svn merge ^/branches/released . --username marha

1 files changed, 575 insertions, 0 deletions

diff --git a/mesalib/src/mesa/shader/programopt.c b/mesalib/src/mesa/shader/programopt.c
new file mode 100644
index 000000000..f70c75cec
--- /dev/null
+++ b/mesalib/src/mesa/shader/programopt.c
@@ -0,0 +1,575 @@
+/*
+ * Mesa 3-D graphics library
+ * Version:  6.5.3
+ *
+ * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file  programopt.c 
+ * Vertex/Fragment program optimizations and transformations for program
+ * options, etc.
+ *
+ * \author Brian Paul
+ */
+
+
+#include "main/glheader.h"
+#include "main/context.h"
+#include "prog_parameter.h"
+#include "prog_statevars.h"
+#include "program.h"
+#include "programopt.h"
+#include "prog_instruction.h"
+
+
+/**
+ * This function inserts instructions for coordinate modelview * projection
+ * into a vertex program.
+ * May be used to implement the position_invariant option.
+ */
+static void
+_mesa_insert_mvp_dp4_code(GLcontext *ctx, struct gl_vertex_program *vprog)
+{
+   struct prog_instruction *newInst;
+   const GLuint origLen = vprog->Base.NumInstructions;
+   const GLuint newLen = origLen + 4;
+   GLuint i;
+
+   /*
+    * Setup state references for the modelview/projection matrix.
+    * XXX we should check if these state vars are already declared.
+    */
+   static const gl_state_index mvpState[4][STATE_LENGTH] = {
+      { STATE_MVP_MATRIX, 0, 0, 0, 0 },  /* state.matrix.mvp.row[0] */
+      { STATE_MVP_MATRIX, 0, 1, 1, 0 },  /* state.matrix.mvp.row[1] */
+      { STATE_MVP_MATRIX, 0, 2, 2, 0 },  /* state.matrix.mvp.row[2] */
+      { STATE_MVP_MATRIX, 0, 3, 3, 0 },  /* state.matrix.mvp.row[3] */
+   };
+   GLint mvpRef[4];
+
+   for (i = 0; i < 4; i++) {
+      mvpRef[i] = _mesa_add_state_reference(vprog->Base.Parameters,
+                                            mvpState[i]);
+   }
+
+   /* Alloc storage for new instructions */
+   newInst = _mesa_alloc_instructions(newLen);
+   if (!newInst) {
+      _mesa_error(ctx, GL_OUT_OF_MEMORY,
+                  "glProgramString(inserting position_invariant code)");
+      return;
+   }
+
+   /*
+    * Generated instructions:
+    * newInst[0] = DP4 result.position.x, mvp.row[0], vertex.position;
+    * newInst[1] = DP4 result.position.y, mvp.row[1], vertex.position;
+    * newInst[2] = DP4 result.position.z, mvp.row[2], vertex.position;
+    * newInst[3] = DP4 result.position.w, mvp.row[3], vertex.position;
+    */
+   _mesa_init_instructions(newInst, 4);
+   for (i = 0; i < 4; i++) {
+      newInst[i].Opcode = OPCODE_DP4;
+      newInst[i].DstReg.File = PROGRAM_OUTPUT;
+      newInst[i].DstReg.Index = VERT_RESULT_HPOS;
+      newInst[i].DstReg.WriteMask = (WRITEMASK_X << i);
+      newInst[i].SrcReg[0].File = PROGRAM_STATE_VAR;
+      newInst[i].SrcReg[0].Index = mvpRef[i];
+      newInst[i].SrcReg[0].Swizzle = SWIZZLE_NOOP;
+      newInst[i].SrcReg[1].File = PROGRAM_INPUT;
+      newInst[i].SrcReg[1].Index = VERT_ATTRIB_POS;
+      newInst[i].SrcReg[1].Swizzle = SWIZZLE_NOOP;
+   }
+
+   /* Append original instructions after new instructions */
+   _mesa_copy_instructions (newInst + 4, vprog->Base.Instructions, origLen);
+
+   /* free old instructions */
+   _mesa_free_instructions(vprog->Base.Instructions, origLen);
+
+   /* install new instructions */
+   vprog->Base.Instructions = newInst;
+   vprog->Base.NumInstructions = newLen;
+   vprog->Base.InputsRead |= VERT_BIT_POS;
+   vprog->Base.OutputsWritten |= (1 << VERT_RESULT_HPOS);
+}
+
+
+static void
+_mesa_insert_mvp_mad_code(GLcontext *ctx, struct gl_vertex_program *vprog)
+{
+   struct prog_instruction *newInst;
+   const GLuint origLen = vprog->Base.NumInstructions;
+   const GLuint newLen = origLen + 4;
+   GLuint hposTemp;
+   GLuint i;
+
+   /*
+    * Setup state references for the modelview/projection matrix.
