This is bad for 2 reasons:
1. if the code under lock ever grows stack,
it will deadlock as stack growing acquires mheap lock.
2. It currently deadlocks with SetCPUProfileRate:
scavenger locks mheap, receives prof signal and tries to lock prof lock;
meanwhile SetCPUProfileRate locks prof lock and tries to grow stack
(presumably in runtime.unlock->futexwakeup). Boom.
Let's assume that it
Fixes#8407.
LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews, khr
https://golang.org/cl/112640043
With cl/112640043 TestCgoDeadlockCrash episodically print:
unexpected return pc for runtime.newstackcall
After adding debug output I see the following trace:
runtime: unexpected return pc for runtime.newstackcall called from 0xc208011b00
runtime.throw(0x414da86)
src/pkg/runtime/panic.c:523 +0x77
runtime.gentraceback(0x40165fc, 0xba440c28, 0x0, 0xc208d15200, 0xc200000000, 0xc208ddfd20, 0x20, 0x0, 0x0, 0x300)
src/pkg/runtime/traceback_x86.c:185 +0xca4
runtime.callers(0x1, 0xc208ddfd20, 0x20)
src/pkg/runtime/traceback_x86.c:438 +0x98
mcommoninit(0xc208ddfc00)
src/pkg/runtime/proc.c:369 +0x5c
runtime.allocm(0xc208052000)
src/pkg/runtime/proc.c:686 +0xa6
newm(0x4017850, 0xc208052000)
src/pkg/runtime/proc.c:933 +0x27
startm(0xc208052000, 0x100000001)
src/pkg/runtime/proc.c:1011 +0xba
wakep()
src/pkg/runtime/proc.c:1071 +0x57
resetspinning()
src/pkg/runtime/proc.c:1297 +0xa1
schedule()
src/pkg/runtime/proc.c:1366 +0x14b
runtime.gosched0(0xc20808e240)
src/pkg/runtime/proc.c:1465 +0x5b
runtime.newstack()
src/pkg/runtime/stack.c:891 +0x44d
runtime: unexpected return pc for runtime.newstackcall called from 0xc208011b00
runtime.newstackcall(0x4000cbd, 0x4000b80)
src/pkg/runtime/asm_amd64.s:278 +0x6f
I suspect that it can happen on any stack split.
So don't unwind g0 stack.
Also, that comment is lying -- we can traceback w/o mcache,
CPU profiler does that.
LGTM=rsc
R=golang-codereviews
CC=golang-codereviews, khr, rsc
https://golang.org/cl/120040043
There are fields in the Addr that do not matter for the
purpose of deciding that the same word is already
in the current literal pool. Copy only the fields that
do matter.
This came up when comparing against the Go version
because the way it is invoked doesn't copy a few fields
(like node) that are never directly used by liblink itself.
Also remove a stray print that is not well-defined in
the new liblink. (Cannot use %D outside of %P, because
%D needs the outer Prog*.)
LGTM=minux
R=minux
CC=golang-codereviews
https://golang.org/cl/119000043
This matches Go's fmt.Printf instead of ANSI C's dumb rules.
It makes the -S output from C liblink match Go's liblink.
LGTM=minux
R=minux
CC=golang-codereviews
https://golang.org/cl/112600043
They do not, but pretend that they do.
The immediate need is that it breaks the new GC because
these are weird symbols as if with pointers but not necessary
pointer aligned.
LGTM=rsc
R=golang-codereviews, dave, josharian, khr, rsc
CC=golang-codereviews, iant, khr, rlh
https://golang.org/cl/116060043
I've found this very useful for generating
good test case lists for -short mode for
the disassemblers.
Fixes#7959.
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/98150043
Currently they are scanned conservatively.
But there is no reason to scan them. C world must not contain
pointers into Go heap. Moreover, we don't have enough information
to emit write barriers nor update pointers there in future.
The immediate need is that it breaks the new GC because
these are weird symbols as if with pointers but not necessary
pointer aligned.
