The .note.GNU-stack section tells the linker that this object does not
require an executable stack.
The .note.GNU-split-stack section tells the linker that functions in
this object can be called directly by split-stack functions, without
require a large stack.
The .note.GNU-no-split-stack section tells the linker that functions
in this object do not have a split-stack prologue.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/198440
From-SVN: r276488
PR go/91781
reflect: promote integer closure return to full word
The libffi library expects an integer return type to be promoted to a
full word. Implement that when returning from a closure written in Go.
This only matters on big-endian systems when returning an integer smaller
than the pointer size, which is why we didn't notice it until now.
Fixes https://gcc.gnu.org/PR91781.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/195858
From-SVN: r275813
Permit putting structs with anonymous and empty fields in the C header
file runtime.inc that is used to build the C runtime code. This is
required for upcoming 1.13 support, as the m struct has picked up an
anonymous field.
Doing this lets the C header contain all the type descriptor structs,
so start using those in the C code. This cuts the number of copies of
type descriptor definitions from 3 to 2.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/192343
From-SVN: r275227
This is a step toward updating libgo to 1.13. This adds the 1.13
version of the osinit function to Go code, and removes the
corresponding code from the C runtime. This should simplify future updates.
Some additional 1.13 code was brought in to simplify this change.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/191717
From-SVN: r275010
Currently, getg is implemented in C, which loads the thread-local
g variable. The g variable is declared static in C.
This CL exposes the g variable, so it can be accessed from the Go
side. This allows the Go compiler to inline getg calls to direct
access of g.
Currently, the actual inlining is only implemented in the gollvm
compiler. The g variable is thread-local and the compiler backend
may choose to cache the TLS address in a register or on stack. If
a thread switch happens the cache may become invalid. I don't
know how to disable the TLS address cache in gccgo, therefore
the inlining of getg is not implemented. In the future gccgo may
gain this if we know how to do it safely.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/186238
From-SVN: r273499
Instead of going through a C function __go_memcmp, we can just
use __builtin_memcmp directly. This allows more optimizations in
the compiler backend.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/183537
From-SVN: r272620
Currently a string slice expression is implemented with a runtime
call __go_string_slice. Change it to open code it, which is more
efficient, and allows the backend to further optimize it.
Also omit the write barrier for length-only update (i.e.
s = s[:n]).
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/182540
From-SVN: r272549
When the runtime collects a stack trace to associate it with some
profiling event (mem alloc, mutex, etc) there is a skip count passed
to runtime.Callers (or equivalent) to skip some known count of frames
in order to get to the "interesting" frame corresponding to the
profile event. Now that the profiling mechanism uses lazy fixup (when
removing compiler artifacts like thunks, morestack calls etc), we also
need to move the frame skipping logic after the fixup, so as to insure
that the skip count isn't thrown off by these artifacts.
Fixesgolang/go#32290.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/179740
From-SVN: r271892
The gc compiler recognizes append(s, make([]T, n)...), and
generates code to directly zero the tail instead of allocating a
new slice and copying. This CL lets the Go frontend do basically
the same.
The difficulty is that at the point we handle append, there may
already be temporaries introduced (e.g. in order_evaluations),
which makes it hard to find the append-of-make pattern. The
compiler could "see through" the value of a temporary, but it is
only safe to do if the temporary is not assigned multiple times.
For this, we add tracking of assignments and uses for temporaries.
This also helps in optimizing non-escape slice make. We already
optimize non-escape slice make with constant len/cap to stack
allocation. But it failed to handle things like f(make([]T, n))
(where the slice doesn't escape and n is constant), because of
the temporary. With tracking of temporary assignments and uses,
it can handle this now as well.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/179597
From-SVN: r271822
Currently, goroutine switches are implemented with libc
getcontext/setcontext functions, which saves/restores the machine
register states and also the signal context. This does more than
what we need, and performs an expensive syscall.
