tgsi: adds tgsi utility to transform a shader to support point sprite

This adds a tgsi utility tgsi_add_point_sprite to transform a geometry
shader to emulate wide points by drawing quads. This utility adds an
extra output for the original point position if the point position is
to be written to a stream output buffer. It also assumes the driver will
add a constant for inverse viewport scale after the user defined constants.

Reviewed-by: Brian Paul <[email protected]>

3 files changed, 622 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/Makefile.sources b/src/gallium/auxiliary/Makefile.sources
index d5986b45e06..cc6fe7d3ae3 100644
--- a/src/gallium/auxiliary/Makefile.sources
+++ b/src/gallium/auxiliary/Makefile.sources
@@ -144,6 +144,8 @@ C_SOURCES := \
 	tgsi/tgsi_opcode_tmp.h \
 	tgsi/tgsi_parse.c \
 	tgsi/tgsi_parse.h \
+	tgsi/tgsi_point_sprite.c \
+	tgsi/tgsi_point_sprite.h \
 	tgsi/tgsi_sanity.c \
 	tgsi/tgsi_sanity.h \
 	tgsi/tgsi_scan.c \
diff --git a/src/gallium/auxiliary/tgsi/tgsi_point_sprite.c b/src/gallium/auxiliary/tgsi/tgsi_point_sprite.c
new file mode 100644
index 00000000000..cb8dbcb29ec
--- /dev/null
+++ b/src/gallium/auxiliary/tgsi/tgsi_point_sprite.c
@@ -0,0 +1,582 @@
+/*
+ * Copyright 2014 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, sub license, 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 (including the
+ * next paragraph) 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 NON-INFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS AND/OR ITS SUPPLIERS 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.
+ */
+
+
+/**
+ * This utility transforms the geometry shader to emulate point sprite by
+ * drawing a quad. It also adds an extra output for the original point position
+ * if the point position is to be written to a stream output buffer.
+ * Note: It assumes the driver will add a constant for the inverse viewport
+ *       after the user defined constants.
+ */
+
+#include "util/u_debug.h"
+#include "util/u_math.h"
+#include "tgsi_info.h"
+#include "tgsi_point_sprite.h"
+#include "tgsi_transform.h"
+#include "pipe/p_state.h"
+
+#define INVALID_INDEX 9999
+
+/* Set swizzle based on the immediates (0, 1, 0, -1) */
+static inline unsigned
+set_swizzle(int x, int y, int z, int w)
+{
+   static const unsigned map[3] = {TGSI_SWIZZLE_W, TGSI_SWIZZLE_X,
+                                   TGSI_SWIZZLE_Y};
+   assert(x >= -1);
+   assert(x <= 1);
+   assert(y >= -1);
+   assert(y <= 1);
+   assert(z >= -1);
+   assert(z <= 1);
+   assert(w >= -1);
+   assert(w <= 1);
+
+   return map[x+1] | (map[y+1] << 2) | (map[z+1] << 4) | (map[w+1] << 6);
+}
+
+static inline unsigned
+get_swizzle(unsigned swizzle, unsigned component)
+{
+   assert(component < 4);
+   return (swizzle >> (component * 2)) & 0x3;
+}
+
+struct psprite_transform_context
+{
+   struct tgsi_transform_context base;
+   unsigned num_tmp;
+   unsigned num_out;
+   unsigned num_orig_out;
+   unsigned num_const;
+   unsigned num_imm;
+   unsigned point_size_in;          // point size input
+   unsigned point_size_out;         // point size output
+   unsigned point_size_tmp;         // point size temp
+   unsigned point_pos_in;           // point pos input
+   unsigned point_pos_out;          // point pos output
+   unsigned point_pos_sout;         // original point pos for streamout
+   unsigned point_pos_tmp;          // point pos temp
+   unsigned point_scale_tmp;        // point scale temp
+   unsigned point_color_out;        // point color output
+   unsigned point_color_tmp;        // point color temp
+   unsigned point_imm;              // point immediates
+   unsigned point_ivp;              // point inverseViewport constant
+   unsigned point_dir_swz[4];       // point direction swizzle
+   unsigned point_coord_swz[4];     // point coord swizzle
+   unsigned point_coord_enable;     // point coord enable mask
+   unsigned point_coord_decl;       // point coord output declared mask
+   unsigned point_coord_out;        // point coord output starting index
+   unsigned point_coord_aa;         // aa point coord semantic index
+   unsigned point_coord_k;          // aa point coord threshold distance
+   unsigned stream_out_point_pos:1; // set if to stream out original point pos
+   unsigned aa_point:1;             // set if doing aa point
+   unsigned out_tmp_index[PIPE_MAX_SHADER_OUTPUTS];
+   int max_generic;
+};
+
+static inline struct psprite_transform_context *
+psprite_transform_context(struct tgsi_transform_context *ctx)
+{
+   return (struct psprite_transform_context *) ctx;
+}
+
+
+/**
+ * TGSI declaration transform callback.
