Implement dFdx, dFdy, and fwidth via new expression opcodes.

builtin_function.cpp

@@ -2496,6 +2496,82 @@ static const char *functions_for_110 [] = {
 
 /* 110_fs builtins */
 
+static const char *builtins_110_fs_derivatives = {
+   "((function dFdx\n"
+   "   (signature float\n"
+   "     (parameters\n"
+   "       (declare (in) float p))\n"
+   "     ((return (expression float dFdx (var_ref p)))))\n"
+   "\n"
+   "   (signature vec2\n"
+   "     (parameters\n"
+   "       (declare (in) vec2 p))\n"
+   "     ((return (expression vec2 dFdx (var_ref p)))))\n"
+   "\n"
+   "   (signature vec3\n"
+   "     (parameters\n"
+   "       (declare (in) vec3 p))\n"
+   "     ((return (expression vec3 dFdx (var_ref p)))))\n"
+   "\n"
+   "   (signature vec4\n"
+   "     (parameters\n"
+   "       (declare (in) vec4 p))\n"
+   "     ((return (expression vec4 dFdx (var_ref p)))))\n"
+   " )\n"
+   "\n"
+   " (function dFdy\n"
+   "   (signature float\n"
+   "     (parameters\n"
+   "       (declare (in) float p))\n"
+   "     ((return (expression float dFdy (var_ref p)))))\n"
+   "\n"
+   "   (signature vec2\n"
+   "     (parameters\n"
+   "       (declare (in) vec2 p))\n"
+   "     ((return (expression vec2 dFdy (var_ref p)))))\n"
+   "\n"
+   "   (signature vec3\n"
+   "     (parameters\n"
+   "       (declare (in) vec3 p))\n"
+   "     ((return (expression vec3 dFdy (var_ref p)))))\n"
+   "\n"
+   "   (signature vec4\n"
+   "     (parameters\n"
+   "       (declare (in) vec4 p))\n"
+   "     ((return (expression vec4 dFdy (var_ref p)))))\n"
+   " )\n"
+   "\n"
+   " (function fwidth\n"
+   "   (signature float\n"
+   "     (parameters\n"
+   "       (declare (in) float p))\n"
+   "     ((return (expression float +\n"
+   "                (expression float abs (expression float dFdx (var_ref p)))\n"
+   "                (expression float abs (expression float dFdy (var_ref p)))))))\n"
+   "\n"
+   "   (signature vec2\n"
+   "     (parameters\n"
+   "       (declare (in) vec2 p))\n"
+   "     ((return (expression vec2 +\n"
+   "                (expression vec2 abs (expression vec2 dFdx (var_ref p)))\n"
+   "                (expression vec2 abs (expression vec2 dFdy (var_ref p)))))))\n"
+   "\n"
+   "   (signature vec3\n"
+   "     (parameters\n"
+   "       (declare (in) vec3 p))\n"
+   "     ((return (expression vec3 +\n"
+   "                (expression vec3 abs (expression vec3 dFdx (var_ref p)))\n"
+   "                (expression vec3 abs (expression vec3 dFdy (var_ref p)))))))\n"
+   "\n"
+   "   (signature vec4\n"
+   "     (parameters\n"
+   "       (declare (in) vec4 p))\n"
+   "     ((return (expression vec4 +\n"
+   "                (expression vec4 abs (expression vec4 dFdx (var_ref p)))\n"
+   "                (expression vec4 abs (expression vec4 dFdy (var_ref p)))))))\n"
+   "))\n"
+};
+
 static const char *builtins_110_fs_textures = {
    "((function texture1D\n"
    "   (signature vec4\n"
@@ -2613,6 +2689,7 @@ static const char *builtins_110_fs_textures = {
 };
 
 static const char *functions_for_110_fs [] = {
+   builtins_110_fs_derivatives,
    builtins_110_fs_textures,
 };
 

builtins/110_fs/derivatives

@@ -0,0 +1,73 @@
+((function dFdx
+   (signature float
+     (parameters
+       (declare (in) float p))
+     ((return (expression float dFdx (var_ref p)))))
+
+   (signature vec2
+     (parameters
+       (declare (in) vec2 p))
+     ((return (expression vec2 dFdx (var_ref p)))))
+
+   (signature vec3
+     (parameters
+       (declare (in) vec3 p))
+     ((return (expression vec3 dFdx (var_ref p)))))
+
+   (signature vec4
+     (parameters
+       (declare (in) vec4 p))
+     ((return (expression vec4 dFdx (var_ref p)))))
+ )
+
+ (function dFdy
+   (signature float
+     (parameters
+       (declare (in) float p))
+     ((return (expression float dFdy (var_ref p)))))
+
+   (signature vec2
+     (parameters
+       (declare (in) vec2 p))
+     ((return (expression vec2 dFdy (var_ref p)))))
+
+   (signature vec3
+     (parameters
+       (declare (in) vec3 p))
+     ((return (expression vec3 dFdy (var_ref p)))))
+
+   (signature vec4
+     (parameters
+       (declare (in) vec4 p))
+     ((return (expression vec4 dFdy (var_ref p)))))
+ )
+
+ (function fwidth
+   (signature float
+     (parameters
+       (declare (in) float p))
+     ((return (expression float +
+                (expression float abs (expression float dFdx (var_ref p)))
+                (expression float abs (expression float dFdy (var_ref p)))))))
+
+   (signature vec2
+     (parameters
+       (declare (in) vec2 p))
+     ((return (expression vec2 +
+                (expression vec2 abs (expression vec2 dFdx (var_ref p)))
+                (expression vec2 abs (expression vec2 dFdy (var_ref p)))))))
+
+   (signature vec3
+     (parameters
+       (declare (in) vec3 p))
+     ((return (expression vec3 +
+                (expression vec3 abs (expression vec3 dFdx (var_ref p)))
+                (expression vec3 abs (expression vec3 dFdy (var_ref p)))))))
+
+   (signature vec4
+     (parameters
+       (declare (in) vec4 p))
+     ((return (expression vec4 +
+                (expression vec4 abs (expression vec4 dFdx (var_ref p)))
+                (expression vec4 abs (expression vec4 dFdy (var_ref p)))))))
+))

ir.cpp

@@ -76,6 +76,9 @@ ir_expression::get_num_operands(ir_expression_operation op)
       1, /* ir_unop_sin */
       1, /* ir_unop_cos */
 
+      1, /* ir_unop_dFdx */
+      1, /* ir_unop_dFdy */
+
       2, /* ir_binop_add */
       2, /* ir_binop_sub */
       2, /* ir_binop_mul */
@@ -136,6 +139,8 @@ static const char *const operator_strs[] = {
    "floor",
    "sin",
    "cos",
+   "dFdx",
+   "dFdy",
    "+",
    "-",
    "*",

ir.h

@@ -494,6 +494,14 @@ enum ir_expression_operation {
    ir_unop_cos,
    /*@}*/
 
+   /**
+    * \name Partial derivatives.
+    */
+   /*@{*/
+   ir_unop_dFdx,
+   ir_unop_dFdy,
+   /*@}*/
+
    ir_binop_add,
    ir_binop_sub,
    ir_binop_mul,