llvmpipe: Factor vector packing/unpacking to a separate source file.

These functions will be needed to implement many of the 8bit operations,
and they are quite complex on its own.

5 files changed, 519 insertions, 237 deletions

diff --git a/src/gallium/drivers/llvmpipe/Makefile b/src/gallium/drivers/llvmpipe/Makefile
index 21aff1967a..b96ee23a99 100644
--- a/src/gallium/drivers/llvmpipe/Makefile
+++ b/src/gallium/drivers/llvmpipe/Makefile
@@ -21,6 +21,7 @@ C_SOURCES = \
 	lp_bld_interp.c \
 	lp_bld_intr.c \
 	lp_bld_logic.c \
+	lp_bld_pack.c \
 	lp_bld_sample_soa.c \
 	lp_bld_swizzle.c \
 	lp_bld_struct.c \
diff --git a/src/gallium/drivers/llvmpipe/SConscript b/src/gallium/drivers/llvmpipe/SConscript
index 13cd465838..403e4daa43 100644
--- a/src/gallium/drivers/llvmpipe/SConscript
+++ b/src/gallium/drivers/llvmpipe/SConscript
@@ -33,6 +33,7 @@ llvmpipe = env.ConvenienceLibrary(
 		'lp_bld_format_soa.c',
 		'lp_bld_interp.c',
 		'lp_bld_intr.c',
+        'lp_bld_pack.c',
 		'lp_bld_sample_soa.c',
 		'lp_bld_struct.c',
 		'lp_bld_logic.c',
diff --git a/src/gallium/drivers/llvmpipe/lp_bld_conv.c b/src/gallium/drivers/llvmpipe/lp_bld_conv.c
index 20c8710214..9935209437 100644
--- a/src/gallium/drivers/llvmpipe/lp_bld_conv.c
+++ b/src/gallium/drivers/llvmpipe/lp_bld_conv.c
@@ -69,6 +69,7 @@
 #include "lp_bld_const.h"
 #include "lp_bld_intr.h"
 #include "lp_bld_arit.h"
+#include "lp_bld_pack.h"
 #include "lp_bld_conv.h"
 
 
@@ -199,241 +200,6 @@ lp_build_unsigned_norm_to_float(LLVMBuilderRef builder,
 
 
 /**
- * Build shuffle vectors that match PUNPCKLxx and PUNPCKHxx instructions.
- */
-static LLVMValueRef
-lp_build_const_unpack_shuffle(unsigned n, unsigned lo_hi)
-{
-   LLVMValueRef elems[LP_MAX_VECTOR_LENGTH];
-   unsigned i, j;
-
-   assert(n <= LP_MAX_VECTOR_LENGTH);
-   assert(lo_hi < 2);
-
-   /* TODO: cache results in a static table */
-
-   for(i = 0, j = lo_hi*n/2; i < n; i += 2, ++j) {
-      elems[i + 0] = LLVMConstInt(LLVMInt32Type(), 0 + j, 0);
-      elems[i + 1] = LLVMConstInt(LLVMInt32Type(), n + j, 0);
-   }
-
-   return LLVMConstVector(elems, n);
-}
-
-
-/**
- * Build shuffle vectors that match PACKxx instructions.
- */
-static LLVMValueRef
-lp_build_const_pack_shuffle(unsigned n)
-{
-   LLVMValueRef elems[LP_MAX_VECTOR_LENGTH];
-   unsigned i;
-
-   assert(n <= LP_MAX_VECTOR_LENGTH);
-
-   /* TODO: cache results in a static table */
-
-   for(i = 0; i < n; ++i)
-      elems[i] = LLVMConstInt(LLVMInt32Type(), 2*i, 0);
-
-   return LLVMConstVector(elems, n);
-}
-
-
-/**
- * Expand the bit width.
- *
- * This will only change the number of bits the values are represented, not the
- * values themselves.