+ */
+static void
+psprite_decl(struct tgsi_transform_context *ctx,
+             struct tgsi_full_declaration *decl)
+{
+   struct psprite_transform_context *ts = psprite_transform_context(ctx);
+
+   if (decl->Declaration.File == TGSI_FILE_INPUT) {
+      if (decl->Semantic.Name == TGSI_SEMANTIC_PSIZE) {
+         ts->point_size_in = decl->Range.First;
+      }
+      else if (decl->Semantic.Name == TGSI_SEMANTIC_POSITION) {
+         ts->point_pos_in = decl->Range.First;
+      }
+   }
+   else if (decl->Declaration.File == TGSI_FILE_OUTPUT) {
+      if (decl->Semantic.Name == TGSI_SEMANTIC_PSIZE) {
+         ts->point_size_out = decl->Range.First;
+      }
+      else if (decl->Semantic.Name == TGSI_SEMANTIC_POSITION) {
+         ts->point_pos_out = decl->Range.First;
+      }
+      else if (decl->Semantic.Name == TGSI_SEMANTIC_GENERIC &&
+               decl->Semantic.Index < 32) {
+         ts->point_coord_decl |= 1 << decl->Semantic.Index;
+         ts->max_generic = MAX2(ts->max_generic, decl->Semantic.Index);
+      }
+      ts->num_out = MAX2(ts->num_out, decl->Range.Last + 1);
+   }
+   else if (decl->Declaration.File == TGSI_FILE_TEMPORARY) {
+      ts->num_tmp = MAX2(ts->num_tmp, decl->Range.Last + 1);
+   }
+   else if (decl->Declaration.File == TGSI_FILE_CONSTANT) {
+      ts->num_const = MAX2(ts->num_const, decl->Range.Last + 1);
+   }
+
+   ctx->emit_declaration(ctx, decl);
+}
+
+/**
+ * TGSI immediate declaration transform callback.
+ */
+static void
+psprite_immediate(struct tgsi_transform_context *ctx,
+                  struct tgsi_full_immediate *imm)
+{
+   struct psprite_transform_context *ts = psprite_transform_context(ctx);
+
+   ctx->emit_immediate(ctx, imm);
+   ts->num_imm++;
+}
+
+
+/**
+ * TGSI transform prolog callback.
+ */
+static void
+psprite_prolog(struct tgsi_transform_context *ctx)
+{
+   struct psprite_transform_context *ts = psprite_transform_context(ctx);
+   unsigned point_coord_enable, en;
+   int i;
+
+   /* Replace output registers with temporary registers */
+   for (i = 0; i < ts->num_out; i++) {
+      ts->out_tmp_index[i] = ts->num_tmp++;
+   }
+   ts->num_orig_out = ts->num_out;
+
+   /* Declare a tmp register for point scale */
+   ts->point_scale_tmp = ts->num_tmp++;
+
+   if (ts->point_size_out != INVALID_INDEX)
+      ts->point_size_tmp = ts->out_tmp_index[ts->point_size_out];
+   else
+      ts->point_size_tmp = ts->num_tmp++;
+
+   assert(ts->point_pos_out != INVALID_INDEX);
+   ts->point_pos_tmp = ts->out_tmp_index[ts->point_pos_out];
+   ts->out_tmp_index[ts->point_pos_out] = INVALID_INDEX;
+
+   /* Declare one more tmp register for point coord threshold distance
+    * if we are generating anti-aliased point.
