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go/src/cmd/8g
Josh Bleecher Snyder 43c87aa481 cmd/6g, cmd/8g, liblink: improve handling of float constants
* Enable basic constant propagation for floats.
  The constant propagation is still not as aggressive as it could be.
* Implement MOVSS $(0), Xx and MOVSD $(0), Xx as XORPS Xx, Xx.

Sample code:

func f32() float32 {
	var f float32
	return f
}

func f64() float64 {
	var f float64
	return f
}

Before:

"".f32 t=1 size=32 value=0 args=0x8 locals=0x0
	0x0000 00000 (demo.go:3)	TEXT	"".f32+0(SB),4,$0-8
	0x0000 00000 (demo.go:3)	FUNCDATA	$0,gclocals·a7a3692b8e27e823add69ec4239ba55f+0(SB)
	0x0000 00000 (demo.go:3)	FUNCDATA	$1,gclocals·3280bececceccd33cb74587feedb1f9f+0(SB)
	0x0000 00000 (demo.go:3)	MOVSS	$f32.00000000+0(SB),X0
	0x0008 00008 (demo.go:4)	MOVSS	$f32.00000000+0(SB),X0
	0x0010 00016 (demo.go:5)	MOVSS	X0,"".~r0+8(FP)
	0x0016 00022 (demo.go:5)	RET	,
"".f64 t=1 size=32 value=0 args=0x8 locals=0x0
	0x0000 00000 (demo.go:8)	TEXT	"".f64+0(SB),4,$0-8
	0x0000 00000 (demo.go:8)	FUNCDATA	$0,gclocals·a7a3692b8e27e823add69ec4239ba55f+0(SB)
	0x0000 00000 (demo.go:8)	FUNCDATA	$1,gclocals·3280bececceccd33cb74587feedb1f9f+0(SB)
	0x0000 00000 (demo.go:8)	MOVSD	$f64.0000000000000000+0(SB),X0
	0x0008 00008 (demo.go:9)	MOVSD	$f64.0000000000000000+0(SB),X0
	0x0010 00016 (demo.go:10)	MOVSD	X0,"".~r0+8(FP)
	0x0016 00022 (demo.go:10)	RET	,

After:

"".f32 t=1 size=16 value=0 args=0x8 locals=0x0
	0x0000 00000 (demo.go:3)	TEXT	"".f32+0(SB),4,$0-8
	0x0000 00000 (demo.go:3)	FUNCDATA	$0,gclocals·a7a3692b8e27e823add69ec4239ba55f+0(SB)
	0x0000 00000 (demo.go:3)	FUNCDATA	$1,gclocals·3280bececceccd33cb74587feedb1f9f+0(SB)
	0x0000 00000 (demo.go:3)	XORPS	X0,X0
	0x0003 00003 (demo.go:5)	MOVSS	X0,"".~r0+8(FP)
	0x0009 00009 (demo.go:5)	RET	,
"".f64 t=1 size=16 value=0 args=0x8 locals=0x0
	0x0000 00000 (demo.go:8)	TEXT	"".f64+0(SB),4,$0-8
	0x0000 00000 (demo.go:8)	FUNCDATA	$0,gclocals·a7a3692b8e27e823add69ec4239ba55f+0(SB)
	0x0000 00000 (demo.go:8)	FUNCDATA	$1,gclocals·3280bececceccd33cb74587feedb1f9f+0(SB)
	0x0000 00000 (demo.go:8)	XORPS	X0,X0
	0x0003 00003 (demo.go:10)	MOVSD	X0,"".~r0+8(FP)
	0x0009 00009 (demo.go:10)	RET	,

Change-Id: Ie9eb65e324af4f664153d0a7cd22bb16b0fba16d
Reviewed-on: https://go-review.googlesource.com/2053
Reviewed-by: Russ Cox <rsc@golang.org>
2015-01-07 22:26:55 +00:00
..
cgen64.c
cgen.c build: adjustments for move from src/pkg to src 2014-09-08 00:06:45 -04:00
doc.go
galign.c build: annotations and modifications for c2go 2014-07-02 15:41:29 -04:00
gg.h cmd/cc, cmd/gc: stop generating 'argsize' PCDATA 2014-09-12 07:51:00 -04:00
ggen.c runtime: make stack frames fixed size by modifying goproc/deferproc. 2014-12-23 01:08:29 +00:00
gobj.c [dev.power64] gc: fix etype of strings 2014-11-06 14:37:39 -05:00
gsubr.c cmd/5g, cmd/8g: make 'out of registers' a fatal error 2014-09-16 13:16:43 -04:00
Makefile
opt.h [dev.power64] 5g,6g,8g,9g: debug prints for regopt pass 6 and paint2 2014-11-14 11:56:31 -05:00
peep.c cmd/6g, cmd/8g, liblink: improve handling of float constants 2015-01-07 22:26:55 +00:00
prog.c cmd/8g: fix liveness for 387 build (including plan9) 2014-04-06 10:30:02 -04:00
reg.c [dev.cc] cmd/8g: fix warning on Plan 9 2014-11-21 20:44:04 +01:00