libunwind/test/floatregister.pass.cpp

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 // REQUIRES: linux && target={{aarch64-.+}}
  11
  12 // Basic test for float registers number are accepted.
  13
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <unwind.h>
  17
  18 // Using __attribute__((section("main_func"))) is ELF specific, but then
  19 // this entire test is marked as requiring Linux, so we should be good.
  20 //
  21 // We don't use dladdr() because on musl it's a no-op when statically linked.
  22 extern char __start_main_func;
  23 extern char __stop_main_func;
  24
  25 _Unwind_Reason_Code frame_handler(struct _Unwind_Context *ctx, void *arg) {
  26   (void)arg;
  27
  28   // Unwind until the main is reached, above frames depend on the platform and
  29   // architecture.
  30   uintptr_t ip = _Unwind_GetIP(ctx);
  31   if (ip >= (uintptr_t)&__start_main_func &&
  32       ip < (uintptr_t)&__stop_main_func) {
  33     _Exit(0);
  34   }
  35
  36   return _URC_NO_REASON;
  37 }
  38
  39 __attribute__((noinline)) void foo() {
  40   // Provide some CFI directives that instructs the unwinder where given
  41   // float register is.
  42 #if defined(__aarch64__)
  43   // DWARF register number for V0-V31 registers are 64-95.
  44   // Previous value of V0 is saved at offset 0 from CFA.
  45   asm volatile(".cfi_offset 64, 0");
  46   // From now on the previous value of register can't be restored anymore.
  47   asm volatile(".cfi_undefined 65");
  48   asm volatile(".cfi_undefined 95");
  49   // Previous value of V2 is in V30.
  50   asm volatile(".cfi_register  66, 94");
  51 #endif
  52   _Unwind_Backtrace(frame_handler, NULL);
  53 }
  54
  55 __attribute__((section("main_func"))) int main() {
  56   foo();
  57   return -2;
  58 }