RFC: preserve line number when skipping prologue

[Tom Tromey <tromey@redhat.com>]

Jeff Johnston noticed a regression in the CDT test suite when using a
recent gdb.  The bug is that if you put a breakpoint on a
non-executable line before a function's start, gdb displays the
breakpoint as being on the function's first line.

E.g. consider this program:

    #include <stdio.h>

    /* Line 3 */

    int main()
    {
      printf ("hi\n");

      /* Line 9 */

      return 0;
    }

If I set a breakpoint on line 3, gdb reports line 7.

(gdb) b 3
Breakpoint 1 at 0x80483c5: file m.c, line 7.

But if I set one on line 9, another non-executable line, gdb reports
line 9:

(gdb) b 9
Breakpoint 2 at 0x80483d1: file m.c, line 9.


I tracked this down to the prologue-skipping code.

This patch fixes the problem by preserving the line number when
skipping the prologue.  I am not sure this is really a valid thing to
do -- I'd appreciate comments on that.  However, I do think that the
principle of reporting the location that the user requested is a valid
one.

Built and regtested on x86-64 (compile farm).

Tom

2009-03-26  Tom Tromey  <tromey@redhat.com>

	* breakpoint.c (resolve_sal_pc): Preserve original line number
	when skipping prologue.

2009-03-26  Tom Tromey  <tromey@redhat.com>

	Update for change to prologue skipping:
	* gdb.mi/mi2-simplerun.exp: Update.
	* gdb.mi/mi2-break.exp: Update.
	* gdb.mi/mi-simplerun.exp: Update.
	* gdb.mi/mi-break.exp: Update.
	* gdb.base/ending-run.exp: Update.

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 7e50342..750d632 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -5754,7 +5754,12 @@ resolve_sal_pc (struct symtab_and_line *sal)
       /* If this SAL corresponds to a breakpoint inserted using
          a line number, then skip the function prologue if necessary.  */
       if (sal->explicit_line)
-        skip_prologue_sal (sal);
+	{
+	  /* Preserve the original line number.  */
+	  int saved_line = sal->line;
+	  skip_prologue_sal (sal);
+	  sal->line = saved_line;
+	}
     }
 
   if (sal->section == 0 && sal->symtab != NULL)
diff --git a/gdb/testsuite/gdb.base/ending-run.exp b/gdb/testsuite/gdb.base/ending-run.exp
index 42b4577..cf33602 100644
--- a/gdb/testsuite/gdb.base/ending-run.exp
+++ b/gdb/testsuite/gdb.base/ending-run.exp
@@ -69,7 +69,7 @@ gdb_expect {
 gdb_test "b ending-run.c:1" ".*Breakpoint.*4.*"
 gdb_test "b ending-run.c:14" ".*Note.*also.*Breakpoint.*5.*" "b ending-run.c:14, two"
 gdb_test "cle ending-run.c:14" \
-	".*Deleted breakpoints 4 5.*" "Cleared 2 by line"
+	".*Deleted breakpoint 5.*" "Cleared 2 by line"
 
 send_gdb "inf line ending-run.c:14\n"
 gdb_expect {
@@ -77,7 +77,7 @@ gdb_expect {
         set line_nine $expect_out(1,string)
         gdb_test "b ending-run.c:14" ".*Breakpoint 6.*ending-run.c, line 14.*"
         gdb_test "b *$line_nine" ".*Note.*also.*Breakpoint 7.*" "Breakpoint 7 at *ending-run.c:14"
-        gdb_test "cle" ".*Deleted breakpoints 6 7.*" "Clear 2 by default"
+        gdb_test "cle" ".*Deleted breakpoints 4 6 7.*" "Clear 2 by default"
     }
     -re ".*$gdb_prompt $" {
         fail "need to fix test for new compile outcome"
diff --git a/gdb/testsuite/gdb.mi/mi-break.exp b/gdb/testsuite/gdb.mi/mi-break.exp
index 6ea59fc..0f91af7 100644
--- a/gdb/testsuite/gdb.mi/mi-break.exp
+++ b/gdb/testsuite/gdb.mi/mi-break.exp
@@ -85,11 +85,11 @@ proc test_tbreak_creation_and_listing {} {
     mi_create_breakpoint "-t basics.c:callee2" 2 del callee2 ".*basics.c" $line_callee2_body $hex \
              "insert temp breakpoint at basics.c:callee2"
 
-    mi_create_breakpoint "-t basics.c:$line_callee3_head" 3 del callee3 ".*basics.c" $line_callee3_body $hex \
+    mi_create_breakpoint "-t basics.c:$line_callee3_head" 3 del callee3 ".*basics.c" $line_callee3_head $hex \
              "insert temp breakpoint at basics.c:\$line_callee3_head"
 
