gh-99633: Inline independent coroutine check

The functions `_PyGen_ActivateContext` and `_PyGen_DeactivateContext`
are called every time a value or exception is sent to a coroutine.
These functions are no-ops for dependent coroutines (coroutines
without their own independent context stack).  Coroutines are
dependent by default, and the vast majority of performance-sensitive
coroutines are expected to be dependent, so move the check that
determines whether the coroutine is dependent or independent to an
inline function to speed up send calls.

Author: rhansen

Include/internal/pycore_context.h

@@ -7,7 +7,9 @@
 
 #include "cpython/context.h"
 #include "cpython/genobject.h"    // PyGenObject
+#include "pycore_genobject.h"     // PyGenObject
 #include "pycore_hamt.h"          // PyHamtObject
+#include "pycore_tstate.h"        // _PyThreadStateImpl
 
 #define CONTEXT_MAX_WATCHERS 8
 
@@ -48,6 +50,9 @@ struct _pycontextobject {
 // (if non-NULL) is immediately entered.
 int _PyGen_ResetContext(PyThreadState *ts, PyGenObject *self, PyObject *ctx);
 
+void _PyGen_ActivateContextImpl(_PyThreadStateImpl *tsi, PyGenObject *self);
+void _PyGen_DeactivateContextImpl(_PyThreadStateImpl *tsi, PyGenObject *self);
+
 // Makes the given coroutine's context stack the active context stack for the
 // thread, shadowing (temporarily deactivating) the thread's previously active
 // context stack.  The context stack remains active until deactivated with a
@@ -59,7 +64,19 @@ int _PyGen_ResetContext(PyThreadState *ts, PyGenObject *self, PyObject *ctx);
 // until deactivated.
 //
 // If the coroutine's context stack is empty this function has no effect.
-void _PyGen_ActivateContext(PyThreadState *ts, PyGenObject *self);
+//
+// This is called each time a value is sent to a coroutine, so it is inlined to
+// avoid function call overhead in the common case of dependent coroutines.
+static inline void
+_PyGen_ActivateContext(PyThreadState *ts, PyGenObject *self)
+{
+    _PyThreadStateImpl *tsi = (_PyThreadStateImpl *)ts;
+    assert(self->_ctx_chain.prev == NULL);
+    if (self->_ctx_chain.ctx == NULL) {
+        return;
+    }
+    _PyGen_ActivateContextImpl(tsi, self);
+}
 
 // Deactivates the given coroutine's context stack, un-shadowing (reactivating)
 // the thread's previously active context stack.  Does not affect any contexts
@@ -70,7 +87,21 @@ void _PyGen_ActivateContext(PyThreadState *ts, PyGenObject *self);
 //
 // If the coroutine's context stack is not the active context stack this
 // function has no effect.
-void _PyGen_DeactivateContext(PyThreadState *ts, PyGenObject *self);
+//
+// This is called each time a value is sent to a coroutine, so it is inlined to
+// avoid function call overhead in the common case of dependent coroutines.
+static inline void
+_PyGen_DeactivateContext(PyThreadState *ts, PyGenObject *self)
+{
+    _PyThreadStateImpl *tsi = (_PyThreadStateImpl *)ts;
+    if (tsi->_ctx_chain.prev != &self->_ctx_chain) {
+        assert(self->_ctx_chain.ctx == NULL);
+        assert(self->_ctx_chain.prev == NULL);
+        return;
+    }
+    assert(self->_ctx_chain.ctx != NULL);
+    _PyGen_DeactivateContextImpl(tsi, self);
+}
 
 
 struct _pycontextvarobject {

Python/context.c

@@ -404,27 +404,15 @@ _PyGen_ResetContext(PyThreadState *ts, PyGenObject *self, PyObject *ctx)
 }
 
 void
-_PyGen_ActivateContext(PyThreadState *ts, PyGenObject *self)
+_PyGen_ActivateContextImpl(_PyThreadStateImpl *tsi, PyGenObject *self)
 {
-    _PyThreadStateImpl *tsi = (_PyThreadStateImpl *)ts;
-    assert(self->_ctx_chain.prev == NULL);
-    if (self->_ctx_chain.ctx == NULL) {
-        return;
-    }
     contextchain_link(&self->_ctx_chain, &tsi->_ctx_chain);
     context_switched(tsi);
 }
 
 void
-_PyGen_DeactivateContext(PyThreadState *ts, PyGenObject *self)
+_PyGen_DeactivateContextImpl(_PyThreadStateImpl *tsi, PyGenObject *self)
 {
-    _PyThreadStateImpl *tsi = (_PyThreadStateImpl *)ts;
-    if (tsi->_ctx_chain.prev != &self->_ctx_chain) {
-        assert(self->_ctx_chain.ctx == NULL);
-        assert(self->_ctx_chain.prev == NULL);
-        return;
-    }
-    assert(self->_ctx_chain.ctx != NULL);
     contextchain_unlink(&self->_ctx_chain, &tsi->_ctx_chain);
     context_switched(tsi);
 }