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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>
This commit is contained in:
David Malcolm 2022-04-25 19:34:33 -04:00
parent b220243191
commit a5dc2641ad
2 changed files with 15 additions and 1 deletions
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3
gcc/gimple-fold.cc
View File

@ -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);
}

13
gcc/testsuite/gcc.dg/analyzer/pr104308.c
View File

@ -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" } */
}