+2007-06-05 Revital Eres <eres@il.ibm.com>
+
+ PR 30957
+ * loop-unroll.c (insert_var_expansion_initialization):
+ Initialize the expansions with -zero instead of +zero.
+
2007-05-05 Aurelien Jarno <aurelien@aurel32.net>
* config/pa/pa.md: Split tgd_load, tld_load and tie_load
/* Initialize the variable expansions in loop preheader.
Callbacks for htab_traverse. PLACE_P is the loop-preheader
basic block where the initialization of the expansions
- should take place. */
+ should take place. The expansions are initialized with (-0)
+ when the operation is plus or minus to honor sign zero.
+ This way we can prevent cases where the sign of the final result is
+ effected by the sign of the expansion.
+ Here is an example to demonstrate this:
+
+ for (i = 0 ; i < n; i++)
+ sum += something;
+
+ ==>
+
+ sum += something
+ ....
+ i = i+1;
+ sum1 += something
+ ....
+ i = i+1
+ sum2 += something;
+ ....
+
+ When SUM is initialized with -zero and SOMETHING is also -zero; the
+ final result of sum should be -zero thus the expansions sum1 and sum2
+ should be initialized with -zero as well (otherwise we will get +zero
+ as the final result). */
static int
insert_var_expansion_initialization (void **slot, void *place_p)
basic_block place = (basic_block)place_p;
rtx seq, var, zero_init, insn;
unsigned i;
-
+ enum machine_mode mode = GET_MODE (ve->reg);
+ bool honor_signed_zero_p = HONOR_SIGNED_ZEROS (mode);
+
if (VEC_length (rtx, ve->var_expansions) == 0)
return 1;
if (ve->op == PLUS || ve->op == MINUS)
for (i = 0; VEC_iterate (rtx, ve->var_expansions, i, var); i++)
{
- zero_init = CONST0_RTX (GET_MODE (var));
+ if (honor_signed_zero_p)
+ zero_init = simplify_gen_unary (NEG, mode, CONST0_RTX (mode), mode);
+ else
+ zero_init = CONST0_RTX (mode);
+
emit_move_insn (var, zero_init);
}
else if (ve->op == MULT)
--- /dev/null
+/* { dg-do run { xfail vax-*-* powerpc-*-*spe } } */
+/* { dg-options "-O2 -funroll-loops -funsafe-math-optimizations -fvariable-expansion-in-unroller -dL" } */
+
+extern void abort (void);
+extern void exit (int);
+
+float
+foo (float d, int n)
+{
+ unsigned i;
+ float accum = d;
+
+ for (i = 0; i < n; i++)
+ accum += d;
+
+ return accum;
+}
+
+int
+main ()
+{
+ if (__builtin_copysignf (1.0, foo (0.0 / -5.0, 10)) != -1.0)
+ abort ();
+ exit (0);
+}
+
+/* { dg-final { scan-rtl-dump "Expanding Accumulator" "loop2_unroll" } } */
+/* { dg-final { cleanup-rtl-dump "loop*" } } */
+
+