     # Getting the quoting right is tricky.  That is "\"<file>\":$line_callee4_head"
-    mi_create_breakpoint "-t \"\\\"${srcfile}\\\":$line_callee4_head\"" 4 del callee4 ".*basics.c" $line_callee4_body $hex \
+    mi_create_breakpoint "-t \"\\\"${srcfile}\\\":$line_callee4_head\"" 4 del callee4 ".*basics.c" $line_callee4_head $hex \
              "insert temp breakpoint at \"<fullfilename>\":\$line_callee4_head"
 
     mi_gdb_test "666-break-list" \
diff --git a/gdb/testsuite/gdb.mi/mi-simplerun.exp b/gdb/testsuite/gdb.mi/mi-simplerun.exp
index 654146a..14a1446 100644
--- a/gdb/testsuite/gdb.mi/mi-simplerun.exp
+++ b/gdb/testsuite/gdb.mi/mi-simplerun.exp
@@ -74,10 +74,10 @@ proc test_breakpoints_creation_and_listing {} {
     mi_create_breakpoint "basics.c:callee2" 2 keep callee2 ".*basics.c" $line_callee2_body $hex \
              "insert breakpoint at basics.c:callee2"
 
-    mi_create_breakpoint "basics.c:$line_callee3_head" 3 keep callee3 ".*basics.c" $line_callee3_body $hex \
+    mi_create_breakpoint "basics.c:$line_callee3_head" 3 keep callee3 ".*basics.c" $line_callee3_head $hex \
              "insert breakpoint at basics.c:\$line_callee3_head"
 
-    mi_create_breakpoint "\"\\\"${srcfile}\\\":$line_callee4_head\"" 4 keep callee4 ".*basics.c" $line_callee4_body $hex \
+    mi_create_breakpoint "\"\\\"${srcfile}\\\":$line_callee4_head\"" 4 keep callee4 ".*basics.c" $line_callee4_head $hex \
              "insert breakpoint at \"<fullfilename>\":\$line_callee4_head"
 
     mi_gdb_test "204-break-list" \
diff --git a/gdb/testsuite/gdb.mi/mi2-break.exp b/gdb/testsuite/gdb.mi/mi2-break.exp
index d08081a..7f43315 100644
--- a/gdb/testsuite/gdb.mi/mi2-break.exp
+++ b/gdb/testsuite/gdb.mi/mi2-break.exp
@@ -85,11 +85,11 @@ proc test_tbreak_creation_and_listing {} {
     mi_create_breakpoint "-t basics.c:callee2" 2 del callee2 ".*basics.c" $line_callee2_body $hex \
              "insert temp breakpoint at basics.c:callee2"
 
-    mi_create_breakpoint "-t basics.c:$line_callee3_head" 3 del callee3 ".*basics.c" $line_callee3_body $hex \
+    mi_create_breakpoint "-t basics.c:$line_callee3_head" 3 del callee3 ".*basics.c" $line_callee3_head $hex \
              "insert temp breakpoint at basics.c:\$line_callee3_head"
 
     # Getting the quoting right is tricky.  That is "\"<file>\":$line_callee4_head"
-    mi_create_breakpoint "-t \"\\\"${srcfile}\\\":$line_callee4_head\"" 4 del callee4 ".*basics.c" $line_callee4_body $hex \
+    mi_create_breakpoint "-t \"\\\"${srcfile}\\\":$line_callee4_head\"" 4 del callee4 ".*basics.c" $line_callee4_head $hex \
              "insert temp breakpoint at \"<fullfilename>\":\$line_callee4_head"
 
     mi_gdb_test "666-break-list" \
diff --git a/gdb/testsuite/gdb.mi/mi2-simplerun.exp b/gdb/testsuite/gdb.mi/mi2-simplerun.exp
index eddb2ed..13443ee 100644
--- a/gdb/testsuite/gdb.mi/mi2-simplerun.exp
+++ b/gdb/testsuite/gdb.mi/mi2-simplerun.exp
@@ -74,10 +74,10 @@ proc test_breakpoints_creation_and_listing {} {
     mi_create_breakpoint "basics.c:callee2" 2 keep callee2 ".*basics.c" $line_callee2_body $hex \
              "insert breakpoint at basics.c:callee2"
 
-    mi_create_breakpoint "basics.c:$line_callee3_head" 3 keep callee3 ".*basics.c" $line_callee3_body $hex \
+    mi_create_breakpoint "basics.c:$line_callee3_head" 3 keep callee3 ".*basics.c" $line_callee3_head $hex \
              "insert breakpoint at basics.c:\$line_callee3_head"
 
-    mi_create_breakpoint "\"\\\"${srcfile}\\\":$line_callee4_head\"" 4 keep callee4 ".*basics.c" $line_callee4_body $hex \
+    mi_create_breakpoint "\"\\\"${srcfile}\\\":$line_callee4_head\"" 4 keep callee4 ".*basics.c" $line_callee4_head $hex \
              "insert breakpoint at \"<fullfilename>\":\$line_callee4_head"
 
     mi_gdb_test "204-break-list" \