gallivm: fix indirect addressing of constant buffer
[mesa.git] / src / gallium / auxiliary / gallivm / lp_bld_format_aos.c
index a07f7418f2c16fc51b7f66159f68e2ca0c6b8666..0f01fc1d75fa50a0a51abbbcd3c99b71299b0e16 100644 (file)
  */
 
 
-#include "util/u_cpu_detect.h"
 #include "util/u_format.h"
+#include "util/u_memory.h"
+#include "util/u_math.h"
+#include "util/u_string.h"
 
+#include "lp_bld_arit.h"
+#include "lp_bld_init.h"
 #include "lp_bld_type.h"
+#include "lp_bld_flow.h"
 #include "lp_bld_const.h"
+#include "lp_bld_conv.h"
 #include "lp_bld_swizzle.h"
+#include "lp_bld_gather.h"
 #include "lp_bld_format.h"
 
 
+/**
+ * Basic swizzling.  Rearrange the order of the unswizzled array elements
+ * according to the format description.  PIPE_SWIZZLE_ZERO/ONE are supported
+ * too.
+ * Ex: if unswizzled[4] = {B, G, R, x}, then swizzled_out[4] = {R, G, B, 1}.
+ */
+LLVMValueRef
+lp_build_format_swizzle_aos(const struct util_format_description *desc,
+                            struct lp_build_context *bld,
+                            LLVMValueRef unswizzled)
+{
+   unsigned char swizzles[4];
+   unsigned chan;
+
+   assert(bld->type.length % 4 == 0);
+
+   for (chan = 0; chan < 4; ++chan) {
+      enum util_format_swizzle swizzle;
+
+      if (desc->colorspace == UTIL_FORMAT_COLORSPACE_ZS) {
+         /*
+          * For ZS formats do RGBA = ZZZ1
+          */
+         if (chan == 3) {
+            swizzle = UTIL_FORMAT_SWIZZLE_1;
+         } else if (desc->swizzle[0] == UTIL_FORMAT_SWIZZLE_NONE) {
+            swizzle = UTIL_FORMAT_SWIZZLE_0;
+         } else {
+            swizzle = desc->swizzle[0];
+         }
+      } else {
+         swizzle = desc->swizzle[chan];
+      }
+      swizzles[chan] = swizzle;
+   }
+
+   return lp_build_swizzle_aos(bld, unswizzled, swizzles);
+}
+
+
+/**
+ * Whether the format matches the vector type, apart of swizzles.
+ */
+static INLINE boolean
+format_matches_type(const struct util_format_description *desc,
+                    struct lp_type type)
+{
+   enum util_format_type chan_type;
+   unsigned chan;
+
+   assert(type.length % 4 == 0);
+
+   if (desc->layout != UTIL_FORMAT_LAYOUT_PLAIN ||
+       desc->colorspace != UTIL_FORMAT_COLORSPACE_RGB ||
+       desc->block.width != 1 ||
+       desc->block.height != 1) {
+      return FALSE;
+   }
+
+   if (type.floating) {
+      chan_type = UTIL_FORMAT_TYPE_FLOAT;
+   } else if (type.fixed) {
+      chan_type = UTIL_FORMAT_TYPE_FIXED;
+   } else if (type.sign) {
+      chan_type = UTIL_FORMAT_TYPE_SIGNED;
+   } else {
+      chan_type = UTIL_FORMAT_TYPE_UNSIGNED;
+   }
+
+   for (chan = 0; chan < desc->nr_channels; ++chan) {
+      if (desc->channel[chan].size != type.width) {
+         return FALSE;
+      }
+
+      if (desc->channel[chan].type != UTIL_FORMAT_TYPE_VOID) {
+         if (desc->channel[chan].type != chan_type ||
+             desc->channel[chan].normalized != type.norm) {
+            return FALSE;
+         }
+      }
+   }
+
+   return TRUE;
+}
+
+
 /**
  * Unpack a single pixel into its RGBA components.
  *
- * @param packed integer.
+ * @param desc  the pixel format for the packed pixel value
+ * @param packed integer pixel in a format such as PIPE_FORMAT_B8G8R8A8_UNORM
  *
- * @return RGBA in a 4 floats vector.
- *
- * XXX: This is mostly for reference and testing -- operating a single pixel at
- * a time is rarely if ever needed.
+ * @return RGBA in a float[4] or ubyte[4] or ushort[4] vector.
  */
-LLVMValueRef
-lp_build_unpack_rgba_aos(LLVMBuilderRef builder,
-                         const struct util_format_description *desc,
-                         LLVMValueRef packed)
+static INLINE LLVMValueRef
+lp_build_unpack_arith_rgba_aos(LLVMBuilderRef builder,
+                               const struct util_format_description *desc,
+                               LLVMValueRef packed)
 {
-   LLVMTypeRef type;
    LLVMValueRef shifted, casted, scaled, masked;
    LLVMValueRef shifts[4];
    LLVMValueRef masks[4];
    LLVMValueRef scales[4];
-   LLVMValueRef swizzles[4];
-   LLVMValueRef aux[4];
-   bool normalized;
-   int empty_channel;
+
+   boolean normalized;
+   boolean needs_uitofp;
    unsigned shift;
    unsigned i;
 
