From 81c29232b6f36235693ec12b319f5786ba83de03 Mon Sep 17 00:00:00 2001
From: Lewis Hyatt <lhyatt@gmail.com>
Date: Fri, 25 Oct 2024 14:55:09 -0400
Subject: [PATCH] tree-cfg: Fix call to next_discriminator_for_locus()
While testing future 64-bit location_t support, I ran into an
-fcompare-debug issue that was traced back here. Despite the name,
next_discriminator_for_locus() is meant to take an integer line number
argument, not a location_t. There is one call site which has been passing a
location_t instead. For the most part that is harmless, although in case
there are two CALL stmts on the same line with different location_t, it may
fail to generate a unique discriminator where it should. If/when location_t
changes to be 64-bit, however, it will produce an -fcompare-debug
failure. Fix it by passing the line number rather than the location_t.
I am not aware of a testcase that demonstrates any observable wrong
behavior, but the file debug/pr53466.C is an example where the discriminator
assignment is indeed different before and after this change.
gcc/ChangeLog:
* tree-cfg.cc (assign_discriminators): Fix incorrect value passed to
next_discriminator_for_locus().
---
gcc/tree-cfg.cc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index 3eede0d61cdc..c2100a51a7a5 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -1251,7 +1251,7 @@ assign_discriminators (void)
}
/* Allocate a new discriminator for CALL stmt. */
if (gimple_code (stmt) == GIMPLE_CALL)
- curr_discr = next_discriminator_for_locus (curr_locus);
+ curr_discr = next_discriminator_for_locus (curr_locus_e.line);
}
gimple *last = last_nondebug_stmt (bb);
--
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