Keith Randall deb4177cf0 cmd/compile: use masks instead of branches for slicing ... When we do var x []byte = ... y := x[i:] We can't just use y.ptr = x.ptr + i, as the new pointer may point to the next object in memory after the backing array. We used to fix this by doing: y.cap = x.cap - i delta := i if y.cap == 0 { delta = 0 } y.ptr = x.ptr + delta That generates a branch in what is otherwise straight-line code. Better to do: y.cap = x.cap - i mask := (y.cap - 1) >> 63 // -1 if y.cap==0, 0 otherwise y.ptr = x.ptr + i &^ mask It's about the same number of instructions (~4, depending on what parts are constant, and the target architecture), but it is all inline. It plays nicely with CSE, and the mask can be computed in parallel with the index (in cases where a multiply is required). It is a minor win in both speed and space. Change-Id: Ied60465a0b8abb683c02208402e5bb7ac0e8370f Reviewed-on: https://go-review.googlesource.com/32022 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Cherry Zhang <cherryyz@google.com>		2016-10-27 20:22:49 +00:00
..
alias3.dir	cmd/compile: import/export of alias declarations	2016-10-27 17:44:45 +00:00
bench	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
chan	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
ddd2.dir	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
dwarf	test: make rundir match compiledir/errorcheckdir.	2013-01-11 22:00:48 +01:00
fixedbugs	cmd/compile: emit assignments after calls in the right order	2016-10-27 16:52:30 +00:00
import2.dir	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
import4.dir	test: adjust gccgo expected import errors	2015-10-07 14:37:44 +00:00
interface	cmd/compile: inline x, ok := y.(T) where T is a scalar	2016-08-17 01:12:01 +00:00
intrinsic.dir	cmd/compile: intrinsify Ctz, Bswap on ARM	2016-09-12 19:26:31 +00:00
ken	all: fix spelling mistakes	2016-04-03 17:03:15 +00:00
method4.dir	cmd/gc: do not omit wrapper for expression (interface{...}).F	2014-01-07 13:26:48 +01:00
safe	test: adapt old-style tests to new flag parsing.	2013-01-11 22:05:46 +01:00
stress	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
syntax	cmd/compile/internal/gc: enable new parser by default	2016-10-25 22:28:40 +00:00
uintptrescapes.dir	cmd/compile, syscall: add //go:uintptrescapes comment, and use it	2016-07-06 20:48:41 +00:00
64bit.go	cmd/gc: Error out on division by constant zero.	2013-01-30 20:21:08 +01:00
235.go
alg.go	test: add test that required algs get generated	2016-04-24 21:36:52 +00:00
alias1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
alias2.go	cmd/compile: disallow "init" as alias	2016-10-27 20:01:20 +00:00
alias3.go	cmd/compile: import/export of alias declarations	2016-10-27 17:44:45 +00:00
alias.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
append.go
args.go	test: run some more tests by default	2012-11-08 09:04:27 -08:00
assign1.go
assign.go	cmd/gc: prohibit short variable declarations containing duplicate symbols	2014-10-06 17:16:39 -04:00
atomicload.go	cmd/compile: keep value use counts in SSA	2016-03-17 04:20:02 +00:00
bigalg.go	test: ensure all failing tests exit nonzero.	2013-02-12 13:17:49 -05:00
bigmap.go
blank1.go	cmd/compile: don't allow blank method declarations on builtins	2015-12-02 18:26:38 +00:00
blank.go	test: revert changes made for Go SSA interpreter test.	2013-10-08 14:36:20 -04:00
bom.go
bombad.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
bounds.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
chancap.go
chanlinear.go	runtime: test for linear enqueue/dequeue behavior	2014-12-08 22:18:17 +00:00
char_lit1.go
char_lit.go
checkbce.go	cmd/compile: optimize integer "in range" expressions	2016-08-25 03:49:16 +00:00
clearfat.go	[dev.power64] 9g: fix under-zeroing in clearfat	2014-10-31 11:08:27 -04:00
closedchan.go
closure1.go	cmd/gc: capture variables by value	2015-01-29 13:07:30 +00:00
closure2.go	cmd/gc: fix capturing by value for range statements	2015-02-03 15:48:48 +00:00
closure.go
cmp6.go	cmd/gc: do not consider length zero arrays as comparable.	2014-01-31 00:30:56 +01:00
cmp.go	Fix several out of date references to 4g/5g/6g/8g/9g.	2015-06-26 03:38:21 +00:00
cmplx.go	cmd/gc: reject complex calls with mismatched argument types.	2013-03-11 22:55:14 +01:00
cmplxdivide1.go
cmplxdivide.c	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
cmplxdivide.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
complit1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
complit.go
compos.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
const1.go	test: match gccgo error messages	2013-12-12 17:18:12 -08:00
const2.go	test: match gccgo error messages	2012-09-28 08:30:30 -07:00
const3.go
const4.go	all: link to https instead of http	2015-07-11 14:36:33 +00:00
const5.go	all: link to https instead of http	2015-07-11 14:36:33 +00:00
const6.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
const.go	cmd/compile: fix compiler bug for constant equality comparison	2016-09-17 01:12:24 +00:00
convert1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
convert2.go	cmd/compile: ignore struct tags when converting structs	2016-10-04 17:10:47 +00:00
convert3.go
convert.go
convlit1.go
convlit.go	cmd/internal/gc: unsafe.Pointer constants may only be converted to uintptr	2015-05-07 23:54:28 +00:00
convT2X.go
copy.go	test: ensure all failing tests exit nonzero.	2013-02-12 13:17:49 -05:00
crlf.go
ddd1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
ddd2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
ddd.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
decl.go	test: ensure all failing tests exit nonzero.	2013-02-12 13:17:49 -05:00
declbad.go	test: correct type in declbad.go	2012-10-07 21:52:57 +02:00