-   /* FIXME: Support more formats */
+   /* TODO: Support more formats */
    assert(desc->layout == UTIL_FORMAT_LAYOUT_PLAIN);
    assert(desc->block.width == 1);
    assert(desc->block.height == 1);
    assert(desc->block.bits <= 32);
 
-   type = LLVMIntType(desc->block.bits);
-
    /* Do the intermediate integer computations with 32bit integers since it
     * matches floating point size */
-   if (desc->block.bits < 32)
-      packed = LLVMBuildZExt(builder, packed, LLVMInt32Type(), "");
+   assert (LLVMTypeOf(packed) == LLVMInt32Type());
 
-   /* Broadcast the packed value to all four channels */
+   /* Broadcast the packed value to all four channels
+    * before: packed = BGRA
+    * after: packed = {BGRA, BGRA, BGRA, BGRA}
+    */
    packed = LLVMBuildInsertElement(builder,
                                    LLVMGetUndef(LLVMVectorType(LLVMInt32Type(), 4)),
                                    packed,
@@ -96,8 +185,10 @@ lp_build_unpack_rgba_aos(LLVMBuilderRef builder,
 
    /* Initialize vector constants */
    normalized = FALSE;
-   empty_channel = -1;
+   needs_uitofp = FALSE;
    shift = 0;
+
+   /* Loop over 4 color components */
    for (i = 0; i < 4; ++i) {
       unsigned bits = desc->channel[i].size;
 
@@ -105,13 +196,15 @@ lp_build_unpack_rgba_aos(LLVMBuilderRef builder,
          shifts[i] = LLVMGetUndef(LLVMInt32Type());
          masks[i] = LLVMConstNull(LLVMInt32Type());
          scales[i] =  LLVMConstNull(LLVMFloatType());
-         empty_channel = i;
       }
       else {
-         unsigned mask = (1 << bits) - 1;
+         unsigned long long mask = (1ULL << bits) - 1;
 
          assert(desc->channel[i].type == UTIL_FORMAT_TYPE_UNSIGNED);
-         assert(bits < 32);
+
+         if (bits == 32) {
+            needs_uitofp = TRUE;
+         }
 
          shifts[i] = LLVMConstInt(LLVMInt32Type(), shift, 0);
          masks[i] = LLVMConstInt(LLVMInt32Type(), mask, 0);
@@ -127,156 +220,31 @@ lp_build_unpack_rgba_aos(LLVMBuilderRef builder,
       shift += bits;
    }
 
