program: add a helper for rewriting FP position input to sysval

Reviewed-by: Edward O'Callaghan <[email protected]
Reviewed-by: Brian Paul <[email protected]>

2 files changed, 29 insertions, 0 deletions

diff --git a/src/mesa/program/programopt.c b/src/mesa/program/programopt.c
index af78150d594..24dde57725e 100644
--- a/src/mesa/program/programopt.c
+++ b/src/mesa/program/programopt.c
@@ -589,3 +589,30 @@ _mesa_remove_output_reads(struct gl_program *prog, gl_register_file type)
       }
    }
 }
+
+void
+_mesa_program_fragment_position_to_sysval(struct gl_program *prog)
+{
+   GLuint i;
+
+   if (prog->Target != GL_FRAGMENT_PROGRAM_ARB ||
+       !(prog->InputsRead & BITFIELD64_BIT(VARYING_SLOT_POS)))
+      return;
+
+   prog->InputsRead &= ~BITFIELD64_BIT(VARYING_SLOT_POS);
+   prog->SystemValuesRead |= 1 << SYSTEM_VALUE_FRAG_COORD;
+
+   for (i = 0; i < prog->NumInstructions; i++) {
+      struct prog_instruction *inst = prog->Instructions + i;
+      const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode);
+      GLuint j;
+
+      for (j = 0; j < numSrc; j++) {
+         if (inst->SrcReg[j].File == PROGRAM_INPUT &&
+             inst->SrcReg[j].Index == VARYING_SLOT_POS) {
+            inst->SrcReg[j].File = PROGRAM_SYSTEM_VALUE;
+            inst->SrcReg[j].Index = SYSTEM_VALUE_FRAG_COORD;
+         }
+      }
+   }
+}
diff --git a/src/mesa/program/programopt.h b/src/mesa/program/programopt.h
index 757421edfe1..1520d161ea8 100644
--- a/src/mesa/program/programopt.h
+++ b/src/mesa/program/programopt.h
@@ -51,6 +51,8 @@ _mesa_count_texture_instructions(struct gl_program *prog);
 extern void
 _mesa_remove_output_reads(struct gl_program *prog, gl_register_file type);
 
+extern void
+_mesa_program_fragment_position_to_sysval(struct gl_program *prog);
 
 #ifdef __cplusplus
 }