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https://github.com/golang/go
synced 2024-11-19 17:14:44 -07:00
a5d1a72a40
Acquire and release the TSAN synchronization point when calling malloc, just as we do when calling any other C function. If we don't do this, TSAN will report false positive errors about races calling malloc and free. We used to have a special code path for malloc and free, going through the runtime functions cmalloc and cfree. The special code path for cfree was no longer used even before this CL. This CL stops using the special code path for malloc, because there is no place along that path where we could conditionally insert the TSAN synchronization. This CL removes the support for the special code path for both functions. Instead, cgo now automatically generates the malloc function as though it were referenced as C.malloc. We need to automatically generate it even if C.malloc is not called, even if malloc and size_t are not declared, to support cgo-provided functions like C.CString. Change-Id: I829854ec0787a80f33fa0a8a0dc2ee1d617830e2 Reviewed-on: https://go-review.googlesource.com/23260 Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Austin Clements <austin@google.com>
51 lines
1.9 KiB
Go
51 lines
1.9 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import "unsafe"
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//go:cgo_export_static main
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// Filled in by runtime/cgo when linked into binary.
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//go:linkname _cgo_init _cgo_init
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//go:linkname _cgo_thread_start _cgo_thread_start
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//go:linkname _cgo_sys_thread_create _cgo_sys_thread_create
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//go:linkname _cgo_notify_runtime_init_done _cgo_notify_runtime_init_done
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//go:linkname _cgo_callers _cgo_callers
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//go:linkname _cgo_set_context_function _cgo_set_context_function
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var (
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_cgo_init unsafe.Pointer
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_cgo_thread_start unsafe.Pointer
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_cgo_sys_thread_create unsafe.Pointer
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_cgo_notify_runtime_init_done unsafe.Pointer
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_cgo_callers unsafe.Pointer
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_cgo_set_context_function unsafe.Pointer
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)
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// iscgo is set to true by the runtime/cgo package
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var iscgo bool
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// cgoHasExtraM is set on startup when an extra M is created for cgo.
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// The extra M must be created before any C/C++ code calls cgocallback.
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var cgoHasExtraM bool
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// cgoUse is called by cgo-generated code (using go:linkname to get at
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// an unexported name). The calls serve two purposes:
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// 1) they are opaque to escape analysis, so the argument is considered to
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// escape to the heap.
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// 2) they keep the argument alive until the call site; the call is emitted after
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// the end of the (presumed) use of the argument by C.
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// cgoUse should not actually be called (see cgoAlwaysFalse).
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func cgoUse(interface{}) { throw("cgoUse should not be called") }
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// cgoAlwaysFalse is a boolean value that is always false.
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// The cgo-generated code says if cgoAlwaysFalse { cgoUse(p) }.
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// The compiler cannot see that cgoAlwaysFalse is always false,
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// so it emits the test and keeps the call, giving the desired
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// escape analysis result. The test is cheaper than the call.
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var cgoAlwaysFalse bool
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