+   /* Ex: convert packed = {BGRA, BGRA, BGRA, BGRA}
+    * into masked = {B, G, R, A}
+    */
    shifted = LLVMBuildLShr(builder, packed, LLVMConstVector(shifts, 4), "");
    masked = LLVMBuildAnd(builder, shifted, LLVMConstVector(masks, 4), "");
-   /* UIToFP can't be expressed in SSE2 */
-   casted = LLVMBuildSIToFP(builder, masked, LLVMVectorType(LLVMFloatType(), 4), "");
 
-   if (normalized)
-      scaled = LLVMBuildMul(builder, casted, LLVMConstVector(scales, 4), "");
-   else
-      scaled = casted;
 
-   for (i = 0; i < 4; ++i)
-      aux[i] = LLVMGetUndef(LLVMFloatType());
-
-   for (i = 0; i < 4; ++i) {
-      enum util_format_swizzle swizzle = desc->swizzle[i];
-
-      switch (swizzle) {
-      case UTIL_FORMAT_SWIZZLE_X:
-      case UTIL_FORMAT_SWIZZLE_Y:
-      case UTIL_FORMAT_SWIZZLE_Z:
-      case UTIL_FORMAT_SWIZZLE_W:
-         swizzles[i] = LLVMConstInt(LLVMInt32Type(), swizzle, 0);
-         break;
-      case UTIL_FORMAT_SWIZZLE_0:
-         assert(empty_channel >= 0);
-         swizzles[i] = LLVMConstInt(LLVMInt32Type(), empty_channel, 0);
-         break;
-      case UTIL_FORMAT_SWIZZLE_1:
-         swizzles[i] = LLVMConstInt(LLVMInt32Type(), 4, 0);
-         aux[0] = LLVMConstReal(LLVMFloatType(), 1.0);
-         break;
-      case UTIL_FORMAT_SWIZZLE_NONE:
-         swizzles[i] = LLVMGetUndef(LLVMFloatType());
-         assert(0);
-         break;
-      }
+   if (!needs_uitofp) {
+      /* UIToFP can't be expressed in SSE2 */
+      casted = LLVMBuildSIToFP(builder, masked, LLVMVectorType(LLVMFloatType(), 4), "");
+   } else {
+      casted = LLVMBuildUIToFP(builder, masked, LLVMVectorType(LLVMFloatType(), 4), "");
    }
 
-   return LLVMBuildShuffleVector(builder, scaled, LLVMConstVector(aux, 4), LLVMConstVector(swizzles, 4), "");
-}
-
-
-/**
- * Take a vector with packed pixels and unpack into a rgba8 vector.
- *
- * Formats with bit depth smaller than 32bits are accepted, but they must be
- * padded to 32bits.
- */
-LLVMValueRef
-lp_build_unpack_rgba8_aos(LLVMBuilderRef builder,
-                          const struct util_format_description *desc,
-                          struct lp_type type,
-                          LLVMValueRef packed)
-{
-   struct lp_build_context bld;
-   bool rgba8;
-   LLVMValueRef res;
-   unsigned i;
-
-   lp_build_context_init(&bld, builder, type);
-
-   /* FIXME: Support more formats */
-   assert(desc->layout == UTIL_FORMAT_LAYOUT_PLAIN);
-   assert(desc->block.width == 1);
-   assert(desc->block.height == 1);
-   assert(desc->block.bits <= 32);
+   /* At this point 'casted' may be a vector of floats such as
+    * {255.0, 255.0, 255.0, 255.0}.  Next, if the pixel values are normalized
+    * we'll scale this to {1.0, 1.0, 1.0, 1.0}.
+    */
 
