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go/test
Josh Bleecher Snyder 4a7e363288 cmd/compile: optimize Move with all-zero ro sym src to Zero
We set up static symbols during walk that
we later make copies of to initialize local variables.
It is difficult to ascertain at that time exactly
when copying a symbol is profitable vs locally
initializing an autotmp.

During SSA, we are much better placed to optimize.
This change recognizes when we are copying from a
global readonly all-zero symbol and replaces it with
direct zeroing.

This often allows the all-zero symbol to be
deadcode eliminated at link time.
This is not ideal--it makes for large object files,
and longer link times--but it is the cleanest fix I could find.

This makes the final binary for the program in #38554
shrink from >500mb to ~2.2mb.

It also shrinks the standard binaries:

file      before    after     Δ       %
addr2line 4412496   4404304   -8192   -0.186%
buildid   2893816   2889720   -4096   -0.142%
cgo       4841048   4832856   -8192   -0.169%
compile   19926480  19922432  -4048   -0.020%
cover     5281816   5277720   -4096   -0.078%
link      6734648   6730552   -4096   -0.061%
nm        4366240   4358048   -8192   -0.188%
objdump   4755968   4747776   -8192   -0.172%
pprof     14653060  14612100  -40960  -0.280%
trace     11805940  11777268  -28672  -0.243%
vet       7185560   7181416   -4144   -0.058%
total     113588440 113465560 -122880 -0.108%

And not just by removing unnecessary symbols;
the program text shrinks a bit as well.

Fixes #38554

Change-Id: I8381ae6084ae145a5e0cd9410c451e52c0dc51c8
Reviewed-on: https://go-review.googlesource.com/c/go/+/229704
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
2020-04-24 23:58:10 +00:00
..
alias3.dir
bench
chan
closure3.dir
codegen
ddd2.dir
dwarf
fixedbugs
import2.dir
import4.dir
interface
intrinsic.dir
ken
linkname.dir
method4.dir
oldescape_linkname.dir
retjmp.dir
runtime
stress
syntax
uintptrescapes.dir
64bit.go
235.go
alg.go
alias1.go
alias2.go
alias3.go
alias.go
align.go
append1.go
append.go
args.go
armimm.go
assign1.go
assign.go
atomicload.go
bigalg.go
bigmap.go
blank1.go
blank.go
bom.go
bombad.go
bounds.go
chancap.go
chanlinear.go
char_lit1.go
char_lit.go
checkbce.go
clearfat.go
closedchan.go
closure1.go
closure2.go
closure3.go
closure4.go
closure.go
cmp6.go
cmp.go
cmplx.go
cmplxdivide1.go
cmplxdivide.c
cmplxdivide.go
complit1.go
complit.go
compos.go
const1.go
const2.go
const3.go
const4.go
const5.go
const6.go
const.go
convert1.go
convert2.go
convert3.go
convert.go
convlit1.go
convlit.go
convT2X.go
copy1.go
copy.go
crlf.go
ddd1.go
ddd2.go
ddd.go
decl.go
declbad.go
defer.go
defererrcheck.go
deferfin.go
defernil.go
deferprint.go
deferprint.out
devirt.go
directive.go
divide.go
divmod.go
empty.go
env.go
eof1.go
eof.go
escape2.go
escape2n.go
escape3.go
escape4.go
escape5.go
escape_array.go
escape_calls.go
escape_closure.go
escape_field.go
escape_goto.go
escape_hash_maphash.go
escape_iface.go
escape_indir.go
escape_level.go
escape_map.go
escape_param.go
escape_runtime_atomic.go
escape_selfassign.go
escape_slice.go
escape_struct_param1.go
escape_struct_param2.go
escape_struct_return.go
escape_sync_atomic.go
escape_unsafe.go
escape.go
fibo.go
finprofiled.go
float_lit2.go
float_lit3.go
float_lit.go
floatcmp.go
for.go
func1.go
func2.go
func3.go
func4.go
func5.go
func6.go
func7.go
func8.go
func.go
funcdup2.go
funcdup.go
gc1.go
gc2.go
gc.go
gcgort.go
gcstring.go
goprint.go
goprint.out
goto.go
heapsampling.go
helloworld.go
helloworld.out
if.go
import1.go
import2.go
import4.go
import5.go
import6.go
import.go
index0.go
index1.go
index2.go
index.go
indirect1.go
indirect.go
init1.go
init.go
initcomma.go
initempty.go
initialize.go
initializerr.go
initloop.go
inline_big.go
inline_caller.go
inline_callers.go
inline_literal.go
inline_math_bits_rotate.go
inline_sync.go
inline_variadic.go
inline.go
int_lit.go
intcvt.go
intrinsic_atomic.go
intrinsic.go
iota.go
label1.go
label.go
linkmain_run.go
linkmain.go
linkname.go
linkobj.go
linkx_run.go
linkx.go
literal2.go
literal.go
live1.go
live2.go
live_syscall.go
live.go
locklinear.go
loopbce.go
makechan.go
makemap.go
makenew.go
mallocfin.go
map1.go
map.go
mapclear.go
maplinear.go
mergemul.go
method1.go
method2.go
method3.go
method4.go
method5.go
method6.go
method7.go
method.go
named1.go
named.go
nil.go
nilcheck.go
nilptr2.go
nilptr3.go
nilptr4.go
nilptr5_aix.go
nilptr5_wasm.go
nilptr5.go
nilptr_aix.go
nilptr.go
nosplit.go
notinheap2.go
notinheap3.go
notinheap.go
nowritebarrier.go
nul1.go
opt_branchlikely.go
parentype.go
peano.go
phiopt.go
print.go
print.out
printbig.go
printbig.out
prove.go
range.go
README.md
recover1.go
recover2.go
recover3.go
recover4.go
recover5.go
recover.go
reflectmethod1.go
reflectmethod2.go
reflectmethod3.go
reflectmethod4.go
reflectmethod5.go
reflectmethod6.go
rename1.go
rename.go
reorder2.go
reorder.go
retjmp.go
return.go
rotate0.go
rotate1.go
rotate2.go
rotate3.go
rotate.go
run.go
rune.go
runtime.go
shift1.go
shift2.go
sieve.go
sigchld.go
sigchld.out
simassign.go
sinit_run.go
sinit.go
sizeof.go
slice3.go
slice3err.go
slicecap.go
sliceopt.go
solitaire.go
stack.go
stackobj2.go
stackobj3.go
stackobj.go
strcopy.go
strength.go
string_lit.go
stringrange.go
struct0.go
switch2.go
switch3.go
switch4.go
switch5.go
switch6.go
switch7.go
switch.go
tinyfin.go
torture.go
turing.go
typecheck.go
typecheckloop.go
typeswitch1.go
typeswitch2.go
typeswitch2b.go
typeswitch3.go
typeswitch.go
uintptrescapes2.go
uintptrescapes3.go
uintptrescapes.go
undef.go
utf.go
varerr.go
varinit.go
winbatch.go
writebarrier.go
zerodivide.go

The test directory contains tests of the Go tool chain and runtime. It includes black box tests, regression tests, and error output tests. They are run as part of all.bash.

To run just these tests, execute:

../bin/go run run.go

Standard library tests should be written as regular Go tests in the appropriate package.

The tool chain and runtime also have regular Go tests in their packages. The main reasons to add a new test to this directory are:

  • it is most naturally expressed using the test runner; or
  • it is also applicable to gccgo and other Go tool chains.