+    */
+   if (ts->aa_point)
+      ts->point_coord_k = ts->num_tmp++;
+
+   tgsi_transform_temps_decl(ctx, ts->point_size_tmp, ts->num_tmp-1);
+
+   /* Declare an extra output for the original point position for stream out */
+   if (ts->stream_out_point_pos) {
+      ts->point_pos_sout = ts->num_out++;
+      tgsi_transform_output_decl(ctx, ts->point_pos_sout,
+                                 TGSI_SEMANTIC_GENERIC, 0, 0);
+   }
+
+   /* point coord outputs to be declared */
+   point_coord_enable = ts->point_coord_enable & ~ts->point_coord_decl;
+
+   /* Declare outputs for those point coord that are enabled but are not
+    * already declared in this shader.
+    */
+   ts->point_coord_out = ts->num_out;
+   if (point_coord_enable) {
+      for (i = 0, en = point_coord_enable; en; en>>=1, i++) {
+         if (en & 0x1) {
+            tgsi_transform_output_decl(ctx, ts->num_out++,
+                                       TGSI_SEMANTIC_GENERIC, i, 0);
+            ts->max_generic = MAX2(ts->max_generic, i);
+         }
+      }
+   }
+
+   /* add an extra generic output for aa point texcoord */
+   if (ts->aa_point) {
+      ts->point_coord_aa = ts->max_generic + 1;
+      assert((ts->point_coord_enable & (1 << ts->point_coord_aa)) == 0);
+      ts->point_coord_enable |= 1 << (ts->point_coord_aa);
+      tgsi_transform_output_decl(ctx, ts->num_out++, TGSI_SEMANTIC_GENERIC,
+                                 ts->point_coord_aa, 0);
+   }
+
+   /* Declare extra immediates */
+   ts->point_imm = ts->num_imm;
+   tgsi_transform_immediate_decl(ctx, 0, 1, 0.5, -1);
+
+   /* Declare point constant -
+    * constant.xy -- inverseViewport
+    * constant.z -- current point size
+    * constant.w -- max point size
+    * The driver needs to add this constant to the constant buffer
+    */
+   ts->point_ivp = ts->num_const++;
+   tgsi_transform_const_decl(ctx, ts->point_ivp, ts->point_ivp);
+
+   /* If this geometry shader does not specify point size,
+    * get the current point size from the point constant.
+    */
+   if (ts->point_size_out == INVALID_INDEX) {
+      struct tgsi_full_instruction inst;
+
+      inst = tgsi_default_full_instruction();
+      inst.Instruction.Opcode = TGSI_OPCODE_MOV;
+      inst.Instruction.NumDstRegs = 1;
+      tgsi_transform_dst_reg(&inst.Dst[0], TGSI_FILE_TEMPORARY,
+                             ts->point_size_tmp, TGSI_WRITEMASK_XYZW);
+      inst.Instruction.NumSrcRegs = 1;
+      tgsi_transform_src_reg(&inst.Src[0], TGSI_FILE_CONSTANT,
+                             ts->point_ivp, TGSI_SWIZZLE_Z,
+                             TGSI_SWIZZLE_Z, TGSI_SWIZZLE_Z, TGSI_SWIZZLE_Z);
+      ctx->emit_instruction(ctx, &inst);
+   }
+}
+
+
+/**
+ * Add the point sprite emulation instructions at the emit vertex instruction
+ */
+static void
+psprite_emit_vertex_inst(struct tgsi_transform_context *ctx,
+                         struct tgsi_full_instruction *vert_inst)
+{
+   struct psprite_transform_context *ts = psprite_transform_context(ctx);
+   struct tgsi_full_instruction inst;
+   unsigned point_coord_enable, en;
+   unsigned i, j, s;
+
+   /* new point coord outputs */
+   point_coord_enable = ts->point_coord_enable & ~ts->point_coord_decl;
+
+   /* OUTPUT[pos_sout] = TEMP[pos] */
+   if (ts->point_pos_sout != INVALID_INDEX) {