-   assert(!type.floating);
-   assert(!type.fixed);
-   assert(type.norm);
-   assert(type.width == 8);
-   assert(type.length % 4 == 0);
-
-   rgba8 = TRUE;
-   for(i = 0; i < 4; ++i) {
-      assert(desc->channel[i].type == UTIL_FORMAT_TYPE_UNSIGNED ||
-             desc->channel[i].type == UTIL_FORMAT_TYPE_VOID);
-      if(desc->channel[0].size != 8)
-         rgba8 = FALSE;
-   }
-
-   if(rgba8) {
-      /*
-       * The pixel is already in a rgba8 format variant. All it is necessary
-       * is to swizzle the channels.
-       */
-
-      unsigned char swizzles[4];
-      boolean zeros[4]; /* bitwise AND mask */
-      boolean ones[4]; /* bitwise OR mask */
-      boolean swizzles_needed = FALSE;
-      boolean zeros_needed = FALSE;
-      boolean ones_needed = FALSE;
-
-      for(i = 0; i < 4; ++i) {
-         enum util_format_swizzle swizzle = desc->swizzle[i];
-
-         /* Initialize with the no-op case */
-         swizzles[i] = util_cpu_caps.little_endian ? 3 - i : i;
-         zeros[i] = TRUE;
-         ones[i] = FALSE;
-
-         switch (swizzle) {
-         case UTIL_FORMAT_SWIZZLE_X:
-         case UTIL_FORMAT_SWIZZLE_Y:
-         case UTIL_FORMAT_SWIZZLE_Z:
-         case UTIL_FORMAT_SWIZZLE_W:
-            if(swizzle != swizzles[i]) {
-               swizzles[i] = swizzle;
-               swizzles_needed = TRUE;
-            }
-            break;
-         case UTIL_FORMAT_SWIZZLE_0:
-            zeros[i] = FALSE;
-            zeros_needed = TRUE;
-            break;
-         case UTIL_FORMAT_SWIZZLE_1:
-            ones[i] = TRUE;
-            ones_needed = TRUE;
-            break;
-         case UTIL_FORMAT_SWIZZLE_NONE:
-            assert(0);
-            break;
-         }
-      }
-
-      res = packed;
-
-      if(swizzles_needed)
-         res = lp_build_swizzle1_aos(&bld, res, swizzles);
-
-      if(zeros_needed) {
-         /* Mask out zero channels */
-         LLVMValueRef mask = lp_build_const_mask_aos(type, zeros);
-         res = LLVMBuildAnd(builder, res, mask, "");
-      }
-
-      if(ones_needed) {
-         /* Or one channels */
-         LLVMValueRef mask = lp_build_const_mask_aos(type, ones);
-         res = LLVMBuildOr(builder, res, mask, "");
-      }
-   }
-   else {
-      /* FIXME */
-      assert(0);
-      res = lp_build_undef(type);
-   }
+   if (normalized)
+      scaled = LLVMBuildMul(builder, casted, LLVMConstVector(scales, 4), "");
+   else
+      scaled = casted;
 
-   return res;
+   return scaled;
 }
 
 
@@ -299,7 +267,7 @@ lp_build_pack_rgba_aos(LLVMBuilderRef builder,
    LLVMValueRef shifted, casted, scaled, unswizzled;
    LLVMValueRef shifts[4];
    LLVMValueRef scales[4];
-   bool normalized;
+   boolean normalized;
    unsigned shift;
    unsigned i, j;
 
