https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61837
luoxhu at gcc dot gnu.org changed:
What |Removed |Added
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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
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