Bug 29920 - [gdb/testsuite] FAIL: gdb.cp/step-and-next-inline.exp: no_header: next step 1
Summary: [gdb/testsuite] FAIL: gdb.cp/step-and-next-inline.exp: no_header: next step 1
Status: RESOLVED FIXED
Alias: None
Product: gdb
Classification: Unclassified
Component: testsuite (show other bugs)
Version: HEAD
: P2 normal
Target Milestone: 14.1
Assignee: Not yet assigned to anyone
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2022-12-20 08:58 UTC by Tom de Vries
Modified: 2022-12-30 13:02 UTC (History)
0 users

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Description Tom de Vries 2022-12-20 08:58:26 UTC
On ubuntu 22.04.1 x86_64 with gcc 11.3.0, I run into:
...
(gdb) PASS: gdb.cp/step-and-next-inline.exp: no_header: step into get_alias_set
bt^M
#0  get_alias_set (t=t@entry=0x555555558018 <xx>) at /home/vries/gdb/src/gdb/testsuite/gdb.cp/step-and-next-inline.cc:50^M
#1  0x0000555555555084 in main () at /home/vries/gdb/src/gdb/testsuite/gdb.cp/step-and-next-inline.cc:64^M
((gdb) PASS: gdb.cp/step-and-next-inline.exp: no_header: not in inline 1
next^M
51        if (t != NULL^M
(gdb) FAIL: gdb.cp/step-and-next-inline.exp: no_header: next step 1
...
Comment 1 Tom de Vries 2022-12-20 09:14:16 UTC
Likewise with gcc 12.1.0, 10.4.0, 9.5.0, 8.4.0,
Comment 2 Tom de Vries 2022-12-20 09:48:18 UTC
Fix:
...
diff --git a/gdb/testsuite/gdb.cp/step-and-next-inline.exp b/gdb/testsuite/gdb.cp/step-and-next-inline.exp
index 8b2ad2766bc..36fac239e2f 100644
--- a/gdb/testsuite/gdb.cp/step-and-next-inline.exp
+++ b/gdb/testsuite/gdb.cp/step-and-next-inline.exp
@@ -60,7 +60,16 @@ proc do_test { use_header } {
     }
 
     gdb_test "bt" "\\s*\\#0\\s+main.*" "in main"
-    gdb_test "step" ".*" "step into get_alias_set"
+    set line1 {\t\{}
+    set line2 {\t  if \(t != NULL}
+    gdb_test_multiple "step" "step into get_alias_set" {
+       -re -wrap $line1 {
+           gdb_test "next" $line2 $gdb_test_name
+       }
+       -re -wrap $line2 {
+           pass $gdb_test_name
+       }
+    }
     gdb_test "bt" "\\s*\\#0\\s+get_alias_set\[^\r\]*${srcfile}:.*" \
        "not in inline 1"
 
...
Comment 3 Tom de Vries 2022-12-21 08:07:14 UTC
Root cause: compilation defaults to -fcf-protection, which adds the endbr64:
...
0000000000001180 <_Z13get_alias_setP4tree>:
    1180:       f3 0f 1e fa             endbr64
    1184:       48 85 ff                test   %rdi,%rdi
...
which is the insn with line number 50 that we stop at:
...
11     50     0x0000000000001180 Y                    
12     50     0x0000000000001180                      
13     51     0x0000000000001184 Y                    
...
Comment 5 Sourceware Commits 2022-12-30 13:00:45 UTC
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b1b0f69cb4a2ccd421419f9703edfcc5c3032dc0

commit b1b0f69cb4a2ccd421419f9703edfcc5c3032dc0
Author: Tom de Vries <tdevries@suse.de>
Date:   Fri Dec 30 14:00:39 2022 +0100

    [gdb/testsuite] Fix gdb.cp/step-and-next-inline.exp with -fcf-protection
    
    On Ubuntu 22.04.1 x86_64, I run into:
    ...
    (gdb) PASS: gdb.cp/step-and-next-inline.exp: no_header: not in inline 1
    next^M
    51        if (t != NULL^M
    (gdb) FAIL: gdb.cp/step-and-next-inline.exp: no_header: next step 1
    ...
    
    This is due to -fcf-protection, which adds the endbr64 at the start of get_alias_set:
    ...
    0000000000001180 <_Z13get_alias_setP4tree>:
        1180:       f3 0f 1e fa             endbr64
        1184:       48 85 ff                test   %rdi,%rdi
    ...
    so the extra insn gets an is-stmt line number entry:
    ...
    INDEX  LINE   ADDRESS            IS-STMT PROLOGUE-END
      ...
    11     50     0x0000000000001180 Y
    12     50     0x0000000000001180
    13     51     0x0000000000001184 Y
    14     54     0x0000000000001184
    ...
    and when stepping into get_alias_set we step to line 50:
    ...
    (gdb) PASS: gdb.cp/step-and-next-inline.exp: no_header: in main
    step^M
    get_alias_set (t=t@entry=0x555555558018 <xx>) at step-and-next-inline.cc:50^M
    50      {^M
    ...
    
    In contrast, with -fcf-protection=none, we get:
    ...
    0000000000001170 <_Z13get_alias_setP4tree>:
        1170:       48 85 ff                test   %rdi,%rdi
    ...
    and:
    ...
    INDEX  LINE   ADDRESS            IS-STMT PROLOGUE-END
      ...
    11     50     0x0000000000001170 Y
    12     51     0x0000000000001170 Y
    13     54     0x0000000000001170
    ...
    so when stepping into get_alias_set we step to line 51:
    ...
    (gdb) PASS: gdb.cp/step-and-next-inline.exp: no_header: in main
    step^M
    get_alias_set (t=t@entry=0x555555558018 <xx>) at step-and-next-inline.cc:51^M
    51        if (t != NULL^M
    ...
    
    Fix this by rewriting the gdb_test issuing the step command to check which
    line the step lands on, and issuing an extra next if needed.
    
    Tested on x86_64-linux, both with and without -fcf-protection=none.
    
    PR testsuite/29920
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29920
Comment 6 Tom de Vries 2022-12-30 13:02:14 UTC
Fixed by commit above.