defer.go	test: ensure all failing tests exit nonzero.	2013-02-12 13:17:49 -05:00
deferfin.go	runtime: combine small NoScan allocations	2014-01-24 22:35:11 +04:00
deferprint.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
deferprint.out
divide.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
divmod.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
empty.go
env.go
eof1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
eof.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
errchk	cmd/vet: make checking example names in _test packages more robust	2016-06-28 22:09:00 +00:00
escape2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape2n.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape3.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape4.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape5.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_array.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_because.go	cmd/compile: add explicit 'where' to EscStep data for explanations	2016-10-26 18:46:59 +00:00
escape_calls.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_closure.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_field.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_iface.go	cmd/compile: avoid leak of dottype expression on double assignment form	2016-10-10 12:09:16 +00:00
escape_indir.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_level.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_map.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_param.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_slice.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_struct_param1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_struct_param2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape_struct_return.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
escape.go	test: ensure all failing tests exit nonzero.	2013-02-12 13:17:49 -05:00
fibo.go	Fix whitespace (use blanks consistently).	2014-12-08 22:22:58 +00:00
finprofiled.go	runtime: fix finalization and profiling of tiny allocations	2015-11-03 18:57:18 +00:00
float_lit2.go	test/float_lit2: fix expressions in comment	2016-09-14 16:39:47 +00:00
float_lit3.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
float_lit.go	test: ensure all failing tests exit nonzero.	2013-02-12 13:17:49 -05:00
floatcmp.go	test: ensure all failing tests exit nonzero.	2013-02-12 13:17:49 -05:00
for.go
func1.go	cmd/gc: ensure unique parameter and result names in function types	2013-03-15 15:24:13 -04:00
func2.go
func3.go
func4.go
func5.go
func6.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
func7.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
func8.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
func.go
funcdup2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
funcdup.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
gc1.go
gc2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
gc.go
gcstring.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
goprint.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
goprint.out
goto.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
heapsampling.go	test: really force heap profile update in heapsampling.go	2015-11-12 18:32:13 +00:00
helloworld.go
helloworld.out
if.go
import1.go	test: match gccgo import error messages	2013-12-12 19:02:11 -08:00
import2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
import4.go	test: convert more tests to rundir/compiledir conventions	2012-10-07 23:22:01 +02:00
import5.go
import.go
index0.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
index1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
index2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
index.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
indirect1.go
indirect.go
init1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
init.go
initcomma.go
initialize.go
initializerr.go	test: add "duplicate" struct map key test	2012-12-17 11:05:58 -05:00
initloop.go	cmd/compile: use []*Node instead of NodeList in sinit	2015-09-05 02:25:01 +00:00
inline.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
int_lit.go
intcvt.go
intrinsic_atomic.go	cmd/compile: intrinsify Ctz, Bswap on ARM	2016-09-12 19:26:31 +00:00
intrinsic.go	cmd/compile: intrinsify Ctz{32,64} and Bswap{32,64} on s390x	2016-09-19 19:03:01 +00:00
iota.go
label1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
label.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
linkmain_run.go	test: fix linkmain test	2015-12-17 23:36:13 +00:00
linkmain.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
linkobj.go	cmd/compile: add -linkobj flag to allow writing object file in two parts	2016-05-09 17:31:45 +00:00
linkx_run.go	test: print output on link -X failure	2016-04-20 17:37:35 +00:00
linkx.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
literal.go	test: ensure all failing tests exit nonzero.	2013-02-12 13:17:49 -05:00
live1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
live2.go	test: re-enable live2 test on amd64	2016-10-07 17:34:02 +00:00
live_syscall.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
live.go	cmd/compile,runtime: redo how map assignments work	2016-10-12 20:41:23 +00:00
loopbce.go	cmd/compile: bce when max and limit are consts	2016-04-11 16:01:22 +00:00
mallocfin.go
map1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
map.go	test/mapnan.go: add regression test for non-empty interfaces.	2014-08-06 17:02:55 -04:00
maplinear.go	test: make maplinear more robust	2014-10-27 18:59:02 -04:00
method1.go	cmd/compile: ignore receiver parameters in Eqtype	2016-03-17 00:38:15 +00:00
method2.go	test: avoid matching file names in errcheck	2016-10-18 05:32:37 +00:00
method3.go
