2010-07-07 Sergio Durigan Junior <sergiodj@linux.vnet.ibm.com>

[deliverable/binutils-gdb.git] / gdb / eval.c

diff --git a/gdb/eval.c b/gdb/eval.c
index 9a60616d56cb9ae3e2841c32fcd40593313e76ae..ff17c34018194d970516b168ba0f257e91b05c75 100644 (file)
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -43,6 +43,7 @@
 #include "gdb_obstack.h"
 #include "objfiles.h"
 #include "python/python.h"
+#include "wrapper.h"
 
 #include "gdb_assert.h"
 
@@ -186,6 +187,84 @@ evaluate_subexpression_type (struct expression *exp, int subexp)
   return evaluate_subexp (NULL_TYPE, exp, &subexp, EVAL_AVOID_SIDE_EFFECTS);
 }
 
+/* Find the current value of a watchpoint on EXP.  Return the value in
+   *VALP and *RESULTP and the chain of intermediate and final values
+   in *VAL_CHAIN.  RESULTP and VAL_CHAIN may be NULL if the caller does
+   not need them.
+
+   If a memory error occurs while evaluating the expression, *RESULTP will
+   be set to NULL.  *RESULTP may be a lazy value, if the result could
+   not be read from memory.  It is used to determine whether a value
+   is user-specified (we should watch the whole value) or intermediate
+   (we should watch only the bit used to locate the final value).
+
+   If the final value, or any intermediate value, could not be read
+   from memory, *VALP will be set to NULL.  *VAL_CHAIN will still be
+   set to any referenced values.  *VALP will never be a lazy value.
+   This is the value which we store in struct breakpoint.
+
+   If VAL_CHAIN is non-NULL, *VAL_CHAIN will be released from the
+   value chain.  The caller must free the values individually.  If
+   VAL_CHAIN is NULL, all generated values will be left on the value
+   chain.  */
+
+void
+fetch_subexp_value (struct expression *exp, int *pc, struct value **valp,
+                   struct value **resultp, struct value **val_chain)
+{
+  struct value *mark, *new_mark, *result;
+  volatile struct gdb_exception ex;
+
+  *valp = NULL;
+  if (resultp)
+    *resultp = NULL;
+  if (val_chain)
+    *val_chain = NULL;
+
+  /* Evaluate the expression.  */
+  mark = value_mark ();
+  result = NULL;
+
+  TRY_CATCH (ex, RETURN_MASK_ALL)
+    {
+      result = evaluate_subexp (NULL_TYPE, exp, pc, EVAL_NORMAL);
+    }
+  if (ex.reason < 0)
+    {
+      /* Ignore memory errors, we want watchpoints pointing at
+        inaccessible memory to still be created; otherwise, throw the
+        error to some higher catcher.  */
+      switch (ex.error)
+       {
+       case MEMORY_ERROR:
+         break;
+       default:
+         throw_exception (ex);
+         break;
+       }
+    }
+
+  new_mark = value_mark ();
+  if (mark == new_mark)
+    return;
+  if (resultp)
+    *resultp = result;
+
+  /* Make sure it's not lazy, so that after the target stops again we
+     have a non-lazy previous value to compare with.  */
+  if (result != NULL
+      && (!value_lazy (result) || gdb_value_fetch_lazy (result)))
+    *valp = result;
+
+  if (val_chain)
+    {
+      /* Return the chain of intermediate values.  We use this to
+        decide which addresses to watch.  */
+      *val_chain = new_mark;
+      value_release_to_mark (mark);
+    }
+}
+
 /* Extract a field operation from an expression.  If the subexpression
    of EXP starting at *SUBEXP is not a structure dereference
    operation, return NULL.  Otherwise, return the name of the