- */
-static void
-lp_build_expand(LLVMBuilderRef builder,
-               struct lp_type src_type,
-               struct lp_type dst_type,
-               LLVMValueRef src,
-               LLVMValueRef *dst, unsigned num_dsts)
-{
-   unsigned num_tmps;
-   unsigned i;
-
-   /* Register width must remain constant */
-   assert(src_type.width * src_type.length == dst_type.width * dst_type.length);
-
-   /* We must not loose or gain channels. Only precision */
-   assert(src_type.length == dst_type.length * num_dsts);
-
-   num_tmps = 1;
-   dst[0] = src;
-
-   while(src_type.width < dst_type.width) {
-      struct lp_type new_type = src_type;
-      LLVMTypeRef new_vec_type;
-
-      new_type.width *= 2;
-      new_type.length /= 2;
-      new_vec_type = lp_build_vec_type(new_type);
-
-      for(i = num_tmps; i--; ) {
-         LLVMValueRef zero;
-         LLVMValueRef shuffle_lo;
-         LLVMValueRef shuffle_hi;
-         LLVMValueRef lo;
-         LLVMValueRef hi;
-
-         zero = lp_build_zero(src_type);
-         shuffle_lo = lp_build_const_unpack_shuffle(src_type.length, 0);
-         shuffle_hi = lp_build_const_unpack_shuffle(src_type.length, 1);
-
-         /*  PUNPCKLBW, PUNPCKHBW */
-         lo = LLVMBuildShuffleVector(builder, dst[i], zero, shuffle_lo, "");
-         hi = LLVMBuildShuffleVector(builder, dst[i], zero, shuffle_hi, "");
-
-         dst[2*i + 0] = LLVMBuildBitCast(builder, lo, new_vec_type, "");
-         dst[2*i + 1] = LLVMBuildBitCast(builder, hi, new_vec_type, "");
-      }
-
-      src_type = new_type;
-
-      num_tmps *= 2;
-   }
-
-   assert(num_tmps == num_dsts);
-}
-
-
-/**
- * Non-interleaved pack.
- *
- * This will move values as
- *
- *   lo =   __ l0 __ l1 __ l2 __..  __ ln
- *   hi =   __ h0 __ h1 __ h2 __..  __ hn
- *   res =  l0 l1 l2 .. ln h0 h1 h2 .. hn
- *
- * TODO: handle saturation consistently.
- */
-static LLVMValueRef
-lp_build_pack2(LLVMBuilderRef builder,
-               struct lp_type src_type,
-               struct lp_type dst_type,
-               boolean clamped,
-               LLVMValueRef lo,
-               LLVMValueRef hi)
-{
-   LLVMTypeRef src_vec_type = lp_build_vec_type(src_type);
-   LLVMTypeRef dst_vec_type = lp_build_vec_type(dst_type);
-   LLVMValueRef shuffle;
-   LLVMValueRef res;
-
-   /* Register width must remain constant */
-   assert(src_type.width * src_type.length == dst_type.width * dst_type.length);
-
-   /* We must not loose or gain channels. Only precision */
-   assert(src_type.length * 2 == dst_type.length);
-
-   assert(!src_type.floating);
-   assert(!dst_type.floating);
-
-   if(util_cpu_caps.has_sse2 && src_type.width * src_type.length == 128) {
-      /* All X86 non-interleaved pack instructions all take signed inputs and
-       * saturate them, so saturate beforehand. */
-      if(!src_type.sign && !clamped) {
-         struct lp_build_context bld;
-         unsigned dst_bits = dst_type.sign ? dst_type.width - 1 : dst_type.width;
-         LLVMValueRef dst_max = lp_build_int_const_scalar(src_type, ((unsigned long long)1 << dst_bits) - 1);
-         lp_build_context_init(&bld, builder, src_type);
-         lo = lp_build_min(&bld, lo, dst_max);
-         hi = lp_build_min(&bld, hi, dst_max);
-      }
-
-      switch(src_type.width) {
-      case 32:
-         if(dst_type.sign || !util_cpu_caps.has_sse4_1)
-            res = lp_build_intrinsic_binary(builder, "llvm.x86.sse2.packssdw.128", src_vec_type, lo, hi);
-         else
-            /* PACKUSDW is the only instrinsic with a consistent signature */
