From d3b00a8cc463267b24ade4cf57aafdd02440e19c Mon Sep 17 00:00:00 2001
From: Shahar Kohanim <skohanim@gmail.com>
Date: Mon, 29 Feb 2016 11:49:49 +0200
Subject: [PATCH] cmd/link: batch writing of bytes
In best of 10, linking cmd/go shows a ~10% improvement.
tip: real 0m1.152s user 0m1.005s
this: real 0m1.065s user 0m0.924s
Change-Id: I303a20b94332feaedc1033c453247a0e4c05c843
Reviewed-on: https://go-review.googlesource.com/19978
Reviewed-by: David Crawshaw <crawshaw@golang.org>
---
src/cmd/link/internal/ld/data.go | 48 +++++++++++++++++++-------------
src/cmd/link/internal/ld/lib.go | 4 +++
2 files changed, 32 insertions(+), 20 deletions(-)
diff --git a/src/cmd/link/internal/ld/data.go b/src/cmd/link/internal/ld/data.go
index ca8eabbcca..67af9d5ba8 100644
--- a/src/cmd/link/internal/ld/data.go
+++ b/src/cmd/link/internal/ld/data.go
@@ -708,7 +708,6 @@ func blk(start *LSym, addr int64, size int64) {
}
eaddr := addr + size
- var ep []byte
var p []byte
for ; sym != nil; sym = sym.Next {
if sym.Type&obj.SSUB != 0 {
@@ -723,18 +722,16 @@ func blk(start *LSym, addr int64, size int64) {
errorexit()
}
- for ; addr < sym.Value; addr++ {
- Cput(0)
+ if addr < sym.Value {
+ strnput("", int(sym.Value-addr))
+ addr = sym.Value
}
p = sym.P
- ep = p[len(sym.P):]
- for -cap(p) < -cap(ep) {
- Cput(uint8(p[0]))
- p = p[1:]
- }
+ Cwrite(p)
addr += int64(len(sym.P))
- for ; addr < sym.Value+sym.Size; addr++ {
- Cput(0)
+ if addr < sym.Value+sym.Size {
+ strnput("", int(sym.Value+sym.Size-addr))
+ addr = sym.Value + sym.Size
}
if addr != sym.Value+sym.Size {
Diag("phase error: addr=%#x value+size=%#x", int64(addr), int64(sym.Value)+sym.Size)
@@ -746,8 +743,8 @@ func blk(start *LSym, addr int64, size int64) {
}
}
- for ; addr < eaddr; addr++ {
- Cput(0)
+ if addr < eaddr {
+ strnput("", int(eaddr-addr))
}
Cflush()
}
@@ -899,15 +896,26 @@ func Datblk(addr int64, size int64) {
fmt.Fprintf(&Bso, "\t%.8x|\n", uint(eaddr))
}
-func strnput(s string, n int) {
- for ; n > 0 && s != ""; s = s[1:] {
- Cput(uint8(s[0]))
- n--
- }
+var zeros [512]byte
- for n > 0 {
- Cput(0)
- n--
+// strnput writes the first n bytes of s.
+// If n is larger then len(s),
+// it is padded with NUL bytes.
+func strnput(s string, n int) {
+ if len(s) >= n {
+ Cwritestring(s[:n])
+ } else {
+ Cwritestring(s)
+ n -= len(s)
+ for n > 0 {
+ if len(zeros) >= n {
+ Cwrite(zeros[:n])
+ return
+ } else {
+ Cwrite(zeros[:])
+ n -= len(zeros)
+ }
+ }
}
}
diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index 93b2dab304..27fef60f18 100644
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -1850,6 +1850,10 @@ func Cseek(p int64) {
coutbuf.off = p
}
+func Cwritestring(s string) {
+ coutbuf.WriteString(s)
+}
+
func Cwrite(p []byte) {
coutbuf.Write(p)
}
--
2.30.9