stencil generation improved, relying on tail call optimization (TOC)

stencils/aux_functions.c

@@ -1,18 +1,19 @@
 #include <stdint.h>
+#include "stencil_helper.h"
 
 //double (*math_pow)(double, double);
 
 volatile extern int dummy_int;
 volatile extern float dummy_float;
 
-__attribute__((noinline)) int floor_div(float arg1, float arg2) {
+NOINLINE int floor_div(float arg1, float arg2) {
     float x = arg1 / arg2;
     int i = (int)x;
     if (x < 0 && x != (float)i) i -= 1;
     return i;
 }
 
-__attribute__((noinline)) float aux_sqrt(float x) {
+NOINLINE float aux_sqrt(float x) {
     if (x <= 0.0f) return 0.0f;
 
     // --- Improved initial guess using bit-level trick ---
@@ -28,7 +29,7 @@ __attribute__((noinline)) float aux_sqrt(float x) {
     return y;
 }
 
-__attribute__((noinline)) float aux_get_42(float n) {
+NOINLINE float aux_get_42(float n) {
     return n + 42.0;
 }
 

stencils/generate_stencils.py

@@ -9,11 +9,11 @@ op_signs = {'add': '+', 'sub': '-', 'mul': '*', 'div': '/', 'pow': '**',
             'bwand': '&', 'bwor': '|', 'bwxor': '^'}
 
 entry_func_prefix = ''
-stencil_func_prefix = '__attribute__((naked)) '  # Remove callee prolog
+stencil_func_prefix = ''  # Remove callee prolog
 
 stack_size = 64
 
-includes = ['aux_functions.c', 'trigonometry.c']
+includes = ['stencil_helper.h', 'aux_functions.c', 'trigonometry.c']
 
 
 def read_files(files: list[str]) -> str:
@@ -25,6 +25,10 @@ def read_files(files: list[str]) -> str:
             file_path = Path(file_name)
         with open(file_path) as f:
             ret += f.read().strip(' \n') + '\n\n'
+
+    for incl in includes:
+        ret = ret.replace(f'#include "{incl}"\n', '')
+
     return ret
 
