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Martin Möhrmann 4e2b84ffc5 compile: prefer an AND instead of SHR+SHL instructions 
On modern 64bit CPUs a SHR, SHL or AND instruction take 1 cycle to execute.
A pair of shifts that operate on the same register will take 2 cycles
and needs to wait for the input register value to be available.

Large constants used to mask the high bits of a register with an AND
instruction can not be encoded as an immediate in the AND instruction
on amd64 and therefore need to be loaded into a register with a MOV
instruction.

However that MOV instruction is not dependent on the output register and
on many CPUs does not compete with the AND or shift instructions for
execution ports.

Using a pair of shifts to mask high bits instead of an AND to mask high
bits of a register has a shorter encoding and uses one less general
purpose register but is slower due to taking one clock cycle longer
if there is no register pressure that would make the AND variant need to
generate a spill.

For example the instructions emitted for (x & 1 << 63) before this CL are:
48c1ea3f                SHRQ $0x3f, DX
48c1e23f                SHLQ $0x3f, DX

after this CL the instructions are the same as GCC and LLVM use:
48b80000000000000080    MOVQ $0x8000000000000000, AX
4821d0                  ANDQ DX, AX

Some platforms such as arm64 already have SSA optimization rules to fuse
two shift instructions back into an AND.

Removing the general rule to rewrite AND to SHR+SHL speeds up this benchmark:

    var GlobalU uint

    func BenchmarkAndHighBits(b *testing.B) {
        x := uint(0)
        for i := 0; i < b.N; i++ {
                x &= 1 << 63
        }
        GlobalU = x
    }

amd64/darwin on Intel(R) Core(TM) i7-3520M CPU @ 2.90GHz:
name           old time/op  new time/op  delta
AndHighBits-4  0.61ns ± 6%  0.42ns ± 6%  -31.42%  (p=0.000 n=25+25):

'go run run.go -all_codegen -v codegen' passes  with following adjustments:

ARM64: The BFXIL pattern ((x << lc) >> rc | y & ac) needed adjustment
       since ORshiftRL generation fusing '>> rc' and '|' interferes
       with matching ((x << lc) >> rc) to generate UBFX. Previously
       ORshiftLL was created first using the shifts generated for (y & ac).

S390X: Add rules for abs and copysign to match use of AND instead of SHIFTs.

