From: Keith Randall <khr@golang.org>
Date: Mon, 30 Dec 2013 20:14:27 +0000 (-0800)
Subject: cmd/6g: inline copies of up to 4 words in length.
X-Git-Tag: go1.3beta1~1089
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=0ea20bc981b2135cd67e7ff4ec71c05214bccc52;p=gostls13.git

cmd/6g: inline copies of up to 4 words in length.

This change fixes a serious performance regression
with reflect.Value growing to 4 words instead of 3.
The json benchmark was ~50% slower, with this change
it is ~5% slower (and the binary is 0.5% larger).

Longer term, we probably need to rethink our copy
generation.  Using REP is really expensive time-wise.
But inlining the copy grows the binary.

R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/44990043
---

diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index ada2baa81c..da16071a8d 100644
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -1513,7 +1513,7 @@ componentgen(Node *nr, Node *nl)
 				fatal("componentgen: not a TFIELD: %lT", t);
 			fldcount++;
 		}
-		if(fldcount == 0 || fldcount > 3)
+		if(fldcount == 0 || fldcount > 4)
 			goto no;
 
 		break;