+    * XXX we should check if these state vars are already declared.
+    */
+   static const gl_state_index mvpState[4][STATE_LENGTH] = {
+      { STATE_MVP_MATRIX, 0, 0, 0, STATE_MATRIX_TRANSPOSE },
+      { STATE_MVP_MATRIX, 0, 1, 1, STATE_MATRIX_TRANSPOSE },
+      { STATE_MVP_MATRIX, 0, 2, 2, STATE_MATRIX_TRANSPOSE },
+      { STATE_MVP_MATRIX, 0, 3, 3, STATE_MATRIX_TRANSPOSE },
+   };
+   GLint mvpRef[4];
+
+   for (i = 0; i < 4; i++) {
+      mvpRef[i] = _mesa_add_state_reference(vprog->Base.Parameters,
+                                            mvpState[i]);
+   }
+
+   /* Alloc storage for new instructions */
+   newInst = _mesa_alloc_instructions(newLen);
+   if (!newInst) {
+      _mesa_error(ctx, GL_OUT_OF_MEMORY,
+                  "glProgramString(inserting position_invariant code)");
+      return;
+   }
+
+   /* TEMP hposTemp; */
+   hposTemp = vprog->Base.NumTemporaries++;
+
+   /*
+    * Generated instructions:
+    *    emit_op2(p, OPCODE_MUL, tmp, 0, swizzle1(src,X), mat[0]);
+    *    emit_op3(p, OPCODE_MAD, tmp, 0, swizzle1(src,Y), mat[1], tmp);
+    *    emit_op3(p, OPCODE_MAD, tmp, 0, swizzle1(src,Z), mat[2], tmp);
+    *    emit_op3(p, OPCODE_MAD, dest, 0, swizzle1(src,W), mat[3], tmp);
+    */
+   _mesa_init_instructions(newInst, 4);
+
+   newInst[0].Opcode = OPCODE_MUL;
+   newInst[0].DstReg.File = PROGRAM_TEMPORARY;
+   newInst[0].DstReg.Index = hposTemp;
+   newInst[0].DstReg.WriteMask = WRITEMASK_XYZW;
+   newInst[0].SrcReg[0].File = PROGRAM_INPUT;
+   newInst[0].SrcReg[0].Index = VERT_ATTRIB_POS;
+   newInst[0].SrcReg[0].Swizzle = SWIZZLE_XXXX;
+   newInst[0].SrcReg[1].File = PROGRAM_STATE_VAR;
+   newInst[0].SrcReg[1].Index = mvpRef[0];
+   newInst[0].SrcReg[1].Swizzle = SWIZZLE_NOOP;
+
+   for (i = 1; i <= 2; i++) {
+      newInst[i].Opcode = OPCODE_MAD;
+      newInst[i].DstReg.File = PROGRAM_TEMPORARY;
+      newInst[i].DstReg.Index = hposTemp;
+      newInst[i].DstReg.WriteMask = WRITEMASK_XYZW;
+      newInst[i].SrcReg[0].File = PROGRAM_INPUT;
+      newInst[i].SrcReg[0].Index = VERT_ATTRIB_POS;
+      newInst[i].SrcReg[0].Swizzle = MAKE_SWIZZLE4(i,i,i,i);
+      newInst[i].SrcReg[1].File = PROGRAM_STATE_VAR;
+      newInst[i].SrcReg[1].Index = mvpRef[i];
+      newInst[i].SrcReg[1].Swizzle = SWIZZLE_NOOP;
+      newInst[i].SrcReg[2].File = PROGRAM_TEMPORARY;
+      newInst[i].SrcReg[2].Index = hposTemp;
+      newInst[1].SrcReg[2].Swizzle = SWIZZLE_NOOP;
+   }
+
+   newInst[3].Opcode = OPCODE_MAD;
+   newInst[3].DstReg.File = PROGRAM_OUTPUT;
+   newInst[3].DstReg.Index = VERT_RESULT_HPOS;
+   newInst[3].DstReg.WriteMask = WRITEMASK_XYZW;
+   newInst[3].SrcReg[0].File = PROGRAM_INPUT;
+   newInst[3].SrcReg[0].Index = VERT_ATTRIB_POS;
+   newInst[3].SrcReg[0].Swizzle = SWIZZLE_WWWW;