This CL implements a simplified version of getcontext/setcontext,
in assembly, that only saves/restores the necessary part, i.e.
the callee-save registers, and the PC, SP. A simplified version
of makecontext, written in C, is also added. Currently this is
only implemented on Linux/AMD64.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/178298
From-SVN: r271818
Revise the gccgo version of memory/block/mutex profiling to reduce
runtime overhead. The main change is to collect raw stack traces while
the profile is on line, then post-process the stacks just prior to the
point where we are ready to use the final product. Memory profiling
(at a very low sampling rate) is enabled by default, and the overhead
of the symbolization / DWARF-reading from backtrace_full was slowing
things down relative to the main Go runtime.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/171497
From-SVN: r271172
runtime.throw needs a g to work properly. Set up g early, to
ensure that if something goes wrong in the runtime startup (e.g.
runtime.check fails), the program terminates in a reasonable way.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/176657
From-SVN: r271088
A direct interface is an interface whose data word contains the
actual data value, instead of a pointer to it. The gc toolchain
creates a direct interface if the value is pointer shaped, that
includes pointers (including unsafe.Pointer), functions, channels,
maps, and structs and arrays containing a single pointer-shaped
field. In gccgo, we only do this for pointers. This CL unifies
direct interface types with gc. This reduces allocations when
converting such types to interfaces.
Our method functions used to always take pointer receivers, to
make interface calls easy. Now for direct interface types, their
value methods will take value receivers. For a pointer to those
types, when converted to interface, the interface data contains
the pointer. For that interface to call a value method, it will
need a wrapper method that dereference the pointer and invokes
the value method. The wrapper method, instead of the actual one,
is put into the itable of the pointer type.
In the runtime, adjust funcPC for the new layout of interfaces of
functions.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/168409
From-SVN: r270779
Since aix/ppc64 has been added to GC toolchain, a mix between new and
old files were created in gcc toolchain.
This commit corrects this merge for aix/ppc64 and aix/ppc.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/167658
From-SVN: r269797
In signal-triggered stack scan, if the signal is delivered at
certain bad time (e.g. in vdso, or in the middle of setcontext?),
the unwinder may not be able to unwind the whole stack, while it
still reports _URC_END_OF_STACK. So we cannot rely on _URC_END_OF_STACK
to tell if it successfully scanned the stack. Instead, we check
the last Go frame to see it actually reached the end of the stack.
For Go-created stack, this is runtime.kickoff. For C-created
stack, we need to record the outermost Go frame when it enters
the Go side.
Also we cannot unwind the stack if the signal is delivered in the
middle of runtime.gogo, halfway through a goroutine switch, where
the g and the stack don't match. Give up in this case as well.
Reviewed-on: https://go-review.googlesource.com/c/159098
From-SVN: r269018
Currently, the compiler lowers runtime.getcallersp to
__builtin_frame_address(1). In the C side of the runtime,
getcallersp is defined as __builtin_frame_address(0). They don't
match. Further, neither of them actually returns the caller's SP.
On AMD64, __builtin_frame_address(0) just returns the frame
pointer. __builtin_frame_address(1) returns the memory content
where the frame pointer points to, which is typically the
caller's frame pointer but can also be garbage if the frame
pointer is not enabled.
This CL changes it to use __builtin_dwarf_cfa(), which returns
the caller's SP at the call site. This matches the SP we get
from unwinding the stack.
Currently getcallersp is not used for anything real. It will be
used for precise stack scan (a new version of CL 159098).
Reviewed-on: https://go-review.googlesource.com/c/162905
* go-gcc.cc (Gcc_backend::Gcc_backend): Define __builtin_dwarf_cfa
instead of __builtin_frame_address.
From-SVN: r268952
Compiling with LTO revealed a number of cases in the runtime and
standard library where C and Go disagreed about the type of an object or
function (or where Go and code generated by the compiler disagreed). In
all cases the underlying representation was the same (e.g., uintptr vs.
void*), so this wasn't causing actual problems, but it did result in a
number of annoying warnings when compiling with LTO.