LGTM=rsc
R=golang-codereviews, rlh, rsc
CC=golang-codereviews, iant, khr
https://golang.org/cl/117000043
In the runtime, we want to control where allocations happen.
In particular, we don't want the code implementing malloc to
itself trigger a malloc. This change prevents the compiler
from inserting mallocs on our behalf (due to escaping declarations).
This check does not trigger on the current runtime code.
Note: Composite literals are still allowed.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/105280047
So we can tell from a binary which version of
Go built it.
LGTM=minux, rsc
R=golang-codereviews, minux, khr, rsc, dave
CC=golang-codereviews
https://golang.org/cl/117040043
This is more useful than panicking, since otherwise every caller needs
to do the length check before calling; some will forget, and have a
potential submarine crasher as a result. Other implementations of this
functionality do a length check.
This is backward compatible, except if someone has written code that
relies on this panicking with different length args. However, that was
not the case before Go 1.3 either.
Updates #7304.
LGTM=agl
R=agl, minux, hanwen
CC=golang-codereviews
https://golang.org/cl/118750043
In both cases we lie to malloc about the actual size that we need.
In panic we ask for less memory than we are going to use.
In slice we ask for more memory than we are going to use
(potentially asking for a fractional number of elements).
This breaks the new GC.
LGTM=khr
R=golang-codereviews, dave, khr
CC=golang-codereviews, rsc
https://golang.org/cl/116940043
Rewrite gotos that violate Go's stricter rules.
Use uchar* instead of char* in a few places that aren't strings.
Remove dead opcross code from asm5.c.
Declare regstr (in both list6 and list8) static.
LGTM=minux, dave
R=minux, dave
CC=golang-codereviews
https://golang.org/cl/113230043
Even though pointers are 4 bytes the stack frame should be kept
a multiple of 8 bytes so that return addresses pushed on the stack
are properly aligned.
Fixes#8379.
LGTM=dvyukov, minux
R=minux, bradfitz, dvyukov, dave
CC=golang-codereviews
https://golang.org/cl/115840048
We might want to add a go/build.IsInternal(pkg string) bool
later, but this works for now.
LGTM=dave, rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/113300044
These correspond to 2 and 3 word fat copies/clears on 8g, which dominate usage in the stdlib. (70% of copies and 46% of clears are for 2 or 3 words.) I missed these in CL 111350043, which added 2 and 3 word benchmarks for 6g. A follow-up CL will optimize these cases.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/115160043
I'm improving gccgo's detection of variables that are only set
but not used, and it triggers additional errors on this code.
The new gccgo errors are correct; gc seems to suppress them
due to the other, expected, errors. This change uses the
variables so that no compiler will complain.
gccgo change is https://golang.org/cl/119920043 .
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/116050043
benchmark old ns/op new ns/op delta
BenchmarkSelectUncontended 220 165 -25.00%
BenchmarkSelectContended 209 161 -22.97%
BenchmarkSelectProdCons 1042 904 -13.24%
But more importantly this change will allow
to get rid of free function in runtime.
Fixes#6494.
LGTM=rsc, khr
R=golang-codereviews, rsc, dominik.honnef, khr
CC=golang-codereviews, remyoudompheng
https://golang.org/cl/107670043
This is a temporary change to see how far the
builder gets when it times out.
LGTM=aram, 0intro
R=0intro, aram
CC=golang-codereviews, mischief
https://golang.org/cl/111400043
Fix virtual address of the start of the text segment
on amd64 Plan 9.
This issue has been partially fixed in cmd/add2line,
as part of CL 106460044, but we forgot to report the
change to cmd/objdump.
In the meantime, we also fixed the textStart address
in both cmd/add2line and cmd/objdump.
LGTM=aram, ality, mischief
R=rsc, mischief, aram, ality
CC=golang-codereviews, jas
https://golang.org/cl/117920043
Hook pre-commit runs before 'hg commit' command whereas hook precommit runs
after the user has entered commit message.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/106320043
The CopyFat benchmarks were changed in CL 92760044. See CL 111350043 for discussion.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/116000043
These benchmarks are important for performance. When compiling the stdlib:
* 77.1% of the calls to sgen (copyfat) are for 16 bytes; another 8.7% are for 24 bytes. (The next most common is 32 bytes, at 5.7%.)
