workbench/libs/mesa/src/gallium/auxiliary/gallivm/lp_bld_gather.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2010 VMware, Inc.
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
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  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
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  20  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  21  *
  22  * The above copyright notice and this permission notice (including the
  23  * next paragraph) shall be included in all copies or substantial portions
  24  * of the Software.
  25  *
  26  **************************************************************************/
  27
  28
  29 #include "util/u_debug.h"
  30 #include "lp_bld_debug.h"
  31 #include "lp_bld_const.h"
  32 #include "lp_bld_format.h"
  33 #include "lp_bld_gather.h"
  34 #include "lp_bld_init.h"
  35
  36
  37 /**
  38  * Get the pointer to one element from scatter positions in memory.
  39  *
  40  * @sa lp_build_gather()
  41  */
  42 LLVMValueRef
  43 lp_build_gather_elem_ptr(struct gallivm_state *gallivm,
  44                          unsigned length,
  45                          LLVMValueRef base_ptr,
  46                          LLVMValueRef offsets,
  47                          unsigned i)
  48 {
  49    LLVMValueRef offset;
  50    LLVMValueRef ptr;
  51
  52    assert(LLVMTypeOf(base_ptr) == LLVMPointerType(LLVMInt8TypeInContext(gallivm->context), 0));
  53
  54    if (length == 1) {
  55       assert(i == 0);
  56       offset = offsets;
  57    } else {
  58       LLVMValueRef index = lp_build_const_int32(gallivm, i);
  59       offset = LLVMBuildExtractElement(gallivm->builder, offsets, index, "");
  60    }
  61
  62    ptr = LLVMBuildGEP(gallivm->builder, base_ptr, &offset, 1, "");
  63
  64    return ptr;
  65 }
  66
  67
  68 /**
  69  * Gather one element from scatter positions in memory.
  70  *
  71  * @sa lp_build_gather()
  72  */
  73 LLVMValueRef
  74 lp_build_gather_elem(struct gallivm_state *gallivm,
  75                      unsigned length,
  76                      unsigned src_width,
  77                      unsigned dst_width,
  78                      LLVMValueRef base_ptr,
  79                      LLVMValueRef offsets,
  80                      unsigned i)
  81 {
  82    LLVMTypeRef src_type = LLVMIntTypeInContext(gallivm->context, src_width);
  83    LLVMTypeRef src_ptr_type = LLVMPointerType(src_type, 0);
  84    LLVMTypeRef dst_elem_type = LLVMIntTypeInContext(gallivm->context, dst_width);
  85    LLVMValueRef ptr;
  86    LLVMValueRef res;
  87
  88    assert(LLVMTypeOf(base_ptr) == LLVMPointerType(LLVMInt8TypeInContext(gallivm->context), 0));
  89
  90    ptr = lp_build_gather_elem_ptr(gallivm, length, base_ptr, offsets, i);
  91    ptr = LLVMBuildBitCast(gallivm->builder, ptr, src_ptr_type, "");
  92    res = LLVMBuildLoad(gallivm->builder, ptr, "");
  93
  94    assert(src_width <= dst_width);
  95    if (src_width > dst_width)
  96       res = LLVMBuildTrunc(gallivm->builder, res, dst_elem_type, "");
  97    if (src_width < dst_width)
  98       res = LLVMBuildZExt(gallivm->builder, res, dst_elem_type, "");
  99
 100    return res;
 101 }
 102
 103
 104 /**
 105  * Gather elements from scatter positions in memory into a single vector.
 106  * Use for fetching texels from a texture.
 107  * For SSE, typical values are length=4, src_width=32, dst_width=32.
 108  *
 109  * @param length length of the offsets
 110  * @param src_width src element width in bits
 111  * @param dst_width result element width in bits (src will be expanded to fit)
 112  * @param base_ptr base pointer, should be a i8 pointer type.
 113  * @param offsets vector with offsets
 114  */
 115 LLVMValueRef
 116 lp_build_gather(struct gallivm_state *gallivm,
 117                 unsigned length,
 118                 unsigned src_width,
 119                 unsigned dst_width,
 120                 LLVMValueRef base_ptr,
 121                 LLVMValueRef offsets)
 122 {
 123    LLVMValueRef res;
 124
 125    if (length == 1) {
 126       /* Scalar */
 127       return lp_build_gather_elem(gallivm, length,
 128                                   src_width, dst_width,
 129                                   base_ptr, offsets, 0);
 130    } else {
 131       /* Vector */
 132
 133       LLVMTypeRef dst_elem_type = LLVMIntTypeInContext(gallivm->context, dst_width);
 134       LLVMTypeRef dst_vec_type = LLVMVectorType(dst_elem_type, length);
 135       unsigned i;
 136
 137       res = LLVMGetUndef(dst_vec_type);
 138       for (i = 0; i < length; ++i) {
 139          LLVMValueRef index = lp_build_const_int32(gallivm, i);
 140          LLVMValueRef elem;
 141          elem = lp_build_gather_elem(gallivm, length,
 142                                      src_width, dst_width,
 143                                      base_ptr, offsets, i);
 144          res = LLVMBuildInsertElement(gallivm->builder, res, elem, index, "");
 145       }
 146    }
 147
 148    return res;
 149 }