-            return lp_build_intrinsic_binary(builder, "llvm.x86.sse41.packusdw", dst_vec_type, lo, hi);
-         break;
-
-      case 16:
-         if(dst_type.sign)
-            res = lp_build_intrinsic_binary(builder, "llvm.x86.sse2.packsswb.128", src_vec_type, lo, hi);
-         else
-            res = lp_build_intrinsic_binary(builder, "llvm.x86.sse2.packuswb.128", src_vec_type, lo, hi);
-         break;
-
-      default:
-         assert(0);
-         return LLVMGetUndef(dst_vec_type);
-         break;
-      }
-
-      res = LLVMBuildBitCast(builder, res, dst_vec_type, "");
-      return res;
-   }
-
-   lo = LLVMBuildBitCast(builder, lo, dst_vec_type, "");
-   hi = LLVMBuildBitCast(builder, hi, dst_vec_type, "");
-
-   shuffle = lp_build_const_pack_shuffle(dst_type.length);
-
-   res = LLVMBuildShuffleVector(builder, lo, hi, shuffle, "");
-
-   return res;
-}
-
-
-/**
- * Truncate the bit width.
- *
- * TODO: Handle saturation consistently.
- */
-static LLVMValueRef
-lp_build_pack(LLVMBuilderRef builder,
-              struct lp_type src_type,
-              struct lp_type dst_type,
-              boolean clamped,
-              const LLVMValueRef *src, unsigned num_srcs)
-{
-   LLVMValueRef tmp[LP_MAX_VECTOR_LENGTH];
-   unsigned i;
-
-   /* Register width must remain constant */
-   assert(src_type.width * src_type.length == dst_type.width * dst_type.length);
-
-   /* We must not loose or gain channels. Only precision */
-   assert(src_type.length * num_srcs == dst_type.length);
-
-   for(i = 0; i < num_srcs; ++i)
-      tmp[i] = src[i];
-
-   while(src_type.width > dst_type.width) {
-      struct lp_type new_type = src_type;
-
-      new_type.width /= 2;
-      new_type.length *= 2;
-
-      /* Take in consideration the sign changes only in the last step */
-      if(new_type.width == dst_type.width)
-         new_type.sign = dst_type.sign;
-
-      num_srcs /= 2;
-
-      for(i = 0; i < num_srcs; ++i)
-         tmp[i] = lp_build_pack2(builder, src_type, new_type, clamped,
-                                 tmp[2*i + 0], tmp[2*i + 1]);
-
-      src_type = new_type;
-   }
-
-   assert(num_srcs == 1);
-
-   return tmp[0];
-}
-
-
-/**
  * Generic type conversion.
  *
  * TODO: Take a precision argument, or even better, add a new precision member
@@ -572,7 +338,7 @@ lp_build_conv(LLVMBuilderRef builder,
 
    if(tmp_type.width < dst_type.width) {
       assert(num_tmps == 1);
-      lp_build_expand(builder, tmp_type, dst_type, tmp[0], tmp, num_dsts);
+      lp_build_unpack(builder, tmp_type, dst_type, tmp[0], tmp, num_dsts);
       tmp_type.width = dst_type.width;
       tmp_type.length = dst_type.length;
       num_tmps = num_dsts;
@@ -692,7 +458,7 @@ lp_build_conv_mask(LLVMBuilderRef builder,
    }
    else if(src_type.width < dst_type.width) {
       assert(num_srcs == 1);
-      lp_build_expand(builder, src_type, dst_type, src[0], dst, num_dsts);
+      lp_build_unpack(builder, src_type, dst_type, src[0], dst, num_dsts);
    }
    else {
       assert(num_srcs == num_dsts);
diff --git a/src/gallium/drivers/llvmpipe/lp_bld_pack.c b/src/gallium/drivers/llvmpipe/lp_bld_pack.c
new file mode 100644
index 0000000000..fe82fda039
--- /dev/null
+++ b/src/gallium/drivers/llvmpipe/lp_bld_pack.c
@@ -0,0 +1,419 @@
+/**************************************************************************
+ *
+ * Copyright 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, 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 VMWARE 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.
