simplify: port IsTruthy Bool + LongExact paths to C

Bool path: compare input with Py_True via PrimitiveCompare(kEqual).
LongExact path: compare with _PyLong_GetZero() via
PrimitiveCompare(kNotEqual). Falls through to C++ for known-object,
collection-length, and other paths.

Author: SonicField

Python/jit/hir/simplify.cpp

@@ -2782,8 +2782,13 @@ Register* simplifyInstr(Env& env, const Instr* instr) {
       return r;
     }
 
-    case Opcode::kIsTruthy:
+    case Opcode::kIsTruthy: {
+      SimplifyEnv cenv = make_c_env();
+      auto *r = static_cast<Register*>(simplify_is_truthy_c(&cenv, instr));
+      sync_c_env(cenv);
+      if (r) return r;
       return simplifyIsTruthy(env, instr);
+    }
 
 // TODO(T255262756) - Enable this again. See P2169675076 and P2184559031 (same
 // pattern but applied to simplifyLoadAttrTypeReceiver).

Python/jit/hir/simplify_c.c

@@ -7,6 +7,7 @@
 #include "cinderx/Jit/hir/hir_instr_c.h"
 #include "cinderx/Jit/hir/hir_type_c.h"
 #include "Python.h"
+#include "pycore_long.h"
 
 /* Forward declarations (avoid hir_c_api.h typedef conflicts) */
 extern HirType hir_register_type(void *reg);
@@ -212,6 +213,30 @@ void *simplify_primitive_compare_box_true_c(const void *instr) {
     return hir_c_get_operand(left_def, 0);
 }
 
+/* ---- simplifyIsTruthy (partial — Bool + LongExact paths) ---- */
+void *simplify_is_truthy_c(SimplifyEnv *env, const void *instr) {
+    void *input = hir_c_get_operand(instr, 0);
+    HirType input_type = hir_register_type(input);
+
+    /* TBool: compare with Py_True */
+    HirType t_bool = HIR_TYPE_BOOL;
+    if (hir_type_is_subtype(input_type, t_bool)) {
+        simplify_env_emit_use_type(env, input, t_bool);
+        void *right = simplify_env_emit_load_const(env, hir_type_from_object(Py_True));
+        return simplify_env_emit_primitive_compare(env, HIR_PCMP_Equal, input, right);
+    }
+
+    /* TLongExact: compare with _PyLong_GetZero() */
+    HirType t_long_exact = HIR_TYPE_LONGEXACT;
+    if (hir_type_is_subtype(input_type, t_long_exact)) {
+        simplify_env_emit_use_type(env, input, input_type);
+        void *right = simplify_env_emit_load_const(env, hir_type_from_object(_PyLong_GetZero()));
+        return simplify_env_emit_primitive_compare(env, HIR_PCMP_NotEqual, input, right);
+    }
+
+    return NULL;
+}
+
 /* ---- simplifyCheckSequenceBounds ----
  * If sequence is MakeTuple with known length + idx is known int, fold bounds check. */
 void *simplify_check_sequence_bounds_c(SimplifyEnv *env, const void *instr) {

Python/jit/hir/simplify_c.h

@@ -32,6 +32,7 @@ void *simplify_guard_type_identity_c(const void *instr);
 void *simplify_primitive_compare_box_true_c(const void *instr);
 void *simplify_unbox_box_c(const void *instr);
 void *simplify_cond_branch_check_type_c(SimplifyEnv *env, const void *instr);
+void *simplify_is_truthy_c(SimplifyEnv *env, const void *instr);
 void *simplify_check_sequence_bounds_c(SimplifyEnv *env, const void *instr);
 void *simplify_load_array_item_tuple_c(SimplifyEnv *env, const void *instr);
 void *simplify_load_tuple_item_c(SimplifyEnv *env, const void *instr);