Hi,
I am looking at some part of GCC source code which does the translation
from GIMPLE to RTL.
I created an example, having two consecutive instructions, one with "div"
and other with "mod".
Example:
int a, b, c, d;
a = b / c;
d = b % c;
The first-cut RTL code corresponding to these two instructions is a
PARALLEL INSN, with two SET INSNs, one with "div" and other with "mod".
(insn 22 21 23 1 (parallel [
(set (reg:SI 70)
(div:SI (reg:SI 72)
(mem/i:SI (plus:SI (reg/f:SI 54 virtual-stack-vars)
(const_int -8 [0xfffffff8])) [0 c+0 S4 A32])))
(set (reg:SI 71)
(mod:SI (reg:SI 72)
(mem/i:SI (plus:SI (reg/f:SI 54 virtual-stack-vars)
(const_int -8 [0xfffffff8])) [0 c+0 S4 A32])))
)
I am unable to understand how a single INSN gets generated for these two
instructions. The GIMPLE code has two different tree nodes for the two
instructions, namely "trunc_div_expr" and "trunc_mod_expr". So there
should be two different INSNs. My guess is, some pass, like "combine",
must be combining two INSNs into one.
I looked at functions in file "combine.c", but no function in that file is
called!
Can anybody suggest something? I am really stuck at this point And can't
proceed any further.
Regards,
Amruta Gokhale
Graduate Student
IIT Bombay,
Mumbai.
