Merge remote branch 'origin/master' into glsl2

This pulls in multiple i965 driver fixes which will help ensure better
testing coverage during development, and also gets past the conflicts
of the src/mesa/shader -> src/mesa/program move.

Conflicts:
	src/mesa/Makefile
	src/mesa/main/shaderapi.c
	src/mesa/main/shaderobj.h

1 files changed, 1041 insertions, 0 deletions

diff --git a/src/mesa/program/prog_optimize.c b/src/mesa/program/prog_optimize.c
new file mode 100644
index 0000000000..bd120b8643
--- /dev/null
+++ b/src/mesa/program/prog_optimize.c
@@ -0,0 +1,1041 @@
+/*
+ * Mesa 3-D graphics library
+ * Version:  7.5
+ *
+ * Copyright (C) 2009  VMware, Inc.  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
+ * VMWARE 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.
+ */
+
+
+
+#include "main/glheader.h"
+#include "main/context.h"
+#include "main/macros.h"
+#include "program.h"
+#include "prog_instruction.h"
+#include "prog_optimize.h"
+#include "prog_print.h"
+
+
+#define MAX_LOOP_NESTING 50
+
+
+static GLboolean dbg = GL_FALSE;
+
+/* Returns the mask of channels read from the given srcreg in this instruction.
+ */
+static GLuint
+get_src_arg_mask(const struct prog_instruction *inst, int arg)
+{
+   int writemask = inst->DstReg.WriteMask;
+
+   if (inst->CondUpdate)
+      writemask = WRITEMASK_XYZW;
+
+   switch (inst->Opcode) {
+   case OPCODE_MOV:
+   case OPCODE_ABS:
+   case OPCODE_ADD:
+   case OPCODE_MUL:
+   case OPCODE_SUB:
+      return writemask;
+   case OPCODE_RCP:
+   case OPCODE_SIN:
+   case OPCODE_COS:
+   case OPCODE_RSQ:
+   case OPCODE_POW:
+   case OPCODE_EX2:
+      return WRITEMASK_X;
+   case OPCODE_DP2:
+      return WRITEMASK_XY;
+   case OPCODE_DP3:
+   case OPCODE_XPD:
+      return WRITEMASK_XYZ;
+   default:
+      return WRITEMASK_XYZW;
+   }
+}
+
+/**
+ * In 'prog' remove instruction[i] if removeFlags[i] == TRUE.
+ * \return number of instructions removed
+ */
+static GLuint
+remove_instructions(struct gl_program *prog, const GLboolean *removeFlags)
+{
+   GLint i, removeEnd = 0, removeCount = 0;
+   GLuint totalRemoved = 0;
+
+   /* go backward */
+   for (i = prog->NumInstructions - 1; i >= 0; i--) {
+      if (removeFlags[i]) {
+         totalRemoved++;
+         if (removeCount == 0) {
+            /* begin a run of instructions to remove */
+            removeEnd = i;
+            removeCount = 1;
+         }
+         else {
+            /* extend the run of instructions to remove */
+            removeCount++;
+         }
+      }
+      else {
+         /* don't remove this instruction, but check if the preceeding
+          * instructions are to be removed.
+          */
+         if (removeCount > 0) {
+            GLint removeStart = removeEnd - removeCount + 1;
+            _mesa_delete_instructions(prog, removeStart, removeCount);
+            removeStart = removeCount = 0; /* reset removal info */
+         }
+      }
+   }
+   /* Finish removing if the first instruction was to be removed. */
+   if (removeCount > 0) {
+      GLint removeStart = removeEnd - removeCount + 1;
+      _mesa_delete_instructions(prog, removeStart, removeCount);
+   }
+   return totalRemoved;
+}
+
+
+/**
+ * Remap register indexes according to map.
+ * \param prog  the program to search/replace
+ * \param file  the type of register file to search/replace
+ * \param map  maps old register indexes to new indexes
+ */
+static void
+replace_regs(struct gl_program *prog, gl_register_file file, const GLint map[])
+{
+   GLuint i;
+
+   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 == file) {
+            GLuint index = inst->SrcReg[j].Index;
+            ASSERT(map[index] >= 0);
+            inst->SrcReg[j].Index = map[index];
+         }
+      }
+      if (inst->DstReg.File == file) {
+         const GLuint index = inst->DstReg.Index;
+         ASSERT(map[index] >= 0);
+         inst->DstReg.Index = map[index];
+      }
+   }
+}
+
+
+/**
+ * Consolidate temporary registers to use low numbers.  For example, if the
+ * shader only uses temps 4, 5, 8, replace them with 0, 1, 2.