+      tgsi_transform_op1_inst(ctx, TGSI_OPCODE_MOV,
+                              TGSI_FILE_OUTPUT, ts->point_pos_sout,
+                              TGSI_WRITEMASK_XYZW,
+                              TGSI_FILE_TEMPORARY, ts->point_pos_tmp);
+   }
+
+   /**
+    * Set up the point scale vector
+    * scale = pointSize * pos.w * inverseViewport
+    */
+
+   /* MUL point_scale.x, point_size.x, point_pos.w */
+   tgsi_transform_op2_swz_inst(ctx, TGSI_OPCODE_MUL,
+                  TGSI_FILE_TEMPORARY, ts->point_scale_tmp, TGSI_WRITEMASK_X,
+                  TGSI_FILE_TEMPORARY, ts->point_size_tmp, TGSI_SWIZZLE_X,
+                  TGSI_FILE_TEMPORARY, ts->point_pos_tmp, TGSI_SWIZZLE_W);
+
+   /* MUL point_scale.xy, point_scale.xx, inverseViewport.xy */
+   inst = tgsi_default_full_instruction();
+   inst.Instruction.Opcode = TGSI_OPCODE_MUL;
+   inst.Instruction.NumDstRegs = 1;
+   tgsi_transform_dst_reg(&inst.Dst[0], TGSI_FILE_TEMPORARY,
+                          ts->point_scale_tmp, TGSI_WRITEMASK_XY);
+   inst.Instruction.NumSrcRegs = 2;
+   tgsi_transform_src_reg(&inst.Src[0], TGSI_FILE_TEMPORARY,
+                          ts->point_scale_tmp, TGSI_SWIZZLE_X,
+                          TGSI_SWIZZLE_X, TGSI_SWIZZLE_X, TGSI_SWIZZLE_X);
+   tgsi_transform_src_reg(&inst.Src[1], TGSI_FILE_CONSTANT,
+                          ts->point_ivp, TGSI_SWIZZLE_X,
+                          TGSI_SWIZZLE_Y, TGSI_SWIZZLE_Z, TGSI_SWIZZLE_Z);
+   ctx->emit_instruction(ctx, &inst);
+
+   /**
+    * Set up the point coord threshold distance
+    * k = 0.5 - 1 / pointsize
+    */
+   if (ts->aa_point) {
+      tgsi_transform_op2_swz_inst(ctx, TGSI_OPCODE_DIV,
+                                  TGSI_FILE_TEMPORARY, ts->point_coord_k,
+                                  TGSI_WRITEMASK_X,
+                                  TGSI_FILE_IMMEDIATE, ts->point_imm,
+                                  TGSI_SWIZZLE_Y,
+                                  TGSI_FILE_TEMPORARY, ts->point_size_tmp,
+                                  TGSI_SWIZZLE_X);
+
+      tgsi_transform_op2_swz_inst(ctx, TGSI_OPCODE_SUB,
+                                  TGSI_FILE_TEMPORARY, ts->point_coord_k,
+                                  TGSI_WRITEMASK_X,
+                                  TGSI_FILE_IMMEDIATE, ts->point_imm,
+                                  TGSI_SWIZZLE_Z,
+                                  TGSI_FILE_TEMPORARY, ts->point_coord_k,
+                                  TGSI_SWIZZLE_X);
+   }
+
+
+   for (i = 0; i < 4; i++) {
+      unsigned point_dir_swz = ts->point_dir_swz[i];
+      unsigned point_coord_swz = ts->point_coord_swz[i];
+
+      /* All outputs need to be emitted for each vertex */
+      for (j = 0; j < ts->num_orig_out; j++) {
+         if (ts->out_tmp_index[j] != INVALID_INDEX) {
+            tgsi_transform_op1_inst(ctx, TGSI_OPCODE_MOV,
+                                    TGSI_FILE_OUTPUT, j,
+                                    TGSI_WRITEMASK_XYZW,
+                                    TGSI_FILE_TEMPORARY, ts->out_tmp_index[j]);
+         }
+      }
+
+      /* pos = point_scale * point_dir + point_pos */
+      inst = tgsi_default_full_instruction();
+      inst.Instruction.Opcode = TGSI_OPCODE_MAD;
+      inst.Instruction.NumDstRegs = 1;
+      tgsi_transform_dst_reg(&inst.Dst[0], TGSI_FILE_OUTPUT, ts->point_pos_out,
