GCC source code Analysis, Expand_call () function Part IV, EMIT_CALL_1 () function

This article is to explain how the following 4 Rtx are produced, and the Emit_call_1 () function.

(Const_int 4)

(Mem:qi (Symbol_ref/v:si ("printf")))

(Call (Mem:qi (Symbol_ref/v:si ("printf")))
(Const_int 4))

(Set (Reg:si 0)
(Call (Mem:qi (Symbol_ref/v:si ("printf")))
(Const_int 4)))

The following is the debug result after adding the fprintf () function.

(Const_int 4)
Emit_call_1 Funexp Symbol_ref
Before EMIT_CALL_INSN

(Mem:qi (Symbol_ref/v:si ("printf")))

(Call (Mem:qi (Symbol_ref/v:si ("printf")))
(Const_int 4))

(Set (Reg:si 0)
(Call (Mem:qi (Symbol_ref/v:si ("printf")))
(Const_int 4)))
Emit_call_insn
After Emit_call_inst
After Emit_call_1
End Expand_call

The relevant code in the Expand_call () function:

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);

/* ??? Nothing have been done here to record control flow
When the contained functions can do nonlocal gotos. */

static void
Emit_call_1 (funexp, Funtype, Stack_size, Next_arg_reg, Valreg, Old_inhibit_defer_pop, Use_insns )
     rtx funexp;
     Tree Funtype;
     int stack_size;
     rtx Next_arg_reg;
     rtx Valreg;
     int old_inhibit_defer_pop;
     rtx Use_insns;
{
  rtx stack_size_rtx = gen_rtx (Const_int, Voidmode, stack_size);
  RTX CALL_INSN;

  if (valreg)
    emit_call_insn (Gen_call_value (Valreg,
                     gen_rtx (MEM, Function_mode, Funexp),
                     Stack_size_rtx, Next_arg_reg));

The Gen_call_value () function is in the insn-emit.c file and

(Call (Mem:qi (Symbol_ref/v:si ("printf")))
(Const_int 4))

(Set (Reg:si 0)
(Call (Mem:qi (Symbol_ref/v:si ("printf")))
(Const_int 4)))

These 2 RTX related.

Rtx

Gen_call_value (Operand0, Operand1, Operand2)
RTX operand0;
RTX Operand1;
RTX Operand2;
{
ReturnGen_rtx(SET, Voidmode, Operand0,Gen_rtx(Call, Voidmode, Operand1, Operand2));
}

GCC source code Analysis, Expand_call () function Part IV, EMIT_CALL_1 () function