gh-104584: Emit macro expansions to opcode_metadata.h (#106163)

This produces longer traces (superblocks?).

Also improved debug output (uop names are now printed instead of numeric opcodes). This would be simpler if the numeric opcode values were generated by generate_cases.py, but that's another project.

Refactored some code in generate_cases.py so the essential algorithm for cache effects is only run once. (Deciding which effects are used and what the total cache size is, regardless of what's used.)

Author: gvanrossum

Python/ceval.c

@@ -2817,10 +2817,10 @@ _PyUopExecute(_PyExecutorObject *executor, _PyInterpreterFrame *frame, PyObject
         oparg = (int)operand;
 #ifdef LLTRACE
         if (lltrace >= 3) {
-            const char *opname = opcode < 256 ? _PyOpcode_OpName[opcode] : "";
+            const char *opname = opcode < 256 ? _PyOpcode_OpName[opcode] : _PyOpcode_uop_name[opcode];
             int stack_level = (int)(stack_pointer - _PyFrame_Stackbase(frame));
-            fprintf(stderr, "  uop %s %d, operand %" PRIu64 ", stack_level %d\n",
-                    opname, opcode, operand, stack_level);
+            fprintf(stderr, "  uop %s, operand %" PRIu64 ", stack_level %d\n",
+                    opname, operand, stack_level);
         }
 #endif
         pc++;

Python/opcode_metadata.h

@@ -913,6 +913,9 @@ struct opcode_macro_expansion {
 #ifndef NEED_OPCODE_METADATA
 extern const struct opcode_metadata _PyOpcode_opcode_metadata[512];
 extern const struct opcode_macro_expansion _PyOpcode_macro_expansion[256];
+#ifdef Py_DEBUG
+extern const char * const _PyOpcode_uop_name[512];
+#endif
 #else
 const struct opcode_metadata _PyOpcode_opcode_metadata[512] = {
     [NOP] = { true, INSTR_FMT_IX, 0 },
@@ -1131,10 +1134,18 @@ const struct opcode_macro_expansion _PyOpcode_macro_expansion[256] = {
     [STORE_FAST] = { .nuops = 1, .uops = { { STORE_FAST, 0, 0 } } },
     [POP_TOP] = { .nuops = 1, .uops = { { POP_TOP, 0, 0 } } },
     [PUSH_NULL] = { .nuops = 1, .uops = { { PUSH_NULL, 0, 0 } } },
+    [END_FOR] = { .nuops = 2, .uops = { { POP_TOP, 0, 0 }, { POP_TOP, 0, 0 } } },
     [END_SEND] = { .nuops = 1, .uops = { { END_SEND, 0, 0 } } },
     [UNARY_NEGATIVE] = { .nuops = 1, .uops = { { UNARY_NEGATIVE, 0, 0 } } },
     [UNARY_NOT] = { .nuops = 1, .uops = { { UNARY_NOT, 0, 0 } } },
     [UNARY_INVERT] = { .nuops = 1, .uops = { { UNARY_INVERT, 0, 0 } } },
+    [BINARY_OP_MULTIPLY_INT] = { .nuops = 2, .uops = { { _GUARD_BOTH_INT, 0, 0 }, { _BINARY_OP_MULTIPLY_INT, 0, 0 } } },
+    [BINARY_OP_ADD_INT] = { .nuops = 2, .uops = { { _GUARD_BOTH_INT, 0, 0 }, { _BINARY_OP_ADD_INT, 0, 0 } } },
+    [BINARY_OP_SUBTRACT_INT] = { .nuops = 2, .uops = { { _GUARD_BOTH_INT, 0, 0 }, { _BINARY_OP_SUBTRACT_INT, 0, 0 } } },
+    [BINARY_OP_MULTIPLY_FLOAT] = { .nuops = 2, .uops = { { _GUARD_BOTH_FLOAT, 0, 0 }, { _BINARY_OP_MULTIPLY_FLOAT, 0, 0 } } },
+    [BINARY_OP_ADD_FLOAT] = { .nuops = 2, .uops = { { _GUARD_BOTH_FLOAT, 0, 0 }, { _BINARY_OP_ADD_FLOAT, 0, 0 } } },
+    [BINARY_OP_SUBTRACT_FLOAT] = { .nuops = 2, .uops = { { _GUARD_BOTH_FLOAT, 0, 0 }, { _BINARY_OP_SUBTRACT_FLOAT, 0, 0 } } },
+    [BINARY_OP_ADD_UNICODE] = { .nuops = 2, .uops = { { _GUARD_BOTH_UNICODE, 0, 0 }, { _BINARY_OP_ADD_UNICODE, 0, 0 } } },
     [BINARY_SLICE] = { .nuops = 1, .uops = { { BINARY_SLICE, 0, 0 } } },
     [STORE_SLICE] = { .nuops = 1, .uops = { { STORE_SLICE, 0, 0 } } },
     [BINARY_SUBSCR_LIST_INT] = { .nuops = 1, .uops = { { BINARY_SUBSCR_LIST_INT, 0, 0 } } },
@@ -1162,6 +1173,9 @@ const struct opcode_macro_expansion _PyOpcode_macro_expansion[256] = {
     [DELETE_ATTR] = { .nuops = 1, .uops = { { DELETE_ATTR, 0, 0 } } },
     [STORE_GLOBAL] = { .nuops = 1, .uops = { { STORE_GLOBAL, 0, 0 } } },
     [DELETE_GLOBAL] = { .nuops = 1, .uops = { { DELETE_GLOBAL, 0, 0 } } },
+    [LOAD_LOCALS] = { .nuops = 1, .uops = { { _LOAD_LOCALS, 0, 0 } } },
+    [LOAD_NAME] = { .nuops = 2, .uops = { { _LOAD_LOCALS, 0, 0 }, { _LOAD_FROM_DICT_OR_GLOBALS, 0, 0 } } },
+    [LOAD_FROM_DICT_OR_GLOBALS] = { .nuops = 1, .uops = { { _LOAD_FROM_DICT_OR_GLOBALS, 0, 0 } } },
     [DELETE_DEREF] = { .nuops = 1, .uops = { { DELETE_DEREF, 0, 0 } } },
     [LOAD_FROM_DICT_OR_DEREF] = { .nuops = 1, .uops = { { LOAD_FROM_DICT_OR_DEREF, 0, 0 } } },
     [LOAD_DEREF] = { .nuops = 1, .uops = { { LOAD_DEREF, 0, 0 } } },
@@ -1207,4 +1221,22 @@ const struct opcode_macro_expansion _PyOpcode_macro_expansion[256] = {
     [COPY] = { .nuops = 1, .uops = { { COPY, 0, 0 } } },
     [SWAP] = { .nuops = 1, .uops = { { SWAP, 0, 0 } } },
 };
+#ifdef Py_DEBUG
+const char * const _PyOpcode_uop_name[512] = {
+    [300] = "EXIT_TRACE",
+    [301] = "SET_IP",
+    [302] = "_GUARD_BOTH_INT",
+    [303] = "_BINARY_OP_MULTIPLY_INT",
+    [304] = "_BINARY_OP_ADD_INT",
+    [305] = "_BINARY_OP_SUBTRACT_INT",
+    [306] = "_GUARD_BOTH_FLOAT",
+    [307] = "_BINARY_OP_MULTIPLY_FLOAT",
+    [308] = "_BINARY_OP_ADD_FLOAT",
+    [309] = "_BINARY_OP_SUBTRACT_FLOAT",
+    [310] = "_GUARD_BOTH_UNICODE",
+    [311] = "_BINARY_OP_ADD_UNICODE",
+    [312] = "_LOAD_LOCALS",
+    [313] = "_LOAD_FROM_DICT_OR_GLOBALS",
+};
+#endif
 #endif