+                             TGSI_WRITEMASK_XYZW);
+      inst.Instruction.NumSrcRegs = 3;
+      tgsi_transform_src_reg(&inst.Src[0], TGSI_FILE_TEMPORARY, ts->point_scale_tmp,
+                             TGSI_SWIZZLE_X, TGSI_SWIZZLE_Y, TGSI_SWIZZLE_X,
+                             TGSI_SWIZZLE_X);
+      tgsi_transform_src_reg(&inst.Src[1], TGSI_FILE_IMMEDIATE, ts->point_imm,
+                             get_swizzle(point_dir_swz, 0),
+                             get_swizzle(point_dir_swz, 1),
+                             get_swizzle(point_dir_swz, 2),
+                             get_swizzle(point_dir_swz, 3));
+      tgsi_transform_src_reg(&inst.Src[2], TGSI_FILE_TEMPORARY, ts->point_pos_tmp,
+                             TGSI_SWIZZLE_X, TGSI_SWIZZLE_Y, TGSI_SWIZZLE_Z,
+                             TGSI_SWIZZLE_W);
+      ctx->emit_instruction(ctx, &inst);
+
+      /* point coord */
+      for (j = 0, s = 0, en = point_coord_enable; en; en>>=1, s++) {
+         unsigned dstReg;
+
+         if (en & 0x1) {
+            dstReg = ts->point_coord_out + j;
+
+            inst = tgsi_default_full_instruction();
+            inst.Instruction.Opcode = TGSI_OPCODE_MOV;
+            inst.Instruction.NumDstRegs = 1;
+            tgsi_transform_dst_reg(&inst.Dst[0], TGSI_FILE_OUTPUT,
+                                   dstReg, TGSI_WRITEMASK_XYZW);
+            inst.Instruction.NumSrcRegs = 1;
+            tgsi_transform_src_reg(&inst.Src[0], TGSI_FILE_IMMEDIATE, ts->point_imm,
+                                   get_swizzle(point_coord_swz, 0),
+                                   get_swizzle(point_coord_swz, 1),
+                                   get_swizzle(point_coord_swz, 2),
+                                   get_swizzle(point_coord_swz, 3));
+            ctx->emit_instruction(ctx, &inst);
+
+            /* MOV point_coord.z  point_coord_k.x */
+            if (s == ts->point_coord_aa) {
+               tgsi_transform_op1_swz_inst(ctx, TGSI_OPCODE_MOV,
+                                           TGSI_FILE_OUTPUT, dstReg, TGSI_WRITEMASK_Z,
+                                           TGSI_FILE_TEMPORARY, ts->point_coord_k,
+                                           TGSI_SWIZZLE_X);
+            }
+            j++;  /* the next point coord output offset */
+         }
+      }
+
+      /* Emit the EMIT instruction for each vertex of the quad */
+      ctx->emit_instruction(ctx, vert_inst);
+   }
+
+   /* Emit the ENDPRIM instruction for the quad */
+   inst = tgsi_default_full_instruction();
+   inst.Instruction.Opcode = TGSI_OPCODE_ENDPRIM;
+   inst.Instruction.NumDstRegs = 0;
+   inst.Instruction.NumSrcRegs = 1;
+   inst.Src[0] = vert_inst->Src[0];
+   ctx->emit_instruction(ctx, &inst);
+}
+
+
+/**
+ * TGSI instruction transform callback.
+ */
+static void
+psprite_inst(struct tgsi_transform_context *ctx,
+             struct tgsi_full_instruction *inst)
+{
+   struct psprite_transform_context *ts = psprite_transform_context(ctx);
+
+   if (inst->Instruction.Opcode == TGSI_OPCODE_EMIT) {
+      psprite_emit_vertex_inst(ctx, inst);
+   }
+   else if (inst->Dst[0].Register.File == TGSI_FILE_OUTPUT &&
+            inst->Dst[0].Register.Index == ts->point_size_out) {
+      /**
+       * Replace point size output reg with tmp reg.
