Add bottom checks, first approximation

gvanrossum · Feb 29, 2024 · 23d8a15 · 23d8a15
1 parent f4e1382
commit 23d8a15
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Showing 4 changed files with 160 additions and 7 deletions.
diff --git a/Python/optimizer_analysis.c b/Python/optimizer_analysis.c
@@ -339,6 +339,7 @@ optimize_uops(
                 _PyUOpName(opcode),
                 oparg);
         switch (opcode) {
+
 #include "optimizer_cases.c.h"
 
             default:
@@ -363,6 +364,15 @@ optimize_uops(
     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;
 }
 
 

diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
diff --git a/Tools/cases_generator/optimizer_generator.py b/Tools/cases_generator/optimizer_generator.py
@@ -144,7 +144,7 @@ def write_uop(
                 if not var.peek or is_override:
                     out.emit(stack.push(var))
         out.start_line()
-        stack.flush(out, cast_type="_Py_UopsSymbol *")
+        stack.flush(out, cast_type="_Py_UopsSymbol *", add_bottom_check=bool(override))
     except SizeMismatch as ex:
         raise analysis_error(ex.args[0], uop.body[0])