Updates #33826
Updates #32781

Change-Id: I43227da76b625de03fbc51117162b23b9c678cdb
Reviewed-on: https://go-review.googlesource.com/c/go/+/194297
Run-TryBot: Martin Möhrmann <martisch@uos.de>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2019-09-21 18:00:13 +00:00
..
alias3.dir
bench test/bench/go1: add go.mod file 2019-03-06 18:53:12 +00:00
chan test: add a test for gccgo bug in handling break statement in a select 2019-07-10 18:02:11 +00:00
closure3.dir cmd/compile: skip escape analysis diagnostics for OADDR 2019-04-02 16:34:03 +00:00
codegen compile: prefer an AND instead of SHR+SHL instructions 2019-09-21 18:00:13 +00:00
ddd2.dir
dwarf
fixedbugs cmd/compile: support more length types for slice extension optimization 2019-09-17 17:18:17 +00:00
import2.dir
import4.dir
interface cmd/compile: more error position tests for the typechecker 2017-04-24 12:37:49 +00:00
intrinsic.dir cmd/compile: intrinsics for math/bits.TrailingZerosX 2017-03-16 02:44:16 +00:00
ken all: fix typos 2019-09-08 17:28:20 +00:00
linkname.dir cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
method4.dir
oldescape_linkname.dir cmd/compile: update escape analysis tests for newescape 2019-04-16 16:20:39 +00:00
retjmp.dir cmd/asm: fix assembling return jump 2018-03-01 21:11:16 +00:00
runtime test: remove -newescape from regress tests 2019-08-28 19:27:20 +00:00
stress
syntax cmd/compile: better handling of incorrect type switches 2018-04-03 05:34:20 +00:00
uintptrescapes.dir
64bit.go
235.go
alg.go
alias1.go
alias2.go cmd/compile: cleanup method symbol creation 2018-04-05 22:01:17 +00:00
alias3.go
alias.go
align.go test: check that unaligned load-add opcodes work. 2018-04-09 18:57:37 +00:00
append1.go cmd/compile: optimize append(x, make([]T, y)...) slice extension 2018-05-06 04:28:23 +00:00
append.go cmd/compile: optimize append(x, make([]T, y)...) slice extension 2018-05-06 04:28:23 +00:00
args.go
armimm.go cmd/internal/obj: continue to optimize ARM's constant pool 2017-05-11 13:53:54 +00:00
assign1.go
assign.go
atomicload.go
bigalg.go
bigmap.go
blank1.go test: update blank1.go for changed gofrontend error messages 2019-06-23 22:20:39 +00:00
blank.go
bom.go
bombad.go
bounds.go test: gofmt bounds.go 2018-05-29 02:39:16 +00:00
chancap.go runtime: handle 64bits addresses for AIX 2018-11-26 14:06:28 +00:00
chanlinear.go
char_lit1.go
char_lit.go
checkbce.go cmd/compile: fix ordering for short-circuiting ops 2019-03-06 20:04:07 +00:00
clearfat.go
closedchan.go
closure1.go
closure2.go all: fix typos 2019-09-08 17:28:20 +00:00
closure3.go all: fix a bunch of misspellings 2018-10-06 15:40:03 +00:00
closure4.go cmd/compile/internal/gc: add nil check for closure call on wasm 2018-08-14 09:19:38 +00:00
closure.go
cmp6.go
cmp.go
cmplx.go cmd/compile: rewrite f(g()) for multi-value g() during typecheck 2019-03-14 21:00:20 +00:00
cmplxdivide1.go runtime: make complex division c99 compatible 2017-03-15 22:45:17 +00:00
cmplxdivide.c runtime: make complex division c99 compatible 2017-03-15 22:45:17 +00:00
cmplxdivide.go runtime: make complex division c99 compatible 2017-03-15 22:45:17 +00:00
complit1.go cmd/compile: more error position tests for the typechecker 2017-04-24 12:37:49 +00:00
complit.go
compos.go
const1.go cmd/compile: fix ICE from invalid operations on float/complex constants 2019-03-28 17:46:55 +00:00
const2.go
const3.go
const4.go
const5.go
const6.go
const.go cmd/compile: truncate constant arithmetic result with typed complex numbers 2019-08-28 19:45:44 +00:00
convert1.go
convert2.go
convert3.go
convert.go
convlit1.go
convlit.go cmd/compile: rewrite untyped constant conversion logic 2019-09-06 23:15:48 +00:00
