arm: Implement computed goto.

This fixes C/gnu99/combo_load_mode.c, C/gnu99/computed_goto.c, C/gnu99/ijmp.c, C/gnu99/vlabel2.c and C/gnu99/vlabel3.c.

NEWS.md

@@ -35,6 +35,7 @@ libFirm 1.22.1 (2016-01-07)
 * amd64: Improve use of `lea` in instruction selection
 * sparc: Support the asm constaint `K`
 * sparc: Support computed goto
+* arm: Support computed goto
 * Bugfixes
 
 libFirm 1.22.0 (2015-12-31)

ir/be/arm/arm_spec.pl

@@ -486,6 +486,16 @@ Jmp => {
 	out_reqs  => [ "exec" ],
 },
 
+IJmp => {
+	op_flags  => [ "cfopcode", "forking" ],
+	state     => "pinned",
+	in_reqs   => [ "gp" ],
+	ins       => [ "target" ],
+	out_reqs  => [ "exec" ],
+	outs      => [ "jmp" ],
+	emit      => "mov pc, %S0",
+},
+
 SwitchJmp => {
 	op_flags  => [ "cfopcode", "forking" ],
 	state     => "pinned",

ir/be/arm/arm_transform.c

@@ -1187,6 +1187,15 @@ static ir_node *gen_Store(ir_node *node)
 	return new_store;
 }
 
+static ir_node *gen_IJmp(ir_node *const node)
+{
+	dbg_info *const dbgi       = get_irn_dbg_info(node);
+	ir_node  *const block      = be_transform_nodes_block(node);
+	ir_node  *const target     = get_IJmp_target(node);
+	ir_node  *const new_target = be_transform_node(target);
+	return new_bd_arm_IJmp(dbgi, block, new_target);
+}
+
 static ir_node *gen_Jmp(ir_node *node)
 {
 	ir_node  *new_block = be_transform_nodes_block(node);
@@ -1971,6 +1980,7 @@ static void arm_register_transformers(void)
 	be_set_transform_function(op_Conv,        gen_Conv);
 	be_set_transform_function(op_Div,         gen_Div);
 	be_set_transform_function(op_Eor,         gen_Eor);
+	be_set_transform_function(op_IJmp,        gen_IJmp);
 	be_set_transform_function(op_Jmp,         gen_Jmp);
 	be_set_transform_function(op_Load,        gen_Load);
 	be_set_transform_function(op_Member,      gen_Member);