+ *
+ **************************************************************************/
+
+
+/**
+ * @file
+ * Helper functions for packing/unpacking.
+ *
+ * Pack/unpacking is necessary for conversion between types of different
+ * bit width.
+ *
+ * They are also commonly used when an computation needs higher
+ * precision for the intermediate values. For example, if one needs the
+ * function:
+ *
+ *   c = compute(a, b);
+ *
+ * to use more precision for intermediate results then one should implement it
+ * as:
+ *
+ *   LLVMValueRef
+ *   compute(LLVMBuilderRef builder struct lp_type type, LLVMValueRef a, LLVMValueRef b)
+ *   {
+ *      struct lp_type wide_type = lp_wider_type(type);
+ *      LLVMValueRef al, ah, bl, bh, cl, ch, c;
+ *
+ *      lp_build_unpack2(builder, type, wide_type, a, &al, &ah);
+ *      lp_build_unpack2(builder, type, wide_type, b, &bl, &bh);
+ *
+ *      cl = compute_half(al, bl);
+ *      ch = compute_half(ah, bh);
+ *
+ *      c = lp_build_pack2(bld->builder, wide_type, type, cl, ch);
+ *
+ *      return c;
+ *   }
+ *
+ * where compute_half() would do the computation for half the elements with
+ * twice the precision.
+ *
+ * @author Jose Fonseca <jfonseca@vmware.com>
+ */
+
+
+#include "util/u_debug.h"
+#include "util/u_math.h"
+#include "util/u_cpu_detect.h"
+
+#include "lp_bld_type.h"
+#include "lp_bld_const.h"
+#include "lp_bld_intr.h"
+#include "lp_bld_arit.h"
+#include "lp_bld_pack.h"
+
+
+/**
+ * Build shuffle vectors that match PUNPCKLxx and PUNPCKHxx instructions.
+ */
+static LLVMValueRef
+lp_build_const_unpack_shuffle(unsigned n, unsigned lo_hi)
+{
+   LLVMValueRef elems[LP_MAX_VECTOR_LENGTH];
+   unsigned i, j;
+
+   assert(n <= LP_MAX_VECTOR_LENGTH);
+   assert(lo_hi < 2);
+
+   /* TODO: cache results in a static table */
+
+   for(i = 0, j = lo_hi*n/2; i < n; i += 2, ++j) {
+      elems[i + 0] = LLVMConstInt(LLVMInt32Type(), 0 + j, 0);
+      elems[i + 1] = LLVMConstInt(LLVMInt32Type(), n + j, 0);
+   }
+
+   return LLVMConstVector(elems, n);
+}
+
+
+/**
+ * Build shuffle vectors that match PACKxx instructions.
+ */
+static LLVMValueRef
+lp_build_const_pack_shuffle(unsigned n)
+{
+   LLVMValueRef elems[LP_MAX_VECTOR_LENGTH];
+   unsigned i;
+
+   assert(n <= LP_MAX_VECTOR_LENGTH);
+
+   /* TODO: cache results in a static table */
+
+   for(i = 0; i < n; ++i)
+      elems[i] = LLVMConstInt(LLVMInt32Type(), 2*i, 0);
+
+   return LLVMConstVector(elems, n);
+}
+
+
+/**
+ * Interleave vector elements.
+ *
+ * Matches the PUNPCKLxx and PUNPCKHxx SSE instructions.
+ */
+LLVMValueRef
+lp_build_interleave2(LLVMBuilderRef builder,
+                     struct lp_type type,
+                     LLVMValueRef a,
+                     LLVMValueRef b,
+                     unsigned lo_hi)
+{
+   LLVMValueRef shuffle;
+
+   shuffle = lp_build_const_unpack_shuffle(type.length, lo_hi);
+
+   return LLVMBuildShuffleVector(builder, a, b, shuffle, "");
+}
+
+
+/**
+ * Double the bit width.
