From: Jakub Jelinek <jakub@redhat.com>
Date: Fri, 12 Jan 2024 10:19:08 +0000 (+0100)
Subject: lower-bitint: Fix up handling of uninitialized large/huge _BitInt call arguments... 
X-Git-Tag: basepoints/gcc-15~2960
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c1680bd2df187e06089b06ffe211c4abe4c440b0;p=thirdparty%2Fgcc.git

lower-bitint: Fix up handling of uninitialized large/huge _BitInt call arguments [PR113316]

The code to assign large/huge _BitInt SSA_NAMEs to partitions intentionally
ignores uninitialized SSA_NAMEs:
          /* Also ignore uninitialized uses.  */
          if (SSA_NAME_IS_DEFAULT_DEF (s)
              && (!SSA_NAME_VAR (s) || VAR_P (SSA_NAME_VAR (s))))
            continue;
because there is no need to store them into memory, all we need is when
trying to extract some limb from them use uninitialized SSA_NAME for the
limb.

The following testcase shows this is a problem for call arguments though,
for those we need to create replacement SSA_NAMEs which are loaded from
the underlying variable.  For uninitialized SSA_NAMEs because we didn't
create underlying variable for them var_to_partition doesn't work, the
following patch handles it by just creating an uninitialized replacement
SSA_NAME.

2024-01-12  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/113316
	* gimple-lower-bitint.cc (bitint_large_huge::lower_call): Handle
	uninitialized large/huge _BitInt arguments to calls.

	* gcc.dg/bitint-67.c: New test.
---

diff --git a/gcc/gimple-lower-bitint.cc b/gcc/gimple-lower-bitint.cc
index 68e01897ba4e..ea616ea41534 100644
--- a/gcc/gimple-lower-bitint.cc
+++ b/gcc/gimple-lower-bitint.cc
@@ -5118,14 +5118,23 @@ bitint_large_huge::lower_call (tree obj, gimple *stmt)
 	  || TREE_CODE (TREE_TYPE (arg)) != BITINT_TYPE
 	  || bitint_precision_kind (TREE_TYPE (arg)) <= bitint_prec_middle)
 	continue;
-      int p = var_to_partition (m_map, arg);
-      tree v = m_vars[p];
-      gcc_assert (v != NULL_TREE);
-      if (!types_compatible_p (TREE_TYPE (arg), TREE_TYPE (v)))
-	v = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (arg), v);
-      arg = make_ssa_name (TREE_TYPE (arg));
-      gimple *g = gimple_build_assign (arg, v);
-      gsi_insert_before (&gsi, g, GSI_SAME_STMT);
+      if (SSA_NAME_IS_DEFAULT_DEF (arg)
+	  && (!SSA_NAME_VAR (arg) || VAR_P (SSA_NAME_VAR (arg))))
+	{
+	  tree var = create_tmp_reg (TREE_TYPE (arg));
+	  arg = get_or_create_ssa_default_def (cfun, var);
+	}
+      else
+	{
+	  int p = var_to_partition (m_map, arg);
+	  tree v = m_vars[p];
+	  gcc_assert (v != NULL_TREE);
+	  if (!types_compatible_p (TREE_TYPE (arg), TREE_TYPE (v)))
+	    v = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (arg), v);
+	  arg = make_ssa_name (TREE_TYPE (arg));
+	  gimple *g = gimple_build_assign (arg, v);
+	  gsi_insert_before (&gsi, g, GSI_SAME_STMT);
+	}
       gimple_call_set_arg (stmt, i, arg);
       if (m_preserved == NULL)
 	m_preserved = BITMAP_ALLOC (NULL);
diff --git a/gcc/testsuite/gcc.dg/bitint-67.c b/gcc/testsuite/gcc.dg/bitint-67.c
new file mode 100644
index 000000000000..fefa33ab9f7d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-67.c
@@ -0,0 +1,12 @@
+/* PR tree-optimization/113316 */
+/* { dg-do compile { target bitint575 } } */
+/* { dg-options "-std=c23 -O2 -w" } */
+
+void bar (_BitInt(535) y);
+
+void
+foo (void)
+{
+  _BitInt(535) y;
+  bar (y);
+}