (p=0.000 n=50)
memmove/241 10.29n ± 0% 10.20n ± 0% -0.91% (p=0.000 n=50)
memmove/242 10.30n ± 0% 10.22n ± 0% -0.80% (p=0.000 n=50)
memmove/243 10.32n ± 0% 10.23n ± 0% -0.87% (p=0.000 n=50)
memmove/244 10.32n ± 0% 10.24n ± 0% -0.74% (p=0.000 n=50)
memmove/245 10.33n ± 0% 10.23n ± 0% -0.97% (p=0.000 n=50)
memmove/246 10.33n ± 0% 10.24n ± 0% -0.92% (p=0.000 n=50)
memmove/247 10.31n ± 0% 10.24n ± 0% -0.69% (p=0.000 n=50)
memmove/248 10.32n ± 0% 10.26n ± 0% -0.55% (p=0.000 n=50)
memmove/249 10.33n ± 0% 10.28n ± 0% -0.52% (p=0.000 n=50)
memmove/250 10.34n ± 0% 10.27n ± 0% -0.66% (p=0.000 n=50)
memmove/251 10.32n ± 0% 10.27n ± 0% -0.45% (p=0.000 n=50)
memmove/252 10.34n ± 0% 10.30n ± 0% -0.39% (p=0.005 n=50)
memmove/253 10.33n ± 0% 10.27n ± 0% -0.57% (p=0.000 n=50)
memmove/254 10.33n ± 0% 10.27n ± 0% -0.54% (p=0.000 n=50)
memmove/255 10.34n ± 0% 10.29n ± 0% -0.50% (p=0.002 n=50)
memmove/256 10.36n ± 0% 10.31n ± 0% -0.44% (p=0.006 n=50)
memmove/257 10.33n ± 0% 10.29n ± 0% -0.36% (p=0.004 n=50)
geomean 6.142n 5.696n -7.26%
---
libc/src/string/memory_utils/utils.h | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/libc/src/string/memory_utils/utils.h b/libc/src/string/memory_utils/utils.h
index c467ae712b638a2..bd87169c051b750 100644
--- a/libc/src/string/memory_utils/utils.h
+++ b/libc/src/string/memory_utils/utils.h
@@ -89,16 +89,13 @@ template <size_t alignment, typename T> LIBC_INLINE T *assume_aligned(T *ptr) {
// Returns true iff memory regions [p1, p1 + size] and [p2, p2 + size] are
// disjoint.
LIBC_INLINE bool is_disjoint(const void *p1, const void *p2, size_t size) {
- const char *a = static_cast<const char *>(p1);
- const char *b = static_cast<const char *>(p2);
- if (a > b) {
- // Swap a and b, this compiles down to conditionnal move for aarch64, x86
- // and RISCV with zbb extension.
- const char *tmp = a;
- a = b;
- b = tmp;
- }
- return a + size <= b;
+ const ptrdiff_t sdiff =
+ static_cast<const char *>(p1) - static_cast<const char *>(p2);
+ const size_t udiff = cpp::bit_cast<size_t>(sdiff);
+ // Integer promition would be caught here.
+ const size_t neg_udiff = cpp::bit_cast<size_t>(-sdiff);
+ // This is expected to compile a conditional move.
+ return sdiff >= 0 ? size <= udiff : size <= neg_udiff;
}
#if LIBC_HAS_BUILTIN(__builtin_memcpy_inline)
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