 
@@ -66,6 +70,7 @@ def get_entry_function_shell() -> str:
 def get_op_code(op: str, type1: str, type2: str, type_out: str) -> str:
     return f"""
     {stencil_func_prefix}void {op}_{type1}_{type2}({type1} arg1, {type2} arg2) {{
+        STENCIL_START({op}_{type1}_{type2});
         result_{type_out}_{type2}(arg1 {op_signs[op]} arg2, arg2);
     }}
     """
@@ -75,6 +80,7 @@ def get_op_code(op: str, type1: str, type2: str, type_out: str) -> str:
 def get_cast(type1: str, type2: str, type_out: str) -> str:
     return f"""
     {stencil_func_prefix}void cast_{type_out}_{type1}_{type2}({type1} arg1, {type2} arg2) {{
+        STENCIL_START(cast_{type_out}_{type1}_{type2});
         result_{type_out}_{type2}(({type1})arg1, arg2);
     }}
     """
@@ -84,6 +90,7 @@ def get_cast(type1: str, type2: str, type_out: str) -> str:
 def get_func2(func_name: str, type1: str, type2: str) -> str:
     return f"""
     {stencil_func_prefix}void {func_name}_{type1}_{type2}({type1} arg1, {type2} arg2) {{
+        STENCIL_START({func_name}_{type1}_{type2});
         result_float_{type2}(aux_{func_name}((float)arg1), arg2);
     }}
     """
@@ -93,6 +100,7 @@ def get_func2(func_name: str, type1: str, type2: str) -> str:
 def get_conv_code(type1: str, type2: str, type_out: str) -> str:
     return f"""
     {stencil_func_prefix}void conv_{type1}_{type2}({type1} arg1, {type2} arg2) {{
+        STENCIL_START(conv_{type1}_{type2});
         result_{type_out}_{type2}(({type_out})arg1, arg2);
     }}
     """
@@ -102,6 +110,7 @@ def get_conv_code(type1: str, type2: str, type_out: str) -> str:
 def get_op_code_float(op: str, type1: str, type2: str) -> str:
     return f"""
     {stencil_func_prefix}void {op}_{type1}_{type2}({type1} arg1, {type2} arg2) {{
+        STENCIL_START({op}_{type1}_{type2});
         result_float_{type2}((float)arg1 {op_signs[op]} (float)arg2, arg2);
     }}
     """
@@ -111,7 +120,7 @@ def get_op_code_float(op: str, type1: str, type2: str) -> str:
 def get_pow(type1: str, type2: str) -> str:
     return f"""
     {stencil_func_prefix}void pow_{type1}_{type2}({type1} arg1, {type2} arg2) {{
-        //result_float_{type2}((float)math_pow((double)arg1, (double)arg2), arg2);
+        STENCIL_START(pow_{type1}_{type2});
         result_float_{type2}(fast_pow_float((float)arg1, (float)arg2), arg2);
     }}
     """
@@ -121,13 +130,16 @@ def get_pow(type1: str, type2: str) -> str:
 def get_floordiv(op: str, type1: str, type2: str) -> str:
     if type1 == 'int' and type2 == 'int':
         return f"""
-        {stencil_func_prefix}void {op}_{type1}_{type2}({type1} arg1, {type2} arg2) {{
-            result_int_{type2}(floor_div((float)arg1, (float)arg2), arg2);
+        {stencil_func_prefix}void {op}_{type1}_{type2}({type1} a, {type2} b) {{
+            STENCIL_START({op}_{type1}_{type2});
+            int result = a / b - ((a % b != 0) && ((a < 0) != (b < 0)));
+            result_int_{type2}(result, b);
         }}
         """
     else:
         return f"""
         {stencil_func_prefix}void {op}_{type1}_{type2}({type1} arg1, {type2} arg2) {{
+            STENCIL_START({op}_{type1}_{type2});
             result_float_{type2}((float)floor_div((float)arg1, (float)arg2), arg2);
         }}
         """
@@ -151,6 +163,7 @@ def get_result_stubs2(type1: str, type2: str) -> str:
 def get_read_reg0_code(type1: str, type2: str, type_out: str) -> str:
     return f"""
     {stencil_func_prefix}void read_{type_out}_reg0_{type1}_{type2}({type1} arg1, {type2} arg2) {{
+        STENCIL_START(read_{type_out}_reg0_{type1}_{type2});
         result_{type_out}_{type2}(dummy_{type_out}, arg2);
     }}
     """
@@ -160,6 +173,7 @@ def get_read_reg0_code(type1: str, type2: str, type_out: str) -> str:
 def get_read_reg1_code(type1: str, type2: str, type_out: str) -> str:
     return f"""
     {stencil_func_prefix}void read_{type_out}_reg1_{type1}_{type2}({type1} arg1, {type2} arg2) {{
+        STENCIL_START(read_{type_out}_reg1_{type1}_{type2});
         result_{type1}_{type_out}(arg1, dummy_{type_out});
     }}
     """
@@ -169,6 +183,7 @@ def get_read_reg1_code(type1: str, type2: str, type_out: str) -> str:
 def get_write_code(type1: str) -> str:
     return f"""
     {stencil_func_prefix}void write_{type1}({type1} arg1) {{
+        STENCIL_START(write_{type1});
         dummy_{type1} = arg1;
         result_{type1}(arg1);
     }}

stencils/stencil_helper.h

@@ -0,0 +1,12 @@
+#if defined(__GNUC__)
+#define NOINLINE __attribute__((noinline))
+#define STENCIL_START_EX(funcname) \
+    __asm__ __volatile__( \
+        ".global stencil_start_" #funcname "\n" \
+        "stencil_start_" #funcname ":\n" \
+    )
+#define STENCIL_START(funcname)
+#else
+#define NOINLINE
+#define STENCIL_START(funcname)
+#endif

stencils/trigonometry.c

@@ -1,8 +1,10 @@
+#include "stencil_helper.h"
+
 const float PI      = 3.14159265358979323846f;
 const float PI_2    = 1.57079632679489661923f;  // pi/2
 const float TWO_OVER_PI = 0.63661977236758134308f; // 2/pi
 
-__attribute__((noinline)) float aux_sin(float x) {
+NOINLINE float aux_sin(float x) {
     // convert to double for reduction (better precision)
     double xd = (double)x;
 
@@ -48,7 +50,7 @@ __attribute__((noinline)) float aux_sin(float x) {
     }
 }
 
-__attribute__((noinline)) float aux_cos(float x) {
+NOINLINE float aux_cos(float x) {
     // convert to double for reduction (better precision)
     double xd = (double)x;
 
@@ -94,7 +96,7 @@ __attribute__((noinline)) float aux_cos(float x) {
     }
 }
 
-__attribute__((noinline)) float aux_tan(float x) {
+NOINLINE float aux_tan(float x) {
     // Promote to double for argument reduction (improves precision)
     double xd = (double)x;
     double qd = xd * (double)TWO_OVER_PI;   // how many half-pi multiples