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
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  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
  17  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  18  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  19  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  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 #include "lp_bld_intr.h"
  36
  37
  38 /**
  39  * Get the pointer to one element from scatter positions in memory.
  40  *
  41  * @sa lp_build_gather()
  42  */
  43 LLVMValueRef
  44 lp_build_gather_elem_ptr(struct gallivm_state *gallivm,
  45                          unsigned length,
  46                          LLVMValueRef base_ptr,
  47                          LLVMValueRef offsets,
  48                          unsigned i)
  49 {
  50    LLVMValueRef offset;
  51    LLVMValueRef ptr;
  52
  53    assert(LLVMTypeOf(base_ptr) == LLVMPointerType(LLVMInt8TypeInContext(gallivm->context), 0));
  54
  55    if (length == 1) {
  56       assert(i == 0);
  57       offset = offsets;
  58    } else {
  59       LLVMValueRef index = lp_build_const_int32(gallivm, i);
  60       offset = LLVMBuildExtractElement(gallivm->builder, offsets, index, "");
  61    }
  62
  63    ptr = LLVMBuildGEP(gallivm->builder, base_ptr, &offset, 1, "");
  64
  65    return ptr;
  66 }
  67
  68
  69 /**
  70  * Gather one element from scatter positions in memory.
  71  *
  72  * @sa lp_build_gather()
  73  */
  74 LLVMValueRef
  75 lp_build_gather_elem(struct gallivm_state *gallivm,
  76                      unsigned length,
  77                      unsigned src_width,
  78                      unsigned dst_width,
  79                      LLVMValueRef base_ptr,
  80                      LLVMValueRef offsets,
  81                      unsigned i,
  82                      boolean vector_justify)
  83 {
  84    LLVMTypeRef src_type = LLVMIntTypeInContext(gallivm->context, src_width);
  85    LLVMTypeRef src_ptr_type = LLVMPointerType(src_type, 0);
  86    LLVMTypeRef dst_elem_type = LLVMIntTypeInContext(gallivm->context, dst_width);
  87    LLVMValueRef ptr;
  88    LLVMValueRef res;
  89
  90    assert(LLVMTypeOf(base_ptr) == LLVMPointerType(LLVMInt8TypeInContext(gallivm->context), 0));
  91
  92    ptr = lp_build_gather_elem_ptr(gallivm, length, base_ptr, offsets, i);
  93    ptr = LLVMBuildBitCast(gallivm->builder, ptr, src_ptr_type, "");
  94    res = LLVMBuildLoad(gallivm->builder, ptr, "");
  95
  96    assert(src_width <= dst_width);
  97    if (src_width > dst_width) {
  98       res = LLVMBuildTrunc(gallivm->builder, res, dst_elem_type, "");
  99    } else if (src_width < dst_width) {
 100       res = LLVMBuildZExt(gallivm->builder, res, dst_elem_type, "");
 101       if (vector_justify) {
 102 #ifdef PIPE_ARCH_BIG_ENDIAN
 103          res = LLVMBuildShl(gallivm->builder, res,
 104                             LLVMConstInt(dst_elem_type, dst_width - src_width, 0), "");
 105 #endif
 106       }
 107    }
 108
 109    return res;
 110 }
 111
 112
 113 /**
 114  * Gather elements from scatter positions in memory into a single vector.
 115  * Use for fetching texels from a texture.
 116  * For SSE, typical values are length=4, src_width=32, dst_width=32.
 117  *
 118  * When src_width < dst_width, the return value can be justified in
 119  * one of two ways:
 120  * "integer justification" is used when the caller treats the destination
 121  * as a packed integer bitmask, as described by the channels' "shift" and
 122  * "width" fields;
 123  * "vector justification" is used when the caller casts the destination
 124  * to a vector and needs channel X to be in vector element 0.
 125  *
 126  * @param length length of the offsets
 127  * @param src_width src element width in bits
 128  * @param dst_width result element width in bits (src will be expanded to fit)
 129  * @param base_ptr base pointer, should be a i8 pointer type.
 130  * @param offsets vector with offsets
 131  * @param vector_justify select vector rather than integer justification
 132  */
 133 LLVMValueRef
 134 lp_build_gather(struct gallivm_state *gallivm,
 135                 unsigned length,
 136                 unsigned src_width,
 137                 unsigned dst_width,
 138                 LLVMValueRef base_ptr,
 139                 LLVMValueRef offsets,
 140                 boolean vector_justify)
 141 {
 142    LLVMValueRef res;
 143
 144    if (length == 1) {
 145       /* Scalar */
 146       return lp_build_gather_elem(gallivm, length,
 147                                   src_width, dst_width,
 148                                   base_ptr, offsets, 0, vector_justify);
 149    } else {
 150       /* Vector */
 151
 152       LLVMTypeRef dst_elem_type = LLVMIntTypeInContext(gallivm->context, dst_width);
 153       LLVMTypeRef dst_vec_type = LLVMVectorType(dst_elem_type, length);
 154       unsigned i;
 155
 156       res = LLVMGetUndef(dst_vec_type);
 157       for (i = 0; i < length; ++i) {
 158          LLVMValueRef index = lp_build_const_int32(gallivm, i);
 159          LLVMValueRef elem;
 160          elem = lp_build_gather_elem(gallivm, length,
 161                                      src_width, dst_width,
 162                                      base_ptr, offsets, i, vector_justify);
 163          res = LLVMBuildInsertElement(gallivm->builder, res, elem, index, "");
 164       }
 165    }
 166
 167    return res;
 168 }
 169
 170 LLVMValueRef
 171 lp_build_gather_values(struct gallivm_state * gallivm,
 172                        LLVMValueRef * values,
 173                        unsigned value_count)
 174 {
 175    LLVMTypeRef vec_type = LLVMVectorType(LLVMTypeOf(values[0]), value_count);
 176    LLVMBuilderRef builder = gallivm->builder;
 177    LLVMValueRef vec = LLVMGetUndef(vec_type);
 178    unsigned i;
 179
 180    for (i = 0; i < value_count; i++) {
 181       LLVMValueRef index = lp_build_const_int32(gallivm, i);
 182       vec = LLVMBuildInsertElement(builder, vec, values[i], index, "");
 183    }
 184    return vec;
 185 }