convT2X.go
copy1.go cmd/compile: rewrite f(g()) for multi-value g() during typecheck 2019-03-14 21:00:20 +00:00
copy.go
crlf.go
ddd1.go cmd/compile: rewrite untyped constant conversion logic 2019-09-06 23:15:48 +00:00
ddd2.go
ddd.go
decl.go
declbad.go
defer.go
deferfin.go
deferprint.go test: remove rundircmpout and cmpout actions 2018-05-31 17:36:45 +00:00
deferprint.out
devirt.go cmd/compile: de-virtualize interface calls 2017-03-14 18:49:23 +00:00
divide.go
divmod.go
empty.go
env.go
eof1.go
eof.go
escape2.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape2n.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape3.go
escape4.go cmd/compile: skip escape analysis diagnostics for OADDR 2019-04-02 16:34:03 +00:00
escape5.go cmd/compile: silence esc diagnostics about directiface OCONVIFACEs 2019-09-03 17:52:06 +00:00
escape_array.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape_calls.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape_closure.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape_field.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape_goto.go cmd/compile: preserve loop depth when evaluating block 2019-09-06 01:35:46 +00:00
escape_iface.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape_indir.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape_level.go cmd/compile: silence esc diagnostics about directiface OCONVIFACEs 2019-09-03 17:52:06 +00:00
escape_map.go cmd/compile: silence esc diagnostics about directiface OCONVIFACEs 2019-09-03 17:52:06 +00:00
escape_param.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape_runtime_atomic.go test: fix escape_runtime_atomic.go 2019-04-17 22:55:26 +00:00
escape_selfassign.go test: add regress test cases for self-assignment 2019-04-17 16:36:56 +00:00
escape_slice.go cmd/compile: skip escape analysis diagnostics for OADDR 2019-04-02 16:34:03 +00:00
escape_struct_param1.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape_struct_param2.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
escape_struct_return.go test: remove -newescape from regress tests 2019-08-28 19:27:20 +00:00
escape_sync_atomic.go runtime/internal/atomic: remove bad go:noescape annotations on Loadp 2019-04-17 19:09:15 +00:00
escape_unsafe.go cmd/compile: silence esc diagnostics about directiface OCONVIFACEs 2019-09-03 17:52:06 +00:00
escape.go
fibo.go
finprofiled.go all: fix typos 2019-09-08 17:28:20 +00:00
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 all: skip unsupported tests for js/wasm 2018-04-30 19:39:18 +00:00
gc.go
gcgort.go test: fast GC+concurrency+types verification 2018-05-08 21:15:48 +00:00
gcstring.go
goprint.go test: remove rundircmpout and cmpout actions 2018-05-31 17:36:45 +00:00
goprint.out
goto.go cmd/compile: report block start for gotos jumping into blocks 2017-04-19 02:27:58 +00:00
heapsampling.go test: improve test coverage for heap sampling 2019-03-07 21:05:15 +00:00
helloworld.go test: remove rundircmpout and cmpout actions 2018-05-31 17:36:45 +00:00
helloworld.out
if.go
import1.go
import2.go
import4.go
import5.go cmd/compile: be slightly more tolerant in case of certain syntax errors 2017-03-24 20:07:15 +00:00
import6.go
import.go
index0.go
index1.go
index2.go
index.go all: fix typos 2019-09-08 17:28:20 +00:00
indirect1.go
indirect.go
init1.go
init.go cmd/compile: reorganize init functions 2019-03-18 20:10:55 +00:00
initcomma.go
initialize.go
initializerr.go cmd/compile: more error position tests for the typechecker 2017-04-24 12:37:49 +00:00
initloop.go
inline_big.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
