[Bug tree-optimization/63586] x+x+x+x -> 4*x in gimple

["kugan at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63586

kugan at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kugan at gcc dot gnu.org

--- Comment #2 from kugan at gcc dot gnu.org ---
Created attachment 36908
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36908&action=edit
proposed patch

With the patch:
unsigned f1(unsigned x){
    unsigned y = x + x;
    y = y + x;
    y = y + x;
    y = y + x;
    y = y + x;
    y = y + x;
    y = y + x;
    return y;
}
unsigned f2(unsigned x, unsigned z){
    unsigned y = x + x;
    y = y + x;
    y = y + x;
    y = y + z;
    y = y + z;
    y = y + z;
    y = y + z;
    return y;
}

unsigned f3(unsigned x, unsigned z, unsigned k){
    unsigned y = x + x;
    y = y + x;
    y = y + x;
    y = y + z;
    y = y + z;
    y = y + z;
    y = y + k;
    return y;
}
unsigned f4(unsigned x, unsigned z, unsigned k){
    unsigned y = k + x;
    y = y + x;
    y = y + x;
    y = y + z;
    y = y + z;
    y = y + z;
    y = y + x;
    return y;
}


now becomes:

at t7.c.108t.reassoc1 

;; Function f1 (f1, funcdef_no=0, decl_uid=4145, cgraph_uid=0, symbol_order=0)

;; 1 loops found
;;
;; Loop 0
;;  header 0, latch 1
;;  depth 0, outer -1
;;  nodes: 0 1 2
;; 2 succs { 1 }
f1 (unsigned int x)
{
  unsigned int y;
  unsigned int reassocmul_10;

  <bb 2>:
  reassocmul_10 = x_1(D) * 8;
  y_8 = reassocmul_10;
  return y_8;

}



;; Function f2 (f2, funcdef_no=1, decl_uid=4150, cgraph_uid=1, symbol_order=1)

;; 1 loops found
;;
;; Loop 0
;;  header 0, latch 1
;;  depth 0, outer -1
;;  nodes: 0 1 2
;; 2 succs { 1 }
f2 (unsigned int x, unsigned int z)
{
  unsigned int y;
  unsigned int reassocmul_11;
  unsigned int reassocmul_12;

  <bb 2>:
  reassocmul_11 = x_1(D) * 4;
  reassocmul_12 = z_5(D) * 4;
  y_9 = reassocmul_11 + reassocmul_12;
  return y_9;

}



;; Function f3 (f3, funcdef_no=2, decl_uid=4156, cgraph_uid=2, symbol_order=2)

;; 1 loops found
;;
;; Loop 0
;;  header 0, latch 1
;;  depth 0, outer -1
;;  nodes: 0 1 2
;; 2 succs { 1 }
f3 (unsigned int x, unsigned int z, unsigned int k)
{
  unsigned int y;
  unsigned int reassocmul_12;
  unsigned int reassocmul_13;
  unsigned int _14;

  <bb 2>:
  reassocmul_12 = x_1(D) * 4;
  reassocmul_13 = z_5(D) * 3;
  _14 = k_9(D) + reassocmul_13;
  y_10 = _14 + reassocmul_12;
  return y_10;

}



;; Function f4 (f4, funcdef_no=3, decl_uid=4162, cgraph_uid=3, symbol_order=3)

;; 1 loops found
;;
;; Loop 0
;;  header 0, latch 1
;;  depth 0, outer -1
;;  nodes: 0 1 2
;; 2 succs { 1 }
f4 (unsigned int x, unsigned int z, unsigned int k)
{
  unsigned int y;
  unsigned int reassocmul_12;
  unsigned int reassocmul_13;
  unsigned int _14;
  unsigned int _15;

  <bb 2>:
  reassocmul_12 = x_2(D) * 3;
  reassocmul_13 = z_6(D) * 3;
  _14 = x_2(D) + reassocmul_13;
  _15 = _14 + reassocmul_12;
  y_10 = _15 + k_1(D);
  return y_10;

}