From 19199a6f2b0f4ce4b100856c78706d56a16b1956 Mon Sep 17 00:00:00 2001
From: Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Date: Tue, 30 Mar 2021 15:43:36 +0100
Subject: [PATCH] aarch64: PR target/99822 Don't allow zero register in first
 operand of SUBS/ADDS-immediate

In this PR we end up generating an invalid instruction:
adds x1,xzr,#2

because the pattern accepts zero as an operand in the comparison, but the instruction doesn't.
Fix it by adjusting the predicate and constraints.

gcc/ChangeLog:

	PR target/99822
	* config/aarch64/aarch64.md (sub<mode>3_compare1_imm): Do not allow zero
	in operand 1.

gcc/testsuite/ChangeLog:

	PR target/99822
	* gcc.c-torture/compile/pr99822.c: New test.
---
 gcc/config/aarch64/aarch64.md                 |  2 +-
 gcc/testsuite/gcc.c-torture/compile/pr99822.c | 41 +++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr99822.c

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index a398c3d..b139c08 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -3034,7 +3034,7 @@
 (define_insn "sub<mode>3_compare1_imm"
   [(set (reg:CC CC_REGNUM)
 	(compare:CC
-	  (match_operand:GPI 1 "aarch64_reg_or_zero" "rkZ,rkZ")
+	  (match_operand:GPI 1 "register_operand" "rk,rk")
 	  (match_operand:GPI 2 "aarch64_plus_immediate" "I,J")))
    (set (match_operand:GPI 0 "register_operand" "=r,r")
 	(plus:GPI
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr99822.c b/gcc/testsuite/gcc.c-torture/compile/pr99822.c
new file mode 100644
index 0000000..0660784
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr99822.c
@@ -0,0 +1,41 @@
+/* PR target/99822 */
+/* { dg-do assemble } */
+/* { dg-require-effective-target int128 } */
+
+int zt, bm, p5 = 1;
+
+void __attribute__ ((cold))
+l2 (unsigned long int hz)
+{
+  __int128 d9 = 0;
+  unsigned long int *mg = hz ? &hz : (unsigned long int *) &d9;
+
+  while (d9 < 1)
+    {
+      bm = bm > d9;
+      bm = bm == (d9 = bm || hz);
+
+      hz = 0x197000000;
+      d9 = hz * hz;
+
+      while (p5 < 1)
+        {
+          bm = ((hz = 3) ? zt : 0) > 0x1001;
+          if (bm != 0)
+            {
+              __int128 *nd = (__int128 *) bm;
+
+              *nd /= 3;
+            }
+
+          *mg = 0x1001;
+          p5 -= *mg;
+        }
+
+      for (zt = 0; zt >= 0; zt += 2)
+        d9 = 0;
+
+      d9 += 2;
+    }
+}
+
-- 
2.7.4