+       * The tmp reg will be later used as a src reg for computing
+       * the point scale factor.
+       */
+      inst->Dst[0].Register.File = TGSI_FILE_TEMPORARY;
+      inst->Dst[0].Register.Index = ts->point_size_tmp;
+      ctx->emit_instruction(ctx, inst);
+
+      /* Clamp the point size */
+      /* MAX point_size_tmp.x, point_size_tmp.x, point_imm.y */
+      tgsi_transform_op2_swz_inst(ctx, TGSI_OPCODE_MAX,
+                 TGSI_FILE_TEMPORARY, ts->point_size_tmp, TGSI_WRITEMASK_X,
+                 TGSI_FILE_TEMPORARY, ts->point_size_tmp, TGSI_SWIZZLE_X,
+                 TGSI_FILE_IMMEDIATE, ts->point_imm, TGSI_SWIZZLE_Y);
+
+      /* MIN point_size_tmp.x, point_size_tmp.x, point_ivp.w */
+      tgsi_transform_op2_swz_inst(ctx, TGSI_OPCODE_MIN,
+                 TGSI_FILE_TEMPORARY, ts->point_size_tmp, TGSI_WRITEMASK_X,
+                 TGSI_FILE_TEMPORARY, ts->point_size_tmp, TGSI_SWIZZLE_X,
+                 TGSI_FILE_CONSTANT, ts->point_ivp, TGSI_SWIZZLE_W);
+   }
+   else if (inst->Dst[0].Register.File == TGSI_FILE_OUTPUT &&
+            inst->Dst[0].Register.Index == ts->point_pos_out) {
+      /**
+       * Replace point pos output reg with tmp reg.
+       */
+      inst->Dst[0].Register.File = TGSI_FILE_TEMPORARY;
+      inst->Dst[0].Register.Index = ts->point_pos_tmp;
+      ctx->emit_instruction(ctx, inst);
+   }
+   else if (inst->Dst[0].Register.File == TGSI_FILE_OUTPUT) {
+      /**
+       * Replace output reg with tmp reg.
+       */
+      inst->Dst[0].Register.File = TGSI_FILE_TEMPORARY;
+      inst->Dst[0].Register.Index = ts->out_tmp_index[inst->Dst[0].Register.Index];
+      ctx->emit_instruction(ctx, inst);
+   }
+   else {
+      ctx->emit_instruction(ctx, inst);
+   }
+}
+
+
+/**
+ * TGSI property instruction transform callback.
+ * Transforms a point into a 4-vertex triangle strip.
+ */
+static void
+psprite_property(struct tgsi_transform_context *ctx,
+                 struct tgsi_full_property *prop)
+{
+   switch (prop->Property.PropertyName) {
+   case TGSI_PROPERTY_GS_OUTPUT_PRIM:
+       prop->u[0].Data = PIPE_PRIM_TRIANGLE_STRIP;
+       break;
+   case TGSI_PROPERTY_GS_MAX_OUTPUT_VERTICES:
+       prop->u[0].Data *= 4;
+       break;
+   default:
+       break;
+   }
+   ctx->emit_property(ctx, prop);
+}
+
+/**
+ * TGSI utility to transform a geometry shader to support point sprite.