inline_caller.go runtime: make FuncForPC return the innermost inlined frame 2019-01-08 21:54:04 +00:00
inline_callers.go runtime: make FuncForPC return the innermost inlined frame 2019-01-08 21:54:04 +00:00
inline_literal.go cmd/compile: copy literals when inlining 2017-03-03 21:29:32 +00:00
inline_math_bits_rotate.go cmd/compile: make math/bits.RotateLeft* an intrinsic on amd64 2018-08-30 22:48:28 +00:00
inline_sync.go cmd/compile: skip escape analysis diagnostics for OADDR 2019-04-02 16:34:03 +00:00
inline_variadic.go cmd/compile: enable inlining variadic functions 2018-03-13 20:34:03 +00:00
inline.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
int_lit.go
intcvt.go
intrinsic_atomic.go cmd/compile: intrinsify atomics on MIPS64 2017-10-10 19:43:38 +00:00
intrinsic.go
iota.go
label1.go cmd/compile/internal/gc: don't panic on continue in switch 2017-04-12 14:27:45 +00:00
label.go
linkmain_run.go all: skip unsupported tests for js/wasm 2018-04-30 19:39:18 +00:00
linkmain.go
linkname.go test: remove -newescape from regress tests 2019-08-28 19:27:20 +00:00
linkobj.go all: skip unsupported tests for js/wasm 2018-04-30 19:39:18 +00:00
linkx_run.go all: skip unsupported tests for js/wasm 2018-04-30 19:39:18 +00:00
linkx.go
literal2.go cmd/compile: accept 'i' suffix orthogonally on all numbers 2019-02-19 22:45:09 +00:00
literal.go
live1.go
live2.go cmd/compile: extend ssa.go to handle 1-element array and 1-field struct 2019-09-03 19:33:04 +00:00
live_syscall.go cmd/compile: trim function name prefix from escape diagnostics 2019-09-16 15:30:51 +00:00
live.go cmd/compile: extend ssa.go to handle 1-element array and 1-field struct 2019-09-03 19:33:04 +00:00
locklinear.go test: skip locklinear's lockmany test for now 2018-04-05 10:53:40 +00:00
loopbce.go cmd/compile: reverse order of slice bounds checks 2019-03-09 00:52:45 +00:00
makechan.go cmd/compile: generate makechan calls with int arguments 2017-08-15 05:54:24 +00:00
makemap.go test: check that size argument errors are emitted at call site 2018-03-14 08:36:15 +00:00
makenew.go cmd/compile: more error position tests for the typechecker 2017-04-24 12:37:49 +00:00
mallocfin.go
map1.go cmd/compile: more error position tests for the typechecker 2017-04-24 12:37:49 +00:00
map.go
mapclear.go cmd/compile: optimize map-clearing range idiom 2018-05-08 21:15:16 +00:00
maplinear.go
mergemul.go cmd/compile: combine x*n - y*n into (x-y)*n 2017-09-03 14:29:38 +00:00
method1.go
method2.go cmd/compile: add two error position tests for the typechecker 2017-10-12 20:50:20 +00:00
method3.go
method4.go
method5.go
method6.go cmd/compile: add two error position tests for the typechecker 2017-10-12 20:50:20 +00:00
method7.go cmd/compile: fix method expressions with anonymous receivers 2018-04-06 15:39:11 +00:00
method.go
named1.go
named.go
nil.go
nilcheck.go
nilptr2.go test: use a real use function in nilptr2.go 2019-05-11 03:02:33 +00:00
nilptr3.go cmd/compile: fix nilcheck for AIX 2018-11-26 14:13:53 +00:00
nilptr4.go
nilptr5_aix.go test: fix nilptr5 for AIX 2018-11-27 15:36:08 +00:00
nilptr5_wasm.go cmd/compile: fix nilcheck for AIX 2018-11-26 14:13:53 +00:00
nilptr5.go cmd/compile: fix nilcheck for AIX 2018-11-26 14:13:53 +00:00
nilptr_aix.go cmd/compile: fix nilcheck for AIX 2018-11-26 14:13:53 +00:00
nilptr.go cmd/compile: fix nilcheck for AIX 2018-11-26 14:13:53 +00:00
nosplit.go ../test: set GOPATH in nosplit.go 2019-03-12 20:46:29 +00:00
notinheap2.go
notinheap3.go cmd/compile: omit write barriers for slice clears of go:notinheap pointers 2018-12-05 21:54:54 +00:00
notinheap.go cmd/compile: disallow converting string to notinheap slice 2018-11-02 19:53:59 +00:00