+ */
+static void
+_mesa_consolidate_registers(struct gl_program *prog)
+{
+   GLboolean tempUsed[MAX_PROGRAM_TEMPS];
+   GLint tempMap[MAX_PROGRAM_TEMPS];
+   GLuint tempMax = 0, i;
+
+   if (dbg) {
+      printf("Optimize: Begin register consolidation\n");
+   }
+
+   memset(tempUsed, 0, sizeof(tempUsed));
+
+   for (i = 0; i < MAX_PROGRAM_TEMPS; i++) {
+      tempMap[i] = -1;
+   }
+
+   /* set tempUsed[i] if temporary [i] is referenced */
+   for (i = 0; i < prog->NumInstructions; i++) {
+      const 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_TEMPORARY) {
+            const GLuint index = inst->SrcReg[j].Index;
+            ASSERT(index < MAX_PROGRAM_TEMPS);
+            tempUsed[index] = GL_TRUE;
+            tempMax = MAX2(tempMax, index);
+            break;
+         }
+      }
+      if (inst->DstReg.File == PROGRAM_TEMPORARY) {
+         const GLuint index = inst->DstReg.Index;
+         ASSERT(index < MAX_PROGRAM_TEMPS);
+         tempUsed[index] = GL_TRUE;
+         tempMax = MAX2(tempMax, index);
+      }
+   }
+
+   /* allocate a new index for each temp that's used */
+   {
+      GLuint freeTemp = 0;
+      for (i = 0; i <= tempMax; i++) {
+         if (tempUsed[i]) {
+            tempMap[i] = freeTemp++;
+            /*printf("replace %u with %u\n", i, tempMap[i]);*/
+         }
+      }
+      if (freeTemp == tempMax + 1) {
+         /* no consolidation possible */
+         return;
+      }         
+      if (dbg) {
+         printf("Replace regs 0..%u with 0..%u\n", tempMax, freeTemp-1);
+      }
+   }
+
+   replace_regs(prog, PROGRAM_TEMPORARY, tempMap);
+
+   if (dbg) {
+      printf("Optimize: End register consolidation\n");
+   }
+}
+
+
+/**
+ * Remove dead instructions from the given program.
+ * This is very primitive for now.  Basically look for temp registers
+ * that are written to but never read.  Remove any instructions that
+ * write to such registers.  Be careful with condition code setters.
+ */
+static void
+_mesa_remove_dead_code(struct gl_program *prog)
+{
+   GLboolean tempRead[MAX_PROGRAM_TEMPS][4];
+   GLboolean *removeInst; /* per-instruction removal flag */
+   GLuint i, rem = 0, comp;
+
+   memset(tempRead, 0, sizeof(tempRead));
+
+   if (dbg) {
+      printf("Optimize: Begin dead code removal\n");
+      /*_mesa_print_program(prog);*/
+   }
+
+   removeInst = (GLboolean *)
+      calloc(1, prog->NumInstructions * sizeof(GLboolean));
+
+   /* Determine which temps are read and written */
+   for (i = 0; i < prog->NumInstructions; i++) {
+      const struct prog_instruction *inst = prog->Instructions + i;
+      const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode);
+      GLuint j;
+
+      /* check src regs */
+      for (j = 0; j < numSrc; j++) {
+         if (inst->SrcReg[j].File == PROGRAM_TEMPORARY) {
+            const GLuint index = inst->SrcReg[j].Index;
+            GLuint read_mask;
+            ASSERT(index < MAX_PROGRAM_TEMPS);
+	    read_mask = get_src_arg_mask(inst, j);
+
+            if (inst->SrcReg[j].RelAddr) {
+               if (dbg)
+                  printf("abort remove dead code (indirect temp)\n");
+               goto done;
+            }
+
+	    for (comp = 0; comp < 4; comp++) {
+	       GLuint swz = (inst->SrcReg[j].Swizzle >> (3 * comp)) & 0x7;
+
+	       if ((read_mask & (1 << comp)) == 0)
+		  continue;
+
+	       switch (swz) {
+	       case SWIZZLE_X:
+		  tempRead[index][0] = GL_TRUE;
+		  break;
+	       case SWIZZLE_Y:
+		  tempRead[index][1] = GL_TRUE;
+		  break;
+	       case SWIZZLE_Z:
+		  tempRead[index][2] = GL_TRUE;
+		  break;
+	       case SWIZZLE_W:
+		  tempRead[index][3] = GL_TRUE;
+		  break;
+	       }
+	    }
+         }
+      }
+
+      /* check dst reg */
+      if (inst->DstReg.File == PROGRAM_TEMPORARY) {
+         const GLuint index = inst->DstReg.Index;
+         ASSERT(index < MAX_PROGRAM_TEMPS);
+
+         if (inst->DstReg.RelAddr) {
+            if (dbg)
+               printf("abort remove dead code (indirect temp)\n");
+            goto done;
+         }
+
+         if (inst->CondUpdate) {
+            /* If we're writing to this register and setting condition
+             * codes we cannot remove the instruction.  Prevent removal
+             * by setting the 'read' flag.
