xref: /aosp_15_r20/external/vixl/examples/aarch64/literal.cc (revision f5c631da2f1efdd72b5fd1e20510e4042af13d77)

// Copyright 2015, VIXL authors
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are met:
//
//   * Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
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//     used to endorse or promote products derived from this software without
//     specific prior written permission.
//
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#include "examples.h"

using namespace vixl;
using namespace vixl::aarch64;

#define __ masm.

#ifdef VIXL_INCLUDE_SIMULATOR_AARCH64
int64_t LiteralExample(int64_t a, int64_t b) {
  // Create and initialize the macro-assembler and the simulator.
  MacroAssembler masm;
  Decoder decoder;
  Simulator simulator(&decoder);

  Literal<int64_t> automatically_placed_literal(111, masm.GetLiteralPool());
  Literal<int64_t> manually_placed_literal(222);

  // Generate some code.
  Label start;
  masm.Bind(&start);
  {
    ExactAssemblyScope scope(&masm,
                             kInstructionSize + sizeof(int64_t),
                             ExactAssemblyScope::kExactSize);
    Label over_literal;
    __ b(&over_literal);
    __ place(&manually_placed_literal);
    __ bind(&over_literal);
  }
  __ Ldr(x1, &manually_placed_literal);
  __ Ldr(x2, &automatically_placed_literal);
  __ Add(x0, x1, x2);
  __ Ret();

  masm.FinalizeCode();

  // Usually, compilers will move the code to another place in memory before
  // executing it. Emulate that.
  size_t code_size = masm.GetSizeOfCodeGenerated();
  uint8_t* code = reinterpret_cast<uint8_t*>(malloc(code_size));
  if (code == NULL) {
    return 1;
  }
  memcpy(code, masm.GetBuffer()->GetStartAddress<void*>(), code_size);

  // Run the code.
  simulator.RunFrom(masm.GetLabelAddress<Instruction*>(&start));
  printf("111 + 222 = %" PRId64 "\n", simulator.ReadXRegister(0));

  // Now let's modify the values of the literals.
  automatically_placed_literal.UpdateValue(a, code);
  manually_placed_literal.UpdateValue(b, code);

  // Run the code again.
  simulator.RunFrom(reinterpret_cast<Instruction*>(code));
  printf("%" PRId64 " + %" PRId64 " = %" PRId64 "\n",
         a,
         b,
         simulator.ReadXRegister(0));

  return simulator.ReadXRegister(0);
}
#endif

#ifndef TEST_EXAMPLES
#ifdef VIXL_INCLUDE_SIMULATOR_AARCH64
int main(void) {
  VIXL_CHECK(LiteralExample(1, 2) == 3);
  return 0;
}
#else
// Without the simulator there is nothing to test.
int main(void) { return 0; }
#endif  // VIXL_INCLUDE_SIMULATOR_AARCH64
#endif  // TEST_EXAMPLES