[binutils-gdb] [gdb/testsuite] Avoid using .eh_frame in gdb.base/unwind-on-each-insn.exp

[Tom de Vries <vries@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=eb015bf86b6c6764f8acfea01a25a63e9b492dc5

commit eb015bf86b6c6764f8acfea01a25a63e9b492dc5
Author: Tom de Vries <tdevries@suse.de>
Date:   Mon Jan 23 11:54:43 2023 +0100

    [gdb/testsuite] Avoid using .eh_frame in gdb.base/unwind-on-each-insn.exp
    
    One purpose of the gdb.base/unwind-on-each-insn.exp test-case is to test the
    architecture-specific unwinders on foo, so unwind-on-each-insn-foo.c is
    compiled with nodebug, to prevent the dwarf unwinders from taking effect.
    
    For for instance gcc x86_64 though, -fasynchronous-unwind-tables is enabled by
    default, generating an .eh_frame section contribution which might enable the
    dwarf unwinders and bypass the architecture-specific unwinders.
    
    Currently, that happens to be not the case due to the current implementation
    of epilogue_unwind_valid, which assumes that in absence of debug info proving
    that the compiler is gcc >= 4.5.0, the .eh_frame contribution is invalid.
    
    That may change though, see PR30028, in which case
    gdb.base/unwind-on-each-insn.exp stops being a regression test for commit
    49d7cd733a7 ("Change calculation of frame_id by amd64 epilogue unwinder").
    
    Fix this by making sure that we don't use .eh_frame info regardless of
    epilogue_unwind_valid, simply by not generating it using
    -fno-asynchronous-unwind-tables.
    
    Tested on x86_64-linux, target boards unix/{-m64,-m32}, using compilers
    gcc 7.5.0 and clang 13.0.1.

Diff:
---
 gdb/testsuite/gdb.base/unwind-on-each-insn.exp | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/gdb.base/unwind-on-each-insn.exp b/gdb/testsuite/gdb.base/unwind-on-each-insn.exp
index 5e822effaf1..fc48bf5c061 100644
--- a/gdb/testsuite/gdb.base/unwind-on-each-insn.exp
+++ b/gdb/testsuite/gdb.base/unwind-on-each-insn.exp
@@ -25,9 +25,19 @@
 
 standard_testfile .c -foo.c
 
+set debug_flags {debug}
+set nodebug_flags {nodebug}
+
+# Make sure that we don't use .eh_frame info, by not generating it,
+# using -fno-asynchronous-unwind-tables, if supported.
+if { [gdb_can_simple_compile fno-asynchronous-unwind-tables \
+	  { void foo () { } } object -fno-asynchronous-unwind-tables] } {
+    lappend nodebug_flags additional_flags=-fno-asynchronous-unwind-tables
+}
+
 if {[prepare_for_testing_full "failed to prepare" \
-	 [list ${testfile} debug \
-	      $srcfile {debug} $srcfile2 {nodebug}]]} {
+	 [list ${testfile} $debug_flags \
+	      $srcfile $debug_flags $srcfile2 $nodebug_flags]]} {
     return -1
 }