标签：gcc 源代码 分析
(insn_list 6 (nil))
(insn_list 2 (insn_list 6 (nil)))
(sequence[ ] )
(reg:SI 0)
(const_int 4)
这次是解释这5条rtx的产生过程
相关的代码片段：
/* Mark all register-parms as living through the call. */
start_sequence ();
for (i = 0; i < num_actuals; i++)
if (args[i].reg != 0)
{
if (args[i].partial > 0)
use_regs (REGNO (args[i].reg), args[i].partial);
else if (GET_MODE (args[i].reg) == BLKmode)
use_regs (REGNO (args[i].reg),
((int_size_in_bytes (TREE_TYPE (args[i].tree_value))
+ UNITS_PER_WORD - 1)
/ UNITS_PER_WORD));
else
emit_insn (gen_rtx (USE, VOIDmode, args[i].reg));
}
if (structure_value_addr && ! structure_value_addr_parm
&& GET_CODE (struct_value_rtx) == REG)
emit_insn (gen_rtx (USE, VOIDmode, struct_value_rtx));
use_insns = gen_sequence ();
end_sequence ();
/* Figure out the register where the value, if any, will come back. */
valreg = 0;
if (TYPE_MODE (TREE_TYPE (exp)) != VOIDmode
&& ! structure_value_addr)
{
if (pcc_struct_value)
valreg = hard_libcall_value (Pmode);
else
valreg = hard_function_value (TREE_TYPE (exp), fndecl);
}
/* Generate the actual call instruction. */
/* This also has the effect of turning off any pop-inhibition
done in expand_call. */
if (args_size.constant < 0)
args_size.constant = 0;
emit_call_1 (funexp, funtype, args_size.constant,
FUNCTION_ARG (args_so_far, VOIDmode, void_type_node, 1),
valreg, old_inhibit_defer_pop, use_insns);
下面是加了fprintf()的调试结果
before start_sequence
(insn_list 6 (nil))
(insn_list 2 (insn_list 6 (nil)))
after start_sequence
after for if
before gen_sequence
(sequence[ ] )
after end_sequence
before hard
(reg:SI 0)
hard_funtion_value
(const_int 4)
emit_call_1 funexp symbol_ref
逐一说明：
(insn_list 6 (nil))
(insn_list 2 (insn_list 6 (nil)))
和 start_sequence ();有关。
(sequence[ ] )和
use_insns = gen_sequence ();
有关。
(reg:SI 0)和 valreg = hard_function_value (TREE_TYPE (exp), fndecl); 有关。
(const_int 4) 和函数 emit_call_1 ()有关
gcc源代码分析，expand_call()函数第三部分
标签：gcc 源代码 分析
原文地址：http://blog.csdn.net/oldlinux/article/details/42453659
