gh-116088: Insert bottom checks after all sym_set_...() calls (#116089)

This changes the `sym_set_...()` functions to return a `bool` which is `false`
when the symbol is `bottom` after the operation.

All calls to such functions now check this result and go to `hit_bottom`,
a special error label that prints a different message and then reports
that it wasn't able to optimize the trace. No executor will be produced
in this case.

1 files changed, 9 insertions, 0 deletions

diff --git a/Python/optimizer_analysis.c b/Python/optimizer_analysis.c
index 2a7ef4e..a326e22 100644
--- a/Python/optimizer_analysis.c
+++ b/Python/optimizer_analysis.c
@@ -363,6 +363,15 @@ error:
     DPRINTF(1, "Encountered error in abstract interpreter\n");
     _Py_uop_abstractcontext_fini(ctx);
     return 0;
+
+hit_bottom:
+    // Attempted to push a "bottom" (contradition) symbol onto the stack.
+    // This means that the abstract interpreter has hit unreachable code.
+    // We *could* generate an _EXIT_TRACE or _FATAL_ERROR here, but it's
+    // simpler to just admit failure and not create the executor.
+    DPRINTF(1, "Hit bottom in abstract interpreter\n");
+    _Py_uop_abstractcontext_fini(ctx);
+    return 0;
 }