+   newInst[3].SrcReg[1].File = PROGRAM_STATE_VAR;
+   newInst[3].SrcReg[1].Index = mvpRef[3];
+   newInst[3].SrcReg[1].Swizzle = SWIZZLE_NOOP;
+   newInst[3].SrcReg[2].File = PROGRAM_TEMPORARY;
+   newInst[3].SrcReg[2].Index = hposTemp;
+   newInst[3].SrcReg[2].Swizzle = SWIZZLE_NOOP;
+
+
+   /* Append original instructions after new instructions */
+   _mesa_copy_instructions (newInst + 4, vprog->Base.Instructions, origLen);
+
+   /* free old instructions */
+   _mesa_free_instructions(vprog->Base.Instructions, origLen);
+
+   /* install new instructions */
+   vprog->Base.Instructions = newInst;
+   vprog->Base.NumInstructions = newLen;
+   vprog->Base.InputsRead |= VERT_BIT_POS;
+   vprog->Base.OutputsWritten |= (1 << VERT_RESULT_HPOS);
+}
+
+
+void
+_mesa_insert_mvp_code(GLcontext *ctx, struct gl_vertex_program *vprog)
+{
+   if (ctx->mvp_with_dp4) 
+      _mesa_insert_mvp_dp4_code( ctx, vprog );
+   else
+      _mesa_insert_mvp_mad_code( ctx, vprog );
+}
+      
+
+
+
+
+
+/**
+ * Append extra instructions onto the given fragment program to implement
+ * the fog mode specified by fprog->FogOption.
+ * The fragment.fogcoord input is used to compute the fog blend factor.
+ *
+ * XXX with a little work, this function could be adapted to add fog code
+ * to vertex programs too.
+ */
+void
+_mesa_append_fog_code(GLcontext *ctx, struct gl_fragment_program *fprog)
+{
+   static const gl_state_index fogPStateOpt[STATE_LENGTH]
+      = { STATE_INTERNAL, STATE_FOG_PARAMS_OPTIMIZED, 0, 0, 0 };
+   static const gl_state_index fogColorState[STATE_LENGTH]
+      = { STATE_FOG_COLOR, 0, 0, 0, 0};
+   struct prog_instruction *newInst, *inst;
+   const GLuint origLen = fprog->Base.NumInstructions;
+   const GLuint newLen = origLen + 5;
+   GLuint i;
+   GLint fogPRefOpt, fogColorRef; /* state references */
+   GLuint colorTemp, fogFactorTemp; /* temporary registerss */
+
+   if (fprog->FogOption == GL_NONE) {
+      _mesa_problem(ctx, "_mesa_append_fog_code() called for fragment program"
+                    " with FogOption == GL_NONE");
+      return;
+   }
+
+   /* Alloc storage for new instructions */
+   newInst = _mesa_alloc_instructions(newLen);
+   if (!newInst) {
+      _mesa_error(ctx, GL_OUT_OF_MEMORY,
+                  "glProgramString(inserting fog_option code)");
+      return;
+   }
+
+   /* Copy orig instructions into new instruction buffer */
+   _mesa_copy_instructions(newInst, fprog->Base.Instructions, origLen);
+
+   /* PARAM fogParamsRefOpt = internal optimized fog params; */
+   fogPRefOpt
+      = _mesa_add_state_reference(fprog->Base.Parameters, fogPStateOpt);
+   /* PARAM fogColorRef = state.fog.color; */
+   fogColorRef
+      = _mesa_add_state_reference(fprog->Base.Parameters, fogColorState);
+
+   /* TEMP colorTemp; */
+   colorTemp = fprog->Base.NumTemporaries++;