+             */
+            tempRead[index][0] = GL_TRUE;
+            tempRead[index][1] = GL_TRUE;
+            tempRead[index][2] = GL_TRUE;
+            tempRead[index][3] = GL_TRUE;
+         }
+      }
+   }
+
+   /* find instructions that write to dead registers, flag for removal */
+   for (i = 0; i < prog->NumInstructions; i++) {
+      struct prog_instruction *inst = prog->Instructions + i;
+      const GLuint numDst = _mesa_num_inst_dst_regs(inst->Opcode);
+
+      if (numDst != 0 && inst->DstReg.File == PROGRAM_TEMPORARY) {
+         GLint chan, index = inst->DstReg.Index;
+
+	 for (chan = 0; chan < 4; chan++) {
+	    if (!tempRead[index][chan] &&
+		inst->DstReg.WriteMask & (1 << chan)) {
+	       if (dbg) {
+		  printf("Remove writemask on %u.%c\n", i,
+			       chan == 3 ? 'w' : 'x' + chan);
+	       }
+	       inst->DstReg.WriteMask &= ~(1 << chan);
+	       rem++;
+	    }
+	 }
+
+	 if (inst->DstReg.WriteMask == 0) {
+	    /* If we cleared all writes, the instruction can be removed. */
+	    if (dbg)
+	       printf("Remove instruction %u: \n", i);
+	    removeInst[i] = GL_TRUE;
+	 }
+      }
+   }
+
+   /* now remove the instructions which aren't needed */
+   rem = remove_instructions(prog, removeInst);
+
+   if (dbg) {
+      printf("Optimize: End dead code removal.\n");
+      printf("  %u channel writes removed\n", rem);
+      printf("  %u instructions removed\n", rem);
+      /*_mesa_print_program(prog);*/
+   }
+
+done:
+   free(removeInst);
+}
+
+
+enum temp_use
+{
+   READ,
+   WRITE,
+   FLOW,
+   END
+};
+
+/**
+ * Scan forward in program from 'start' for the next occurance of TEMP[index].
+ * Return READ, WRITE, FLOW or END to indicate the next usage or an indicator
+ * that we can't look further.
+ */
+static enum temp_use
+find_next_temp_use(const struct gl_program *prog, GLuint start, GLuint index)
+{
+   GLuint i;
+
+   for (i = start; i < prog->NumInstructions; i++) {
+      const struct prog_instruction *inst = prog->Instructions + i;
+      switch (inst->Opcode) {
+      case OPCODE_BGNLOOP:
+      case OPCODE_ENDLOOP:
+      case OPCODE_BGNSUB:
+      case OPCODE_ENDSUB:
+         return FLOW;
+      default:
+         {
+            const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode);
+            GLuint j;
+            for (j = 0; j < numSrc; j++) {
+               if (inst->SrcReg[j].File == PROGRAM_TEMPORARY &&
+                   inst->SrcReg[j].Index == index)
+                  return READ;
+            }
+            if (inst->DstReg.File == PROGRAM_TEMPORARY &&
+                inst->DstReg.Index == index)
+               return WRITE;
+         }
+      }
+   }
+
+   return END;
+}
+
+static GLboolean _mesa_is_flow_control_opcode(enum prog_opcode opcode)
+{
+   switch (opcode) {
+   case OPCODE_BGNLOOP:
+   case OPCODE_BGNSUB:
+   case OPCODE_BRA:
+   case OPCODE_CAL:
+   case OPCODE_CONT:
+   case OPCODE_IF:
+   case OPCODE_ELSE:
+   case OPCODE_END:
+   case OPCODE_ENDIF:
+   case OPCODE_ENDLOOP:
+   case OPCODE_ENDSUB:
+   case OPCODE_RET:
+      return GL_TRUE;
+   default:
+      return GL_FALSE;
+   }
+}
+
+/**
+ * Try to remove use of extraneous MOV instructions, to free them up for dead
+ * code removal.
