[gdb/testsuite] Fix gdb.base/shlib-call.exp with gcc-8

When running test-case gdb.base/shlib-call.exp with gcc-8 instead of gcc-7, we
have:
...
 (gdb) step^M
-main () at /data/gdb_versions/devel/src/gdb/testsuite/gdb.base/shmain.c:42^M
-42        g = mainshr1(g);^M
-(gdb) PASS: gdb.base/shlib-call.exp: step out of shr2 epilogue to main
+main () at /data/gdb_versions/devel/src/gdb/testsuite/gdb.base/shmain.c:41^M
+41        g = shr2(g);^M
+(gdb) FAIL: gdb.base/shlib-call.exp: step out of shr2 epilogue to main
...

This is due to the fact that gcc-8 generates more precise line info, making
the instruction after the call to shr2 at 0x4008f1:
...
  4008e4:  8b 05 aa 07 20 00  mov    0x2007aa(%rip),%eax  # 601094 <g>
  4008ea:  89 c7              mov    %eax,%edi
  4008ec:  e8 1f fe ff ff     callq  400710 <shr2@plt>
  4008f1:  89 05 9d 07 20 00  mov    %eax,0x20079d(%rip)  # 601094 <g>
...
a "recommended breakpoint location":
...
  [0x00000287]  Special opcode 187: advance Address by 13 to 0x4008f1 and \
    Line by 0 to 41
...
so when stepping out of shr2, gdb steps back onto line 41, the line containing
the call to shr2.

Fix this by detecting this situation and adding an extra step to reach
line 42.

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2020-05-06  Tom de Vries  <tdevries@suse.de>

	* gdb.base/shlib-call.exp: Add extra step to reach shmain.c:42, if
	necessary.

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index d04ce49ade9329828aae1eaf5a779a70a0ebe8c6..b2f90912502fce913c8e89400f1907d7dac77a27 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-05-06  Tom de Vries  <tdevries@suse.de>
+
+       * gdb.base/shlib-call.exp: Add extra step to reach shmain.c:42, if
+       necessary.
+
 2020-05-06  Tom de Vries  <tdevries@suse.de>
 
        * lib/unbuffer_output.c (gdb_unbuffer_output): Change return type to

diff --git a/gdb/testsuite/gdb.base/shlib-call.exp b/gdb/testsuite/gdb.base/shlib-call.exp
index 806fc15157aaaeece3f495291b9995bf27ebe877..97e04cdbb5e09838d6b12ae38f9a303bd49d1ef1 100644 (file)
--- a/gdb/testsuite/gdb.base/shlib-call.exp
+++ b/gdb/testsuite/gdb.base/shlib-call.exp
@@ -142,9 +142,14 @@ gdb_test_multiple "step" "step out of shr2 to main" {
     }
     -re ".*\\\}.*$gdb_prompt $" {
        pass "step out of shr2 to main (stopped in shr2 epilogue)"
-       gdb_test "step" \
-           "main \\(\\) at.*g = mainshr1\\(g\\);" \
-           "step out of shr2 epilogue to main"
+       gdb_test_multiple "step" "step out of shr2 epilogue to main" {
+           -re -wrap "main \\(\\) at.*g = mainshr1\\(g\\);" {
+               pass $gdb_test_name
+           }
+           -re -wrap "main \\(\\) at.*g = shr2\\(g\\);" {
+               gdb_test "step" "g = mainshr1\\(g\\);" $gdb_test_name
+           }
+       }
     }
 }