W27b python#2: emitFormatSimple → C body + delegation stub

FORMAT_VALUE/FORMAT_SIMPLE (mainline) opcode handler. Per W27b Step A scope.

C body: hir_builder_emit_format_simple_c (~38 lines). Block-creation
pattern: cond-branch on TUnicodeExact → format_with_spec (slow path) OR
refine_type (pass-through fast path) → done.

C primitives used: hir_cfg_alloc_block + hir_c_create_cond_branch_check_type_cpp
+ hir_c_create_load_const + hir_c_create_format_with_spec_reg
+ hir_c_create_refine_type_reg + hir_c_create_branch_cpp
+ hir_builder_temps_alloc_stack (all existing).

C++ HIRBuilder::emitFormatSimple → 4-line delegation stub (cfg arg
unused, marked maybe_unused).

Verification: cmake --build target jit/phoenix_jit clean (BUILD_EXIT=0).
Sole-path coverage: FORMAT_VALUE/FORMAT_SIMPLE is mainline-tested per
theologian L2515 coverage observation.

Author: SonicField

Python/jit/hir/builder.cpp

@@ -5054,30 +5054,11 @@ void HIRBuilder::emitConvertValue(
       static_cast<void*>(&tc), static_cast<void*>(current_func_), bc_instr.oparg());
 }
 
-void HIRBuilder::emitFormatSimple(CFG& cfg, TranslationContext& tc) {
-  PhxPtrArray& stack = tc.frame.stack;
-  Register* value = static_cast<Register*>(phx_ptr_arr_pop(&stack));
-
-  BasicBlock* done_block = cfg.AllocateBlock();
-  BasicBlock* do_fmt_block = cfg.AllocateBlock();
-  BasicBlock* pass_through_block = cfg.AllocateBlock();
-
-  tc.emitCondBranchCheckType(
-      value, TUnicodeExact, pass_through_block, do_fmt_block);
-  Register* out = temps_.AllocateStack();
-
-  tc.block = do_fmt_block;
-  Register* fmt_spec = temps_.AllocateStack();
-  tc.emitLoadConst(fmt_spec, TNullptr);
-  tc.emitFormatWithSpec(out, value, fmt_spec, tc.frame);
-  tc.emitBranch(done_block);
-
-  tc.block = pass_through_block;
-  tc.emitRefineType(out, TUnicodeExact, value);
-  tc.emitBranch(done_block);
+extern "C" void hir_builder_emit_format_simple_c(
+    void *tc, void *func, void *builder);
 
-  tc.block = done_block;
-  phx_ptr_arr_push(&stack, out);
+void HIRBuilder::emitFormatSimple(CFG& /*cfg*/, TranslationContext& tc) {
+  hir_builder_emit_format_simple_c(&tc, current_func_, this);
 }
 
 extern "C" void hir_builder_emit_load_common_constant_c(

Python/jit/hir/builder_emit_c.c

@@ -3924,4 +3924,43 @@ void hir_builder_emit_load_special_c(
     phx_ptr_arr_push(&tc->frame.stack, null_or_self);
 }
 
+/* W27b #2: emitFormatSimple (FORMAT_VALUE/FORMAT_SIMPLE mainline opcode).
+ * Mirrors C++ HIRBuilder::emitFormatSimple @ builder.cpp:5057.
+ * Block-creation pattern: cond-branch on TUnicodeExact → format-with-spec
+ * (slow path) OR refine-type (pass-through fast path) → done. */
+void hir_builder_emit_format_simple_c(
+        PhxTranslationContext *tc,
+        void *func,
+        void *builder) {
+    void *value = phx_ptr_arr_pop(&tc->frame.stack);
+
+    void *done_block = hir_cfg_alloc_block(func);
+    void *do_fmt_block = hir_cfg_alloc_block(func);
+    void *pass_through_block = hir_cfg_alloc_block(func);
+
+    HirType t_unicode_exact = HIR_TYPE_UNICODEEXACT;
+    phx_tc_emit(tc, hir_c_create_cond_branch_check_type_cpp(
+        value, t_unicode_exact, pass_through_block, do_fmt_block));
+
+    void *out = hir_builder_temps_alloc_stack(builder);
+
+    /* do_fmt_block: load null fmt_spec + emit format_with_spec + branch done. */
+    tc->block = do_fmt_block;
+    void *fmt_spec = hir_builder_temps_alloc_stack(builder);
+    HirType t_nullptr = HIR_TYPE_NULLPTR;
+    phx_tc_emit(tc, hir_c_create_load_const(fmt_spec, t_nullptr));
+    phx_tc_emit(tc, hir_c_create_format_with_spec_reg(
+        out, value, fmt_spec, &tc->frame));
+    phx_tc_emit(tc, hir_c_create_branch_cpp(done_block));
+
+    /* pass_through_block: refine value type + branch done. */
+    tc->block = pass_through_block;
+    phx_tc_emit(tc, hir_c_create_refine_type_reg(out, t_unicode_exact, value));
+    phx_tc_emit(tc, hir_c_create_branch_cpp(done_block));
+
+    /* done_block: continue with out on stack. */
+    tc->block = done_block;
+    phx_ptr_arr_push(&tc->frame.stack, out);
+}
+