* Over half the calls to clearfat are for 16 or 24 bytes.
LGTM=khr
R=golang-codereviews, khr
CC=golang-codereviews
https://golang.org/cl/111350043
Ken's standalone file server and its derivatives, like cwfs, return
error strings different from fossil when the user opens non-existent
files.
LGTM=aram, 0intro, r
R=0intro, aram, r
CC=golang-codereviews, ken
https://golang.org/cl/112420045
Also, fix a write check in writeBuf and make some bounds checks simpler.
LGTM=gri
R=golang-codereviews, adg, gri, r, minux
CC=golang-codereviews
https://golang.org/cl/113060043
updatememstats is called on both the m and g stacks.
Call into flushallmcaches correctly. flushallmcaches
can only run on the M stack.
This is somewhat temporary. once ReadMemStats is in
Go we can have all of this code M-only.
LGTM=dvyukov
R=golang-codereviews, dvyukov
CC=golang-codereviews
https://golang.org/cl/116880043
Encoder compilation must be enc-independent,
because the resulting program is reused across
different encoders.
LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/115860043
Breaks build for FreeBSD. Probably clang related?
««« original CL description
cmd/cgo: disable inappropriate warnings when the gcc struct is empty
package main
//#cgo CFLAGS: -Wall
//void test() {}
import "C"
func main() {
C.test()
}
This code will cause gcc issuing warnings about unused variable.
This commit use offset of the second return value of
Packages.structType to detect whether the gcc struct is empty,
and if it's directly invoke the C function instead of writing an
unused code.
LGTM=dave, minux
R=golang-codereviews, iant, minux, dave
CC=golang-codereviews
https://golang.org/cl/109640045
»»»
TBR=dfc
R=dave
CC=golang-codereviews
https://golang.org/cl/114990044
package main
//#cgo CFLAGS: -Wall
//void test() {}
import "C"
func main() {
C.test()
}
This code will cause gcc issuing warnings about unused variable.
This commit use offset of the second return value of
Packages.structType to detect whether the gcc struct is empty,
and if it's directly invoke the C function instead of writing an
unused code.
LGTM=dave, minux
R=golang-codereviews, iant, minux, dave
CC=golang-codereviews
https://golang.org/cl/109640045
redo stack allocation. This is mostly the same as
the original CL with a few bug fixes.
1. add racemalloc() for stack allocations
2. fix poolalloc/poolfree to terminate free lists correctly.
3. adjust span ref count correctly.
4. don't use cache for sizes >= StackCacheSize.
Should fix bugs and memory leaks in original changelist.
««« original CL description
undo CL 104200047 / 318b04f28372
Breaks windows and race detector.
TBR=rsc
««« original CL description
runtime: stack allocator, separate from mallocgc
In order to move malloc to Go, we need to have a
separate stack allocator. If we run out of stack
during malloc, malloc will not be available
to allocate a new stack.
Stacks are the last remaining FlagNoGC objects in the
GC heap. Once they are out, we can get rid of the
distinction between the allocated/blockboundary bits.
(This will be in a separate change.)
Fixes#7468Fixes#7424
LGTM=rsc, dvyukov
R=golang-codereviews, dvyukov, khr, dave, rsc
CC=golang-codereviews
https://golang.org/cl/104200047
»»»
TBR=rsc
CC=golang-codereviews
https://golang.org/cl/101570044
»»»
LGTM=dvyukov
R=dvyukov, dave, khr, alex.brainman
CC=golang-codereviews
https://golang.org/cl/112240044
Resolves TODO for not walking all goroutines in NumGoroutines.
LGTM=khr
R=golang-codereviews, khr
CC=golang-codereviews, rsc
https://golang.org/cl/107290044
