[gcc r12-8253] gimple-fold: fix further missing stmt locations [PR104308]

[gcc r12-8253] gimple-fold: fix further missing stmt locations [PR104308]

[David Malcolm]

https://gcc.gnu.org/g:a5dc2641add6b4f54086d40ae706fda3cdaac7f5

commit r12-8253-ga5dc2641add6b4f54086d40ae706fda3cdaac7f5
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Mon Apr 25 19:34:33 2022 -0400

    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:
---
 gcc/gimple-fold.cc                       |  3 +++
 gcc/testsuite/gcc.dg/analyzer/pr104308.c | 13 ++++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index ac22adfd9b1..863ee3d3912 100644
--- 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 9cd5ee6feee..a3a0cbb7317 100644
--- 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" } */
+}