+ *
+ * This will only change the number of bits the values are represented, not the
+ * values themselves.
+ */
+void
+lp_build_unpack2(LLVMBuilderRef builder,
+                 struct lp_type src_type,
+                 struct lp_type dst_type,
+                 LLVMValueRef src,
+                 LLVMValueRef *dst_lo,
+                 LLVMValueRef *dst_hi)
+{
+   LLVMValueRef msb;
+   LLVMTypeRef dst_vec_type;
+
+   assert(!src_type.floating);
+   assert(!dst_type.floating);
+   assert(dst_type.sign == src_type.sign);
+   assert(dst_type.width == src_type.width * 2);
+   assert(dst_type.length * 2 == src_type.length);
+
+   if(src_type.sign) {
+      /* Replicate the sign bit in the most significant bits */
+      msb = LLVMBuildAShr(builder, src, lp_build_int_const_scalar(src_type, src_type.width - 1), "");
+   }
+   else
+      /* Most significant bits always zero */
+      msb = lp_build_zero(src_type);
+
+   /* Interleave bits */
+   if(util_cpu_caps.little_endian) {
+      *dst_lo = lp_build_interleave2(builder, src_type, src, msb, 0);
+      *dst_hi = lp_build_interleave2(builder, src_type, src, msb, 1);
+   }
+   else {
+      *dst_lo = lp_build_interleave2(builder, src_type, msb, src, 0);
+      *dst_hi = lp_build_interleave2(builder, src_type, msb, src, 1);
+   }
+
+   /* Cast the result into the new type (twice as wide) */
+
+   dst_vec_type = lp_build_vec_type(dst_type);
+
+   *dst_lo = LLVMBuildBitCast(builder, *dst_lo, dst_vec_type, "");
+   *dst_hi = LLVMBuildBitCast(builder, *dst_hi, dst_vec_type, "");
+}
+
+
+/**
+ * Expand the bit width.
+ *
+ * This will only change the number of bits the values are represented, not the
+ * values themselves.
+ */
+void
+lp_build_unpack(LLVMBuilderRef builder,
+                struct lp_type src_type,
+                struct lp_type dst_type,
+                LLVMValueRef src,
+                LLVMValueRef *dst, unsigned num_dsts)
+{
+   unsigned num_tmps;
+   unsigned i;
+
+   /* Register width must remain constant */
+   assert(src_type.width * src_type.length == dst_type.width * dst_type.length);
+
+   /* We must not loose or gain channels. Only precision */
+   assert(src_type.length == dst_type.length * num_dsts);
+
+   num_tmps = 1;
+   dst[0] = src;
+
+   while(src_type.width < dst_type.width) {
+      struct lp_type tmp_type = src_type;
+
+      tmp_type.width *= 2;
+      tmp_type.length /= 2;
+
+      for(i = num_tmps; i--; ) {
+         lp_build_unpack2(builder, src_type, tmp_type, dst[i], &dst[2*i + 0], &dst[2*i + 1]);
+      }
+
+      src_type = tmp_type;
+
+      num_tmps *= 2;
+   }
+
+   assert(num_tmps == num_dsts);
+}
+
+
+/**
+ * Non-interleaved pack.
+ *
+ * This will move values as
+ *
+ *   lo =   __ l0 __ l1 __ l2 __..  __ ln
+ *   hi =   __ h0 __ h1 __ h2 __..  __ hn
+ *   res =  l0 l1 l2 .. ln h0 h1 h2 .. hn
+ *
+ * This will only change the number of bits the values are represented, not the
+ * values themselves.
+ *
+ * It is assumed the values are already clamped into the destination type range.
+ * Values outside that range will produce undefined results. Use
+ * lp_build_packs2 instead.
