On 12/6/24 19:00, Juergen Christ wrote:
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.
Ok. Thanks!
Andreas
Signed-off-by: Juergen Christ <jchr...@linux.ibm.com>
Bootstrapped and regression tested on s390. Okay for trunk?
Okay to backport to GCC 14?
---
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 25d43ae3e138..c36c33ff8280 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 000000000000..e25f712e25ca
--- /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} } } */