+ */
+static void
+_mesa_remove_extra_move_use(struct gl_program *prog)
+{
+   GLuint i, j;
+
+   if (dbg) {
+      printf("Optimize: Begin remove extra move use\n");
+      _mesa_print_program(prog);
+   }
+
+   /*
+    * Look for sequences such as this:
+    *    MOV tmpX, arg0;
+    *    ...
+    *    FOO tmpY, tmpX, arg1;
+    * and convert into:
+    *    MOV tmpX, arg0;
+    *    ...
+    *    FOO tmpY, arg0, arg1;
+    */
+
+   for (i = 0; i + 1 < prog->NumInstructions; i++) {
+      const struct prog_instruction *mov = prog->Instructions + i;
+
+      if (mov->Opcode != OPCODE_MOV ||
+	  mov->DstReg.File != PROGRAM_TEMPORARY ||
+	  mov->DstReg.RelAddr ||
+	  mov->DstReg.CondMask != COND_TR ||
+	  mov->SaturateMode != SATURATE_OFF ||
+	  mov->SrcReg[0].RelAddr)
+	 continue;
+
+      /* Walk through remaining instructions until the or src reg gets
+       * rewritten or we get into some flow-control, eliminating the use of
+       * this MOV.
+       */
+      for (j = i + 1; j < prog->NumInstructions; j++) {
+	 struct prog_instruction *inst2 = prog->Instructions + j;
+	 GLuint arg;
+
+	 if (_mesa_is_flow_control_opcode(inst2->Opcode))
+	     break;
+
+	 /* First rewrite this instruction's args if appropriate. */
+	 for (arg = 0; arg < _mesa_num_inst_src_regs(inst2->Opcode); arg++) {
+	    int comp;
+	    int read_mask = get_src_arg_mask(inst2, arg);
+
+	    if (inst2->SrcReg[arg].File != mov->DstReg.File ||
+		inst2->SrcReg[arg].Index != mov->DstReg.Index ||
+		inst2->SrcReg[arg].RelAddr ||
+		inst2->SrcReg[arg].Abs)
+	       continue;
+
+	    /* Check that all the sources for this arg of inst2 come from inst1
+	     * or constants.
+	     */
+	    for (comp = 0; comp < 4; comp++) {
+	       int src_swz = GET_SWZ(inst2->SrcReg[arg].Swizzle, comp);
+
+	       /* If the MOV didn't write that channel, can't use it. */
+	       if ((read_mask & (1 << comp)) &&
+		   src_swz <= SWIZZLE_W &&
+		   (mov->DstReg.WriteMask & (1 << src_swz)) == 0)
+		  break;
+	    }
+	    if (comp != 4)
+	       continue;
+
+	    /* Adjust the swizzles of inst2 to point at MOV's source */
+	    for (comp = 0; comp < 4; comp++) {
+	       int inst2_swz = GET_SWZ(inst2->SrcReg[arg].Swizzle, comp);
+
+	       if (inst2_swz <= SWIZZLE_W) {
+		  GLuint s = GET_SWZ(mov->SrcReg[0].Swizzle, inst2_swz);
+		  inst2->SrcReg[arg].Swizzle &= ~(7 << (3 * comp));
+		  inst2->SrcReg[arg].Swizzle |= s << (3 * comp);
+		  inst2->SrcReg[arg].Negate ^= (((mov->SrcReg[0].Negate >>
+						  inst2_swz) & 0x1) << comp);
+	       }
+	    }
+	    inst2->SrcReg[arg].File = mov->SrcReg[0].File;
+	    inst2->SrcReg[arg].Index = mov->SrcReg[0].Index;
+	 }
+
+	 /* If this instruction overwrote part of the move, our time is up. */
+	 if ((inst2->DstReg.File == mov->DstReg.File &&
+	      (inst2->DstReg.RelAddr ||
+	       inst2->DstReg.Index == mov->DstReg.Index)) ||
+	     (inst2->DstReg.File == mov->SrcReg[0].File &&
+	      (inst2->DstReg.RelAddr ||
+	       inst2->DstReg.Index == mov->SrcReg[0].Index)))
+	    break;
+      }
+   }
+
+   if (dbg) {
+      printf("Optimize: End remove extra move use.\n");
+      /*_mesa_print_program(prog);*/
+   }
+}
+
+/**
+ * Try to remove extraneous MOV instructions from the given program.