method4.go	test: convert more tests to rundir/compiledir conventions	2012-10-07 23:22:01 +02:00
method5.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
method.go	test: a number of fixes.	2013-02-11 18:20:52 -05:00
named1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
named.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
nil.go	test: ensure all failing tests exit nonzero.	2013-02-12 13:17:49 -05:00
nilcheck.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
nilptr2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
nilptr3.go	cmd/compile: re-enable nilcheck removal for newobject	2016-09-28 19:41:49 +00:00
nilptr4.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
nilptr.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
nosplit.go	cmd/compile: ppc64le working, not optimized enough	2016-08-18 16:34:47 +00:00
notinheap2.go	cmd/compile: add go:notinheap type pragma	2016-10-15 17:58:14 +00:00
notinheap.go	cmd/compile: add go:notinheap type pragma	2016-10-15 17:58:14 +00:00
nowritebarrier.go	cmd/compile, runtime: add go:yeswritebarrierrec pragma	2016-10-15 17:58:11 +00:00
nul1.go	cmd/compile/internal/gc: enable new parser by default	2016-10-25 22:28:40 +00:00
opt_branchlikely.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
parentype.go
peano.go
phiopt.go	test: re-enable phi optimization test	2016-09-13 20:06:13 +00:00
print.go	runtime: move built-in print routines to go.	2014-07-31 13:48:48 -07:00
print.out	runtime: move built-in print routines to go.	2014-07-31 13:48:48 -07:00
printbig.go
printbig.out
prove.go	cmd/compile: Repurpose old sliceopt.go for prove phase.	2016-10-20 23:50:19 +00:00
range.go	cmd/gc: implement 'for range x {'	2014-07-16 19:27:10 -04:00
recover1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
recover2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
recover3.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
recover4.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
recover.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
reflectmethod1.go	cmd/compile: track reflect.Type.Method in deadcode	2016-03-11 21:19:20 +00:00
reflectmethod2.go	cmd/compile: track reflect.Type.Method in deadcode	2016-03-11 21:19:20 +00:00
reflectmethod3.go	cmd/compile: track reflect.Type.Method in deadcode	2016-03-11 21:19:20 +00:00
reflectmethod4.go	cmd/link: treat reflect.Value.Method like Call	2016-03-11 22:07:02 +00:00
rename1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
rename.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
reorder2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
reorder.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
return.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
rotate0.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
rotate1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
rotate2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
rotate3.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
rotate.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
run.go	test: delete bugs directory	2016-10-25 00:17:57 +00:00
rune.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
runtime.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
shift1.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
shift2.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
sieve.go
sigchld.go	test: skip SIGCHLD test on Plan 9	2014-01-29 09:28:23 +01:00
sigchld.out
simassign.go
sinit_run.go	all: retire architecture letter in file names, public API	2015-05-21 17:32:17 +00:00
sinit.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
sizeof.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
slice3.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
slice3err.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
slicecap.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
sliceopt.go	cmd/compile: use masks instead of branches for slicing	2016-10-27 20:22:49 +00:00
solitaire.go
stack.go
strength.go	cmd/compile: generalize strength reduction of mulq	2016-03-30 22:27:13 +00:00
string_lit.go	test: add []rune case to string_lit.go	2013-12-12 17:17:02 -08:00
stringrange.go
struct0.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
switch2.go	cmd/compile/internal/syntax: match old parser errors and line numbers	2016-08-19 01:10:21 +00:00
switch3.go
switch4.go	cmd/gc: disallow fallthrough in final case of switch	2013-03-15 00:35:09 -04:00
switch5.go	cmd/compile: fix detection of duplicate cases for integer ranges	2016-10-21 22:55:28 +00:00
switch6.go	cmd/compile: set correct line number for multiple defaults in switch error	2016-08-22 19:56:06 +00:00
switch.go	cmd/gc: disallow fallthrough in final case of switch	2013-03-15 00:35:09 -04:00
tinyfin.go	runtime: fix finalization and profiling of tiny allocations	2015-11-03 18:57:18 +00:00
torture.go	cmd/8g: don't allocate a register early for cap(CHAN).	2014-07-01 09:20:51 +02:00
turing.go
typecheck.go	cmd/gc: silence assignment errors to undefined symbols	2014-01-03 21:03:20 +01:00
typecheckloop.go	cmd/compile: convert typecheck_stack to []*Node	2015-09-06 23:50:51 +00:00
typeswitch1.go
typeswitch2.go
typeswitch3.go	test: match gccgo error messages	2012-09-28 08:30:30 -07:00
typeswitch.go
uintptrescapes2.go	cmd/compile: args no longer live until end-of-function	2016-09-19 16:54:35 +00:00
uintptrescapes.go	cmd/compile, syscall: add //go:uintptrescapes comment, and use it	2016-07-06 20:48:41 +00:00
undef.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
utf.go
varerr.go	all: make copyright headers consistent with one space after period	2016-05-02 13:43:18 +00:00
varinit.go
writebarrier.go	cmd/compile: add a writebarrier phase in SSA	2016-10-25 21:53:40 +00:00
zerodivide.go	test: ensure all failing tests exit nonzero.	2013-02-12 13:17:49 -05:00