[binutils-gdb] Fix gdb.opt/inline-cmds.exp regressions

[Ulrich Weigand <uweigand at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=5033013f17524964564dac5d422739ae5214729e

commit 5033013f17524964564dac5d422739ae5214729e
Author: Ulrich Weigand <ulrich.weigand@de.ibm.com>
Date:   Tue Oct 24 16:33:53 2017 +0200

    Fix gdb.opt/inline-cmds.exp regressions
    
    When sorting pending blocks in end_symtab_get_static_block, blocks
    with the same starting address must remain in the original order
    to preserve inline function caller/callee relationships.
    
    The original code seems to have implicitly relied on the fact that the
    glibc qsort implemention actually (in the common case) provides a stable
    sort, although this is not guaranteed by the standard.  But the GNU
    libstdc++ std::sort implementation is *not* stable.
    
    gdb/ChangeLog:
    2017-10-24  Ulrich Weigand  <uweigand@de.ibm.com>
    
    	* buildsym.c (end_symtab_get_static_block): Use std::stable_sort.

Diff:
---
 gdb/ChangeLog  |  4 ++++
 gdb/buildsym.c | 14 ++++++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e13b0d8..b44349f 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2017-10-24  Ulrich Weigand  <uweigand@de.ibm.com>
+
+	* buildsym.c (end_symtab_get_static_block): Use std::stable_sort.
+
 2017-10-21  Simon Marchi  <simon.marchi@ericsson.com>
 
 	* memattr.h: Don't include vec.h.
diff --git a/gdb/buildsym.c b/gdb/buildsym.c
index c556ac1..07bfbd5 100644
--- a/gdb/buildsym.c
+++ b/gdb/buildsym.c
@@ -1249,12 +1249,14 @@ end_symtab_get_static_block (CORE_ADDR end_addr, int expandable, int required)
       for (pb = pending_blocks; pb != NULL; pb = pb->next)
 	barray.push_back (pb->block);
 
-      std::sort (barray.begin (), barray.end (),
-		 [] (const block *a, const block *b)
-		 {
-		   /* Sort blocks in descending order.  */
-		   return BLOCK_START (a) > BLOCK_START (b);
-		 });
+      /* Sort blocks by start address in descending order.  Blocks with the
+	 same start address must remain in the original order to preserve
+	 inline function caller/callee relationships.  */
+      std::stable_sort (barray.begin (), barray.end (),
+			[] (const block *a, const block *b)
+			{
+			  return BLOCK_START (a) > BLOCK_START (b);
+			});
 
       int i = 0;
       for (pb = pending_blocks; pb != NULL; pb = pb->next)