+ */
+struct tgsi_token *
+tgsi_add_point_sprite(const struct tgsi_token *tokens_in,
+                      const unsigned point_coord_enable,
+                      const bool sprite_origin_lower_left,
+                      const bool stream_out_point_pos,
+                      int *aa_point_coord_index)
+{
+   struct psprite_transform_context transform;
+   const uint num_new_tokens = 200; /* should be enough */
+   const uint new_len = tgsi_num_tokens(tokens_in) + num_new_tokens;
+   struct tgsi_token *new_tokens;
+
+   /* setup transformation context */
+   memset(&transform, 0, sizeof(transform));
+   transform.base.transform_declaration = psprite_decl;
+   transform.base.transform_instruction = psprite_inst;
+   transform.base.transform_property = psprite_property;
+   transform.base.transform_immediate = psprite_immediate;
+   transform.base.prolog = psprite_prolog;
+
+   transform.point_size_in = INVALID_INDEX;
+   transform.point_size_out = INVALID_INDEX;
+   transform.point_size_tmp = INVALID_INDEX;
+   transform.point_pos_in = INVALID_INDEX;
+   transform.point_pos_out = INVALID_INDEX;
+   transform.point_pos_sout = INVALID_INDEX;
+   transform.point_pos_tmp = INVALID_INDEX;
+   transform.point_scale_tmp = INVALID_INDEX;
+   transform.point_imm = INVALID_INDEX;
+   transform.point_coord_aa = INVALID_INDEX;
+   transform.point_coord_k = INVALID_INDEX;
+
+   transform.stream_out_point_pos = stream_out_point_pos;
+   transform.point_coord_enable = point_coord_enable;
+   transform.aa_point = aa_point_coord_index != NULL;
+   transform.max_generic = -1;
+
+   /* point sprite directions based on the immediates (0, 1, 0.5, -1) */
+   /* (-1, -1, 0, 0) */
+   transform.point_dir_swz[0] = set_swizzle(-1, -1, 0, 0);
+   /* (-1, 1, 0, 0) */
+   transform.point_dir_swz[1] = set_swizzle(-1, 1, 0, 0);
+   /* (1, -1, 0, 0) */
+   transform.point_dir_swz[2] = set_swizzle(1, -1, 0, 0);
+   /* (1, 1, 0, 0) */
+   transform.point_dir_swz[3] = set_swizzle(1, 1, 0, 0);
+
+   /* point coord based on the immediates (0, 1, 0, -1) */
+   if (sprite_origin_lower_left) {
+      /* (0, 0, 0, 1) */
+      transform.point_coord_swz[0] = set_swizzle(0, 0, 0, 1);
+      /* (0, 1, 0, 1) */
+      transform.point_coord_swz[1] = set_swizzle(0, 1, 0, 1);
+      /* (1, 0, 0, 1) */
+      transform.point_coord_swz[2] = set_swizzle(1, 0, 0, 1);
+      /* (1, 1, 0, 1) */
+      transform.point_coord_swz[3] = set_swizzle(1, 1, 0, 1);
+   }
+   else {
+      /* (0, 1, 0, 1) */
+      transform.point_coord_swz[0] = set_swizzle(0, 1, 0, 1);
+      /* (0, 0, 0, 1) */
+      transform.point_coord_swz[1] = set_swizzle(0, 0, 0, 1);
+      /* (1, 1, 0, 1) */
+      transform.point_coord_swz[2] = set_swizzle(1, 1, 0, 1);
+      /* (1, 0, 0, 1) */
+      transform.point_coord_swz[3] = set_swizzle(1, 0, 0, 1);
+   }
+
+
+   /* allocate new tokens buffer */
+   new_tokens = tgsi_alloc_tokens(new_len);
+   if (!new_tokens)
+      return NULL;
+
+   /* transform the shader */
+   tgsi_transform_shader(tokens_in, new_tokens, new_len, &transform.base);
+
+   if (aa_point_coord_index)
+      *aa_point_coord_index = transform.point_coord_aa;
+
+   return new_tokens;
+}
diff --git a/src/gallium/auxiliary/tgsi/tgsi_point_sprite.h b/src/gallium/auxiliary/tgsi/tgsi_point_sprite.h
new file mode 100644
index 00000000000..d1958914bc3
--- /dev/null
+++ b/src/gallium/auxiliary/tgsi/tgsi_point_sprite.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright 2014 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, sub license, 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 (including the
+ * next paragraph) 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 NON-INFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS AND/OR ITS SUPPLIERS 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.
+ */
+
+#ifndef TGSI_POINT_SPRITE_H
+#define TGSI_POINT_SPRITE_H
+
+struct tgsi_token;
+
+struct tgsi_token *
+tgsi_add_point_sprite(const struct tgsi_token *tokens_in,
+                      const unsigned point_coord_enable,
+                      const bool sprite_origin_lower_left,
+                      const bool stream_out_point_pos,
+                      int *aa_point_coord_index);
+
+#endif /* TGSI_POINT_SPRITE_H */