cross-project-tests/debuginfo-tests/dexter-tests/memvars/unused-merged-value.c

   1 // Location for variable "parama" optimized out.
   2 // Previously it would carry incorrect location
   3 // information in debug-info, see PR48719.
   4 // Now, the location is simply not emitted.
   5
   6 // REQUIRES: lldb
   7 // UNSUPPORTED: system-windows
   8 // RUN: %dexter --fail-lt 0.1 -w --debugger lldb \
   9 // RUN:     --builder 'clang-c'  --cflags "-O3 -glldb" -- %s
  10 // See NOTE at end for more info about the RUN command.
  11
  12 // 1. SROA/mem2reg fully promotes parama.
  13 // 2. parama's value in the final block is the merge of values for it coming
  14 //    out of entry and if.then. If the variable were used later in the function
  15 //    mem2reg would insert a PHI here and add a dbg.value to track the merged
  16 //    value in debug info. Because it is not used there is no PHI (the merged
  17 //    value is implicit) and subsequently no dbg.value.
  18 // 3. SimplifyCFG later folds the blocks together (if.then does nothing besides
  19 //    provide debug info so it is removed and if.end is folded into the entry
  20 //    block).
  21
  22 // The debug info is not updated to account for the implicit merged value prior
  23 // to (e.g. during mem2reg) or during SimplifyCFG so we end up seeing parama=5
  24 // for the entire function, which is incorrect.
  25
  26 __attribute__((optnone))
  27 void fluff() {}
  28
  29 __attribute__((noinline))
  30 int fun(int parama, int paramb) {
  31   if (parama)
  32     parama = paramb;
  33   fluff();            // DexLabel('s0')
  34   return paramb;
  35 }
  36
  37 int main() {
  38   return fun(5, 20);
  39 }
  40
  41 // DexExpectWatchValue('parama', 20, on_line=ref('s0'))
  42 //
  43 // NOTE: the dexter command uses --fail-lt 0.1 (instead of the standard 1.0)
  44 // because seeing 'optimized out' would still be a win; it's the best we can do
  45 // without using conditional DWARF operators in the location expression. Seeing
  46 // 'optimized out' should result in a score higher than 0.1.