nowritebarrier.go cmd/compile: improve coverage of nowritebarrierrec check 2017-10-29 19:36:44 +00:00
nul1.go
opt_branchlikely.go all: fix typos 2019-09-08 17:28:20 +00:00
parentype.go
peano.go all: skip unsupported tests for js/wasm 2018-04-30 19:39:18 +00:00
phiopt.go
print.go test: remove rundircmpout and cmpout actions 2018-05-31 17:36:45 +00:00
print.out cmd/compile: fix print/println when input is uint 2017-09-26 04:08:38 +00:00
printbig.go test: remove rundircmpout and cmpout actions 2018-05-31 17:36:45 +00:00
printbig.out
prove.go cmd/compile: handle sign/zero extensions in prove, via update method 2019-08-27 16:46:34 +00:00
range.go cmd/compile: improve single blank variable handling in walkrange 2017-09-12 05:50:54 +00:00
README.md test: use the version of Go used to run run.go 2018-03-03 19:52:00 +00:00
recover1.go
recover2.go cmd/compile,runtime: generate hash functions only for types which are map keys 2019-09-03 20:41:29 +00:00
recover3.go
recover4.go all: use Fatalf instead of Fatal if format is given 2018-01-10 01:35:45 +00:00
recover5.go cmd/compile: more error position tests for the typechecker 2017-04-24 12:37:49 +00:00
recover.go
reflectmethod1.go
reflectmethod2.go
reflectmethod3.go
reflectmethod4.go
rename1.go cmd/compile: rewrite untyped constant conversion logic 2019-09-06 23:15:48 +00:00
rename.go
reorder2.go
reorder.go
retjmp.go cmd/asm: fix assembling return jump 2018-03-01 21:11:16 +00:00
return.go
rotate0.go
rotate1.go
rotate2.go
rotate3.go
rotate.go
run.go test/fixedbugs: fix some tests will not be run 2019-05-23 01:39:41 +00:00
rune.go
runtime.go
shift1.go cmd/compile: rewrite untyped constant conversion logic 2019-09-06 23:15:48 +00:00
shift2.go
sieve.go
sigchld.go test: remove rundircmpout and cmpout actions 2018-05-31 17:36:45 +00:00
sigchld.out
simassign.go
sinit_run.go all: skip unsupported tests for js/wasm 2018-04-30 19:39:18 +00:00
sinit.go cmd/compile: fix static initializer 2018-12-03 16:48:21 +00:00
sizeof.go
slice3.go
slice3err.go
slicecap.go
sliceopt.go cmd/compile: make prove pass use unsatisfiability 2018-03-08 22:25:25 +00:00
solitaire.go
stack.go
stackobj2.go test: stress test for stack objects 2018-10-03 19:54:29 +00:00
stackobj3.go cmd/compile,runtime: remove ambiguously live logic 2018-10-03 19:54:16 +00:00
stackobj.go cmd/compile,runtime: remove ambiguously live logic 2018-10-03 19:54:16 +00:00
strcopy.go test: add test to verify that string copies don't get optimized away 2018-06-12 19:10:34 +00:00
strength.go all: fix typos 2019-09-08 17:28:20 +00:00
string_lit.go
stringrange.go
struct0.go
switch2.go
switch3.go
switch4.go
switch5.go Revert "fmt: fix incorrect format of whole-number floats when using %#v" 2018-10-16 21:54:35 +00:00
switch6.go
switch7.go cmd/compile: make duplicate expr cases readable 2017-05-19 18:11:51 +00:00
switch.go
tinyfin.go
torture.go
turing.go
typecheck.go
typecheckloop.go
typeswitch1.go
typeswitch2.go cmd/compile: move duplicate type-case checking into typecheck 2019-09-11 23:33:11 +00:00
typeswitch2b.go cmd/compile: move duplicate type-case checking into typecheck 2019-09-11 23:33:11 +00:00
typeswitch3.go test: fix spelling of caught be the compiler to caught by the compiler 2018-10-04 00:49:49 +00:00
typeswitch.go
uintptrescapes2.go cmd/compile: better integrate parameter tagging with escape.go 2019-09-10 23:01:30 +00:00
uintptrescapes.go
undef.go
utf.go
varerr.go
varinit.go
writebarrier.go cmd/compile: better write barrier removal when initializing new objects 2019-03-18 21:16:19 +00:00
zerodivide.go

README.md

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.