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From: "luoxhu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/61837] missed loop invariant expression optimization
Date: Tue, 07 Apr 2020 07:30:58 +0000 [thread overview]
Message-ID: <bug-61837-4-ahR3brQ4QZ@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-61837-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61837
luoxhu at gcc dot gnu.org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |luoxhu at gcc dot gnu.org
--- Comment #3 from luoxhu at gcc dot gnu.org ---
"addi 8,4,-1" and "subf 9,8,5" could not be hoisted out as there are dependency
to "lbzu 9,1(8)". r8 need be initialized to p2-1 in each iteration of outer
loop. Only the result of subf 9,8,5 is loop invariant (p2+s-1)-(p2-1).
But the latest GCC code could be optimized as A, B, C is loop invariant.
foo:
.LFB0:
.cfi_startproc
cmpwi 7,5,0
li 6,0
rldicl 5,5,0,32
li 7,0
.p2align 4,,15
.L2:
ble 7,.L7
addi 8,5,-1 // A
addi 10,4,-1
rldicl 8,8,0,32 // B
mr 9,3
addi 8,8,1 // C
mtctr 8
.p2align 5
.L4:
lbzu 8,1(10)
cmpw 0,8,7
bne 0,.L3
stw 6,0(9)
.L3:
addi 9,9,4
bdnz .L4
.L7:
addi 6,6,88
addi 7,7,1
cmpwi 0,6,8888
extsw 7,7
extsw 6,6
bne 0,.L2
blr
next parent reply other threads:[~2020-04-07 7:30 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-61837-4@http.gcc.gnu.org/bugzilla/>
2020-04-07 7:30 ` luoxhu at gcc dot gnu.org [this message]
2020-04-07 16:37 ` segher at gcc dot gnu.org
2020-04-13 10:31 ` luoxhu at gcc dot gnu.org
2020-04-14 6:42 ` segher at gcc dot gnu.org
2020-04-14 7:01 ` luoxhu at gcc dot gnu.org
2020-04-14 7:26 ` segher at gcc dot gnu.org
2020-04-14 7:52 ` luoxhu at gcc dot gnu.org
2020-04-14 10:37 ` rguenth at gcc dot gnu.org
2020-05-15 3:27 ` cvs-commit at gcc dot gnu.org
2021-07-29 0:43 ` cvs-commit at gcc dot gnu.org
2021-08-12 2:17 ` guojiufu at gcc dot gnu.org
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