+   /* TEMP fogFactorTemp; */
+   fogFactorTemp = fprog->Base.NumTemporaries++;
+
+   /* Scan program to find where result.color is written */
+   inst = newInst;
+   for (i = 0; i < fprog->Base.NumInstructions; i++) {
+      if (inst->Opcode == OPCODE_END)
+         break;
+      if (inst->DstReg.File == PROGRAM_OUTPUT &&
+          inst->DstReg.Index == FRAG_RESULT_COLOR) {
+         /* change the instruction to write to colorTemp w/ clamping */
+         inst->DstReg.File = PROGRAM_TEMPORARY;
+         inst->DstReg.Index = colorTemp;
+         inst->SaturateMode = SATURATE_ZERO_ONE;
+         /* don't break (may be several writes to result.color) */
+      }
+      inst++;
+   }
+   assert(inst->Opcode == OPCODE_END); /* we'll overwrite this inst */
+
+   _mesa_init_instructions(inst, 5);
+
+   /* emit instructions to compute fog blending factor */
+   if (fprog->FogOption == GL_LINEAR) {
+      /* MAD fogFactorTemp.x, fragment.fogcoord.x, fogPRefOpt.x, fogPRefOpt.y; */
+      inst->Opcode = OPCODE_MAD;
+      inst->DstReg.File = PROGRAM_TEMPORARY;
+      inst->DstReg.Index = fogFactorTemp;
+      inst->DstReg.WriteMask = WRITEMASK_X;
+      inst->SrcReg[0].File = PROGRAM_INPUT;
+      inst->SrcReg[0].Index = FRAG_ATTRIB_FOGC;
+      inst->SrcReg[0].Swizzle = SWIZZLE_XXXX;
+      inst->SrcReg[1].File = PROGRAM_STATE_VAR;
+      inst->SrcReg[1].Index = fogPRefOpt;
+      inst->SrcReg[1].Swizzle = SWIZZLE_XXXX;
+      inst->SrcReg[2].File = PROGRAM_STATE_VAR;
+      inst->SrcReg[2].Index = fogPRefOpt;
+      inst->SrcReg[2].Swizzle = SWIZZLE_YYYY;
+      inst->SaturateMode = SATURATE_ZERO_ONE;
+      inst++;
+   }
+   else {
+      ASSERT(fprog->FogOption == GL_EXP || fprog->FogOption == GL_EXP2);
+      /* fogPRefOpt.z = d/ln(2), fogPRefOpt.w = d/sqrt(ln(2) */
+      /* EXP: MUL fogFactorTemp.x, fogPRefOpt.z, fragment.fogcoord.x; */
+      /* EXP2: MUL fogFactorTemp.x, fogPRefOpt.w, fragment.fogcoord.x; */
+      inst->Opcode = OPCODE_MUL;
+      inst->DstReg.File = PROGRAM_TEMPORARY;
+      inst->DstReg.Index = fogFactorTemp;
+      inst->DstReg.WriteMask = WRITEMASK_X;
+      inst->SrcReg[0].File = PROGRAM_STATE_VAR;
+      inst->SrcReg[0].Index = fogPRefOpt;
+      inst->SrcReg[0].Swizzle
+         = (fprog->FogOption == GL_EXP) ? SWIZZLE_ZZZZ : SWIZZLE_WWWW;
+      inst->SrcReg[1].File = PROGRAM_INPUT;
+      inst->SrcReg[1].Index = FRAG_ATTRIB_FOGC;
+      inst->SrcReg[1].Swizzle = SWIZZLE_XXXX;
+      inst++;
+      if (fprog->FogOption == GL_EXP2) {
+         /* MUL fogFactorTemp.x, fogFactorTemp.x, fogFactorTemp.x; */
+         inst->Opcode = OPCODE_MUL;
+         inst->DstReg.File = PROGRAM_TEMPORARY;
+         inst->DstReg.Index = fogFactorTemp;
+         inst->DstReg.WriteMask = WRITEMASK_X;
