From: Jakub Jelinek <jakub@redhat.com>
Date: Sat, 25 Nov 2023 09:31:55 +0000 (+0100)
Subject: i386: Fix up *jcc_bt*_mask{,_1} [PR111408]
X-Git-Tag: releases/gcc-11.5.0~434
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1fdae54453d115d73d5a4bfa0257e88000ab18b8;p=thirdparty%2Fgcc.git

i386: Fix up *jcc_bt*_mask{,_1} [PR111408]

The following testcase is miscompiled in GCC 14 because the
*jcc_bt<mode>_mask and *jcc_bt<SWI48:mode>_mask_1 patterns have just
one argument in (match_operator 0 "bt_comparison_operator" [...])
but as bt_comparison_operator is eq,ne, we need two.
The md readers don't warn about it, after all, some checks can
be done in the predicate rather than specified explicitly, and the
behavior is that anything is accepted as the second argument.

I went through all other i386.md match_operator uses and all others
looked right (extract_operator using 3 operands, all others 2).

I think we'll want to fix this at different spots in older releases
because I think the bug was introduced already in 2008, though most
likely just latent.

2023-11-25  Jakub Jelinek  <jakub@redhat.com>

	PR target/111408
	* config/i386/i386.md (*jcc_bt<mode>_mask): Add (const_int 0) as
	expected second operand of bt_comparison_operator.

	* gcc.c-torture/execute/pr111408.c: New test.

(cherry picked from commit 9866c98e1015d98b8fc346d7cf73a0070cce5f69)
---

diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 1f0ae023f7e7..cd77c2a52a90 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -12734,7 +12734,8 @@
 			   (const_int 1)
 			   (and:SI
 			     (match_operand:SI 2 "register_operand")
-			     (match_operand 3 "const_int_operand")))])
+			     (match_operand 3 "const_int_operand")))
+			 (const_int 0)])
 		      (label_ref (match_operand 4))
 		      (pc)))
    (clobber (reg:CC FLAGS_REG))]
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr111408.c b/gcc/testsuite/gcc.c-torture/execute/pr111408.c
new file mode 100644
index 000000000000..6dfb0a384f10
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr111408.c
@@ -0,0 +1,26 @@
+/* PR target/111408 */
+
+int a, b, c, d;
+short e;
+
+int
+foo ()
+{
+  c = a % (sizeof (int) * 8);
+  if (b & 1 << c)
+    return -1;
+  return 0;
+}
+
+int
+main ()
+{
+  for (; e != 1; e++)
+    {
+      int g = foo ();
+      if (g + d - 9 + d)
+	continue;
+      for (;;)
+	__builtin_abort ();
+    }
+}