On Fri, Apr 17, 2020 at 02:12:19PM +0200, Uros Bizjak wrote:
> Is it possible to perform widening only for !TARGET_PARTIAL_REG_STALL?
> I'm worried that highpart may not be cleared, so the effects of
> partial reg stall can be quite noticeable.
So, like this then?
All I've added was another condition, interdiff:
diff -u gcc/config/i386/i386.md gcc/config/i386/i386.md
--- gcc/config/i386/i386.md 2020-04-16 14:21:41.686972979 +0200
+++ gcc/config/i386/i386.md 2020-04-17 14:29:33.882690098 +0200
@@ -8750,6 +8750,18 @@
== GET_MODE_PRECISION (GET_MODE (operands[2]))
&& !register_operand (operands[2],
GET_MODE (operands[2])))
+ /* And we shouldn't widen if
+ TARGET_PARTIAL_REG_STALL. */
+ || (TARGET_PARTIAL_REG_STALL
+ && (INTVAL (operands[3]) + INTVAL (operands[4])
+ >= (paradoxical_subreg_p (operands[2])
+ && (GET_MODE_CLASS
+ (GET_MODE (SUBREG_REG (operands[2])))
+ == MODE_INT)
+ ? GET_MODE_PRECISION
+ (GET_MODE (SUBREG_REG (operands[2])))
+ : GET_MODE_PRECISION
+ (GET_MODE (operands[2])))))
? CCZmode : CCNOmode)"
"#"
"&& 1"
and nothing in the splitter would need to change because the condition
would ensure that for TARGET_PARTIAL_REG_STALL we require in all problematic
cases CCZmode. The only exception would be the pos + len == 8
optimization which we wouldn't perform (of course with CCZmode we'd still
do), but that isn't a partial reg stall thing, that is an optimization to
use shorter testb instead of testw.
2020-04-17 Jakub Jelinek <ja...@redhat.com>
Jeff Law <l...@redhat.com>
PR target/94567
* config/i386/i386.md (*testqi_ext_3): Use CCZmode rather than
CCNOmode in ix86_match_ccmode if len is equal to <MODE>mode precision,
or pos + len >= 32, or pos + len is equal to operands[2] precision
and operands[2] is not a register operand. During splitting perform
SImode AND if operands[0] doesn't have CCZmode and pos + len is
equal to mode precision.
* gcc.c-torture/execute/pr94567.c: New test.
--- gcc/config/i386/i386.md.jj 2020-04-17 08:49:33.236921107 +0200
+++ gcc/config/i386/i386.md 2020-04-17 14:29:33.882690098 +0200
@@ -8730,10 +8730,38 @@ (define_insn_and_split "*testqi_ext_3"
&& INTVAL (operands[3]) > 32
&& INTVAL (operands[3]) + INTVAL (operands[4]) == 64))
&& ix86_match_ccmode (insn,
- /* *testdi_1 requires CCZmode if the mask has bit
+ /* If zero_extract mode precision is the same
+ as len, the SF of the zero_extract
+ comparison will be the most significant
+ extracted bit, but this could be matched
+ after splitting only for pos 0 len all bits
+ trivial extractions. Require CCZmode. */
+ (GET_MODE_PRECISION (<MODE>mode)
+ == INTVAL (operands[3]))
+ /* Otherwise, require CCZmode if we'd use a mask
+ with the most significant bit set and can't
+ widen it to wider mode. *testdi_1 also
+ requires CCZmode if the mask has bit
31 set and all bits above it clear. */
- GET_MODE (operands[2]) == DImode
- && INTVAL (operands[3]) + INTVAL (operands[4]) == 32
+ || (INTVAL (operands[3]) + INTVAL (operands[4])
+ >= 32)
+ /* We can't widen also if val is not a REG. */
+ || (INTVAL (operands[3]) + INTVAL (operands[4])
+ == GET_MODE_PRECISION (GET_MODE (operands[2]))
+ && !register_operand (operands[2],
+ GET_MODE (operands[2])))
+ /* And we shouldn't widen if
+ TARGET_PARTIAL_REG_STALL. */
+ || (TARGET_PARTIAL_REG_STALL
+ && (INTVAL (operands[3]) + INTVAL (operands[4])
+ >= (paradoxical_subreg_p (operands[2])
+ && (GET_MODE_CLASS
+ (GET_MODE (SUBREG_REG (operands[2])))
+ == MODE_INT)
+ ? GET_MODE_PRECISION
+ (GET_MODE (SUBREG_REG (operands[2])))
+ : GET_MODE_PRECISION
+ (GET_MODE (operands[2])))))
? CCZmode : CCNOmode)"
"#"
"&& 1"
@@ -8750,7 +8778,10 @@ (define_insn_and_split "*testqi_ext_3"
/* Narrow paradoxical subregs to prevent partial register stalls. */
if (GET_MODE_BITSIZE (mode) > GET_MODE_BITSIZE (submode)
- && GET_MODE_CLASS (submode) == MODE_INT)
+ && GET_MODE_CLASS (submode) == MODE_INT
+ && (GET_MODE (operands[0]) == CCZmode
+ || pos + len < GET_MODE_PRECISION (submode)
+ || REG_P (SUBREG_REG (val))))
{
val = SUBREG_REG (val);
mode = submode;
@@ -8758,14 +8789,32 @@ (define_insn_and_split "*testqi_ext_3"
}
/* Small HImode tests can be converted to QImode. */
- if (register_operand (val, HImode) && pos + len <= 8)
+ if (pos + len <= 8
+ && register_operand (val, HImode))
{
- val = gen_lowpart (QImode, val);
- mode = QImode;
+ rtx nval = gen_lowpart (QImode, val);
+ if (!MEM_P (nval)
+ || GET_MODE (operands[0]) == CCZmode
+ || pos + len < 8)
+ {
+ val = nval;
+ mode = QImode;
+ }
}
gcc_assert (pos + len <= GET_MODE_PRECISION (mode));
+ /* If the mask is going to have the sign bit set in the mode
+ we want to do the comparison in and user isn't interested just
+ in the zero flag, then we must widen the target mode. */
+ if (pos + len == GET_MODE_PRECISION (mode)
+ && GET_MODE (operands[0]) != CCZmode)
+ {
+ gcc_assert (pos + len < 32 && !MEM_P (val));
+ mode = SImode;
+ val = gen_lowpart (mode, val);
+ }
+
wide_int mask
= wi::shifted_mask (pos, len, false, GET_MODE_PRECISION (mode));
--- gcc/testsuite/gcc.c-torture/execute/pr94567.c.jj 2020-04-17
14:19:34.610683856 +0200
+++ gcc/testsuite/gcc.c-torture/execute/pr94567.c 2020-04-17
14:19:34.610683856 +0200
@@ -0,0 +1,26 @@
+/* PR target/94567 */
+
+volatile int a = 1, b;
+short c, d = 4, f = 2, g;
+unsigned short e = 53736;
+
+int
+foo (int i, int j)
+{
+ return i && j ? 0 : i + j;
+}
+
+int
+main ()
+{
+ for (; a; a = 0)
+ {
+ unsigned short k = e;
+ g = k >> 3;
+ if (foo (g < (f || c), b))
+ d = 0;
+ }
+ if (d != 4)
+ __builtin_abort ();
+ return 0;
+}
Jakub