+ */
+static void
+_mesa_remove_extra_moves(struct gl_program *prog)
+{
+   GLboolean *removeInst; /* per-instruction removal flag */
+   GLuint i, rem, loopNesting = 0, subroutineNesting = 0;
+
+   if (dbg) {
+      printf("Optimize: Begin remove extra moves\n");
+      _mesa_print_program(prog);
+   }
+
+   removeInst = (GLboolean *)
+      calloc(1, prog->NumInstructions * sizeof(GLboolean));
+
+   /*
+    * Look for sequences such as this:
+    *    FOO tmpX, arg0, arg1;
+    *    MOV tmpY, tmpX;
+    * and convert into:
+    *    FOO tmpY, arg0, arg1;
+    */
+
+   for (i = 0; i < prog->NumInstructions; i++) {
+      const struct prog_instruction *inst = prog->Instructions + i;
+
+      switch (inst->Opcode) {
+      case OPCODE_BGNLOOP:
+         loopNesting++;
+         break;
+      case OPCODE_ENDLOOP:
+         loopNesting--;
+         break;
+      case OPCODE_BGNSUB:
+         subroutineNesting++;
+         break;
+      case OPCODE_ENDSUB:
+         subroutineNesting--;
+         break;
+      case OPCODE_MOV:
+         if (i > 0 &&
+             loopNesting == 0 &&
+             subroutineNesting == 0 &&
+             inst->SrcReg[0].File == PROGRAM_TEMPORARY &&
+             inst->SrcReg[0].Swizzle == SWIZZLE_XYZW) {
+            /* see if this MOV can be removed */
+            const GLuint tempIndex = inst->SrcReg[0].Index;
+            struct prog_instruction *prevInst;
+            GLuint prevI;
+
+            /* get pointer to previous instruction */
+            prevI = i - 1;
+            while (prevI > 0 && removeInst[prevI])
+               prevI--;
+            prevInst = prog->Instructions + prevI;
+
+            if (prevInst->DstReg.File == PROGRAM_TEMPORARY &&
+                prevInst->DstReg.Index == tempIndex &&
+                prevInst->DstReg.WriteMask == WRITEMASK_XYZW) {
+
+               enum temp_use next_use =
+                  find_next_temp_use(prog, i + 1, tempIndex);
+
+               if (next_use == WRITE || next_use == END) {
+                  /* OK, we can safely remove this MOV instruction.
