In Xtensa ISA, there is no single machine instruction that calculates unary
bitwise negation. But a few optimizers assume that bitwise negation can be
done by a single insn.
As a result, '((x < 0) ? ~x : x)' cannot be optimized to '(x ^ (x >> 31))'
ever before, for example.
This patch relaxes such limitation, by putting the insn expansion off till
the split pass.
gcc/ChangeLog:
* config/xtensa/xtensa.md (one_cmplsi2):
Rearrange as an insn_and_split pattern.
gcc/testsuite/ChangeLog:
* gcc.target/xtensa/one_cmpl_abs.c: New.
---
gcc/config/xtensa/xtensa.md | 26 +++++++++++++------
.../gcc.target/xtensa/one_cmpl_abs.c | 9 +++++++
2 files changed, 27 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/xtensa/one_cmpl_abs.c
diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
index 217879bde15..f11ae4910f8 100644
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -556,16 +556,26 @@
(set_attr "mode" "SI")
(set_attr "length" "3")])
-(define_expand "one_cmplsi2"
- [(set (match_operand:SI 0 "register_operand" "")
- (not:SI (match_operand:SI 1 "register_operand" "")))]
+(define_insn_and_split "one_cmplsi2"
+ [(set (match_operand:SI 0 "register_operand" "=a")
+ (not:SI (match_operand:SI 1 "register_operand" "r")))]
""
+ "#"
+ "&& can_create_pseudo_p ()"
+ [(set (match_dup 2)
+ (const_int -1))
+ (set (match_dup 0)
+ (xor:SI (match_dup 1)
+ (match_dup 2)))]
{
- rtx temp = gen_reg_rtx (SImode);
- emit_insn (gen_movsi (temp, constm1_rtx));
- emit_insn (gen_xorsi3 (operands[0], temp, operands[1]));
- DONE;
-})
+ operands[2] = gen_reg_rtx (SImode);
+}
+ [(set_attr "type" "arith")
+ (set_attr "mode" "SI")
+ (set (attr "length")
+ (if_then_else (match_test "TARGET_DENSITY")
+ (const_int 5)
+ (const_int 6)))])
(define_insn "negsf2"
[(set (match_operand:SF 0 "register_operand" "=f")
diff --git a/gcc/testsuite/gcc.target/xtensa/one_cmpl_abs.c
b/gcc/testsuite/gcc.target/xtensa/one_cmpl_abs.c
new file mode 100644
index 00000000000..608f65fd777
--- /dev/null
+++ b/gcc/testsuite/gcc.target/xtensa/one_cmpl_abs.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+int one_cmpl_abs(int a)
+{
+ return a < 0 ? ~a : a;
+}
+
+/* { dg-final { scan-assembler-not "bgez" } } */
--
2.20.1
