[gcc r13-6907] haifa-sched: fix autopref_rank_for_schedule comparator [PR109187]

[gcc r13-6907] haifa-sched: fix autopref_rank_for_schedule comparator [PR109187]

[Alexander Monakov]

https://gcc.gnu.org/g:fb046e69f0ed2d637ea715ae71ad50131f30cb2d

commit r13-6907-gfb046e69f0ed2d637ea715ae71ad50131f30cb2d
Author: Alexander Monakov <amonakov@ispras.ru>
Date:   Tue Mar 28 16:00:37 2023 +0300

    haifa-sched: fix autopref_rank_for_schedule comparator [PR109187]
    
    Do not attempt to use a plain subtraction for generating a three-way
    comparison result in autopref_rank_for_schedule qsort comparator, as
    offsets are not restricted and subtraction may overflow.  Open-code
    a safe three-way comparison instead.
    
    gcc/ChangeLog:
    
            PR rtl-optimization/109187
            * haifa-sched.cc (autopref_rank_for_schedule): Avoid use of overflowing
            subtraction in three-way comparison.
    
    gcc/testsuite/ChangeLog:
    
            PR rtl-optimization/109187
            * gcc.dg/pr109187.c: New test.

Diff:
---
 gcc/haifa-sched.cc              | 2 +-
 gcc/testsuite/gcc.dg/pr109187.c | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/gcc/haifa-sched.cc b/gcc/haifa-sched.cc
index 48b53776fa9..2c881ede0ec 100644
--- a/gcc/haifa-sched.cc
+++ b/gcc/haifa-sched.cc
@@ -5686,7 +5686,7 @@ autopref_rank_for_schedule (const rtx_insn *insn1, const rtx_insn *insn2)
 
       if (!irrel1 && !irrel2)
 	/* Sort memory references from lowest offset to the largest.  */
-	r = data1->offset - data2->offset;
+	r = (data1->offset > data2->offset) - (data1->offset < data2->offset);
       else if (write)
 	/* Schedule "irrelevant" insns before memory stores to resolve
 	   as many producer dependencies of stores as possible.  */
diff --git a/gcc/testsuite/gcc.dg/pr109187.c b/gcc/testsuite/gcc.dg/pr109187.c
new file mode 100644
index 00000000000..1ef14a73d2b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr109187.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 --param sched-autopref-queue-depth=1" } */
+
+void f(int *a)
+{
+  for (;;)
+    asm("" :: "r"(a[-0x10000000]), "r"(a[0x10000000]), "r"(a[0]) : "memory");
+}