py/emitnative: Load native fun table ptr from const table for all archs.

All architectures now have a dedicated register to hold the pointer to the
native function table mp_fun_table, and so they all need to load this
register at the start of the native function.  This commit makes the
loading of this register uniform across architectures by passing the
pointer in the constant table for the native function, and then loading the
register from the constant table.  Doing it this way means that the pointer
is not stored in the assembly code, helping to make the code more portable.

1 files changed, 21 insertions, 31 deletions

diff --git a/py/emitnative.c b/py/emitnative.c
index 4d6c3445f..26af7f947 100644
--- a/py/emitnative.c
+++ b/py/emitnative.c
@@ -287,7 +287,7 @@ STATIC void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
     emit->pass = pass;
     emit->do_viper_types = scope->emit_options == MP_EMIT_OPT_VIPER;
     emit->stack_size = 0;
-    emit->const_table_cur_obj = 0;
+    emit->const_table_cur_obj = 1; // first entry is for mp_fun_table
     emit->const_table_cur_raw_code = 0;
     emit->last_emit_was_return_value = false;
     emit->scope = scope;
@@ -372,24 +372,16 @@ STATIC void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
         // Entry to function
         ASM_ENTRY(emit->as, emit->stack_start + emit->n_state - num_locals_in_regs);
 
-        // TODO don't load r7 if we don't need it
-        #if N_THUMB
-        asm_thumb_mov_reg_i32(emit->as, ASM_THUMB_REG_R7, (mp_uint_t)mp_fun_table);
-        #elif N_ARM
-        asm_arm_mov_reg_i32(emit->as, ASM_ARM_REG_R7, (mp_uint_t)mp_fun_table);
-        #elif N_XTENSA
-        ASM_MOV_REG_IMM(emit->as, ASM_XTENSA_REG_A15, (uint32_t)mp_fun_table);
-        #elif N_X86
-        asm_x86_mov_i32_to_r32(emit->as, (intptr_t)mp_fun_table, ASM_X86_REG_EBP);
-        #elif N_X64
-        asm_x64_mov_i64_to_r64_optimised(emit->as, (intptr_t)mp_fun_table, ASM_X64_REG_RBP);
+        #if N_X86
+        asm_x86_mov_arg_to_r32(emit->as, 0, REG_ARG_1);
         #endif
 
+        // Load REG_FUN_TABLE with a pointer to mp_fun_table, found in the const_table
+        ASM_LOAD_REG_REG_OFFSET(emit->as, REG_LOCAL_3, REG_ARG_1, offsetof(mp_obj_fun_bc_t, const_table) / sizeof(uintptr_t));
+        ASM_LOAD_REG_REG_OFFSET(emit->as, REG_FUN_TABLE, REG_LOCAL_3, 0);
+
         // Store function object (passed as first arg) to stack if needed
         if (NEED_FUN_OBJ(emit)) {
-            #if N_X86
-            asm_x86_mov_arg_to_r32(emit->as, 0, REG_ARG_1);
-            #endif
             ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_FUN_OBJ(emit), REG_ARG_1);
         }
 
@@ -458,28 +450,18 @@ STATIC void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
             asm_x86_mov_arg_to_r32(emit->as, 1, REG_ARG_2);
             #endif
             ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_VAL(emit), REG_ARG_2);
+
+            // Load REG_FUN_TABLE with a pointer to mp_fun_table, found in the const_table
+            ASM_LOAD_REG_REG_OFFSET(emit->as, REG_TEMP0, REG_GENERATOR_STATE, LOCAL_IDX_FUN_OBJ(emit));
+            ASM_LOAD_REG_REG_OFFSET(emit->as, REG_TEMP0, REG_TEMP0, offsetof(mp_obj_fun_bc_t, const_table) / sizeof(uintptr_t));
+            ASM_LOAD_REG_REG_OFFSET(emit->as, REG_FUN_TABLE, REG_TEMP0, emit->scope->num_pos_args + emit->scope->num_kwonly_args);
         } else {
             // The locals and stack start after the code_state structure
             emit->stack_start = emit->code_state_start + sizeof(mp_code_state_t) / sizeof(mp_uint_t);
 
             // Allocate space on C-stack for code_state structure, which includes state
             ASM_ENTRY(emit->as, emit->stack_start + emit->n_state);
-        }
-
-        // TODO don't load r7 if we don't need it
-        #if N_THUMB
-        asm_thumb_mov_reg_i32(emit->as, ASM_THUMB_REG_R7, (mp_uint_t)mp_fun_table);
-        #elif N_ARM
-        asm_arm_mov_reg_i32(emit->as, ASM_ARM_REG_R7, (mp_uint_t)mp_fun_table);
-        #elif N_XTENSA
-        ASM_MOV_REG_IMM(emit->as, ASM_XTENSA_REG_A15, (uint32_t)mp_fun_table);
-        #elif N_X86
-        asm_x86_mov_i32_to_r32(emit->as, (intptr_t)mp_fun_table, ASM_X86_REG_EBP);
-        #elif N_X64
-        asm_x64_mov_i64_to_r64_optimised(emit->as, (intptr_t)mp_fun_table, ASM_X64_REG_RBP);
-        #endif
 
-        if (!(emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR)) {
             // Prepare incoming arguments for call to mp_setup_code_state
 
             #if N_X86
@@ -489,6 +471,10 @@ STATIC void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
             asm_x86_mov_arg_to_r32(emit->as, 3, REG_ARG_4);
             #endif
 
+            // Load REG_FUN_TABLE with a pointer to mp_fun_table, found in the const_table
+            ASM_LOAD_REG_REG_OFFSET(emit->as, REG_LOCAL_3, REG_ARG_1, offsetof(mp_obj_fun_bc_t, const_table) / sizeof(uintptr_t));
+            ASM_LOAD_REG_REG_OFFSET(emit->as, REG_FUN_TABLE, REG_LOCAL_3, emit->scope->num_pos_args + emit->scope->num_kwonly_args);
+
             // Set code_state.fun_bc
             ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_FUN_OBJ(emit), REG_ARG_1);
 
@@ -591,11 +577,15 @@ STATIC void emit_native_end_pass(emit_t *emit) {
     emit->const_table_num_obj = emit->const_table_cur_obj;
     if (emit->pass == MP_PASS_CODE_SIZE) {
         size_t const_table_alloc = emit->const_table_num_obj + emit->const_table_cur_raw_code;
+        size_t nqstr = 0;
         if (!emit->do_viper_types) {
             // Add room for qstr names of arguments
-            const_table_alloc += emit->scope->num_pos_args + emit->scope->num_kwonly_args;
+            nqstr = emit->scope->num_pos_args + emit->scope->num_kwonly_args;
+            const_table_alloc += nqstr;
         }
         emit->const_table = m_new(mp_uint_t, const_table_alloc);
+        // Store mp_fun_table pointer just after qstrs
+        emit->const_table[nqstr] = (mp_uint_t)(uintptr_t)mp_fun_table;
     }
 
     if (emit->pass == MP_PASS_EMIT) {