libcilkrts/runtime/config/generic/cilk-abi-vla.c

   1 /* cilk-abi-vla.cpp                  -*-C++-*-
   2  *
   3  *************************************************************************
   4  *
   5  *  Copyright (C) 2013-2016, Intel Corporation
   6  *  All rights reserved.
   7  *
   8  *  Redistribution and use in source and binary forms, with or without
   9  *  modification, are permitted provided that the following conditions
  10  *  are met:
  11  *
  12  *    * Redistributions of source code must retain the above copyright
  13  *      notice, this list of conditions and the following disclaimer.
  14  *    * Redistributions in binary form must reproduce the above copyright
  15  *      notice, this list of conditions and the following disclaimer in
  16  *      the documentation and/or other materials provided with the
  17  *      distribution.
  18  *    * Neither the name of Intel Corporation nor the names of its
  19  *      contributors may be used to endorse or promote products derived
  20  *      from this software without specific prior written permission.
  21  *
  22  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23  *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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  34  *
  35  *  *********************************************************************
  36  *
  37  *  PLEASE NOTE: This file is a downstream copy of a file mainitained in
  38  *  a repository at cilkplus.org. Changes made to this file that are not
  39  *  submitted through the contribution process detailed at
  40  *  http://www.cilkplus.org/submit-cilk-contribution will be lost the next
  41  *  time that a new version is released. Changes only submitted to the
  42  *  GNU compiler collection or posted to the git repository at
  43  *  https://bitbucket.org/intelcilkruntime/intel-cilk-runtime.git are
  44  *  not tracked.
  45  *
  46  *  We welcome your contributions to this open source project. Thank you
  47  *  for your assistance in helping us improve Cilk Plus.
  48  *
  49  **************************************************************************/
  50
  51 /*
  52  * Implementation of Variable Length Array (VLA) ABI.
  53  *
  54  * The compiler calls these functions to allocate Variable Length Arrays
  55  * at runtime.  The compiler must guarantee that __cilkrts_stack_free() is
  56  * called to cleanup any memory allocated by __cilkrts_stack_alloc().
  57  *
  58  * This generic implementation always allocates the memory from the heap.
  59  * Optimally, the implementation should expand the frame of the calling
  60  * function if possible, since that will be faster.  See the x86 version
  61  * for one possible implementation.
  62  */
  63
  64 #include <assert.h>
  65 #include <stdlib.h>
  66 #include <stdint.h>
  67
  68 #include "internal/abi.h"
  69 #include "cilk-abi-vla-internal.h"
  70
  71 #define c_cilk_ptr_from_heap  0xc2f2f00d
  72 #define c_cilk_ptr_from_stack 0xc3f30d0f
  73
  74 // Allocate space for a variable length array
  75 CILK_ABI(__cilkrts_void_ptr)
  76 __cilkrts_stack_alloc(
  77     __cilkrts_stack_frame *sf,
  78     size_t size,
  79     size_t distance_from_sp_to_alloca_area,
  80     uint32_t align,     // align is always >= minimum stack alignment and
  81                         // >= ptr_size as well, and must be a power of 2.
  82     uint32_t needs_tag  // non-zero if the pointer being returned needs to
  83                         // be tagged
  84 )
  85 {
  86     // full_size will be a multiple of align, and contains
  87     // enough extra space to allocate a marker.
  88     size_t full_size = (size + align - 1) & ~(align - 1);
  89
  90     // Allocate memory from the heap.  The compiler is responsible
  91     // for guaranteeing us a chance to free it before the function
  92     // exits
  93
  94     return (void *)vla_internal_heap_alloc(sf, full_size, align);
  95 }
  96
  97 // Free the space allocated for a variable length array.
  98 CILK_ABI(void)
  99 __cilkrts_stack_free(
 100     __cilkrts_stack_frame *sf,
 101     void *p,
 102     size_t size,
 103     size_t distance_from_sp_to_alloca_area,
 104     uint32_t align, // same requirements as for align in allocation,
 105                     // and must match alignment that was passed when
 106                     // doing the allocation
 107     uint32_t known_from_stack  // non-zero if this is known to be allocated
 108                                // on the stack, and therefore has no tag
 109 )
 110 {
 111     // full_size will be a multiple of align, and contains
 112     // enough extra space to allocate a marker if one was needed.
 113     size_t full_size = (size + align - 1) & ~(align - 1);
 114
 115     // Just free the allocated memory to the heap since we don't know
 116     // how to expand/contract the calling frame
 117     vla_internal_heap_free(p, full_size);
 118 }