Add patch 'fix-nondeterministic-codegen'

Summary:
This diff adds a patch to the `3.14` Meta-internal fork.

In Python 3.14 NOP instructions can be removed and then that space can later be re-used when a new instruction is added. When this happens not all of the memory is zero'd and when the new instruction is appended not all of the fields are initialized. This leads to some randomness in the generation of the exception handling table.

Reviewed By: alexmalyshev

Differential Revision: D80723451

fbshipit-source-id: 664ff320dc0254fa3b857b6d2ef59b8b4796cf96

Author: DinoV

Lib/test/test_dis.py

@@ -454,52 +454,53 @@ def foo(a: int, b: str) -> str:
 """
 
 dis_traceback = """\
-%4d           RESUME                   0
+%4d            RESUME                   0
 
-%4d           NOP
+%4d            NOP
 
-%4d   L1:     LOAD_SMALL_INT           1
-               LOAD_SMALL_INT           0
-           --> BINARY_OP               11 (/)
-               POP_TOP
+%4d    L1:     LOAD_SMALL_INT           1
+                LOAD_SMALL_INT           0
+            --> BINARY_OP               11 (/)
+                POP_TOP
 
-%4d   L2:     LOAD_FAST_CHECK          1 (tb)
-               RETURN_VALUE
+%4d    L2:     LOAD_FAST_CHECK          1 (tb)
+                RETURN_VALUE
 
-  --   L3:     PUSH_EXC_INFO
+  --    L3:     PUSH_EXC_INFO
 
-%4d           LOAD_GLOBAL              0 (Exception)
-               CHECK_EXC_MATCH
-               POP_JUMP_IF_FALSE       24 (to L7)
-               NOT_TAKEN
-               STORE_FAST               0 (e)
+%4d            LOAD_GLOBAL              0 (Exception)
+                CHECK_EXC_MATCH
+                POP_JUMP_IF_FALSE       24 (to L9)
+        L4:     NOT_TAKEN
+        L5:     STORE_FAST               0 (e)
 
-%4d   L4:     LOAD_FAST                0 (e)
-               LOAD_ATTR                2 (__traceback__)
-               STORE_FAST               1 (tb)
-       L5:     POP_EXCEPT
-               LOAD_CONST               1 (None)
-               STORE_FAST               0 (e)
-               DELETE_FAST              0 (e)
+%4d    L6:     LOAD_FAST                0 (e)
+                LOAD_ATTR                2 (__traceback__)
+                STORE_FAST               1 (tb)
+        L7:     POP_EXCEPT
+                LOAD_CONST               1 (None)
+                STORE_FAST               0 (e)
+                DELETE_FAST              0 (e)
 
-%4d           LOAD_FAST                1 (tb)
-               RETURN_VALUE
+%4d            LOAD_FAST                1 (tb)
+                RETURN_VALUE
 
-  --   L6:     LOAD_CONST               1 (None)
-               STORE_FAST               0 (e)
-               DELETE_FAST              0 (e)
-               RERAISE                  1
+  --    L8:     LOAD_CONST               1 (None)
+                STORE_FAST               0 (e)
+                DELETE_FAST              0 (e)
+                RERAISE                  1
 
-%4d   L7:     RERAISE                  0
+%4d    L9:     RERAISE                  0
 
-  --   L8:     COPY                     3
-               POP_EXCEPT
-               RERAISE                  1
+  --   L10:     COPY                     3
+                POP_EXCEPT
+                RERAISE                  1
 ExceptionTable:
   L1 to L2 -> L3 [0]
-  L3 to L4 -> L8 [1] lasti
-  L4 to L5 -> L6 [1] lasti
-  L6 to L8 -> L8 [1] lasti
+  L3 to L4 -> L10 [1] lasti
+  L5 to L6 -> L10 [1] lasti
+  L6 to L7 -> L8 [1] lasti
+  L8 to L10 -> L10 [1] lasti
 """ % (TRACEBACK_CODE.co_firstlineno,
        TRACEBACK_CODE.co_firstlineno + 1,
        TRACEBACK_CODE.co_firstlineno + 2,
@@ -568,11 +569,11 @@ def _with(c):
 %4d   L3:     PUSH_EXC_INFO
                WITH_EXCEPT_START
                TO_BOOL
-               POP_JUMP_IF_TRUE         2 (to L4)
-               NOT_TAKEN
-               RERAISE                  2
-       L4:     POP_TOP
-       L5:     POP_EXCEPT
+               POP_JUMP_IF_TRUE         2 (to L6)
+       L4:     NOT_TAKEN
+       L5:     RERAISE                  2
+       L6:     POP_TOP
+       L7:     POP_EXCEPT
                POP_TOP
                POP_TOP
                POP_TOP
@@ -582,12 +583,13 @@ def _with(c):
                LOAD_CONST               1 (None)
                RETURN_VALUE
 
-  --   L6:     COPY                     3
+  --   L8:     COPY                     3
                POP_EXCEPT
                RERAISE                  1
 ExceptionTable:
   L1 to L2 -> L3 [2] lasti
-  L3 to L5 -> L6 [4] lasti
+  L3 to L4 -> L8 [4] lasti
+  L5 to L7 -> L8 [4] lasti
 """ % (_with.__code__.co_firstlineno,
        _with.__code__.co_firstlineno + 1,
        _with.__code__.co_firstlineno + 2,

Python/flowgraph.c

@@ -199,7 +199,6 @@ basicblock_addop(basicblock *b, int opcode, int oparg, location loc)
     cfg_instr *i = &b->b_instr[off];
     i->i_opcode = opcode;
     i->i_oparg = oparg;
-    i->i_target = NULL;
     i->i_loc = loc;
 
     return SUCCESS;
@@ -1096,6 +1095,7 @@ basicblock_remove_redundant_nops(basicblock *bb) {
     assert(dest <= bb->b_iused);
     int num_removed = bb->b_iused - dest;
     bb->b_iused = dest;
+    memset(&bb->b_instr[dest], 0, sizeof(cfg_instr) * num_removed);
     return num_removed;
 }