https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87727
--- Comment #4 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> Most likely r265398, i.e. another far-reaching RTL change like r264897.
The change seems to be a clear pessimization on SPARC, especially on small
functions where there is often
mov %o0, %g1
at the beginning now. That's the cant_combine_insn_p part alone (I don't
really understand make_more_copies, it looks redundant with the other part).
--- gcc.0/920608-1.s Sat Nov 17 09:40:14 2018
+++ gcc.1/920608-1.s Sat Nov 17 09:44:54 2018
@@ -13,9 +13,8 @@
.type bar, #function
.proc 04
bar:
- mov %o0, %g1
+ ldsh [%o0+2], %g1
mov 0, %o0
- ldsh [%g1+2], %g1
cmp %g1, 44
jmp %o7+8
movle %icc, 1, %o0
--- gcc.0/930503-1.s Sat Nov 17 09:40:15 2018
+++ gcc.1/930503-1.s Sat Nov 17 09:44:54 2018
@@ -5,12 +5,10 @@
.type f, #function
.proc 04
f:
- mov %o0, %g4
- mov %o1, %g3
mov 0, %g1
.LL2:
- ldub [%g4+%g1], %g2
- stb %g2, [%g3+%g1]
+ ldub [%o0+%g1], %g2
+ stb %g2, [%o1+%g1]
ba,pt %xcc, .LL2
add %g1, 1, %g1
.size f, .-f
--- gcc.0/941014-1.s Sat Nov 17 09:40:15 2018
+++ gcc.1/941014-1.s Sat Nov 17 09:44:54 2018
@@ -5,8 +5,7 @@
.type f, #function
.proc 04
f:
- mov %o0, %g2
- stb %g0, [%g2]
+ stb %g0, [%o0]
jmp %o7+8
mov %g1, %o0
.size f, .-f
--- gcc.0/HIcmp.s Sat Nov 17 09:40:16 2018
+++ gcc.1/HIcmp.s Sat Nov 17 09:44:56 2018
@@ -30,9 +30,8 @@
.type reg0imm1, #function
.proc 04
reg0imm1:
- mov %o0, %g1
+ sll %o0, 16, %g1
mov 0, %o0
- sll %g1, 16, %g1
sra %g1, 16, %g1
cmp %g1, 33
jmp %o7+8
--- gcc.0/aos.s Sat Nov 17 09:40:15 2018
+++ gcc.1/aos.s Sat Nov 17 09:44:55 2018
@@ -5,9 +5,8 @@
.type foo, #function
.proc 04
foo:
- mov %o0, %g1
+ cmp %o0, 0
mov 0, %o0
- cmp %g1, 0
jmp %o7+8
movg %icc, 1, %o0
.size foo, .-foo
--- gcc.0/b1.s Sat Nov 17 09:40:16 2018
+++ gcc.1/b1.s Sat Nov 17 09:44:55 2018
@@ -6,10 +6,9 @@
.proc 04
foo:
orcc %o0, %o1, %g0
- mov 255, %g1
- move %icc, 0, %g1
+ mov 255, %o0
jmp %o7+8
- mov %g1, %o0
+ move %icc, 0, %o0
--- gcc.0/complex-1.s Sat Nov 17 09:40:16 2018
+++ gcc.1/complex-1.s Sat Nov 17 09:44:55 2018
@@ -16,9 +16,8 @@
.type g, #function
.proc 020
g:
- mov %o0, %g1
+ ld [%o0], %o1
mov 0, %o0
- ld [%g1], %o1
or %o7, %g0, %g1
call v, 0
or %g1, %g0, %o7
--- gcc.0/stor.s Sat Nov 17 09:40:20 2018
+++ gcc.1/stor.s Sat Nov 17 09:45:00 2018
@@ -12,8 +12,7 @@
st %g2, [%g1+8]
st %g2, [%g1+12]
st %g2, [%g1+16]
- st %g2, [%g1+20]
jmp %o7+8
- mov %g3, %o0
+ st %g2, [%g1+20]
.size foo, .-foo
Another annoying effect
--- gcc.0/pr34966.s Sat Nov 17 09:40:17 2018
+++ gcc.1/pr34966.s Sat Nov 17 09:44:57 2018
@@ -16,11 +16,9 @@
.type f, #function
.proc 07
f:
- save %sp, -120, %sp
- std %i0, [%fp-24]
- ldd [%fp-24], %f8
+ save %sp, -112, %sp
stx %g0, [%fp-16]
- std %f8, [%fp-8]
+ std %i0, [%fp-8]
call cexp, 0
add %fp, -16, %o0
return %i7+8
[-] is the baseline
[+] is with the change reverted
