cross-project-tests/debuginfo-tests/dexter-tests/memvars/bitcast.c

   1 // XFAIL:*
   2 //// Suboptimal coverage, see description below.
   3
   4 // REQUIRES: lldb
   5 // UNSUPPORTED: system-windows
   6 // RUN: %clang -std=gnu11 -O3 -glldb %s -o %t
   7 // RUN: %dexter --fail-lt 1.0 -w --debugger lldb --binary %t -- %s
   8
   9 //// Adapted from https://bugs.llvm.org/show_bug.cgi?id=34136#c1
  10 //// LowerDbgDeclare has since been updated to look through bitcasts. We still
  11 //// get suboptimal coverage at the beginning of 'main' though. For each local,
  12 //// LowerDbgDeclare inserts a dbg.value and a dbg.value+DW_OP_deref before the
  13 //// store (after the call to 'getint') and the call to 'alias' respectively.
  14 //// The first dbg.value describes the result of the 'getint' call, eventually
  15 //// becoming a register location. The second points back into the stack
  16 //// home. There is a gap in the coverage between the quickly clobbered register
  17 //// location and the stack location, even though the stack location is valid
  18 //// during that gap. For x86 we end up with this code at the start of main:
  19 //// 00000000004004b0 <main>:
  20 ////   4004b0:  sub    rsp,0x18
  21 ////   4004b4:  mov    edi,0x5
  22 ////   4004b9:  call   400480 <getint>
  23 ////   4004be:  mov    DWORD PTR [rsp+0x14],eax
  24 ////   4004c2:  mov    edi,0x5
  25 ////   4004c7:  call   400480 <getint>
  26 ////   4004cc:  mov    DWORD PTR [rsp+0x10],eax
  27 ////   4004d0:  mov    edi,0x5
  28 ////   4004d5:  call   400480 <getint>
  29 ////   4004da:  mov    DWORD PTR [rsp+0xc],eax
  30 ////   ...
  31 //// With these variable locations:
  32 ////  DW_TAG_variable
  33 ////    DW_AT_location        (0x00000000:
  34 ////       [0x00000000004004be, 0x00000000004004cc): DW_OP_reg0 RAX
  35 ////       [0x00000000004004de, 0x0000000000400503): DW_OP_breg7 RSP+20)
  36 ////    DW_AT_name    ("x")
  37 ////    ...
  38 ////  DW_TAG_variable
  39 ////    DW_AT_location        (0x00000037:
  40 ////       [0x00000000004004cc, 0x00000000004004da): DW_OP_reg0 RAX
  41 ////       [0x00000000004004e8, 0x0000000000400503): DW_OP_breg7 RSP+16)
  42 ////    DW_AT_name    ("y")
  43 ////    ...
  44 ////  DW_TAG_variable
  45 ////    DW_AT_location        (0x0000006e:
  46 ////       [0x00000000004004da, 0x00000000004004e8): DW_OP_reg0 RAX
  47 ////       [0x00000000004004f2, 0x0000000000400503): DW_OP_breg7 RSP+12)
  48 ////    DW_AT_name    ("z")
  49 ////    ...
  50
  51 char g = 1;
  52 int five = 5;
  53 __attribute__((__noinline__))
  54 int getint(int x) {
  55   g = x - 4;
  56   return x * g;
  57 }
  58
  59 __attribute__((__noinline__))
  60 void alias(char* c) {
  61   g = *c;
  62   *c = (char)five;
  63 }
  64
  65 int main() {
  66   int x = getint(5);
  67   int y = getint(5); // DexLabel('s1')
  68   int z = getint(5); // DexLabel('s2')
  69   alias((char*)&x);  // DexLabel('s3')
  70   alias((char*)&y);
  71   alias((char*)&z);
  72   return 0;          // DexLabel('s4')
  73 }
  74
  75 // DexExpectWatchValue('x', '5',  from_line=ref('s1'), to_line=ref('s4'))
  76 // DexExpectWatchValue('y', '5',  from_line=ref('s2'), to_line=ref('s4'))
  77 // DexExpectWatchValue('z', '5',  from_line=ref('s3'), to_line=ref('s4'))