This makes it cheaper to copy string literals.
This happens just about anywhere that they are used.
Example:
func f() string {
return "f"
}
Using 6g, compiler output before:
"".f t=1 size=32 value=0 args=0x10 locals=0x0
0x0000 00000 (p.go:3) TEXT "".f+0(SB),4,$0-16
0x0000 00000 (p.go:3) FUNCDATA $0,gclocals·d64e51a4c4bfeaa840e480961ec6b0b3+0(SB)
0x0000 00000 (p.go:3) FUNCDATA $1,gclocals·3280bececceccd33cb74587feedb1f9f+0(SB)
0x0000 00000 (p.go:4) LEAQ go.string."f"+0(SB),BX
0x0007 00007 (p.go:4) MOVQ (BX),BP
0x000a 00010 (p.go:4) MOVQ BP,"".~r0+8(FP)
0x000f 00015 (p.go:4) MOVQ 8(BX),BP
0x0013 00019 (p.go:4) MOVQ BP,"".~r0+16(FP)
0x0018 00024 (p.go:4) RET ,
After:
"".f t=1 size=32 value=0 args=0x10 locals=0x0
0x0000 00000 (p.go:3) TEXT "".f+0(SB),4,$0-16
0x0000 00000 (p.go:3) FUNCDATA $0,gclocals·d64e51a4c4bfeaa840e480961ec6b0b3+0(SB)
0x0000 00000 (p.go:3) FUNCDATA $1,gclocals·3280bececceccd33cb74587feedb1f9f+0(SB)
0x0000 00000 (p.go:4) MOVQ $go.string."f"+16(SB),BX
0x0007 00007 (p.go:4) MOVQ BX,"".~r0+8(FP)
0x000c 00012 (p.go:4) MOVQ $1,"".~r0+16(FP)
0x0015 00021 (p.go:4) RET ,
The leading MOVQ here will be converted into a LEAQ by the linker,
but there is still a net reduction of two MOVQs.
Before:
TEXT main.f(SB)
p.go:4 0x2000 488d1d49500500 LEAQ 0x55049(IP), BX
p.go:4 0x2007 488b2b MOVQ 0(BX), BP
p.go:4 0x200a 48896c2408 MOVQ BP, 0x8(SP)
p.go:4 0x200f 488b6b08 MOVQ 0x8(BX), BP
p.go:4 0x2013 48896c2410 MOVQ BP, 0x10(SP)
p.go:4 0x2018 c3 RET
After:
TEXT main.f(SB)
p.go:4 0x2000 488d1dd94c0500 LEAQ 0x54cd9(IP), BX
p.go:4 0x2007 48895c2408 MOVQ BX, 0x8(SP)
p.go:4 0x200c 48c744241001000000 MOVQ $0x1, 0x10(SP)
p.go:4 0x2015 c3 RET
The performance improvement is small but widespread.
As a nice small example, net/url's sole benchmark using 6g:
benchmark old ns/op new ns/op delta
BenchmarkString 16372 16118 -1.55%
And with 8g:
benchmark old ns/op new ns/op delta
BenchmarkString 22034 21709 -1.47%
Change-Id: I4ce202ee7dbd4057be869e2faaaa638c28a1fff0
Reviewed-on: https://go-review.googlesource.com/2587
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
These can be implemented with just a compare and a move instruction.
Do so, avoiding the overhead of a call into the runtime.
These assertions are a significant cost in Go code that uses interface{}
as a safe alternative to C's void* (or unsafe.Pointer), such as the
current version of the Go compiler.
*T here includes pointer to T but also any Go type represented as
a single pointer (chan, func, map). It does not include [1]*T or struct{*int}.
That requires more work in other parts of the compiler; there is a TODO.
Change-Id: I7ff681c20d2c3eb6ad11dd7b3a37b1f3dda23965
Reviewed-on: https://go-review.googlesource.com/7862
Reviewed-by: Rob Pike <r@golang.org>
This CL moves the bulk of the code that has been copy-and-pasted
since the initial 386 port back into a shared place, cutting 5 copies to 1.
The motivation here is not cleanup per se but instead to reduce the
cost of introducing changes in shared concepts like regalloc or general
expression evaluation. For example, a change after this one will
implement x.(*T) without a call into the runtime. This CL makes that
followup work 5x easier.