+         inst->SrcReg[0].File = PROGRAM_TEMPORARY;
+         inst->SrcReg[0].Index = fogFactorTemp;
+         inst->SrcReg[0].Swizzle = SWIZZLE_XXXX;
+         inst->SrcReg[1].File = PROGRAM_TEMPORARY;
+         inst->SrcReg[1].Index = fogFactorTemp;
+         inst->SrcReg[1].Swizzle = SWIZZLE_XXXX;
+         inst++;
+      }
+      /* EX2_SAT fogFactorTemp.x, -fogFactorTemp.x; */
+      inst->Opcode = OPCODE_EX2;
+      inst->DstReg.File = PROGRAM_TEMPORARY;
+      inst->DstReg.Index = fogFactorTemp;
+      inst->DstReg.WriteMask = WRITEMASK_X;
+      inst->SrcReg[0].File = PROGRAM_TEMPORARY;
+      inst->SrcReg[0].Index = fogFactorTemp;
+      inst->SrcReg[0].Negate = NEGATE_XYZW;
+      inst->SrcReg[0].Swizzle = SWIZZLE_XXXX;
+      inst->SaturateMode = SATURATE_ZERO_ONE;
+      inst++;
+   }
+   /* LRP result.color.xyz, fogFactorTemp.xxxx, colorTemp, fogColorRef; */
+   inst->Opcode = OPCODE_LRP;
+   inst->DstReg.File = PROGRAM_OUTPUT;
+   inst->DstReg.Index = FRAG_RESULT_COLOR;
+   inst->DstReg.WriteMask = WRITEMASK_XYZ;
+   inst->SrcReg[0].File = PROGRAM_TEMPORARY;
+   inst->SrcReg[0].Index = fogFactorTemp;
+   inst->SrcReg[0].Swizzle = SWIZZLE_XXXX;
+   inst->SrcReg[1].File = PROGRAM_TEMPORARY;
+   inst->SrcReg[1].Index = colorTemp;
+   inst->SrcReg[1].Swizzle = SWIZZLE_NOOP;
+   inst->SrcReg[2].File = PROGRAM_STATE_VAR;
+   inst->SrcReg[2].Index = fogColorRef;
+   inst->SrcReg[2].Swizzle = SWIZZLE_NOOP;
+   inst++;
+   /* MOV result.color.w, colorTemp.x;  # copy alpha */
+   inst->Opcode = OPCODE_MOV;
+   inst->DstReg.File = PROGRAM_OUTPUT;
+   inst->DstReg.Index = FRAG_RESULT_COLOR;
+   inst->DstReg.WriteMask = WRITEMASK_W;
+   inst->SrcReg[0].File = PROGRAM_TEMPORARY;
+   inst->SrcReg[0].Index = colorTemp;
+   inst->SrcReg[0].Swizzle = SWIZZLE_NOOP;
+   inst++;
+   /* END; */
+   inst->Opcode = OPCODE_END;
+   inst++;
+
+   /* free old instructions */
+   _mesa_free_instructions(fprog->Base.Instructions, origLen);
+
+   /* install new instructions */
+   fprog->Base.Instructions = newInst;
+   fprog->Base.NumInstructions = inst - newInst;
+   fprog->Base.InputsRead |= FRAG_BIT_FOGC;
+   /* XXX do this?  fprog->FogOption = GL_NONE; */
+}
+
+
+
+static GLboolean
+is_texture_instruction(const struct prog_instruction *inst)
+{
+   switch (inst->Opcode) {
+   case OPCODE_TEX:
+   case OPCODE_TXB:
+   case OPCODE_TXD:
+   case OPCODE_TXL:
+   case OPCODE_TXP:
+   case OPCODE_TXP_NV:
+      return GL_TRUE;
+   default:
+      return GL_FALSE;
+   }
+}
+      
+
+/**
+ * Count the number of texure indirections in the given program.
+ * The program's NumTexIndirections field will be updated.
+ * See the GL_ARB_fragment_program spec (issue 24) for details.
+ * XXX we count texture indirections in texenvprogram.c (maybe use this code
+ * instead and elsewhere).
