[3/4] xtensa: Optimize '(~x & y)' to '((x & y) ^ y)'
Commit Message
In Xtensa ISA, there is no single machine instruction that calculates unary
bitwise negation.
gcc/ChangeLog:
* config/xtensa/xtensa.md (*andsi3_bitcmpl):
New insn_and_split pattern.
gcc/testsuite/ChangeLog:
* gcc.target/xtensa/check_zero_byte.c: New.
---
gcc/config/xtensa/xtensa.md | 20 +++++++++++++++++++
.../gcc.target/xtensa/check_zero_byte.c | 9 +++++++++
2 files changed, 29 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/xtensa/check_zero_byte.c
Comments
On Sun, May 29, 2022 at 4:00 AM Takayuki 'January June' Suwa
<jjsuwa_sys3175@yahoo.co.jp> wrote:
>
> In Xtensa ISA, there is no single machine instruction that calculates unary
> bitwise negation.
>
> gcc/ChangeLog:
>
> * config/xtensa/xtensa.md (*andsi3_bitcmpl):
> New insn_and_split pattern.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/xtensa/check_zero_byte.c: New.
> ---
> gcc/config/xtensa/xtensa.md | 20 +++++++++++++++++++
> .../gcc.target/xtensa/check_zero_byte.c | 9 +++++++++
> 2 files changed, 29 insertions(+)
> create mode 100644 gcc/testsuite/gcc.target/xtensa/check_zero_byte.c
Regtested for target=xtensa-linux-uclibc, no new regressions.
Committed to master.
@@ -601,6 +601,26 @@
(set_attr "mode" "SI")
(set_attr "length" "3,3")])
+(define_insn_and_split "*andsi3_bitcmpl"
+ [(set (match_operand:SI 0 "register_operand" "=a")
+ (and:SI (not:SI (match_operand:SI 1 "register_operand" "r"))
+ (match_operand:SI 2 "register_operand" "r")))]
+ ""
+ "#"
+ "&& can_create_pseudo_p ()"
+ [(set (match_dup 3)
+ (and:SI (match_dup 1)
+ (match_dup 2)))
+ (set (match_dup 0)
+ (xor:SI (match_dup 3)
+ (match_dup 2)))]
+{
+ operands[3] = gen_reg_rtx (SImode);
+}
+ [(set_attr "type" "arith")
+ (set_attr "mode" "SI")
+ (set_attr "length" "6")])
+
(define_insn "iorsi3"
[(set (match_operand:SI 0 "register_operand" "=a")
(ior:SI (match_operand:SI 1 "register_operand" "%r")
b/gcc/testsuite/gcc.target/xtensa/check_zero_byte.c
new file mode 100644
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+int check_zero_byte(int v)
+{
+ return (v - 0x01010101) & ~v & 0x80808080;
+}
+
+/* { dg-final { scan-assembler-not "movi" } } */