[COMMITTED] aarch64: Fix failure in cmpimm_branch_1.c

[Richard Sandiford]

gcc.target/aarch64/cmpimm_branch_1.c started failing after Bernd's
fix to make combine take the costs of jumps into account
(g:391500af1932e696a007).  This is because the rtx costs
of *compare_condjump<GPI:mode> were higher than the costs
of the instructions it combines.

Tested on aarch64-linux-gnu & pushed.

Richard


2020-01-27  Richard Sandiford  <richard.sandif...@arm.com>

gcc/
        * config/aarch64/aarch64.c (aarch64_if_then_else_costs): Match
        jump conditions for *compare_condjump<GPI:mode>.
---
 gcc/config/aarch64/aarch64.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 3437fff6811..11197bd033e 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -11020,6 +11020,8 @@ aarch64_if_then_else_costs (rtx op0, rtx op1, rtx op2, 
int *cost, bool speed)
   rtx inner;
   rtx comparator;
   enum rtx_code cmpcode;
+  const struct cpu_cost_table *extra_cost
+    = aarch64_tune_params.insn_extra_cost;
 
   if (COMPARISON_P (op0))
     {
@@ -11054,8 +11056,17 @@ aarch64_if_then_else_costs (rtx op0, rtx op1, rtx op2, 
int *cost, bool speed)
                    /* CBZ/CBNZ.  */
                    *cost += rtx_cost (inner, VOIDmode, cmpcode, 0, speed);
 
-               return true;
-             }
+                 return true;
+               }
+             if (register_operand (inner, VOIDmode)
+                 && aarch64_imm24 (comparator, VOIDmode))
+               {
+                 /* SUB and SUBS.  */
+                 *cost += COSTS_N_INSNS (2);
+                 if (speed)
+                   *cost += extra_cost->alu.arith * 2;
+                 return true;
+               }
            }
          else if (cmpcode == LT || cmpcode == GE)
            {