On Mon, Jun 20, 2011 at 09:38:22PM +0200, Bernd Schmidt wrote:
> On 06/16/2011 06:25 PM, Richard Henderson wrote:
> > On 06/16/2011 05:44 AM, Bernd Schmidt wrote:
> >> +@deftypefn {Built-in Function} int __builtin_clrsb (unsigned int x)
> >> +Returns the number of leading redundant sign bits in @var{x}, starting
> >> +at the most significant bit position.
> >> +@end deftypefn
> >
> > Do we want a signed argument, since we're talking about signs?
>
> Err, yes. It's signed everywhere else (builtins.def etc.).
But unfortunately not during expansion.
gcc.c-torture/execute/builtin-bitops-1.c fails on x86_64-linux, because
there is no SImode libcall, only DImode, and it was zero-extending instead
of sign-extending the argument, and not subtracting the mode difference
afterwards. So int foo (int x) { return __builtin_clrsb (x); }
expanded the same as
int foo (int x) { return __builtin_clrsbl ((unsigned) x); }
instead of the correct
int foo (int x) { return __builtin_clrsbl (x) - 32; }
Fixed thusly, I've also added folding of constant arguments
during tree optimizations for it.
Ok for trunk?
2011-06-21 Jakub Jelinek <ja...@redhat.com>
PR middle-end/49489
* builtins.c (expand_builtin_unop): Call expand_unop with 0 as
unsignedp argument instead of 1 for clrsb_optab.
(fold_builtin_bitop): Fix masking for width > HOST_BITS_PER_WIDE_INT
and < 2 * HOST_BITS_PER_WIDE_INT. Optimize BUILT_IN_CLRSB*.
(fold_builtin_1): Call fold_builtin_binop for BUILT_IN_CLRSB*.
* optabs.c (widen_leading): Call widen_operand and expand_unop
with 0 as unsignedp argument instead of 1 for clrsb_optab.
(expand_unop): Subtract difference of mode sizes also for
clrsb_optab.
--- gcc/builtins.c.jj 2011-06-21 16:46:01.000000000 +0200
+++ gcc/builtins.c 2011-06-21 17:36:38.000000000 +0200
@@ -4578,7 +4578,7 @@ expand_builtin_unop (enum machine_mode t
/* Compute op, into TARGET if possible.
Set TARGET to wherever the result comes back. */
target = expand_unop (TYPE_MODE (TREE_TYPE (CALL_EXPR_ARG (exp, 0))),
- op_optab, op0, target, 1);
+ op_optab, op0, target, op_optab != clrsb_optab);
gcc_assert (target);
return convert_to_mode (target_mode, target, 0);
@@ -7265,7 +7265,8 @@ fold_builtin_bitop (tree fndecl, tree ar
{
hi = TREE_INT_CST_HIGH (arg);
if (width < 2 * HOST_BITS_PER_WIDE_INT)
- hi &= ~((HOST_WIDE_INT) (-1) >> (width - HOST_BITS_PER_WIDE_INT));
+ hi &= ~((unsigned HOST_WIDE_INT) (-1)
+ << (width - HOST_BITS_PER_WIDE_INT));
}
else
{
@@ -7303,6 +7304,26 @@ fold_builtin_bitop (tree fndecl, tree ar
result = width;
break;
+ CASE_INT_FN (BUILT_IN_CLRSB):
+ if (width > HOST_BITS_PER_WIDE_INT
+ && (hi & ((unsigned HOST_WIDE_INT) 1
+ << (width - HOST_BITS_PER_WIDE_INT - 1))) != 0)
+ {
+ hi = ~hi & ~((unsigned HOST_WIDE_INT) (-1)
+ << (width - HOST_BITS_PER_WIDE_INT - 1));
+ lo = ~lo;
+ }
+ else if (width <= HOST_BITS_PER_WIDE_INT
+ && (lo & ((unsigned HOST_WIDE_INT) 1 << (width - 1))) != 0)
+ lo = ~lo & ~((unsigned HOST_WIDE_INT) (-1) << (width - 1));
+ if (hi != 0)
+ result = width - floor_log2 (hi) - 2 - HOST_BITS_PER_WIDE_INT;
+ else if (lo != 0)
+ result = width - floor_log2 (lo) - 2;
+ else
+ result = width - 1;
+ break;
+
CASE_INT_FN (BUILT_IN_POPCOUNT):
result = 0;
while (lo)
@@ -9737,6 +9758,7 @@ fold_builtin_1 (location_t loc, tree fnd
CASE_INT_FN (BUILT_IN_FFS):
CASE_INT_FN (BUILT_IN_CLZ):
CASE_INT_FN (BUILT_IN_CTZ):
+ CASE_INT_FN (BUILT_IN_CLRSB):
CASE_INT_FN (BUILT_IN_POPCOUNT):
CASE_INT_FN (BUILT_IN_PARITY):
return fold_builtin_bitop (fndecl, arg0);
--- gcc/optabs.c.jj 2011-06-21 16:46:01.000000000 +0200
+++ gcc/optabs.c 2011-06-21 17:50:35.000000000 +0200
@@ -2350,8 +2350,10 @@ widen_leading (enum machine_mode mode, r
if (target == 0)
target = gen_reg_rtx (mode);
- xop0 = widen_operand (op0, wider_mode, mode, true, false);
- temp = expand_unop (wider_mode, unoptab, xop0, NULL_RTX, true);
+ xop0 = widen_operand (op0, wider_mode, mode,
+ unoptab != clrsb_optab, false);
+ temp = expand_unop (wider_mode, unoptab, xop0, NULL_RTX,
+ unoptab != clrsb_optab);
if (temp != 0)
temp = expand_binop (wider_mode, sub_optab, temp,
GEN_INT (GET_MODE_BITSIZE (wider_mode)
@@ -3075,8 +3077,9 @@ expand_unop (enum machine_mode mode, opt
unsignedp);
/* If we are generating clz using wider mode, adjust the
- result. */
- if (unoptab == clz_optab && temp != 0)
+ result. Similarly for clrsb. */
+ if ((unoptab == clz_optab || unoptab == clrsb_optab)
+ && temp != 0)
temp = expand_binop (wider_mode, sub_optab, temp,
GEN_INT (GET_MODE_BITSIZE (wider_mode)
- GET_MODE_BITSIZE (mode)),
Jakub