+                   * Transform:
+                   *   prevI: FOO tempIndex, x, y;
+                   *       i: MOV z, tempIndex;
+                   * Into:
+                   *   prevI: FOO z, x, y;
+                   */
+
+                  /* patch up prev inst */
+                  prevInst->DstReg.File = inst->DstReg.File;
+                  prevInst->DstReg.Index = inst->DstReg.Index;
+
+                  /* flag this instruction for removal */
+                  removeInst[i] = GL_TRUE;
+
+                  if (dbg) {
+                     printf("Remove MOV at %u\n", i);
+                     printf("new prev inst %u: ", prevI);
+                     _mesa_print_instruction(prevInst);
+                  }
+               }
+            }
+         }
+         break;
+      default:
+         ; /* nothing */
+      }
+   }
+
+   /* now remove the instructions which aren't needed */
+   rem = remove_instructions(prog, removeInst);
+
+   free(removeInst);
+
+   if (dbg) {
+      printf("Optimize: End remove extra moves.  %u instructions removed\n", rem);
+      /*_mesa_print_program(prog);*/
+   }
+}
+
+
+/** A live register interval */
+struct interval
+{
+   GLuint Reg;         /** The temporary register index */
+   GLuint Start, End;  /** Start/end instruction numbers */
+};
+
+
+/** A list of register intervals */
+struct interval_list
+{
+   GLuint Num;
+   struct interval Intervals[MAX_PROGRAM_TEMPS];
+};
+
+
+static void
+append_interval(struct interval_list *list, const struct interval *inv)
+{
+   list->Intervals[list->Num++] = *inv;
+}
+
+
+/** Insert interval inv into list, sorted by interval end */
+static void
+insert_interval_by_end(struct interval_list *list, const struct interval *inv)
+{
+   /* XXX we could do a binary search insertion here since list is sorted */
+   GLint i = list->Num - 1;
+   while (i >= 0 && list->Intervals[i].End > inv->End) {
+      list->Intervals[i + 1] = list->Intervals[i];
+      i--;
+   }
+   list->Intervals[i + 1] = *inv;
+   list->Num++;
+
+#ifdef DEBUG
+   {
+      GLuint i;
+      for (i = 0; i + 1 < list->Num; i++) {
+         ASSERT(list->Intervals[i].End <= list->Intervals[i + 1].End);
+      }
+   }
+#endif
+}
+
+
+/** Remove the given interval from the interval list */
+static void
+remove_interval(struct interval_list *list, const struct interval *inv)
+{
+   /* XXX we could binary search since list is sorted */
+   GLuint k;
+   for (k = 0; k < list->Num; k++) {
+      if (list->Intervals[k].Reg == inv->Reg) {
+         /* found, remove it */
+         ASSERT(list->Intervals[k].Start == inv->Start);
+         ASSERT(list->Intervals[k].End == inv->End);
+         while (k < list->Num - 1) {
+            list->Intervals[k] = list->Intervals[k + 1];
+            k++;
+         }
+         list->Num--;
+         return;
+      }
+   }
+}
+
+
+/** called by qsort() */
+static int
+compare_start(const void *a, const void *b)
+{
+   const struct interval *ia = (const struct interval *) a;
+   const struct interval *ib = (const struct interval *) b;
+   if (ia->Start < ib->Start)
+      return -1;
+   else if (ia->Start > ib->Start)
+      return +1;
+   else
+      return 0;
+}
+
+/** sort the interval list according to interval starts */
+static void
+sort_interval_list_by_start(struct interval_list *list)
+{
+   qsort(list->Intervals, list->Num, sizeof(struct interval), compare_start);
+#ifdef DEBUG
+   {
+      GLuint i;
+      for (i = 0; i + 1 < list->Num; i++) {
+         ASSERT(list->Intervals[i].Start <= list->Intervals[i + 1].Start);
+      }
+   }
+#endif
+}
+
+struct loop_info
+{
+   GLuint Start, End;  /**< Start, end instructions of loop */
+};
+
+/**
+ * Update the intermediate interval info for register 'index' and
+ * instruction 'ic'.
+ */
+static void
+update_interval(GLint intBegin[], GLint intEnd[],
+		struct loop_info *loopStack, GLuint loopStackDepth,
+		GLuint index, GLuint ic)
+{
+   int i;
+
+   /* If the register is used in a loop, extend its lifetime through the end
+    * of the outermost loop that doesn't contain its definition.
+    */
+   for (i = 0; i < loopStackDepth; i++) {
+      if (intBegin[index] < loopStack[i].Start) {
+	 ic = loopStack[i].End;
+	 break;
+      }
+   }
+
+   ASSERT(index < MAX_PROGRAM_TEMPS);
+   if (intBegin[index] == -1) {
+      ASSERT(intEnd[index] == -1);
+      intBegin[index] = intEnd[index] = ic;
+   }
+   else {
+      intEnd[index] = ic;
+   }
+}
+
+
+/**
+ * Find first/last instruction that references each temporary register.
