src/gallium/auxiliary/gallivm/lp_bld_intr.c

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 *
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/**
 * @file
 * Helpers for emiting intrinsic calls.
 *
 * LLVM vanilla IR doesn't represent all basic arithmetic operations we care
 * about, and it is often necessary to resort target-specific intrinsics for
 * performance, convenience.
 *
 * Ideally we would like to stay away from target specific intrinsics and
 * move all the instruction selection logic into upstream LLVM where it belongs.
 *
 * These functions are also used for calling C functions provided by us from
 * generated LLVM code.
 *
 * @author Jose Fonseca <jfonseca@vmware.com>
 */


#include "util/u_debug.h"

#include "lp_bld_const.h"
#include "lp_bld_intr.h"
#include "lp_bld_type.h"
#include "lp_bld_pack.h"


LLVMValueRef
lp_declare_intrinsic(LLVMModuleRef module,
                     const char *name,
                     LLVMTypeRef ret_type,
                     LLVMTypeRef *arg_types,
                     unsigned num_args)
{
   LLVMTypeRef function_type;
   LLVMValueRef function;

   assert(!LLVMGetNamedFunction(module, name));

   function_type = LLVMFunctionType(ret_type, arg_types, num_args, 0);
   function = LLVMAddFunction(module, name, function_type);

   LLVMSetFunctionCallConv(function, LLVMCCallConv);
   LLVMSetLinkage(function, LLVMExternalLinkage);

   assert(LLVMIsDeclaration(function));

   return function;
}


LLVMValueRef
lp_build_intrinsic(LLVMBuilderRef builder,
                   const char *name,
                   LLVMTypeRef ret_type,
                   LLVMValueRef *args,
                   unsigned num_args)
{
   LLVMModuleRef module = LLVMGetGlobalParent(LLVMGetBasicBlockParent(LLVMGetInsertBlock(builder)));
   LLVMValueRef function;

   function = LLVMGetNamedFunction(module, name);
   if(!function) {
      LLVMTypeRef arg_types[LP_MAX_FUNC_ARGS];
      unsigned i;

      assert(num_args <= LP_MAX_FUNC_ARGS);

      for(i = 0; i < num_args; ++i) {
         assert(args[i]);
         arg_types[i] = LLVMTypeOf(args[i]);
      }

      function = lp_declare_intrinsic(module, name, ret_type, arg_types, num_args);
   }

   return LLVMBuildCall(builder, function, args, num_args, "");
}


LLVMValueRef
lp_build_intrinsic_unary(LLVMBuilderRef builder,
                         const char *name,
                         LLVMTypeRef ret_type,
                         LLVMValueRef a)
{
   return lp_build_intrinsic(builder, name, ret_type, &a, 1);
}


LLVMValueRef
lp_build_intrinsic_binary(LLVMBuilderRef builder,
                          const char *name,
                          LLVMTypeRef ret_type,
                          LLVMValueRef a,
                          LLVMValueRef b)
{
   LLVMValueRef args[2];

   args[0] = a;
   args[1] = b;

   return lp_build_intrinsic(builder, name, ret_type, args, 2);
}


/**
 * Call intrinsic with arguments adapted to intrinsic vector length.
 *
 * Split vectors which are too large for the hw, or expand them if they
 * are too small, so a caller calling a function which might use intrinsics
 * doesn't need to do splitting/expansion on its own.
 * This only supports intrinsics where src and dst types match.
 */
LLVMValueRef
lp_build_intrinsic_binary_anylength(struct gallivm_state *gallivm,
                                    const char *name,
                                    struct lp_type src_type,
                                    unsigned intr_size,
                                    LLVMValueRef a,
                                    LLVMValueRef b)
{
   unsigned i;
   struct lp_type intrin_type = src_type;
   LLVMBuilderRef builder = gallivm->builder;
   LLVMValueRef i32undef = LLVMGetUndef(LLVMInt32TypeInContext(gallivm->context));
   LLVMValueRef anative, bnative;
   unsigned intrin_length = intr_size / src_type.width;

   intrin_type.length = intrin_length;

   if (intrin_length > src_type.length) {
      LLVMValueRef elems[LP_MAX_VECTOR_LENGTH];
      LLVMValueRef constvec, tmp;