+ */
+LLVMValueRef
+lp_build_pack2(LLVMBuilderRef builder,
+               struct lp_type src_type,
+               struct lp_type dst_type,
+               LLVMValueRef lo,
+               LLVMValueRef hi)
+{
+   LLVMTypeRef src_vec_type = lp_build_vec_type(src_type);
+   LLVMTypeRef dst_vec_type = lp_build_vec_type(dst_type);
+   LLVMValueRef shuffle;
+   LLVMValueRef res;
+
+   dst_vec_type = lp_build_vec_type(dst_type);
+
+   assert(!src_type.floating);
+   assert(!dst_type.floating);
+   assert(src_type.width == dst_type.width * 2);
+   assert(src_type.length * 2 == dst_type.length);
+
+   if(util_cpu_caps.has_sse2 && src_type.width * src_type.length == 128) {
+      switch(src_type.width) {
+      case 32:
+         if(dst_type.sign) {
+            res = lp_build_intrinsic_binary(builder, "llvm.x86.sse2.packssdw.128", src_vec_type, lo, hi);
+         }
+         else {
+            if (util_cpu_caps.has_sse4_1) {
+               /* PACKUSDW is the only instrinsic with a consistent signature */
+               return lp_build_intrinsic_binary(builder, "llvm.x86.sse41.packusdw", dst_vec_type, lo, hi);
+            }
+            else {
+               assert(0);
+               return LLVMGetUndef(dst_vec_type);
+            }
+         }
+         break;
+
+      case 16:
+         if(dst_type.sign)
+            res = lp_build_intrinsic_binary(builder, "llvm.x86.sse2.packsswb.128", src_vec_type, lo, hi);
+         else
+            res = lp_build_intrinsic_binary(builder, "llvm.x86.sse2.packuswb.128", src_vec_type, lo, hi);
+         break;
+
+      default:
+         assert(0);
+         return LLVMGetUndef(dst_vec_type);
+         break;
+      }
+
+      res = LLVMBuildBitCast(builder, res, dst_vec_type, "");
+      return res;
+   }
+
+   lo = LLVMBuildBitCast(builder, lo, dst_vec_type, "");
+   hi = LLVMBuildBitCast(builder, hi, dst_vec_type, "");
+
+   shuffle = lp_build_const_pack_shuffle(dst_type.length);
+
+   res = LLVMBuildShuffleVector(builder, lo, hi, shuffle, "");
+
+   return res;
+}
+
+
+
+/**
+ * Non-interleaved pack and saturate.
+ *
+ * Same as lp_build_pack2 but will saturate values so that they fit into the
+ * destination type.
+ */
+LLVMValueRef
+lp_build_packs2(LLVMBuilderRef builder,
+                struct lp_type src_type,
+                struct lp_type dst_type,
+                LLVMValueRef lo,
+                LLVMValueRef hi)
+{
+   boolean clamp;
+
+   assert(!src_type.floating);
+   assert(!dst_type.floating);
+   assert(src_type.sign == dst_type.sign);
+   assert(src_type.width == dst_type.width * 2);
+   assert(src_type.length * 2 == dst_type.length);
+
+   clamp = TRUE;
+
+   /* All X86 SSE non-interleaved pack instructions take signed inputs and
+    * saturate them, so no need to clamp for those cases. */
+   if(util_cpu_caps.has_sse2 &&
+      src_type.width * src_type.length == 128 &&
+      src_type.sign)
+      clamp = FALSE;
+
+   if(clamp) {
+      struct lp_build_context bld;
+      unsigned dst_bits = dst_type.sign ? dst_type.width - 1 : dst_type.width;
+      LLVMValueRef dst_max = lp_build_int_const_scalar(src_type, ((unsigned long long)1 << dst_bits) - 1);
+      lp_build_context_init(&bld, builder, src_type);
+      lo = lp_build_min(&bld, lo, dst_max);
+      hi = lp_build_min(&bld, hi, dst_max);
+      /* FIXME: What about lower bound? */
+   }
+
+   return lp_build_pack2(builder, src_type, dst_type, lo, hi);
+}
+
+
+/**
+ * Truncate the bit width.
+ *
+ * TODO: Handle saturation consistently.