+ */
+GLboolean
+_mesa_find_temp_intervals(const struct prog_instruction *instructions,
+                          GLuint numInstructions,
+                          GLint intBegin[MAX_PROGRAM_TEMPS],
+                          GLint intEnd[MAX_PROGRAM_TEMPS])
+{
+   struct loop_info loopStack[MAX_LOOP_NESTING];
+   GLuint loopStackDepth = 0;
+   GLuint i;
+
+   for (i = 0; i < MAX_PROGRAM_TEMPS; i++){
+      intBegin[i] = intEnd[i] = -1;
+   }
+
+   /* Scan instructions looking for temporary registers */
+   for (i = 0; i < numInstructions; i++) {
+      const struct prog_instruction *inst = instructions + i;
+      if (inst->Opcode == OPCODE_BGNLOOP) {
+         loopStack[loopStackDepth].Start = i;
+         loopStack[loopStackDepth].End = inst->BranchTarget;
+         loopStackDepth++;
+      }
+      else if (inst->Opcode == OPCODE_ENDLOOP) {
+         loopStackDepth--;
+      }
+      else if (inst->Opcode == OPCODE_CAL) {
+         return GL_FALSE;
+      }
+      else {
+         const GLuint numSrc = 3;/*_mesa_num_inst_src_regs(inst->Opcode);*/
+         GLuint j;
+         for (j = 0; j < numSrc; j++) {
+            if (inst->SrcReg[j].File == PROGRAM_TEMPORARY) {
+               const GLuint index = inst->SrcReg[j].Index;
+               if (inst->SrcReg[j].RelAddr)
+                  return GL_FALSE;
+               update_interval(intBegin, intEnd, loopStack, loopStackDepth,
+			       index, i);
+            }
+         }
+         if (inst->DstReg.File == PROGRAM_TEMPORARY) {
+            const GLuint index = inst->DstReg.Index;
+            if (inst->DstReg.RelAddr)
+               return GL_FALSE;
+            update_interval(intBegin, intEnd, loopStack, loopStackDepth,
+			    index, i);
+         }
+      }
+   }
+
+   return GL_TRUE;
+}
+
+
+/**
+ * Find the live intervals for each temporary register in the program.
+ * For register R, the interval [A,B] indicates that R is referenced
+ * from instruction A through instruction B.
+ * Special consideration is needed for loops and subroutines.
+ * \return GL_TRUE if success, GL_FALSE if we cannot proceed for some reason
+ */
+static GLboolean
+find_live_intervals(struct gl_program *prog,
+                    struct interval_list *liveIntervals)
+{
+   GLint intBegin[MAX_PROGRAM_TEMPS], intEnd[MAX_PROGRAM_TEMPS];
+   GLuint i;
+
+   /*
+    * Note: we'll return GL_FALSE below if we find relative indexing
+    * into the TEMP register file.  We can't handle that yet.
+    * We also give up on subroutines for now.
+    */
+
+   if (dbg) {
+      printf("Optimize: Begin find intervals\n");
+   }
+
+   /* build intermediate arrays */
+   if (!_mesa_find_temp_intervals(prog->Instructions, prog->NumInstructions,
+                                  intBegin, intEnd))
+      return GL_FALSE;
+
+   /* Build live intervals list from intermediate arrays */
+   liveIntervals->Num = 0;
+   for (i = 0; i < MAX_PROGRAM_TEMPS; i++) {
+      if (intBegin[i] >= 0) {
+         struct interval inv;
+         inv.Reg = i;
+         inv.Start = intBegin[i];
+         inv.End = intEnd[i];
+         append_interval(liveIntervals, &inv);
+      }
+   }
+
+   /* Sort the list according to interval starts */
+   sort_interval_list_by_start(liveIntervals);
+
+   if (dbg) {
+      /* print interval info */
+      for (i = 0; i < liveIntervals->Num; i++) {
+         const struct interval *inv = liveIntervals->Intervals + i;
+         printf("Reg[%d] live [%d, %d]:",
+                      inv->Reg, inv->Start, inv->End);
+         if (1) {
+            GLuint j;
+            for (j = 0; j < inv->Start; j++)
+               printf(" ");
+            for (j = inv->Start; j <= inv->End; j++)
+               printf("x");
+         }
+         printf("\n");
+      }
+   }
+
+   return GL_TRUE;
+}
+
+
+/** Scan the array of used register flags to find free entry */
+static GLint
+alloc_register(GLboolean usedRegs[MAX_PROGRAM_TEMPS])
+{
+   GLuint k;
+   for (k = 0; k < MAX_PROGRAM_TEMPS; k++) {
+      if (!usedRegs[k]) {
+         usedRegs[k] = GL_TRUE;
+         return k;
+      }
+   }
+   return -1;
+}
+
+
+/**
+ * This function implements "Linear Scan Register Allocation" to reduce
+ * the number of temporary registers used by the program.
