[PATCH][gdb/exp] Fix exception when printing optimized out vla

[Tom de Vries <tdevries@suse.de>]

Hi,

when compiling vla-optimized-out.c with -O3 and a recent gcc, and trying to
print the vla a in f1, we run into this gdb exception:
...
Cannot find matching parameter at DW_TAG_call_site 0x4003be at main
...

This is a regression introduced by 42dc7699a2 "[gdb/exp] Fix printing of type
of optimized out vla".

This patch fixes the regression by wrapping the ctx.eval call in
dwarf2_locexpr_baton_eval in try/catch, similar to what is done in
dwarf2_evaluate_loc_desc_full.

Build and reg-tested on x86_64-linux.

OK for trunk?

Thanks,
- Tom

[gdb/exp] Fix exception when printing optimized out vla

2018-07-19  Tom de Vries  <tdevries@suse.de>

	* dwarf2loc.c (dwarf2_locexpr_baton_eval): Wrap ctx.eval call in
	try/catch.

	* gdb.base/vla-optimized-out.c: Make noclone attribute conditional on
	NOCLONE macro.
	* gdb.base/vla-optimized-out.exp: Use additional_flags -DNOCLONE.
	* gdb.base/vla-optimized-out-o3.exp: New file.  Reuse
	vla-optimized-out.c.

---
 gdb/dwarf2loc.c                                 | 21 ++++++++++++++-
 gdb/testsuite/gdb.base/vla-optimized-out-o3.exp | 36 +++++++++++++++++++++++++
 gdb/testsuite/gdb.base/vla-optimized-out.c      |  7 ++++-
 gdb/testsuite/gdb.base/vla-optimized-out.exp    |  2 +-
 4 files changed, 63 insertions(+), 3 deletions(-)

diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index 730934fe6e..a98b676b30 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -2573,7 +2573,26 @@ dwarf2_locexpr_baton_eval (const struct dwarf2_locexpr_baton *dlbaton,
   ctx.ref_addr_size = dwarf2_per_cu_ref_addr_size (dlbaton->per_cu);
   ctx.offset = dwarf2_per_cu_text_offset (dlbaton->per_cu);
 
-  ctx.eval (dlbaton->data, dlbaton->size);
+  TRY
+    {
+      ctx.eval (dlbaton->data, dlbaton->size);
+    }
+  CATCH (ex, RETURN_MASK_ERROR)
+    {
+      if (ex.error == NOT_AVAILABLE_ERROR)
+	{
+	  return 0;
+	}
+      else if (ex.error == NO_ENTRY_VALUE_ERROR)
+	{
+	  if (entry_values_debug)
+	    exception_print (gdb_stdout, ex);
+	  return 0;
+	}
+      else
+	throw_exception (ex);
+    }
+  END_CATCH
 
   switch (ctx.location)
     {
diff --git a/gdb/testsuite/gdb.base/vla-optimized-out-o3.exp b/gdb/testsuite/gdb.base/vla-optimized-out-o3.exp
new file mode 100644
index 0000000000..60707e7aff
--- /dev/null
+++ b/gdb/testsuite/gdb.base/vla-optimized-out-o3.exp
@@ -0,0 +1,36 @@
+# Copyright 2018 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Check whether we can print an optimized-out vla.
+
+standard_testfile
+
+if { [prepare_for_testing "failed to prepare" $testfile "vla-optimized-out.c" \
+	  {debug optimize=-O3}] } {
+    return -1
+}
+
+proc vla_optimized_out { } {
+    if ![runto f1] {
+	fail "can't run to f1"
+	return
+    }
+
+    gdb_test "p a" \
+	{ = <optimized out>} \
+	"printed optimized out vla"
+}
+
+vla_optimized_out
diff --git a/gdb/testsuite/gdb.base/vla-optimized-out.c b/gdb/testsuite/gdb.base/vla-optimized-out.c
index 913e8ea867..ec0a6fdd80 100644
--- a/gdb/testsuite/gdb.base/vla-optimized-out.c
+++ b/gdb/testsuite/gdb.base/vla-optimized-out.c
@@ -15,7 +15,12 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-int __attribute__((noinline, noclone))
+int
+#ifdef NOCLONE
+__attribute__((noinline, noclone))
+#else
+__attribute__((noinline))
+#endif
 f1 (int i)
 {
   char a[i + 1];
diff --git a/gdb/testsuite/gdb.base/vla-optimized-out.exp b/gdb/testsuite/gdb.base/vla-optimized-out.exp
index 39abb795c8..b27569ed1e 100644
--- a/gdb/testsuite/gdb.base/vla-optimized-out.exp
+++ b/gdb/testsuite/gdb.base/vla-optimized-out.exp
@@ -18,7 +18,7 @@
 standard_testfile
 
 if { [prepare_for_testing "failed to prepare" $testfile $srcfile \
-	  {debug optimize=-O1}] } {
+	  {debug optimize=-O1 additional_flags=-DNOCLONE}] } {
     return -1
 }