re PR rtl-optimization/49977 (CFI notes are missed for delayed slot)

PR rtl-opt/49977
        * dwarf2cfi.c (scan_insn_after): Split out of ...
        (scan_trace): ... here.  Correctly place notes wrt sequences.

From-SVN: r177466

diff --git a/gcc/dwarf2cfi.c b/gcc/dwarf2cfi.c
index f6ab38d4b2cb048e3dd6593dd9d8456d29a2792f..80cce3209fc97dbbeac0a94a9bc445737215e3da 100644 (file)
--- a/gcc/dwarf2cfi.c
+++ b/gcc/dwarf2cfi.c
@@ -2355,13 +2355,23 @@ create_trace_edges (rtx insn)
     }
 }
 
+/* A subroutine of scan_trace.  Do what needs to be done "after" INSN.  */
+
+static void
+scan_insn_after (rtx insn)
+{
+  if (RTX_FRAME_RELATED_P (insn))
+    dwarf2out_frame_debug (insn);
+  notice_args_size (insn);
+}
+
 /* Scan the trace beginning at INSN and create the CFI notes for the
    instructions therein.  */
 
 static void
 scan_trace (dw_trace_info *trace)
 {
-  rtx insn = trace->head;
+  rtx prev, insn = trace->head;
   dw_cfa_location this_cfa;
 
   if (dump_file)
@@ -2378,10 +2388,14 @@ scan_trace (dw_trace_info *trace)
   this_cfa = cur_row->cfa;
   cur_cfa = &this_cfa;
 
-  for (insn = NEXT_INSN (insn); insn ; insn = NEXT_INSN (insn))
+  for (prev = insn, insn = NEXT_INSN (insn);
+       insn;
+       prev = insn, insn = NEXT_INSN (insn))
     {
+      rtx control;
+
       /* Do everything that happens "before" the insn.  */
-      add_cfi_insn = PREV_INSN (insn);
+      add_cfi_insn = prev;
 
       /* Notice the end of a trace.  */
       if (BARRIER_P (insn))
@@ -2401,34 +2415,25 @@ scan_trace (dw_trace_info *trace)
       if (DEBUG_INSN_P (insn) || !inside_basic_block_p (insn))
        continue;
 
-      /* Flush data before calls and jumps, and of course if necessary.  */
-      if (can_throw_internal (insn))
-       {
-         dwarf2out_flush_queued_reg_saves ();
-         notice_eh_throw (insn);
-       }
-      else if (!NONJUMP_INSN_P (insn)
-              || clobbers_queued_reg_save (insn)
-              || find_reg_note (insn, REG_CFA_FLUSH_QUEUE, NULL))
-       dwarf2out_flush_queued_reg_saves ();
-
-      /* Do everything that happens "after" the insn.  */
-      add_cfi_insn = insn;
-
-      /* Handle changes to the row state.  */
-      if (RTX_FRAME_RELATED_P (insn))
-       dwarf2out_frame_debug (insn);
-
-      /* Look for REG_ARGS_SIZE, and handle it.  */
+      /* Handle all changes to the row state.  Sequences require special
+        handling for the positioning of the notes.  */
       if (GET_CODE (PATTERN (insn)) == SEQUENCE)
        {
          rtx elt, pat = PATTERN (insn);
          int i, n = XVECLEN (pat, 0);
 
-         if (INSN_ANNULLED_BRANCH_P (XVECEXP (pat, 0, 0)))
+         control = XVECEXP (pat, 0, 0);
+         if (can_throw_internal (control))
+           notice_eh_throw (control);
+         dwarf2out_flush_queued_reg_saves ();
+
+         if (INSN_ANNULLED_BRANCH_P (control))
            {
              /* ??? Hopefully multiple delay slots are not annulled.  */
              gcc_assert (n == 2);
+             gcc_assert (!RTX_FRAME_RELATED_P (control));
+             gcc_assert (!find_reg_note (control, REG_ARGS_SIZE, NULL));
+
              elt = XVECEXP (pat, 0, 1);
 
              /* If ELT is an instruction from target of an annulled branch,
@@ -2438,11 +2443,16 @@ scan_trace (dw_trace_info *trace)
                {
                  HOST_WIDE_INT restore_args_size;
 
+                 add_cfi_insn = NULL;
                  restore_args_size = cur_trace->end_true_args_size;
                  cur_cfa = &cur_row->cfa;
 
-                 notice_args_size (elt);
-                 create_trace_edges (insn);
+                 scan_insn_after (elt);
+
+                 /* ??? Should we instead save the entire row state?  */
+                 gcc_assert (!VEC_length (queued_reg_save, queued_reg_saves));
+
+                 create_trace_edges (control);
 
                  cur_trace->end_true_args_size = restore_args_size;
                  cur_row->cfa = this_cfa;
@@ -2451,14 +2461,48 @@ scan_trace (dw_trace_info *trace)
                }
            }
 
+         /* The insns in the delay slot should all be considered to happen
+            "before" a call insn.  Consider a call with a stack pointer
+            adjustment in the delay slot.  The backtrace from the callee
+            should include the sp adjustment.  Unfortunately, that leaves
+            us with an unavoidable unwinding error exactly at the call insn
+            itself.  For jump insns we'd prefer to avoid this error by
+            placing the notes after the sequence.  */
+         if (JUMP_P (control))
+           add_cfi_insn = insn;
+
          for (i = 1; i < n; ++i)
            {
              elt = XVECEXP (pat, 0, i);
-             notice_args_size (elt);
+             scan_insn_after (elt);
            }
+
+         /* Make sure any register saves are visible at the jump target.  */
+         dwarf2out_flush_queued_reg_saves ();
+
+          /* However, if there is some adjustment on the call itself, e.g.
+            a call_pop, that action should be considered to happen after
+            the call returns.  */
+         add_cfi_insn = insn;
+         scan_insn_after (control);
        }
       else
-       notice_args_size (insn);
+       {
+         /* Flush data before calls and jumps, and of course if necessary.  */
+         if (can_throw_internal (insn))
+           {
+             notice_eh_throw (insn);
+             dwarf2out_flush_queued_reg_saves ();
+           }
+         else if (!NONJUMP_INSN_P (insn)
+                  || clobbers_queued_reg_save (insn)
+                  || find_reg_note (insn, REG_CFA_FLUSH_QUEUE, NULL))
+           dwarf2out_flush_queued_reg_saves ();
+
+         add_cfi_insn = insn;
+         scan_insn_after (insn);
+         control = insn;
+       }
 
       /* Between frame-related-p and args_size we might have otherwise
         emitted two cfa adjustments.  Do it now.  */
@@ -2468,7 +2512,7 @@ scan_trace (dw_trace_info *trace)
         same tests as are done to actually create the edges.  So
         always call the routine and let it not create edges for
         non-control-flow insns.  */
-      create_trace_edges (insn);
+      create_trace_edges (control);
     }
 
   add_cfi_insn = NULL;