This patch effectively revert the past commit
9777d446e2148ef9a6e9f35db3f4eab99ee8812c.
Almost the only reason we committed that was because some optimizers in the
RTL ifcvt pass needed '(set (reg) (not (reg)))' RTX, however, in recent
versions of gcc, the equivalent optimizations are performed before RTL
passes, so the need for that commit has all but disappeared.
/* example 1 */
int test0(int a) {
return a < 0 ? ~a : a;
}
;; result 1
test0:
entry sp, 32
srai a8, a2, 31 ;; If-conversion before RTL expansion
xor a2, a8, a2
retw.n
Instead, expanding it to an XOR with a pseudo whose value of -1 early in
the RTL passes will take advantage of CSE, forward propagation, or loop-
invariant hoisting.
/* example 2 */
long long test1(long long a) {
return ~a;
}
void test2(int a[]) {
int i;
for (i = 0; i < 16; ++i)
a[i] = ~a[i];
}
;; result 2
test1:
entry sp, 32
movi.n a8, -1 ;; consolidated by CSE
xor a2, a2, a8
xor a3, a3, a8
retw.n
test2:
entry sp, 32
movi.n a10, -1 ;; hoisted out
movi.n a9, 0x10
loop a9, .L5_LEND
.L5:
l32i.n a8, a2, 0
xor a8, a8, a10
s32i.n a8, a2, 0
addi.n a2, a2, 4
.L5_LEND:
retw.n
Another concern with reverting that commit is the impact on complex insns
that have '(not)' as part of them, but also nothing to worry about; because
the RTL insn combiner can correctly recognize an XOR with a register value
of -1 as a one's complement operation even without such RTX, and apply the
result to subsequent combine operations.
gcc/ChangeLog:
* config/xtensa/xtensa.md (one_cmplsi2):
Rearrange back as an expand pattern.
gcc/testsuite/ChangeLog:
* gcc.target/xtensa/one_cmpl_abs.c: Remove.
---
gcc/config/xtensa/xtensa.md | 25 ++++++-------------
.../gcc.target/xtensa/one_cmpl_abs.c | 9 -------
2 files changed, 7 insertions(+), 27 deletions(-)
delete 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 374288df708..4ba7f54c940 100644
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -680,26 +680,15 @@
(set_attr "mode" "SI")
(set_attr "length" "3")])
-(define_insn_and_split "one_cmplsi2"
- [(set (match_operand:SI 0 "register_operand" "=a")
- (not:SI (match_operand:SI 1 "register_operand" "r")))]
+(define_expand "one_cmplsi2"
+ [(set (match_operand:SI 0 "register_operand")
+ (not:SI (match_operand:SI 1 "register_operand")))]
""
- "#"
- "&& can_create_pseudo_p ()"
- [(set (match_dup 2)
- (const_int -1))
- (set (match_dup 0)
- (xor:SI (match_dup 1)
- (match_dup 2)))]
{
- 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)))])
+ emit_insn (gen_xorsi3 (operands[0], operands[1],
+ force_reg (SImode, constm1_rtx)));
+ DONE;
+})
(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
deleted file mode 100644
index 608f65fd777..00000000000
--- a/gcc/testsuite/gcc.target/xtensa/one_cmpl_abs.c
+++ /dev/null
@@ -1,9 +0,0 @@
-/* { dg-do compile } */
-/* { dg-options "-O1" } */
-
-int one_cmpl_abs(int a)
-{
- return a < 0 ? ~a : a;
-}
-
-/* { dg-final { scan-assembler-not "bgez" } } */
--
2.39.5
