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cmd/compile: move slice construction to callers of makeslice

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Only return a pointer p to the new slices backing array from makeslice.
Makeslice callers then construct sliceheader{p, len, cap} explictly
instead of makeslice returning the slice.

Reduces go binary size by ~0.2%.
Removes 92 (~3.5%) panicindex calls from go binary.

Change-Id: I29b7c3b5fe8b9dcec96e2c43730575071cfe8a94
Reviewed-on: https://go-review.googlesource.com/c/141822
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This commit is contained in:
Martin Möhrmann 2018-10-14 22:28:58 +02:00 • committed by Martin Möhrmann
parent c86d464734
commit 020a18c545
9 changed files with 136 additions and 76 deletions
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7
src/runtime/slice.go
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@ -31,7 +31,7 @@ func panicmakeslicecap() {
panic(errorString("makeslice: cap out of range"))
}
func makeslice(et *_type, len, cap int) slice {
func makeslice(et *_type, len, cap int) unsafe.Pointer {
mem, overflow := math.MulUintptr(et.size, uintptr(cap))
if overflow || mem > maxAlloc || len < 0 || len > cap {
// NOTE: Produce a 'len out of range' error instead of a
@ -45,12 +45,11 @@ func makeslice(et *_type, len, cap int) slice {
}
panicmakeslicecap()
}
p := mallocgc(mem, et, true)
return slice{p, len, cap}
return mallocgc(mem, et, true)
}
func makeslice64(et *_type, len64, cap64 int64) slice {
func makeslice64(et *_type, len64, cap64 int64) unsafe.Pointer {
len := int(len64)
if int64(len) != len64 {
panicmakeslicelen()