loop2_unroll: Add param to allow unrolling of loops containig multiple branches

Signed-off-by: Michiel Derhaeg <michiel@synopsys.com>

Author: MichielDerhaeg

gcc/loop-unroll.cc

@@ -1193,7 +1193,7 @@ decide_unroll_stupid (class loop *loop, int flags)
      of mispredicts.
      TODO: this heuristic needs tunning; call inside the loop body
      is also relatively good reason to not unroll.  */
-  if (num_loop_branches (loop) > 1)
+  if (num_loop_branches (loop) > (unsigned) param_max_unroll_branches)
     {
       if (dump_file)
 	fprintf (dump_file, ";; Not unrolling, contains branches\n");

gcc/params.opt

@@ -784,6 +784,10 @@ Maximum number of arguments in a PHI supported by TREE if-conversion unless the
 Common Joined UInteger Var(param_max_unroll_times) Init(8) Param Optimization
 The maximum number of unrollings of a single loop.
 
+-param=max-unroll-branches=
+Common Joined UInteger Var(param_max_unroll_branches) Init(1) Param Optimization
+The maximum number of branches allowed in a loop to be unrolled stupidly.
+
 -param=max-unrolled-insns=
 Common Joined UInteger Var(param_max_unrolled_insns) Init(200) Param Optimization
 The maximum number of instructions to consider to unroll in a loop.