      for (i = 0; i < src_type.length; i++) {
         elems[i] = lp_build_const_int32(gallivm, i);
      }
      for (; i < intrin_length; i++) {
         elems[i] = i32undef;
      }
      if (src_type.length == 1) {
         LLVMTypeRef elem_type = lp_build_elem_type(gallivm, intrin_type);
         a = LLVMBuildBitCast(builder, a, LLVMVectorType(elem_type, 1), "");
         b = LLVMBuildBitCast(builder, b, LLVMVectorType(elem_type, 1), "");
      }
      constvec = LLVMConstVector(elems, intrin_length);
      anative = LLVMBuildShuffleVector(builder, a, a, constvec, "");
      bnative = LLVMBuildShuffleVector(builder, b, b, constvec, "");
      tmp = lp_build_intrinsic_binary(builder, name,
                                      lp_build_vec_type(gallivm, intrin_type),
                                      anative, bnative);
      if (src_type.length > 1) {
         constvec = LLVMConstVector(elems, src_type.length);
         return LLVMBuildShuffleVector(builder, tmp, tmp, constvec, "");
      }
      else {
         return LLVMBuildExtractElement(builder, tmp, elems[0], "");
      }
   }
   else if (intrin_length < src_type.length) {
      unsigned num_vec = src_type.length / intrin_length;
      LLVMValueRef tmp[LP_MAX_VECTOR_LENGTH];

      /* don't support arbitrary size here as this is so yuck */
      if (src_type.length % intrin_length) {
         /* FIXME: This is something which should be supported
          * but there doesn't seem to be any need for it currently
          * so crash and burn.
          */
         debug_printf("%s: should handle arbitrary vector size\n",
                      __FUNCTION__);
         assert(0);
         return NULL;
      }

      for (i = 0; i < num_vec; i++) {
         anative = lp_build_extract_range(gallivm, a, i*intrin_length,
                                        intrin_length);
         bnative = lp_build_extract_range(gallivm, b, i*intrin_length,
                                        intrin_length);
         tmp[i] = lp_build_intrinsic_binary(builder, name,
                                            lp_build_vec_type(gallivm, intrin_type),
                                            anative, bnative);
      }
      return lp_build_concat(gallivm, tmp, intrin_type, num_vec);
   }
   else {
      return lp_build_intrinsic_binary(builder, name,
                                       lp_build_vec_type(gallivm, src_type),
                                       a, b);
   }
}


LLVMValueRef
lp_build_intrinsic_map(struct gallivm_state *gallivm,
                       const char *name,
                       LLVMTypeRef ret_type,
                       LLVMValueRef *args,
                       unsigned num_args)
{
   LLVMBuilderRef builder = gallivm->builder;
   LLVMTypeRef ret_elem_type = LLVMGetElementType(ret_type);
   unsigned n = LLVMGetVectorSize(ret_type);
   unsigned i, j;
   LLVMValueRef res;

   assert(num_args <= LP_MAX_FUNC_ARGS);

   res = LLVMGetUndef(ret_type);
   for(i = 0; i < n; ++i) {
      LLVMValueRef index = lp_build_const_int32(gallivm, i);
      LLVMValueRef arg_elems[LP_MAX_FUNC_ARGS];
      LLVMValueRef res_elem;
      for(j = 0; j < num_args; ++j)
         arg_elems[j] = LLVMBuildExtractElement(builder, args[j], index, "");
      res_elem = lp_build_intrinsic(builder, name, ret_elem_type, arg_elems, num_args);
      res = LLVMBuildInsertElement(builder, res, res_elem, index, "");
   }

   return res;
}


LLVMValueRef
lp_build_intrinsic_map_unary(struct gallivm_state *gallivm,
                             const char *name,
                             LLVMTypeRef ret_type,
                             LLVMValueRef a)
{
   return lp_build_intrinsic_map(gallivm, name, ret_type, &a, 1);
}


LLVMValueRef
lp_build_intrinsic_map_binary(struct gallivm_state *gallivm,
                              const char *name,
                              LLVMTypeRef ret_type,
                              LLVMValueRef a,
                              LLVMValueRef b)
{
   LLVMValueRef args[2];

   args[0] = a;
   args[1] = b;

   return lp_build_intrinsic_map(gallivm, name, ret_type, args, 2);
}