The single copy still has more special cases for architecture details
than I'd like, but having them called out explicitly like this at least
opens the door to generalizing the conditions and smoothing out
the distinctions in the future.
This is a LARGE CL. I started by trying to pull in one function at a time
in a sequence of CLs and it became clear that everything was so
interrelated that it had to be moved as a whole. Apologies for the size.
It is not clear how many more releases this code will matter for;
eventually it will be replaced by Keith's SSA work. But as noted above,
the deduplication was necessary to reduce the cost of working on
the current code while we have it.
Passes tests on amd64, 386, arm, and ppc64le.
Can build arm64 binaries but not tested there.
Being able to build binaries means it is probably very close.
Change-Id: I735977f04c0614f80215fb12966dfe9bbd1f5861
Reviewed-on: https://go-review.googlesource.com/7853
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
namebuf was a global char buffer in the C version of gc, which was
useful for providing common storage for constructing symbol and file
names. However, now that it's just a global Go string and the string
data is dynamically allocated anyway, it doesn't serve any purpose
except to force extra write barriers everytime it's assigned to.
Also, introduce Lookupf(fmt, args...) as shorthand for
Lookup(fmt.Sprintf(fmt, args...)), which was a very common pattern for
using namebuf.
Passes "go build -toolexec 'toolstash -cmp' -a std".
Notably, this CL shrinks 6g's text section by ~15kB:
$ size toolstash/6g tool/linux_amd64/6g
text data bss dec hex filename
4600805 605968 342988 5549761 54aec1 toolstash/6g
4585547 605968 342956 5534471 547307 tool/linux_amd64/6g
Change-Id: I98abb44fc7f43a2e2e48425cc9f215cd0be37442
Reviewed-on: https://go-review.googlesource.com/7080
Reviewed-by: Ian Lance Taylor <iant@golang.org>
More Node cleanups, these ones touch go.y.
- convert Node.Implicit to bool
- convert Node.Used to bool
Change-Id: I85c7ff9e66cee7122b560adedc995166c874f2f2
Reviewed-on: https://go-review.googlesource.com/7124
Reviewed-by: Keith Randall <khr@golang.org>
Run rsc.io/grind rev 796d0f2 on C->Go conversions.
This replaces various awkward := initializations with plain var declarations.
Checked bit-for-bit compatibility with toolstash + buildall.
Change-Id: I601101d8177894adb9b0e3fb55dfe0ed4f544716
Reviewed-on: https://go-review.googlesource.com/6517
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
No functional changes.
This diff was generated as follows:
* Manually edit cmd/internal/gc/go.go to update types and group variables.
* Manually edit initialization in cmd/internal/gc/align.go--localized s/1/true.
* Manually fix the handling of sign in cmd/internal/gc/walk.go in func bounded (near line 4000).
* Manually update go.y and regenerate y.go.
* Run gofmt -r many times to do the rest, using https://gist.github.com/josharian/0f61dbb2dff81f938e70.
toolstash -cmp on the stdlib comes back green.
Change-Id: I19766ed551714e51b325133e7138818d117b3a9a
Reviewed-on: https://go-review.googlesource.com/6530
Reviewed-by: Russ Cox <rsc@golang.org>
Ran rsc.io/grind rev 6f0e601 on the source files.
The cleanups move var declarations as close to the use
as possible, splitting disjoint uses of the var into separate
variables. They also remove dead code (especially in
func sudoaddable), which helps with the var moving.
There's more cleanup to come, but this alone cuts the
time spent compiling html/template on my 2013 MacBook Pro
from 3.1 seconds to 2.3 seconds.
Change-Id: I4de499f47b1dd47a560c310bbcde6b08d425cfd6
Reviewed-on: https://go-review.googlesource.com/5637
Reviewed-by: Rob Pike <r@golang.org>
Reconvert using rsc.io/c2go rev 27b3f59.
Changes to converter:
- fatal does not return, so no fallthrough after fatal in switch
- many more function results and variables identified as bool
- simplification of negated boolean expressions
Change-Id: I3bc67da5e46cb7ee613e230cf7e9533036cc870b
Reviewed-on: https://go-review.googlesource.com/5171
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
First draft of converted Go compiler, using rsc.io/c2go rev 83d795a.
Change-Id: I29f4c7010de07d2ff1947bbca9865879d83c32c3
Reviewed-on: https://go-review.googlesource.com/4851
Reviewed-by: Rob Pike <r@golang.org>
