Hi!
The newly added absdi2 expander doesn't work well on ia32, because it
requires a xordi3 pattern, which is available even for !TARGET_64BIT,
but only if TARGET_STV && TARGET_SSE2.
The following patch just uses expand_simple_binop which is able to handle
the splitting of it into two xorsi3 patterns if needed etc., plus is shorter
in the expander. Also, there is no need to build a DImode shift amount and
then convert_modes it.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, on the
testcase we now get identical code to what GCC 9 emitted in all of -m32
-mno-stv -mno-sse, -m32 -msse2 -mstv and -m64 modes, ok for trunk?
2020-01-03 Jakub Jelinek <ja...@redhat.com>
PR target/93110
* config/i386/i386.md (abs<mode>2): Use expand_simple_binop instead of
emitting ASHIFTRT, XOR and MINUS by hand. Use gen_int_mode with QImode
instead of gen_int_shift_amount + convert_modes.
* gcc.dg/torture/pr93110.c: New test.
--- gcc/config/i386/i386.md.jj 2020-01-01 12:16:10.071276261 +0100
+++ gcc/config/i386/i386.md 2020-01-02 10:47:26.638399487 +0100
@@ -9711,30 +9711,16 @@ (define_expand "abs<mode>2"
/* Generate rtx abs using abs (x) = (((signed) x >> (W-1)) ^ x) -
((signed) x >> (W-1)) */
- rtx shift_amount = gen_int_shift_amount (mode,
- GET_MODE_PRECISION (mode)
- - 1);
- shift_amount = convert_modes (E_QImode, GET_MODE (shift_amount),
- shift_amount, 1);
- rtx shift_dst = gen_reg_rtx (mode);
- rtx shift_op = gen_rtx_SET (shift_dst,
- gen_rtx_fmt_ee (ASHIFTRT, mode,
- operands[1], shift_amount));
- rtx clobber = gen_rtx_CLOBBER (VOIDmode, gen_rtx_REG (CCmode,
- FLAGS_REG));
- emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, shift_op,
- clobber)));
-
- rtx xor_op = gen_rtx_SET (operands[0],
- gen_rtx_fmt_ee (XOR, mode, shift_dst,
- operands[1]));
- emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, xor_op, clobber)));
-
- rtx minus_op = gen_rtx_SET (operands[0],
- gen_rtx_fmt_ee (MINUS, mode,
- operands[0], shift_dst));
- emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, minus_op,
- clobber)));
+ rtx shift_amount = gen_int_mode (GET_MODE_PRECISION (mode) - 1, QImode);
+ rtx shift_dst = expand_simple_binop (mode, ASHIFTRT, operands[1],
+ shift_amount, NULL_RTX,
+ 0, OPTAB_DIRECT);
+ rtx xor_dst = expand_simple_binop (mode, XOR, shift_dst, operands[1],
+ operands[0], 0, OPTAB_DIRECT);
+ rtx minus_dst = expand_simple_binop (mode, MINUS, xor_dst, shift_dst,
+ operands[0], 0, OPTAB_DIRECT);
+ if (!rtx_equal_p (minus_dst, operands[0]))
+ emit_move_insn (operands[0], minus_dst);
DONE;
})
--- gcc/testsuite/gcc.dg/torture/pr93110.c.jj 2020-01-02 10:50:10.335895988
+0100
+++ gcc/testsuite/gcc.dg/torture/pr93110.c 2020-01-02 10:49:54.248142020
+0100
@@ -0,0 +1,9 @@
+/* PR target/93110 */
+/* { dg-do compile } */
+/* { dg-additional-options "-mtune=core2 -mno-stv" { target { i?86-*-*
x86_64-*-* } } } */
+
+long long
+foo (long long a)
+{
+ return a > 0 ? a : -a;
+}
Jakub
