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      1 // Copyright 2015, ARM Limited
      2 // All rights reserved.
      3 //
      4 // Redistribution and use in source and binary forms, with or without
      5 // modification, are permitted provided that the following conditions are met:
      6 //
      7 //   * Redistributions of source code must retain the above copyright notice,
      8 //     this list of conditions and the following disclaimer.
      9 //   * Redistributions in binary form must reproduce the above copyright notice,
     10 //     this list of conditions and the following disclaimer in the documentation
     11 //     and/or other materials provided with the distribution.
     12 //   * Neither the name of ARM Limited nor the names of its contributors may be
     13 //     used to endorse or promote products derived from this software without
     14 //     specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
     17 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     18 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     19 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
     20 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     21 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     22 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
     23 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     24 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     25 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26 
     27 #include "vixl/a64/macro-assembler-a64.h"
     28 #include "vixl/a64/instructions-a64.h"
     29 #include "vixl/globals.h"
     30 
     31 using namespace vixl;
     32 
     33 static const int kDefaultInstructionCount = 100000;
     34 
     35 // This program focuses on emitting branch instructions.
     36 //
     37 // This code will emit a given number of branch immediate to the next
     38 // instructions in a fixed size buffer, looping over the buffer if necessary.
     39 // This code therefore focuses on Emit and label binding/patching.
     40 int main(int argc, char* argv[]) {
     41   int instructions = 0;
     42 
     43   switch (argc) {
     44     case 1: instructions = kDefaultInstructionCount; break;
     45     case 2: instructions = atoi(argv[1]); break;
     46     default:
     47       printf("Usage: %s [#instructions]\n", argv[0]);
     48       exit(1);
     49   }
     50 
     51   const int buffer_size = 256 * KBytes;
     52   const int buffer_instruction_count = buffer_size / kInstructionSize;
     53   MacroAssembler masm(buffer_size);
     54 
     55   #define __ masm.
     56   // We emit a branch to the next instruction.
     57 
     58   int rounds = instructions / buffer_instruction_count;
     59   for (int i = 0; i < rounds; ++i) {
     60     {
     61       InstructionAccurateScope scope(&masm, buffer_instruction_count);
     62       for (int j = 0; j < buffer_instruction_count; ++j) {
     63         Label target;
     64         __ b(&target);
     65         __ bind(&target);
     66       }
     67     }
     68     masm.Reset();
     69   }
     70 
     71   int remaining = instructions % buffer_instruction_count;
     72   {
     73     InstructionAccurateScope scope(&masm, remaining);
     74     for (int i = 0; i < remaining; ++i) {
     75       Label target;
     76       __ b(&target);
     77       __ bind(&target);
     78     }
     79   }
     80 
     81   masm.FinalizeCode();
     82 
     83   return 0;
     84 }
     85