@@ -381,3 +349,332 @@ lp_build_pack_rgba_aos(LLVMBuilderRef builder,
 
    return packed;
 }
+
+
+
+
+/**
+ * Fetch a pixel into a 4 float AoS.
+ *
+ * \param format_desc  describes format of the image we're fetching from
+ * \param ptr  address of the pixel block (or the texel if uncompressed)
+ * \param i, j  the sub-block pixel coordinates.  For non-compressed formats
+ *              these will always be (0, 0).
+ * \return  a 4 element vector with the pixel's RGBA values.
+ */
+LLVMValueRef
+lp_build_fetch_rgba_aos(LLVMBuilderRef builder,
+                        const struct util_format_description *format_desc,
+                        struct lp_type type,
+                        LLVMValueRef base_ptr,
+                        LLVMValueRef offset,
+                        LLVMValueRef i,
+                        LLVMValueRef j)
+{
+   unsigned num_pixels = type.length / 4;
+   struct lp_build_context bld;
+
+   assert(type.length <= LP_MAX_VECTOR_LENGTH);
+   assert(type.length % 4 == 0);
+
+   lp_build_context_init(&bld, builder, type);
+
+   /*
+    * Trivial case
+    *
+    * The format matches the type (apart of a swizzle) so no need for
+    * scaling or converting.
+    */
+
+   if (format_matches_type(format_desc, type) &&
+       format_desc->block.bits <= type.width * 4 &&
+       util_is_pot(format_desc->block.bits)) {
+      LLVMValueRef packed;
+
+      /*
+       * The format matches the type (apart of a swizzle) so no need for
+       * scaling or converting.
+       */
+
+      packed = lp_build_gather(builder, type.length/4,
+                               format_desc->block.bits, type.width*4,
+                               base_ptr, offset);
+
+      assert(format_desc->block.bits <= type.width * type.length);
+
+      packed = LLVMBuildBitCast(builder, packed, lp_build_vec_type(type), "");
+
+      return lp_build_format_swizzle_aos(format_desc, &bld, packed);
+   }
+
+   /*
+    * Bit arithmetic
+    */
+
+   if (format_desc->layout == UTIL_FORMAT_LAYOUT_PLAIN &&
+       (format_desc->colorspace == UTIL_FORMAT_COLORSPACE_RGB ||
+        format_desc->colorspace == UTIL_FORMAT_COLORSPACE_ZS) &&
+       format_desc->block.width == 1 &&
+       format_desc->block.height == 1 &&
+       util_is_pot(format_desc->block.bits) &&
+       format_desc->block.bits <= 32 &&
+       format_desc->is_bitmask &&
+       !format_desc->is_mixed &&
+       (format_desc->channel[0].type == UTIL_FORMAT_TYPE_UNSIGNED ||
+        format_desc->channel[1].type == UTIL_FORMAT_TYPE_UNSIGNED)) {
+
+      LLVMValueRef tmps[LP_MAX_VECTOR_LENGTH/4];
+      LLVMValueRef res;
+      unsigned k;
+
+      /*
+       * Unpack a pixel at a time into a <4 x float> RGBA vector
+       */
+
+      for (k = 0; k < num_pixels; ++k) {
+         LLVMValueRef packed;
+
+         packed = lp_build_gather_elem(builder, num_pixels,
+                                       format_desc->block.bits, 32,
+                                       base_ptr, offset, k);
+
+         tmps[k] = lp_build_unpack_arith_rgba_aos(builder, format_desc,
+                                                  packed);
+      }
+
+      /*
+       * Type conversion.
+       *
+       * TODO: We could avoid floating conversion for integer to
+       * integer conversions.
+       */
+
+      lp_build_conv(builder,
+                    lp_float32_vec4_type(),
+                    type,
+                    tmps, num_pixels, &res, 1);
+
+      return lp_build_format_swizzle_aos(format_desc, &bld, res);
+   }
+
+   /*
+    * YUV / subsampled formats
+    */
+
+   if (format_desc->layout == UTIL_FORMAT_LAYOUT_SUBSAMPLED) {
