gdb/dwarf: pass an array of values to the dwarf evaluator

When we need to evaluate a DWARF expression in order to resolve some
dynamic property of a type we call the dwarf2_evaluate_property
function, which is declared in gdb/dwarf/loc.h and defined in
gdb/dwarf/loc.c.

Currently, this function takes (amongst other things) an argument of
type property_addr_info called addr_stack and a boolean called
push_initial_value.  When push_initial_value then the top value of
addr_stack is pushed onto the dwarf expression evaluation stack before
the expression is evaluated.

So far this has worked fine, as the only two cases we needed to handle
are the case the DWARF expression doesn't require the object
address (what the top of addr_stack represents), and the case where
the DWARF expression does require the address.

In the next commit this is going to change.  As we add support for
Fortran assumed rank arrays, we need to start resolving the dynamic
properties of arrays.  To do this, we need to push the array rank onto
the dwarf expression evaluation stack before the expression is
evaluated.

This commit is a refactoring commit aimed at making it easier to
support Fortran assumed rank arrays.  Instead of passing a boolean,
and using this to decide if we should push the object address or not,
we instead pass an array (view) of values that should be pushed to the
dwarf expression evaluation stack.

In the couple of places where we previously passed push_initial_value
as true (mostly this was defaulting to false), we now have to pass the
address from the addr_stack as an item in the array view.

In the next commit, when we want to handle passing the array rank,
this will easily be supported too.

There should be no user visible changes after this commit.

diff --git a/gdb/dwarf2/loc.c b/gdb/dwarf2/loc.c
index 634b51ef279f69ecbc76dfa74ed4ad215f2b9adc..bb9778d9edde2f595818cf634025ba7709e069a4 100644 (file)
--- a/gdb/dwarf2/loc.c
+++ b/gdb/dwarf2/loc.c
@@ -1570,10 +1570,9 @@ dwarf2_evaluate_loc_desc (struct type *type, struct frame_info *frame,
    evaluated.  ADDR_STACK is a context (location of a variable) and
    might be needed to evaluate the location expression.
 
-   PUSH_INITIAL_VALUE is true if the first address from ADDR_STACK, should
-   be pushed on the DWARF expression evaluation stack before evaluating the
-   expression; this is required by certain forms of DWARF expression.  When
-   PUSH_INITIAL_VALUE is true ADDR_STACK can't be nullptr.
+   PUSH_VALUES is an array of values to be pushed to the expression stack
+   before evaluation starts.  PUSH_VALUES[0] is pushed first, then
+   PUSH_VALUES[1], and so on.
 
    Returns 1 on success, 0 otherwise.  */
 
@@ -1582,7 +1581,7 @@ dwarf2_locexpr_baton_eval (const struct dwarf2_locexpr_baton *dlbaton,
                           struct frame_info *frame,
                           const struct property_addr_info *addr_stack,
                           CORE_ADDR *valp,
-                          bool push_initial_value,
+                          gdb::array_view<CORE_ADDR> push_values,
                           bool *is_reference)
 {
   if (dlbaton == NULL || dlbaton->size == 0)
@@ -1595,11 +1594,9 @@ dwarf2_locexpr_baton_eval (const struct dwarf2_locexpr_baton *dlbaton,
   value *result;
   scoped_value_mark free_values;
 
-  if (push_initial_value)
-    {
-      gdb_assert (addr_stack != nullptr);
-      ctx.push_address (addr_stack->addr, false);
-    }
+  /* Place any initial values onto the expression stack.  */
+  for (const auto &val : push_values)
+    ctx.push_address (val, false);
 
   try
     {
@@ -1645,7 +1642,7 @@ dwarf2_evaluate_property (const struct dynamic_prop *prop,
                          struct frame_info *frame,
                          const struct property_addr_info *addr_stack,
                          CORE_ADDR *value,
-                         bool push_initial_value)
+                         gdb::array_view<CORE_ADDR> push_values)
 {
   if (prop == NULL)
     return false;
@@ -1663,7 +1660,7 @@ dwarf2_evaluate_property (const struct dynamic_prop *prop,
 
        bool is_reference = baton->locexpr.is_reference;
        if (dwarf2_locexpr_baton_eval (&baton->locexpr, frame, addr_stack,
-                                      value, push_initial_value, &is_reference))
+                                      value, push_values, &is_reference))
          {
            if (is_reference)
              {

diff --git a/gdb/dwarf2/loc.h b/gdb/dwarf2/loc.h
index cf02f609cb05d815824773fe9d7f855a6a2d41ff..a9834d32066bb5ca5613bd0faf2652fe50ba2983 100644 (file)
--- a/gdb/dwarf2/loc.h
+++ b/gdb/dwarf2/loc.h
@@ -114,14 +114,16 @@ struct property_addr_info
    Returns true if PROP could be converted and the static value is passed
    back into VALUE, otherwise returns false.
 
-   If PUSH_INITIAL_VALUE is true, then the top value of ADDR_STACK
-   will be pushed before evaluating a location expression.  */
+   Any values in PUSH_VALUES will be pushed before evaluating the location
+   expression, PUSH_VALUES[0] will be pushed first, then PUSH_VALUES[1],
+   etc.  This means the during evaluation PUSH_VALUES[0] will be at the
+   bottom of the stack.  */
 
 bool dwarf2_evaluate_property (const struct dynamic_prop *prop,
                               struct frame_info *frame,
                               const struct property_addr_info *addr_stack,
                               CORE_ADDR *value,
-                              bool push_initial_value = false);
+                              gdb::array_view<CORE_ADDR> push_values = {});
 
 /* A helper for the compiler interface that compiles a single dynamic
    property to C code.

diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index 1769796ab336225e5a149a6fc9fb6489debb5ece..ae3b4cdaa561b7132bc1ece1e1eadebbbb90a817 100644 (file)
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -2601,7 +2601,7 @@ resolve_dynamic_struct (struct type *type,
 
          CORE_ADDR addr;
          if (dwarf2_evaluate_property (&prop, nullptr, addr_stack, &addr,
-                                       true))
+                                       {addr_stack->addr}))
            resolved_type->field (i).set_loc_bitpos
              (TARGET_CHAR_BIT * (addr - addr_stack->addr));
        }

diff --git a/gdb/gnu-v3-abi.c b/gdb/gnu-v3-abi.c
index b8640d6f7292dfff8de56db07eab2eb6f33aee5d..baf015b9813d33fd6c790e6db2175ac9f6300573 100644 (file)
--- a/gdb/gnu-v3-abi.c
+++ b/gdb/gnu-v3-abi.c
@@ -483,7 +483,7 @@ gnuv3_baseclass_offset (struct type *type, int index,
 
       CORE_ADDR result;
       if (dwarf2_evaluate_property (&prop, nullptr, &addr_stack, &result,
-                                   true))
+                                   {addr_stack.addr}))
        return (int) (result - addr_stack.addr);
     }