Reviewed-on: https://go-review.googlesource.com/c/160700
From-SVN: r268923
GCC has supported the __atomic intrinsics since 4.7. They are better
than the __sync intrinsics in that they specify a memory model and,
more importantly for our purposes, they are reliably implemented
either in the compiler or in libatomic.
Fixes https://gcc.gnu.org/PR52084
Reviewed-on: https://go-review.googlesource.com/c/160820
From-SVN: r268458
If a panic happens in the runtime we turn that into a fatal error.
We use the caller's PC to determine if the panic call is inside
the runtime. getcallerpc returns the PC immediately after the
call instruction. If the call is the very last instruction of a
function, it may not find this PC belong to a runtime function,
giving false result. We need to back off the PC by 1 to the call
instruction.
The gc runtime doesn't do this because the gc compiler always
emit an instruction following a panic call, presumably an UNDEF
instruction which turns into an architecture-specific illegal
instruction. Our compiler doesn't do this.
Reviewed-on: https://go-review.googlesource.com/c/159437
From-SVN: r268358
Restore some of the fixes that were applied to golang_org/x/net/lif
but were lost when 1.12 moved the directory to internal/x/net/lif.
Add support for reading /proc to fetch argc/argv/env for c-archive mode.
Reviewed-on: https://go-review.googlesource.com/c/158640
From-SVN: r268130
Reviewed-on: https://go-review.googlesource.com/c/158019
gotools/:
* Makefile.am (go_cmd_vet_files): Update for Go1.12beta2 release.
(GOTOOLS_TEST_TIMEOUT): Increase to 600.
(check-runtime): Export LD_LIBRARY_PATH before computing GOARCH
and GOOS.
(check-vet): Copy golang.org/x/tools into check-vet-dir.
* Makefile.in: Regenerate.
gcc/testsuite/:
* go.go-torture/execute/names-1.go: Stop using debug/xcoff, which
is no longer externally visible.
From-SVN: r268084
This is following CL 156038. doscanstackswitch uses the same
mechanism of switching goroutines as getTraceback, and so has
the same problem as described in issue golang/go#29448. This CL
applies the same fix.
Reviewed-on: https://go-review.googlesource.com/c/156697
From-SVN: r267661
Currently, when collecting a traceback for another goroutine,
getTraceback calls gogo(gp) switching to gp, which will resume in
mcall, which will call gtraceback, which will set up gp->m. There
is a gap between setting the current running g to gp and setting
gp->m. If a profiling signal arrives in between, sigtramp will
see a non-nil gp with a nil m, and will seg fault. Fix this by
setting up gp->m first.
Fixesgolang/go#29448.
Reviewed-on: https://go-review.googlesource.com/c/156038
From-SVN: r267658
Traceback routines, e.g. callers and funcentry, may call
__go_get_backtrace_state. If a profiling signal arrives while we
are in the critical section of __go_get_backtrace_state, it tries
to do a traceback, which also calls __go_get_backtrace_state,
which tries to enter the same critical section and will deadlock.
Prevent this deadlock by setting up runtime_in_callers before
calling __go_get_backtrace_state.
Found while investigating golang/go#29448. Will add a test in the
next CL.
Updates golang/go#29448.
Reviewed-on: https://go-review.googlesource.com/c/156037
From-SVN: r267590
Precise stack scan needs to unwind the stack. When it is
unwinding the stack, if a profiling signal arrives, which also
does a traceback, it may deadlock in dl_iterate_phdr. Prevent
this deadlock by setting up runtime_in_callers before traceback.
Reviewed-on: https://go-review.googlesource.com/c/155766
From-SVN: r267457
On ARM32 EABI, unlike other platforms, the personality function is
called during _Unwind_Backtrace (libgcc/unwind-arm-common.inc:581).
In this case, simply unwind the frame without returning any
handlers. Otherwise traceback will loop if there is a frame with
a defer on stack.