+ */
+LLVMValueRef
+lp_build_pack(LLVMBuilderRef builder,
+              struct lp_type src_type,
+              struct lp_type dst_type,
+              boolean clamped,
+              const LLVMValueRef *src, unsigned num_srcs)
+{
+   LLVMValueRef (*pack2)(LLVMBuilderRef builder,
+                         struct lp_type src_type,
+                         struct lp_type dst_type,
+                         LLVMValueRef lo,
+                         LLVMValueRef hi);
+   LLVMValueRef tmp[LP_MAX_VECTOR_LENGTH];
+   unsigned i;
+
+
+   /* Register width must remain constant */
+   assert(src_type.width * src_type.length == dst_type.width * dst_type.length);
+
+   /* We must not loose or gain channels. Only precision */
+   assert(src_type.length * num_srcs == dst_type.length);
+
+   if(clamped)
+      pack2 = &lp_build_pack2;
+   else
+      pack2 = &lp_build_packs2;
+
+   for(i = 0; i < num_srcs; ++i)
+      tmp[i] = src[i];
+
+   while(src_type.width > dst_type.width) {
+      struct lp_type tmp_type = src_type;
+
+      tmp_type.width /= 2;
+      tmp_type.length *= 2;
+
+      /* Take in consideration the sign changes only in the last step */
+      if(tmp_type.width == dst_type.width)
+         tmp_type.sign = dst_type.sign;
+
+      num_srcs /= 2;
+
+      for(i = 0; i < num_srcs; ++i)
+         tmp[i] = pack2(builder, src_type, tmp_type, tmp[2*i + 0], tmp[2*i + 1]);
+
+      src_type = tmp_type;
+   }
+
+   assert(num_srcs == 1);
+
+   return tmp[0];
+}
diff --git a/src/gallium/drivers/llvmpipe/lp_bld_pack.h b/src/gallium/drivers/llvmpipe/lp_bld_pack.h
new file mode 100644
index 0000000000..fb2a34984a
--- /dev/null
+++ b/src/gallium/drivers/llvmpipe/lp_bld_pack.h
@@ -0,0 +1,95 @@
+/**************************************************************************
+ *
+ * Copyright 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, 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 VMWARE 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.
+ *
+ **************************************************************************/
+
+/**
+ * @file
+ * Helper functions for packing/unpacking conversions.
+ *
+ * @author Jose Fonseca <jfonseca@vmware.com>
+ */
+
+
+#ifndef LP_BLD_PACK_H
+#define LP_BLD_PACK_H
+
+
+#include <llvm-c/Core.h>  
+
+
+struct lp_type;
+
+
+LLVMValueRef
+lp_build_interleave2(LLVMBuilderRef builder,
+                     struct lp_type type,
+                     LLVMValueRef a,
+                     LLVMValueRef b,
+                     unsigned lo_hi);
+
+
+void
+lp_build_unpack2(LLVMBuilderRef builder,
+                 struct lp_type src_type,
+                 struct lp_type dst_type,
+                 LLVMValueRef src,
+                 LLVMValueRef *dst_lo,
+                 LLVMValueRef *dst_hi);
+
+
+void
+lp_build_unpack(LLVMBuilderRef builder,
+                struct lp_type src_type,
+                struct lp_type dst_type,
+                LLVMValueRef src,
+                LLVMValueRef *dst, unsigned num_dsts);
+
+
+LLVMValueRef
+lp_build_packs2(LLVMBuilderRef builder,
+                struct lp_type src_type,
+                struct lp_type dst_type,
+                LLVMValueRef lo,
+                LLVMValueRef hi);
+
+
+LLVMValueRef
+lp_build_pack2(LLVMBuilderRef builder,
+               struct lp_type src_type,
+               struct lp_type dst_type,
+               LLVMValueRef lo,
+               LLVMValueRef hi);
+
+
+LLVMValueRef
+lp_build_pack(LLVMBuilderRef builder,
+              struct lp_type src_type,
+              struct lp_type dst_type,
+              boolean clamped,
+              const LLVMValueRef *src, unsigned num_srcs);
+
+
+#endif /* !LP_BLD_PACK_H */