gimple-fold: fix further missing stmt locations [PR104308]

PR analyzer/104308 initially reported about a
-Wanalyzer-use-of-uninitialized-value diagnostic using UNKNOWN_LOCATION
when complaining about certain memmove operations where the source
is uninitialized.

In r12-7856-g875342766d4298 I fixed the missing location for
a stmt generated by gimple_fold_builtin_memory_op, but the reporter
then found another way to generate such a stmt with UNKNOWN_LOCATION.

I've now gone through gimple_fold_builtin_memory_op looking at all
statement creation, and found three places in which a new statement
doesn't have a location set on it (either directly via
gimple_set_location, or indirectly via gsi_replace), one of which is
the new reproducer.

This patch adds a gimple_set_location to these three cases, and adds
test coverage for one of them (the third hunk within the patch), fixing
the new reproducer for PR analyzer/104308.

gcc/ChangeLog:
	PR analyzer/104308
	* gimple-fold.cc (gimple_fold_builtin_memory_op): Explicitly set
	the location of new_stmt in all places that don't already set it,
	whether explicitly, or via a call to gsi_replace.

gcc/testsuite/ChangeLog:
	PR analyzer/104308
	* gcc.dg/analyzer/pr104308.c: Add test coverage.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index ac22adfd9b19ca8096b1b4c67ffdb806f20e3bde..863ee3d391222a73e4d655ea89be89990b3a26db 100644 (file)
--- a/gcc/gimple-fold.cc
+++ b/gcc/gimple-fold.cc
@@ -1048,6 +1048,7 @@ gimple_fold_builtin_memory_op (gimple_stmt_iterator *gsi,
                          gsi_replace (gsi, new_stmt, false);
                          return true;
                        }
+                     gimple_set_location (new_stmt, loc);
                      gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
                      goto done;
                    }
@@ -1302,6 +1303,7 @@ gimple_fold_builtin_memory_op (gimple_stmt_iterator *gsi,
                                                   new_stmt);
              gimple_assign_set_lhs (new_stmt, srcvar);
              gimple_set_vuse (new_stmt, gimple_vuse (stmt));
+             gimple_set_location (new_stmt, loc);
              gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
            }
          new_stmt = gimple_build_assign (destvar, srcvar);
@@ -1338,6 +1340,7 @@ set_vop_and_replace:
          gsi_replace (gsi, new_stmt, false);
          return true;
        }
+      gimple_set_location (new_stmt, loc);
       gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
     }
 

diff --git a/gcc/testsuite/gcc.dg/analyzer/pr104308.c b/gcc/testsuite/gcc.dg/analyzer/pr104308.c
index 9cd5ee6feeeabdfb839720e868ebfb7e95cbc182..a3a0cbb731776b26e2ba9447baa7c39f80821a57 100644 (file)
--- a/gcc/testsuite/gcc.dg/analyzer/pr104308.c
+++ b/gcc/testsuite/gcc.dg/analyzer/pr104308.c
@@ -1,8 +1,19 @@
+/* Verify that we have source locations for
+   -Wanalyzer-use-of-uninitialized-value warnings involving folded
+   memory ops.  */
+
 #include <string.h>
 
-int main()
+int test_memmove_within_uninit (void)
 {
   char s[5]; /* { dg-message "region created on stack here" } */
   memmove(s, s + 1, 2); /* { dg-warning "use of uninitialized value" } */
   return 0;
 }
+
+int test_memcpy_from_uninit (void)
+{
+  char a1[5];
+  char a2[5]; /* { dg-message "region created on stack here" } */
+  return (memcpy(a1, a2, 5) == a1); /* { dg-warning "use of uninitialized value" } */
+}