Python/optimizer.c

@@ -325,8 +325,8 @@ translate_bytecode_to_trace(
     }
 #define ADD_TO_TRACE(OPCODE, OPERAND) \
         if (lltrace >= 2) { \
-            const char *opname = (OPCODE) < 256 ? _PyOpcode_OpName[(OPCODE)] : ""; \
-            fprintf(stderr, "  ADD_TO_TRACE(%s %d, %" PRIu64 ")\n", opname, (OPCODE), (uint64_t)(OPERAND)); \
+            const char *opname = (OPCODE) < 256 ? _PyOpcode_OpName[(OPCODE)] : _PyOpcode_uop_name[(OPCODE)]; \
+            fprintf(stderr, "  ADD_TO_TRACE(%s, %" PRIu64 ")\n", opname, (uint64_t)(OPERAND)); \
         } \
         trace[trace_length].opcode = (OPCODE); \
         trace[trace_length].operand = (OPERAND); \
@@ -474,6 +474,8 @@ PyUnstable_Optimizer_NewUOpOptimizer(void)
     }
     opt->optimize = uop_optimize;
     opt->resume_threshold = UINT16_MAX;
-    opt->backedge_threshold = 0;
+    // Need at least 3 iterations to settle specializations.
+    // A few lower bits of the counter are reserved for other flags.
+    opt->backedge_threshold = 3 << OPTIMIZER_BITS_IN_COUNTER;
     return (PyObject *)opt;
 }