Reviewed-on: https://go-review.googlesource.com/c/155759
From-SVN: r267434
On ARM32 EABI, when the "compact" unwinding model is used, it
does not have standard LSDA and _Unwind_GetLanguageSpecificData
will not return data that is parseable by us. Check this
conditon before calling _Unwind_GetLanguageSpecificData.
Fix ARM32 build.
Reviewed-on: https://go-review.googlesource.com/c/155758
From-SVN: r267428
The type table encoding can be DW_EH_PE_absptr, but this case
was missing, which was causing abort on ARM32 EABI. Add the
missing case.
Reviewed-on: https://go-review.googlesource.com/c/153857
From-SVN: r267070
ARM32 EABI unwinder does not define _URC_NORMAL_STOP. Instead,
it has _URC_FAILURE. Use _URC_FAILURE there.
Should fix ARM32 build.
Reviewed-on: https://go-review.googlesource.com/c/153417
From-SVN: r267033
This CL adds support of precise stack scan using stack maps to
the runtime. The stack maps are generated by the compiler (if
supported). Each safepoint is associated with a (real or dummy)
landing pad, and its "type info" in the exception table is a
pointer to the stack map. When a stack is scanned, the stack map
is found by the stack unwinding code by inspecting the exception
table (LSDA).
For precise stack scan we need to unwind the stack. There are
three cases:
- If a goroutine is scanning its own stack, it can unwind the
stack and scan the frames.
- If a goroutine is scanning another, stopped, goroutine, it
cannot directly unwind the target stack. We handle this by
switching (runtime.gogo) to the target g, letting it unwind
and scan the stack, and switch back.
- If we are scanning a goroutine that is blocked in a syscall,
we send a signal to the target goroutine's thread, and let the
signal handler unwind and scan the stack. Extra care is needed
as this races with enter/exit syscall.
Currently this is only implemented on linux.
Reviewed-on: https://go-review.googlesource.com/c/140518
From-SVN: r266832
Rewrite the arm64 AES hashing code from gc assembler to C code using
intrinsics. The resulting code generates the same hash code for the
same input as the gc code--that doesn't matter as such, but testing it
ensures that the C code does something useful.
Reviewed-on: https://go-review.googlesource.com/138535
From-SVN: r264771
Reviewed-on: https://go-review.googlesource.com/136435
gotools/:
* Makefile.am (mostlyclean-local): Run chmod on check-go-dir to
make sure it is writable.
(check-go-tools): Likewise.
(check-vet): Copy internal/objabi to check-vet-dir.
* Makefile.in: Rebuild.
From-SVN: r264546
Unlike the gc runtime, libgo stores traceback information in location
structs, which contain strings. Therefore, copying location structs
around appears to require write barriers, although in fact write
barriers are never important because the strings are never allocated
in Go memory. They come from libbacktrace.
Some of the generated write barriers come at times when write barriers
are not permitted. For example, exitsyscall, marked
nowritebarrierrec, calls exitsyscallfast which calls traceGoSysExit
which calls traceEvent which calls traceStackID which calls
trace.stackTab.put which copies location values into memory allocated
by tab.newStack. This write barrier can be invoked when there is no
p, causing a crash.
This change fixes the problem by ensuring that location values are
copied around in the tracing code with no write barriers.
This was found by fixing the compiler to fully implement
//go:nowritebarrierrec; CL to follow.
Reviewed-on: https://go-review.googlesource.com/134226
From-SVN: r264282
This is a port of https://golang.org/cl/109596 to the gofrontend, in
preparation for updating libgo to 1.11.
Original CL description:
getcallersp is intrinsified, and so the dummy arg is no longer
needed. Remove it, as well as a few dummy args that are solely
to feed getcallersp.
Reviewed-on: https://go-review.googlesource.com/131116
From-SVN: r263840
USING_SPLIT_STACK is configured as defined/undefined, not 0/1.
Most of the places test USING_SPLIT_STACK with #ifdef, with a
few exceptions. This CL fixes the exceptions.
Reviewed-on: https://go-review.googlesource.com/120596
From-SVN: r261980
