GCC source code Analysis, Expand_call () function Part III

(Insn_list 6 (nil))

(Insn_list 2 (insn_list 6 (nil)))

(sequence[])

(Reg:si 0)

(Const_int 4)

This is the process of explaining the 5 of these rtx.

Related Code snippet:

/* 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, would 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 have 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);

Here is the debug result with fprintf () added

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

Describe each of them individually:

(Insn_list 6 (nil))

(Insn_list 2 (insn_list 6 (nil)))

and Start_sequence ();

(sequence[]) and

Use_insns = Gen_sequence ();

About.

(Reg:si 0) and Valreg = Hard_function_value (Tree_type (exp), FNDECL); About.

(Const_int 4) and function Emit_call_1 ()

GCC source code Analysis, Expand_call () function Part III