[patch] PR debug/58123: Set correct location for TRY blocks

[Aldy Hernandez]

[Ughh...I'm apparently incapable of CCing gcc-patches on the first try. 
 My apologies again.]

Please see the long explanation in the PR:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58123

But the short explanation for this patch is that, at the very least, we
should fix the location of the GIMPLE_TRY_FINALLY.  Currently  we're
preferring the input_location, instead of the location of the
TRY_FINALLY_EXPR.

An incorrect GIMPLE_TRY_FINALLY location causes the location of
location-less FINALLY statements to also have an incorrect location,
causing an inconsistent debugging experience.

As explained in the PR, I would ideally like to get rid of the kludge
where we set the location of location-less FINALLY statements to be that
of the TRY statement, but that may be by design, and/or beyond the scope
of this fix.

Tested on x86-64 Linux.

OK for mainline?



commit 119b6f5c628831706ac8fa26a906d80cf996bbe3
Author: Aldy Hernandez <al...@redhat.com>
Date:   Wed Feb 18 13:31:41 2015 -0800

        PR debug/58123
        * gimplify.c (gimplify_expr): Prefer location of TRY_FINALLY_EXPR
        over input_location.
testsuite/
        * g++.dg/debug/dwarf2/deallocator.C: Adjust for correct try
        location.
        * g++.dg/gcov/gcov-2.C: Likewise.

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 1353ada..d822913 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -8244,10 +8244,10 @@ gimplify_expr (tree *expr_p, gimple_seq *pre_p, 
gimple_seq *post_p,
                                     TREE_CODE (*expr_p) == TRY_FINALLY_EXPR
                                     ? GIMPLE_TRY_FINALLY
                                     : GIMPLE_TRY_CATCH);
-           if (LOCATION_LOCUS (saved_location) != UNKNOWN_LOCATION)
-             gimple_set_location (try_, saved_location);
-           else
+           if (EXPR_HAS_LOCATION (save_expr))
              gimple_set_location (try_, EXPR_LOCATION (save_expr));
+           else if (LOCATION_LOCUS (saved_location) != UNKNOWN_LOCATION)
+             gimple_set_location (try_, saved_location);
            if (TREE_CODE (*expr_p) == TRY_CATCH_EXPR)
              gimple_try_set_catch_is_cleanup (try_,
                                               TRY_CATCH_IS_CLEANUP (*expr_p));
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/deallocator.C 
b/gcc/testsuite/g++.dg/debug/dwarf2/deallocator.C
index 4057393..0fcd08e 100644
--- a/gcc/testsuite/g++.dg/debug/dwarf2/deallocator.C
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/deallocator.C
@@ -41,6 +41,6 @@ void foo(int i)
   return;
 }
 // { dg-final { scan-assembler "deallocator.C:29" } }
-// { dg-final { scan-assembler "deallocator.C:31" } }
-// { dg-final { scan-assembler "deallocator.C:38" } }
-// { dg-final { scan-assembler "deallocator.C:41" } }
+// { dg-final { scan-assembler "deallocator.C:24" } }
+// { dg-final { scan-assembler "deallocator.C:34" } }
+// { dg-final { scan-assembler "deallocator.C:21" } }
diff --git a/gcc/testsuite/g++.dg/gcov/gcov-2.C 
b/gcc/testsuite/g++.dg/gcov/gcov-2.C
index 66d8af3..6d002f5 100644
--- a/gcc/testsuite/g++.dg/gcov/gcov-2.C
+++ b/gcc/testsuite/g++.dg/gcov/gcov-2.C
@@ -20,7 +20,7 @@ private:
 
 void foo()
 {
-  C c;                                 /* count(1) */
+  C c;                                 /* count(2) */
   c.seti (1);                          /* count(1) */
 }
 
diff --git a/gcc/testsuite/g++.dg/pr58123.C b/gcc/testsuite/g++.dg/pr58123.C
new file mode 100644
index 0000000..7fe1a27
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr58123.C
@@ -0,0 +1,18 @@
+// { dg-do compile }
+// { dg-options "-fdump-tree-gimple-lineno" }
+
+// Test that the TRY block's location is the definition of "C a".
+
+class C {
+public:
+  C() {}
+  ~C() {}
+  int m() { return 0; }
+};
+int main() {
+   C a;
+   return a.m();
+}
+
+// { dg-final { scan-tree-dump-times "pr58123.C:13\.6\] try" 1 "gimple" } }
+// { dg-final { cleanup-tree-dump "gimple" } }