+      struct lp_type tmp_type;
+      LLVMValueRef tmp;
+
+      memset(&tmp_type, 0, sizeof tmp_type);
+      tmp_type.width = 8;
+      tmp_type.length = num_pixels * 4;
+      tmp_type.norm = TRUE;
+
+      tmp = lp_build_fetch_subsampled_rgba_aos(builder,
+                                               format_desc,
+                                               num_pixels,
+                                               base_ptr,
+                                               offset,
+                                               i, j);
+
+      lp_build_conv(builder,
+                    tmp_type, type,
+                    &tmp, 1, &tmp, 1);
+
+      return tmp;
+   }
+
+   /*
+    * Fallback to util_format_description::fetch_rgba_8unorm().
+    */
+
+   if (format_desc->fetch_rgba_8unorm &&
+       !type.floating && type.width == 8 && !type.sign && type.norm) {
+      /*
+       * Fallback to calling util_format_description::fetch_rgba_8unorm.
+       *
+       * This is definitely not the most efficient way of fetching pixels, as
+       * we miss the opportunity to do vectorization, but this it is a
+       * convenient for formats or scenarios for which there was no opportunity
+       * or incentive to optimize.
+       */
+
+      LLVMModuleRef module = LLVMGetGlobalParent(LLVMGetBasicBlockParent(LLVMGetInsertBlock(builder)));
+      char name[256];
+      LLVMTypeRef i8t = LLVMInt8Type();
+      LLVMTypeRef pi8t = LLVMPointerType(i8t, 0);
+      LLVMTypeRef i32t = LLVMInt32Type();
+      LLVMValueRef function;
+      LLVMValueRef tmp_ptr;
+      LLVMValueRef tmp;
+      LLVMValueRef res;
+      unsigned k;
+
+      util_snprintf(name, sizeof name, "util_format_%s_fetch_rgba_8unorm",
+                    format_desc->short_name);
+
+      /*
+       * Declare and bind format_desc->fetch_rgba_8unorm().
+       */
+
+      function = LLVMGetNamedFunction(module, name);
+      if (!function) {
+         LLVMTypeRef ret_type;
+         LLVMTypeRef arg_types[4];
+         LLVMTypeRef function_type;
+
+         ret_type = LLVMVoidType();
+         arg_types[0] = pi8t;
+         arg_types[1] = pi8t;
+         arg_types[3] = arg_types[2] = LLVMIntType(sizeof(unsigned) * 8);
+         function_type = LLVMFunctionType(ret_type, arg_types, Elements(arg_types), 0);
+         function = LLVMAddFunction(module, name, function_type);
+
+         LLVMSetFunctionCallConv(function, LLVMCCallConv);
+         LLVMSetLinkage(function, LLVMExternalLinkage);
+
+         assert(LLVMIsDeclaration(function));
+
+         LLVMAddGlobalMapping(lp_build_engine, function,
+                              func_to_pointer((func_pointer)format_desc->fetch_rgba_8unorm));
+      }
+
+      tmp_ptr = lp_build_alloca(builder, i32t, "");
+
+      res = LLVMGetUndef(LLVMVectorType(i32t, num_pixels));
+
+      /*
+       * Invoke format_desc->fetch_rgba_8unorm() for each pixel and insert the result
+       * in the SoA vectors.
+       */
+
+      for (k = 0; k < num_pixels; ++k) {
+         LLVMValueRef index = LLVMConstInt(LLVMInt32Type(), k, 0);
+         LLVMValueRef args[4];
+
+         args[0] = LLVMBuildBitCast(builder, tmp_ptr, pi8t, "");
+         args[1] = lp_build_gather_elem_ptr(builder, num_pixels,
+                                            base_ptr, offset, k);
+
+         if (num_pixels == 1) {
+            args[2] = i;
+            args[3] = j;
+         }
+         else {
+            args[2] = LLVMBuildExtractElement(builder, i, index, "");
+            args[3] = LLVMBuildExtractElement(builder, j, index, "");
+         }
+
