The -Walloca pass can receive a malformed alloca, courtesy of someone
providing a faulty prototype. This was causing an ICE because we
assumed alloca calls had at least one argument, which the testcase does not:
+void *alloca ();
+__typeof__(alloca ()) a () { return alloca (); }
I don't believe it should be the responsibility of the
-Walloca-larger-than=* pass to warn against such things, so I propose we
just ignore this.
I also think we should handle this testcase, regardless of the target
having an alloca builtin, since the testcase includes its own
prototype. Thus, the missing "{dg-require-effect-target alloca}".
OK?
gcc/
PR tree-optimization/84224
* gimple-ssa-warn-alloca.c (execute): Do not ICE on malformed
allocas.
diff --git a/gcc/gimple-ssa-warn-alloca.c b/gcc/gimple-ssa-warn-alloca.c
index 941810a997e..7457a16d21f 100644
--- a/gcc/gimple-ssa-warn-alloca.c
+++ b/gcc/gimple-ssa-warn-alloca.c
@@ -443,9 +443,10 @@ pass_walloca::execute (function *fun)
gimple *stmt = gsi_stmt (si);
location_t loc = gimple_location (stmt);
- if (!gimple_alloca_call_p (stmt))
+ if (!gimple_alloca_call_p (stmt)
+ /* A faulty prototype can yield a malformed alloca() call. */
+ || gimple_call_num_args (stmt) < 1)
continue;
- gcc_assert (gimple_call_num_args (stmt) >= 1);
const bool is_vla
= gimple_call_alloca_for_var_p (as_a <gcall *> (stmt));
diff --git a/gcc/testsuite/gcc.dg/Walloca-16.c b/gcc/testsuite/gcc.dg/Walloca-16.c
new file mode 100644
index 00000000000..3ee96a9570a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Walloca-16.c
@@ -0,0 +1,6 @@
+/* PR tree-optimization/84224 */
+/* { dg-do compile } */
+/* { dg-options "-O0 -Walloca" } */
+
+void *alloca ();
+__typeof__(alloca ()) a () { return alloca (); }
