cmd/link,runtime: switch openbsd/amd64 to pthreads

This switches openbsd/amd64 to thread creation via pthreads, rather than doing
direct system calls.

Update #36435

Change-Id: I1105d5c392aa3e4c445d99c8cb80b927712e3529
Reviewed-on: https://go-review.googlesource.com/c/go/+/250180
Trust: Joel Sing <joel@sing.id.au>
Run-TryBot: Joel Sing <joel@sing.id.au>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 0 insertions, 44 deletions

diff --git a/src/runtime/sys_darwin.go b/src/runtime/sys_darwin.go
index 55845bf2e5..4a3f2fc453 100644
--- a/src/runtime/sys_darwin.go
+++ b/src/runtime/sys_darwin.go
@@ -6,50 +6,6 @@ package runtime
 
 import "unsafe"
 
-// Call fn with arg as its argument. Return what fn returns.
-// fn is the raw pc value of the entry point of the desired function.
-// Switches to the system stack, if not already there.
-// Preserves the calling point as the location where a profiler traceback will begin.
-//go:nosplit
-func libcCall(fn, arg unsafe.Pointer) int32 {
-	// Leave caller's PC/SP/G around for traceback.
-	gp := getg()
-	var mp *m
-	if gp != nil {
-		mp = gp.m
-	}
-	if mp != nil && mp.libcallsp == 0 {
-		mp.libcallg.set(gp)
-		mp.libcallpc = getcallerpc()
-		// sp must be the last, because once async cpu profiler finds
-		// all three values to be non-zero, it will use them
-		mp.libcallsp = getcallersp()
-	} else {
-		// Make sure we don't reset libcallsp. This makes
-		// libcCall reentrant; We remember the g/pc/sp for the
-		// first call on an M, until that libcCall instance
-		// returns.  Reentrance only matters for signals, as
-		// libc never calls back into Go.  The tricky case is
-		// where we call libcX from an M and record g/pc/sp.
-		// Before that call returns, a signal arrives on the
-		// same M and the signal handling code calls another
-		// libc function.  We don't want that second libcCall
-		// from within the handler to be recorded, and we
-		// don't want that call's completion to zero
-		// libcallsp.
-		// We don't need to set libcall* while we're in a sighandler
-		// (even if we're not currently in libc) because we block all
-		// signals while we're handling a signal. That includes the
-		// profile signal, which is the one that uses the libcall* info.
-		mp = nil
-	}
-	res := asmcgocall(fn, arg)
-	if mp != nil {
-		mp.libcallsp = 0
-	}
-	return res
-}
-
 // The X versions of syscall expect the libc call to return a 64-bit result.
 // Otherwise (the non-X version) expects a 32-bit result.
 // This distinction is required because an error is indicated by returning -1,