+         LLVMBuildCall(builder, function, args, Elements(args), "");
+
+         tmp = LLVMBuildLoad(builder, tmp_ptr, "");
+
+         if (num_pixels == 1) {
+            res = tmp;
+         }
+         else {
+            res = LLVMBuildInsertElement(builder, res, tmp, index, "");
+         }
+      }
+
+      /* Bitcast from <n x i32> to <4n x i8> */
+      res = LLVMBuildBitCast(builder, res, bld.vec_type, "");
+
+      return res;
+   }
+
+
+   /*
+    * Fallback to util_format_description::fetch_rgba_float().
+    */
+
+   if (format_desc->fetch_rgba_float) {
+      /*
+       * Fallback to calling util_format_description::fetch_rgba_float.
+       *
+       * This is definitely not the most efficient way of fetching pixels, as
+       * we miss the opportunity to do vectorization, but this it is a
+       * convenient for formats or scenarios for which there was no opportunity
+       * or incentive to optimize.
+       */
+
+      LLVMModuleRef module = LLVMGetGlobalParent(LLVMGetBasicBlockParent(LLVMGetInsertBlock(builder)));
+      char name[256];
+      LLVMTypeRef f32t = LLVMFloatType();
+      LLVMTypeRef f32x4t = LLVMVectorType(f32t, 4);
+      LLVMTypeRef pf32t = LLVMPointerType(f32t, 0);
+      LLVMValueRef function;
+      LLVMValueRef tmp_ptr;
+      LLVMValueRef tmps[LP_MAX_VECTOR_LENGTH/4];
+      LLVMValueRef res;
+      unsigned k;
+
+      util_snprintf(name, sizeof name, "util_format_%s_fetch_rgba_float",
+                    format_desc->short_name);
+
+      /*
+       * Declare and bind format_desc->fetch_rgba_float().
+       */
+
+      function = LLVMGetNamedFunction(module, name);
+      if (!function) {
+         LLVMTypeRef ret_type;
+         LLVMTypeRef arg_types[4];
+         LLVMTypeRef function_type;
+
+         ret_type = LLVMVoidType();
+         arg_types[0] = pf32t;
+         arg_types[1] = LLVMPointerType(LLVMInt8Type(), 0);
+         arg_types[3] = arg_types[2] = LLVMIntType(sizeof(unsigned) * 8);
+         function_type = LLVMFunctionType(ret_type, arg_types, Elements(arg_types), 0);
+         function = LLVMAddFunction(module, name, function_type);
+
+         LLVMSetFunctionCallConv(function, LLVMCCallConv);
+         LLVMSetLinkage(function, LLVMExternalLinkage);
+
+         assert(LLVMIsDeclaration(function));
+
+         LLVMAddGlobalMapping(lp_build_engine, function,
+                              func_to_pointer((func_pointer)format_desc->fetch_rgba_float));
+      }
+
+      tmp_ptr = lp_build_alloca(builder, f32x4t, "");
+
+      /*
+       * Invoke format_desc->fetch_rgba_float() for each pixel and insert the result
+       * in the SoA vectors.
+       */
+
+      for (k = 0; k < num_pixels; ++k) {
+         LLVMValueRef args[4];
+
+         args[0] = LLVMBuildBitCast(builder, tmp_ptr, pf32t, "");
+         args[1] = lp_build_gather_elem_ptr(builder, num_pixels,
+                                            base_ptr, offset, k);
+
+         if (num_pixels == 1) {
+            args[2] = i;
+            args[3] = j;
+         }
+         else {
+            LLVMValueRef index = LLVMConstInt(LLVMInt32Type(), k, 0);
+            args[2] = LLVMBuildExtractElement(builder, i, index, "");
+            args[3] = LLVMBuildExtractElement(builder, j, index, "");
+         }
+
+         LLVMBuildCall(builder, function, args, Elements(args), "");
+
+         tmps[k] = LLVMBuildLoad(builder, tmp_ptr, "");
+      }
+
+      lp_build_conv(builder,
+                    lp_float32_vec4_type(),
+                    type,
+                    tmps, num_pixels, &res, 1);
+
+      return res;
+   }
+
+   assert(0);
+   return lp_build_undef(type);
+}