[PATCH 3/7] Move follow_static_link to frame.c

[Tom Tromey <tromey@adacore.com>]

This moves the follow_static_link function to frame.c and exports it
for use elsewhere.  The API is changed slightly to make it more
generically useful.
---
 gdb/findvar.c | 59 ++++++-----------------------------------------------------
 gdb/frame.c   | 40 ++++++++++++++++++++++++++++++++++++++++
 gdb/frame.h   |  7 +++++++
 3 files changed, 53 insertions(+), 53 deletions(-)

diff --git a/gdb/findvar.c b/gdb/findvar.c
index 1079b85df82..952ec20c0b7 100644
--- a/gdb/findvar.c
+++ b/gdb/findvar.c
@@ -31,7 +31,6 @@
 #include "block.h"
 #include "objfiles.h"
 #include "language.h"
-#include "dwarf2/loc.h"
 #include "gdbsupport/selftest.h"
 
 /* Basic byte-swapping routines.  All 'extract' functions return a
@@ -391,41 +390,6 @@ symbol_read_needs_frame (struct symbol *sym)
   return symbol_read_needs (sym) == SYMBOL_NEEDS_FRAME;
 }
 
-/* Given static link expression and the frame it lives in, look for the frame
-   the static links points to and return it.  Return NULL if we could not find
-   such a frame.   */
-
-static frame_info_ptr
-follow_static_link (frame_info_ptr frame,
-		    const struct dynamic_prop *static_link)
-{
-  CORE_ADDR upper_frame_base;
-
-  if (!dwarf2_evaluate_property (static_link, frame, NULL, &upper_frame_base))
-    return NULL;
-
-  /* Now climb up the stack frame until we reach the frame we are interested
-     in.  */
-  for (; frame != NULL; frame = get_prev_frame (frame))
-    {
-      struct symbol *framefunc = get_frame_function (frame);
-
-      /* Stacks can be quite deep: give the user a chance to stop this.  */
-      QUIT;
-
-      /* If we don't know how to compute FRAME's base address, don't give up:
-	 maybe the frame we are looking for is upper in the stack frame.  */
-      if (framefunc != NULL
-	  && SYMBOL_BLOCK_OPS (framefunc) != NULL
-	  && SYMBOL_BLOCK_OPS (framefunc)->get_frame_base != NULL
-	  && (SYMBOL_BLOCK_OPS (framefunc)->get_frame_base (framefunc, frame)
-	      == upper_frame_base))
-	break;
-    }
-
-  return frame;
-}
-
 /* Assuming VAR is a symbol that can be reached from FRAME thanks to lexical
    rules, look for the frame that is actually hosting VAR and return it.  If,
    for some reason, we found no such frame, return NULL.
@@ -494,25 +458,14 @@ get_hosting_frame (struct symbol *var, const struct block *var_block,
       /* Assuming we have a block for this frame: if we are at the function
 	 level, the immediate upper lexical block is in an outer function:
 	 follow the static link.  */
-      else if (frame_block->function ())
+      else if (frame_block->function () != nullptr)
 	{
-	  const struct dynamic_prop *static_link
-	    = frame_block->static_link ();
-	  int could_climb_up = 0;
-
-	  if (static_link != NULL)
-	    {
-	      frame = follow_static_link (frame, static_link);
-	      if (frame != NULL)
-		{
-		  frame_block = get_frame_block (frame, NULL);
-		  could_climb_up = frame_block != NULL;
-		}
-	    }
-	  if (!could_climb_up)
+	  frame = frame_follow_static_link (frame);
+	  if (frame != nullptr)
 	    {
-	      frame = NULL;
-	      break;
+	      frame_block = get_frame_block (frame, nullptr);
+	      if (frame_block == nullptr)
+		frame = nullptr;
 	    }
 	}
 
diff --git a/gdb/frame.c b/gdb/frame.c
index 7077016ccba..4a46ccb9abc 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -43,6 +43,7 @@
 #include "hashtab.h"
 #include "valprint.h"
 #include "cli/cli-option.h"
+#include "dwarf2/loc.h"
 
 /* The sentinel frame terminates the innermost end of the frame chain.
    If unwound, it returns the information needed to construct an
@@ -3120,6 +3121,45 @@ get_frame_sp (frame_info_ptr this_frame)
   return gdbarch_unwind_sp (gdbarch, frame_info_ptr (this_frame->next));
 }
 
+/* See frame.h.  */
+
+frame_info_ptr
+frame_follow_static_link (frame_info_ptr frame)
+{
+  const block *frame_block = get_frame_block (frame, nullptr);
+  frame_block = frame_block->function_block ();
+
+  const struct dynamic_prop *static_link = frame_block->static_link ();
+  if (static_link == nullptr)
+    return {};
+
+  CORE_ADDR upper_frame_base;
+
+  if (!dwarf2_evaluate_property (static_link, frame, NULL, &upper_frame_base))
+    return {};
+
+  /* Now climb up the stack frame until we reach the frame we are interested
+     in.  */
+  for (; frame != nullptr; frame = get_prev_frame (frame))
+    {
+      struct symbol *framefunc = get_frame_function (frame);
+
+      /* Stacks can be quite deep: give the user a chance to stop this.  */
+      QUIT;
+
+      /* If we don't know how to compute FRAME's base address, don't give up:
+	 maybe the frame we are looking for is upper in the stack frame.  */
+      if (framefunc != NULL
+	  && SYMBOL_BLOCK_OPS (framefunc) != NULL
+	  && SYMBOL_BLOCK_OPS (framefunc)->get_frame_base != NULL
+	  && (SYMBOL_BLOCK_OPS (framefunc)->get_frame_base (framefunc, frame)
+	      == upper_frame_base))
+	break;
+    }
+
+  return frame;
+}
+
 /* Return the reason why we can't unwind past FRAME.  */
 
 enum unwind_stop_reason
diff --git a/gdb/frame.h b/gdb/frame.h
index 1d7422cac32..19bf8176682 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -640,6 +640,13 @@ class address_space;
 /* Return the frame's address space.  */
 extern const address_space *get_frame_address_space (frame_info_ptr);
 
+/* A frame may have a "static link".  That is, in some languages, a
+   nested function may have access to variables from the enclosing
+   block and frame.  This function looks for a frame's static link.
+   If found, returns the corresponding frame; otherwise, returns a
+   null frame_info_ptr.  */
+extern frame_info_ptr frame_follow_static_link (frame_info_ptr frame);
+
 /* For frames where we can not unwind further, describe why.  */
 
 enum unwind_stop_reason

-- 
2.40.1