+ *
+ * We compute the "live interval" for all temporary registers then
+ * examine the overlap of the intervals to allocate new registers.
+ * Basically, if two intervals do not overlap, they can use the same register.
+ */
+static void
+_mesa_reallocate_registers(struct gl_program *prog)
+{
+   struct interval_list liveIntervals;
+   GLint registerMap[MAX_PROGRAM_TEMPS];
+   GLboolean usedRegs[MAX_PROGRAM_TEMPS];
+   GLuint i;
+   GLint maxTemp = -1;
+
+   if (dbg) {
+      printf("Optimize: Begin live-interval register reallocation\n");
+      _mesa_print_program(prog);
+   }
+
+   for (i = 0; i < MAX_PROGRAM_TEMPS; i++){
+      registerMap[i] = -1;
+      usedRegs[i] = GL_FALSE;
+   }
+
+   if (!find_live_intervals(prog, &liveIntervals)) {
+      if (dbg)
+         printf("Aborting register reallocation\n");
+      return;
+   }
+
+   {
+      struct interval_list activeIntervals;
+      activeIntervals.Num = 0;
+
+      /* loop over live intervals, allocating a new register for each */
+      for (i = 0; i < liveIntervals.Num; i++) {
+         const struct interval *live = liveIntervals.Intervals + i;
+
+         if (dbg)
+            printf("Consider register %u\n", live->Reg);
+
+         /* Expire old intervals.  Intervals which have ended with respect
+          * to the live interval can have their remapped registers freed.
+          */
+         {
+            GLint j;
+            for (j = 0; j < (GLint) activeIntervals.Num; j++) {
+               const struct interval *inv = activeIntervals.Intervals + j;
+               if (inv->End >= live->Start) {
+                  /* Stop now.  Since the activeInterval list is sorted
+                   * we know we don't have to go further.
+                   */
+                  break;
+               }
+               else {
+                  /* Interval 'inv' has expired */
+                  const GLint regNew = registerMap[inv->Reg];
+                  ASSERT(regNew >= 0);
+
+                  if (dbg)
+                     printf("  expire interval for reg %u\n", inv->Reg);
+
+                  /* remove interval j from active list */
+                  remove_interval(&activeIntervals, inv);
+                  j--;  /* counter-act j++ in for-loop above */
+
+                  /* return register regNew to the free pool */
+                  if (dbg)
+                     printf("  free reg %d\n", regNew);
+                  ASSERT(usedRegs[regNew] == GL_TRUE);
+                  usedRegs[regNew] = GL_FALSE;
+               }
+            }
+         }
+
+         /* find a free register for this live interval */
+         {
+            const GLint k = alloc_register(usedRegs);
+            if (k < 0) {
+               /* out of registers, give up */
+               return;
+            }
+            registerMap[live->Reg] = k;
+            maxTemp = MAX2(maxTemp, k);
+            if (dbg)
+               printf("  remap register %u -> %d\n", live->Reg, k);
+         }
+
+         /* Insert this live interval into the active list which is sorted
+          * by increasing end points.
+          */
+         insert_interval_by_end(&activeIntervals, live);
+      }
+   }
+
+   if (maxTemp + 1 < (GLint) liveIntervals.Num) {
+      /* OK, we've reduced the number of registers needed.
+       * Scan the program and replace all the old temporary register
+       * indexes with the new indexes.
+       */
+      replace_regs(prog, PROGRAM_TEMPORARY, registerMap);
+
+      prog->NumTemporaries = maxTemp + 1;
+   }
+
+   if (dbg) {
+      printf("Optimize: End live-interval register reallocation\n");
+      printf("Num temp regs before: %u  after: %u\n",
+                   liveIntervals.Num, maxTemp + 1);
+      _mesa_print_program(prog);
+   }
+}
+
+
+/**
+ * Apply optimizations to the given program to eliminate unnecessary
+ * instructions, temp regs, etc.
+ */
+void
+_mesa_optimize_program(GLcontext *ctx, struct gl_program *program)
+{
+   _mesa_remove_extra_move_use(program);
+
+   if (1)
+      _mesa_remove_dead_code(program);
+
+   if (0) /* not tested much yet */
+      _mesa_remove_extra_moves(program);
+
+   if (0)
+      _mesa_consolidate_registers(program);
+   else
+      _mesa_reallocate_registers(program);
+}