Hi!
Before combiner added 2 to 2 combinations, the following testcase functions
have been all compiled into 2 instructions, zero/sign extensions or and
followed by orr with lsl, e.g. for the first function
Trying 7 -> 8:
7: r96:SI=r94:SI<<0xb
8: r95:SI=r96:SI|r94:SI
REG_DEAD r96:SI
REG_DEAD r94:SI
Successfully matched this instruction:
(set (reg:SI 95)
(ior:SI (ashift:SI (reg/v:SI 94 [ i ])
(const_int 11 [0xb]))
(reg/v:SI 94 [ i ])))
is the important successful try_combine and so we end up with
and w0, w0, 255
orr w0, w0, w0, lsl 11
in the body.
With 2 to 2 combination, before that can trigger, another successful
combination:
Trying 2 -> 7:
2: r94:SI=zero_extend(x0:QI)
REG_DEAD x0:QI
7: r96:SI=r94:SI<<0xb
is replaced with:
(set (reg/v:SI 94 [ i ])
(zero_extend:SI (reg:QI 0 x0 [ i ])))
and
(set (reg:SI 96)
(and:SI (ashift:SI (reg:SI 0 x0 [ i ])
(const_int 11 [0xb]))
(const_int 522240 [0x7f800])))
and in the end results in 3 instructions in the body:
and w1, w0, 255
ubfiz w0, w0, 11, 8
orr w0, w0, w1
The following combine splitters help undo that when combiner tries to
combine 3 instructions - the zero/sign extend or and, the other insn
from the 2 to 2 combination ([us]bfiz) and the logical op, the CPUs
don't have an insn to do everything in one op, but we can split it
back into the zero/sign extend or and followed by logical with lsl.
Bootstrapped/regtested on aarch64-linux, ok for trunk?
2021-04-14 Jakub Jelinek <ja...@redhat.com>
PR target/100056
* config/aarch64/aarch64.md (*<LOGICAL:optab>_<SHIFT:optab><mode>3):
Add combine splitters for *<LOGICAL:optab>_ashl<mode>3 with
ZERO_EXTEND, SIGN_EXTEND or AND.
* gcc.target/aarch64/pr100056.c: New test.
--- gcc/config/aarch64/aarch64.md.jj 2021-04-13 12:40:57.000000000 +0200
+++ gcc/config/aarch64/aarch64.md 2021-04-13 19:54:17.015764651 +0200
@@ -4431,6 +4431,59 @@ (define_insn "*<LOGICAL:optab>_<SHIFT:op
[(set_attr "type" "logic_shift_imm")]
)
+(define_split
+ [(set (match_operand:GPI 0 "register_operand")
+ (LOGICAL:GPI
+ (and:GPI (ashift:GPI (match_operand:GPI 1 "register_operand")
+ (match_operand:QI 2 "aarch64_shift_imm_<mode>"))
+ (match_operand:GPI 4 "const_int_operand"))
+ (zero_extend:GPI (match_operand 3 "register_operand"))))]
+ "can_create_pseudo_p ()
+ && REG_P (operands[1])
+ && REG_P (operands[3])
+ && REGNO (operands[1]) == REGNO (operands[3])
+ && ((unsigned HOST_WIDE_INT)
+ trunc_int_for_mode (GET_MODE_MASK (GET_MODE (operands[3]))
+ << INTVAL (operands[2]), <MODE>mode)
+ == UINTVAL (operands[4]))"
+ [(set (match_dup 4) (zero_extend:GPI (match_dup 3)))
+ (set (match_dup 0) (LOGICAL:GPI (ashift:GPI (match_dup 4) (match_dup 2))
+ (match_dup 4)))]
+ "operands[4] = gen_reg_rtx (<MODE>mode);"
+)
+
+(define_split
+ [(set (match_operand:GPI 0 "register_operand")
+ (LOGICAL:GPI
+ (and:GPI (ashift:GPI (match_operand:GPI 1 "register_operand")
+ (match_operand:QI 2 "aarch64_shift_imm_<mode>"))
+ (match_operand:GPI 4 "const_int_operand"))
+ (and:GPI (match_dup 1) (match_operand:GPI 3 "const_int_operand"))))]
+ "can_create_pseudo_p ()
+ && pow2_or_zerop (UINTVAL (operands[3]) + 1)
+ && ((unsigned HOST_WIDE_INT)
+ trunc_int_for_mode (UINTVAL (operands[3])
+ << INTVAL (operands[2]), <MODE>mode)
+ == UINTVAL (operands[4]))"
+ [(set (match_dup 4) (and:GPI (match_dup 1) (match_dup 3)))
+ (set (match_dup 0) (LOGICAL:GPI (ashift:GPI (match_dup 4) (match_dup 2))
+ (match_dup 4)))]
+ "operands[4] = gen_reg_rtx (<MODE>mode);"
+)
+
+(define_split
+ [(set (match_operand:GPI 0 "register_operand")
+ (LOGICAL:GPI
+ (ashift:GPI (sign_extend:GPI (match_operand 1 "register_operand"))
+ (match_operand:QI 2 "aarch64_shift_imm_<mode>"))
+ (sign_extend:GPI (match_dup 1))))]
+ "can_create_pseudo_p ()"
+ [(set (match_dup 4) (sign_extend:GPI (match_dup 1)))
+ (set (match_dup 0) (LOGICAL:GPI (ashift:GPI (match_dup 4) (match_dup 2))
+ (match_dup 4)))]
+ "operands[4] = gen_reg_rtx (<MODE>mode);"
+)
+
(define_insn "*<optab>_rol<mode>3"
[(set (match_operand:GPI 0 "register_operand" "=r")
(LOGICAL:GPI (rotate:GPI
--- gcc/testsuite/gcc.target/aarch64/pr100056.c.jj 2021-04-13
14:20:53.334784184 +0200
+++ gcc/testsuite/gcc.target/aarch64/pr100056.c 2021-04-13 19:44:09.358529648
+0200
@@ -0,0 +1,50 @@
+/* PR target/100056 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-not {\t[us]bfiz\tw[0-9]+, w[0-9]+, 11} } } */
+
+int
+or_shift_u8 (unsigned char i)
+{
+ return i | (i << 11);
+}
+
+int
+or_shift_u3a (unsigned i)
+{
+ i &= 7;
+ return i | (i << 11);
+}
+
+int
+or_shift_u3b (unsigned i)
+{
+ i = (i << 29) >> 29;
+ return i | (i << 11);
+}
+
+int
+or_shift_s16 (signed short i)
+{
+ return i | (i << 11);
+}
+
+int
+or_shift_s8 (signed char i)
+{
+ return i | (i << 11);
+}
+
+int
+or_shift_s13 (int i)
+{
+ i = (i << 19) >> 19;
+ return i | (i << 11);
+}
+
+int
+or_shift_s3 (int i)
+{
+ i = (i << 29) >> 29;
+ return i | (i << 11);
+}
Jakub
