From bdc572f9a42b6a68dec1a5593d5311f45bd29cc9 Mon Sep 17 00:00:00 2001
From: Juergen Christ <jchrist@linux.ibm.com>
Date: Fri, 6 Dec 2024 18:52:36 +0100
Subject: s390: Fix UNSPEC_CC_TO_INT canonicalization

Canonicalization of comparisons for UNSPEC_CC_TO_INT missed one case
causing unnecessarily complex code.  This especially seems to hit the
Linux kernel.

gcc/ChangeLog:

	* config/s390/s390.cc (s390_canonicalize_comparison): Add
	missing UNSPEC_CC_TO_INT case.

gcc/testsuite/ChangeLog:

	* gcc.target/s390/ccusage.c: New test.

Signed-off-by: Juergen Christ <jchrist@linux.ibm.com>
---
 gcc/config/s390/s390.cc                 |  2 +-
 gcc/testsuite/gcc.target/s390/ccusage.c | 37 +++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/s390/ccusage.c

diff --git a/gcc/config/s390/s390.cc b/gcc/config/s390/s390.cc
index cec0548..573b229 100644
--- a/gcc/config/s390/s390.cc
+++ b/gcc/config/s390/s390.cc
@@ -1859,7 +1859,7 @@ s390_canonicalize_comparison (int *code, rtx *op0, rtx *op1,
       && CONST_INT_P (XEXP (*op0, 1))
       && CONST_INT_P (*op1)
       && INTVAL (XEXP (*op0, 1)) == -3
-      && *code == EQ)
+      && (*code == EQ || *code == NE))
     {
       if (INTVAL (*op1) == 0)
 	{
diff --git a/gcc/testsuite/gcc.target/s390/ccusage.c b/gcc/testsuite/gcc.target/s390/ccusage.c
new file mode 100644
index 0000000..e25f712
--- /dev/null
+++ b/gcc/testsuite/gcc.target/s390/ccusage.c
@@ -0,0 +1,37 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -march=zEC12 -mzarch" } */
+
+static __attribute__((always_inline)) inline
+int __atomic_dec_and_test(int *ptr)
+{
+        int cc;
+        asm volatile(
+                "       alsi    %[ptr],-1\n"
+                : "=@cc" (cc), [ptr] "+QS" (*ptr) : : "memory");
+        return (cc == 0) || (cc == 2);
+}
+ 
+int a;
+void dummy(void);
+long fu(void)
+{
+        if (__atomic_dec_and_test(&a))
+                return 5;
+        return 8;
+}
+ 
+void bar(void)
+{
+        if (__atomic_dec_and_test(&a))
+                dummy();
+}
+
+int foo(int x)
+{
+        int cc;
+        asm volatile ("ahi %[x],42\n"
+                        : [x] "+d" (x), "=@cc" (cc));
+        return !(cc == 0 || cc == 2) ? 42 : 13;
+}
+
+/* { dg-final { scan-assembler-not {ipm} } } */
-- 
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