(expand_binop): For complex mult, compute res in each alternative, not before.

From-SVN: r3165

diff --git a/gcc/optabs.c b/gcc/optabs.c
index a62951317788c24ed979d3c706dd1d1594fcbf35..f46f4597be48ad57ba502de18911fe64abb7121c 100644 (file)
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -889,7 +889,9 @@ expand_binop (mode, binoptab, op0, op1, target, unsignedp, methods)
       switch (binoptab->code)
        {
        case PLUS:
+         /* (a+ib) + (c+id) = (a+c) + i(b+d) */
        case MINUS:
+         /* (a+ib) - (c+id) = (a-c) + i(b-d) */
          res = expand_binop (submode, binoptab, real0, real1,
                              realr, unsignedp, methods);
          if (res != realr)
@@ -912,15 +914,14 @@ expand_binop (mode, binoptab, op0, op1, target, unsignedp, methods)
        case MULT:
          /* (a+ib) * (c+id) = (ac-bd) + i(ad+cb) */
 
-         res = expand_binop (submode, binoptab, real0, real1,
-                             realr, unsignedp, methods);
-
          if (imag0 && imag1)
            {
              rtx temp =
-               expand_binop (submode, sub_optab, res,
-                             expand_binop (submode, binoptab, imag0, imag1,
-                                           0, unsignedp, methods),
+               expand_binop (submode, sub_optab,
+                             expand_binop (submode, binoptab, real0,
+                                           real1, 0, unsignedp, methods),
+                             expand_binop (submode, binoptab, imag0,
+                                           imag1, 0, unsignedp, methods),
                              realr, unsignedp, methods);
 
              if (temp != realr)
@@ -939,6 +940,8 @@ expand_binop (mode, binoptab, op0, op1, target, unsignedp, methods)
            }
          else
            {
+             res = expand_binop (submode, binoptab, real0, real1,
+                                 realr, unsignedp, methods);
              if (res != realr)
                emit_move_insn (realr, res);
 
@@ -954,11 +957,11 @@ expand_binop (mode, binoptab, op0, op1, target, unsignedp, methods)
          break;
 
        case DIV:
-         /* (c+id)/(a+ib) == ((c+id)*(a-ib))/(a*a+b*b) */
+         /* (a+ib) / (c+id) = ((ac+bd)/(cc+dd)) + i((bc-ad)/(cc+dd)) */
          
          if (! imag1)
-           {
-             /* Simply divide the real and imaginary parts by `a' */
+           {   /* (a+ib) / (c+i0) = (a/c) + i(b/c) */
+             /* Simply divide the real and imaginary parts by `c' */
              res = expand_binop (submode, binoptab, real0, real1,
                                  realr, unsignedp, methods);
              if (res != realr)