From b1d15146b636120f49fbecdb65302ac8d3b48e8b Mon Sep 17 00:00:00 2001
From: Richard Sandiford <richard.sandiford@arm.com>
Date: Tue, 30 Nov 2021 09:52:27 +0000
Subject: [PATCH] Mark IFN_ADD/MUL_OVERFLOW as commutative

gcc/
	* internal-fn.c (commutative_binary_fn_p): Handle IFN_ADD_OVERFLOW
	and IFN_MUL_OVERFLOW.

gcc/testsuite/
	* gcc.dg/add-mul-overflow-1.c: New test.
---
 gcc/internal-fn.c                         |  2 ++
 gcc/testsuite/gcc.dg/add-mul-overflow-1.c | 28 +++++++++++++++++++++++
 2 files changed, 30 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/add-mul-overflow-1.c

diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index 0e377b1b1f8f..6ac3460d538b 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -3834,6 +3834,8 @@ commutative_binary_fn_p (internal_fn fn)
     case IFN_COMPLEX_MUL:
     case IFN_UBSAN_CHECK_ADD:
     case IFN_UBSAN_CHECK_MUL:
+    case IFN_ADD_OVERFLOW:
+    case IFN_MUL_OVERFLOW:
       return true;
 
     default:
diff --git a/gcc/testsuite/gcc.dg/add-mul-overflow-1.c b/gcc/testsuite/gcc.dg/add-mul-overflow-1.c
new file mode 100644
index 000000000000..b23cdddbb631
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/add-mul-overflow-1.c
@@ -0,0 +1,28 @@
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+int res[4];
+
+void
+f1 (int x, int y)
+{
+  res[2] = __builtin_add_overflow (x, y, res + 0);
+  res[3] = __builtin_add_overflow (y, x, res + 1);
+}
+
+void
+f2 (int x, int y)
+{
+  res[2] = __builtin_sub_overflow (x, y, res + 0);
+  res[3] = __builtin_sub_overflow (y, x, res + 1);
+}
+
+void
+f3 (int x, int y)
+{
+  res[2] = __builtin_mul_overflow (x, y, res + 0);
+  res[3] = __builtin_mul_overflow (y, x, res + 1);
+}
+
+/* { dg-final { scan-tree-dump-times {\.ADD_OVERFLOW} 1 "optimized" } } */
+/* { dg-final { scan-tree-dump-times {\.SUB_OVERFLOW} 2 "optimized" } } */
+/* { dg-final { scan-tree-dump-times {\.MUL_OVERFLOW} 1 "optimized" } } */