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authorDaniel Shahaf <d.s@daniel.shahaf.name>2016-07-30 10:14:35 +0000
committerDaniel Shahaf <d.s@daniel.shahaf.name>2016-08-01 08:01:28 +0000
commit1a368bf31f2b2e6e96290a4803bdcd81e9f17393 (patch)
tree2a9678d0f590d02cb63a701d72887664e065c872 /Src/subst.c
parentfaa163cd5fe9c578e3ed35bd5b10e56b7b357ba7 (diff)
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38973: Optimize indexing array parameters.
% () { for 1 in $prefix/zsh/bin/zsh Src/zsh; do $1 -f -c 'a=( {1..1000000} ); repeat 3 time ( repeat 300 : $a[1]  )'; done }
( repeat 300; do; : $a[1]; done; )  1.68s user 0.01s system 98% cpu 1.718 total
( repeat 300; do; : $a[1]; done; )  1.69s user 0.01s system 99% cpu 1.710 total
( repeat 300; do; : $a[1]; done; )  1.69s user 0.01s system 99% cpu 1.714 total

( repeat 300; do; : $a[1]; done; )  0.00s user 0.01s system 72% cpu 0.022 total
( repeat 300; do; : $a[1]; done; )  0.00s user 0.01s system 72% cpu 0.022 total
( repeat 300; do; : $a[1]; done; )  0.01s user 0.01s system 69% cpu 0.023 total
Diffstat (limited to 'Src/subst.c')
-rw-r--r--Src/subst.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/Src/subst.c b/Src/subst.c
index 8e704b1c1..e3af15694 100644
--- a/Src/subst.c
+++ b/Src/subst.c
@@ -2548,12 +2548,19 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int pf_flags,
 		 * necessary joining of arrays until this point
 		 * to avoid the multsub() horror.
 		 */
-		int tmplen = arrlen(v->pm->gsu.a->getfn(v->pm));
 
-		if (v->start < 0)
+		/* arrlen() is expensive, so only compute it if needed. */
+		int tmplen = -1;
+
+		if (v->start < 0) {
+		    tmplen = arrlen(v->pm->gsu.a->getfn(v->pm));
 		    v->start += tmplen + ((v->flags & VALFLAG_INV) ? 1 : 0);
-		if (!(v->flags & VALFLAG_INV) &&
-		    (v->start >= tmplen || v->start < 0))
+		}
+		if (!(v->flags & VALFLAG_INV))
+		    if (v->start < 0 ||
+			(tmplen != -1
+			 ? v->start >= tmplen
+			 : arrlen_le(v->pm->gsu.a->getfn(v->pm), v->start)))
 		    vunset = 1;
 	    }
 	    if (!vunset) {