+ */
+void
+_mesa_count_texture_indirections(struct gl_program *prog)
+{
+   GLuint indirections = 1;
+   GLbitfield tempsOutput = 0x0;
+   GLbitfield aluTemps = 0x0;
+   GLuint i;
+
+   for (i = 0; i < prog->NumInstructions; i++) {
+      const struct prog_instruction *inst = prog->Instructions + i;
+
+      if (is_texture_instruction(inst)) {
+         if (((inst->SrcReg[0].File == PROGRAM_TEMPORARY) && 
+              (tempsOutput & (1 << inst->SrcReg[0].Index))) ||
+             ((inst->Opcode != OPCODE_KIL) &&
+              (inst->DstReg.File == PROGRAM_TEMPORARY) && 
+              (aluTemps & (1 << inst->DstReg.Index)))) 
+            {
+               indirections++;
+               tempsOutput = 0x0;
+               aluTemps = 0x0;
+            }
+      }
+      else {
+         GLuint j;
+         for (j = 0; j < 3; j++) {
+            if (inst->SrcReg[j].File == PROGRAM_TEMPORARY)
+               aluTemps |= (1 << inst->SrcReg[j].Index);
+         }
+         if (inst->DstReg.File == PROGRAM_TEMPORARY)
+            aluTemps |= (1 << inst->DstReg.Index);
+      }
+
+      if ((inst->Opcode != OPCODE_KIL) && (inst->DstReg.File == PROGRAM_TEMPORARY))
+         tempsOutput |= (1 << inst->DstReg.Index);
+   }
+
+   prog->NumTexIndirections = indirections;
+}
+
+
+/**
+ * Count number of texture instructions in given program and update the
+ * program's NumTexInstructions field.
+ */
+void
+_mesa_count_texture_instructions(struct gl_program *prog)
+{
+   GLuint i;
+   prog->NumTexInstructions = 0;
+   for (i = 0; i < prog->NumInstructions; i++) {
+      prog->NumTexInstructions += is_texture_instruction(prog->Instructions + i);
+   }
+}
+
+
+/**
+ * Scan/rewrite program to remove reads of custom (output) registers.
+ * The passed type has to be either PROGRAM_OUTPUT or PROGRAM_VARYING
+ * (for vertex shaders).
+ * In GLSL shaders, varying vars can be read and written.
+ * On some hardware, trying to read an output register causes trouble.
+ * So, rewrite the program to use a temporary register in this case.
+ */
+void
+_mesa_remove_output_reads(struct gl_program *prog, gl_register_file type)
+{
+   GLuint i;
+   GLint outputMap[VERT_RESULT_MAX];
+   GLuint numVaryingReads = 0;
+
+   assert(type == PROGRAM_VARYING || type == PROGRAM_OUTPUT);
+   assert(prog->Target == GL_VERTEX_PROGRAM_ARB || type != PROGRAM_VARYING);
+
+   for (i = 0; i < VERT_RESULT_MAX; i++)
+      outputMap[i] = -1;
+
+   /* look for instructions which read from varying vars */
+   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 == type) {
+            /* replace the read with a temp reg */
+            const GLuint var = inst->SrcReg[j].Index;
+            if (outputMap[var] == -1) {
+               numVaryingReads++;
+               outputMap[var] = _mesa_find_free_register(prog,
+                                                         PROGRAM_TEMPORARY);
+            }
+            inst->SrcReg[j].File = PROGRAM_TEMPORARY;
+            inst->SrcReg[j].Index = outputMap[var];
+         }
+      }
+   }
+
+   if (numVaryingReads == 0)
+      return; /* nothing to be done */
+
+   /* look for instructions which write to the varying vars identified above */
+   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->DstReg.File == type &&
+             outputMap[inst->DstReg.Index] >= 0) {
+            /* change inst to write to the temp reg, instead of the varying */
+            inst->DstReg.File = PROGRAM_TEMPORARY;
+            inst->DstReg.Index = outputMap[inst->DstReg.Index];
+         }
+      }
+   }
+
+   /* insert new instructions to copy the temp vars to the varying vars */
+   {
+      struct prog_instruction *inst;
+      GLint endPos, var;
+
+      /* Look for END instruction and insert the new varying writes */
+      endPos = -1;
+      for (i = 0; i < prog->NumInstructions; i++) {
+         struct prog_instruction *inst = prog->Instructions + i;
+         if (inst->Opcode == OPCODE_END) {
+            endPos = i;
+            _mesa_insert_instructions(prog, i, numVaryingReads);
+            break;
+         }
+      }
+
+      assert(endPos >= 0);
+
+      /* insert new MOV instructions here */
+      inst = prog->Instructions + endPos;
+      for (var = 0; var < VERT_RESULT_MAX; var++) {
+         if (outputMap[var] >= 0) {
+            /* MOV VAR[var], TEMP[tmp]; */
+            inst->Opcode = OPCODE_MOV;
+            inst->DstReg.File = type;
+            inst->DstReg.Index = var;
+            inst->SrcReg[0].File = PROGRAM_TEMPORARY;
+            inst->SrcReg[0].Index = outputMap[var];
+            inst++;
+         }
+      }
+   }
+}