https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99888
Kewen Lin <linkw at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Ever confirmed|0 |1
CC| |linkw at gcc dot gnu.org
Last reconfirmed| |2022-08-03
Assignee|unassigned at gcc dot gnu.org |linkw at gcc dot gnu.org
--- Comment #1 from Kewen Lin <linkw at gcc dot gnu.org> ---
cat test.c
extern int a;
int foo (int b){
return a + b;
}
on ppc64le, with option "-mcpu=power9 -fpatchable-function-entry=5,3", the
generated assembly looks like:
.LPFE1:
nop
nop
nop
.type foo, @function
foo:
nop
nop
.LFB0:
.cfi_startproc
.LCF0:
0: addis 2,12,.TOC.-.LCF0@ha
addi 2,2,.TOC.-.LCF0@l
.localentry foo,.-foo
std 31,-8(1)
Jakub's #c0 noted that the "after" nops should be placed after local entry, but
there seem two choices to put the "before" nops, such as:
1)
0: addis 2,12,.TOC.-.LCF0@ha
addi 2,2,.TOC.-.LCF0@l
nop
nop
nop
.localentry foo,.-foo
nop
nop
std 31,-8(1)
2)
0: nop
nop
nop
addis 2,12,.TOC.-.LCF0@ha
addi 2,2,.TOC.-.LCF0@l
.localentry foo,.-foo
nop
nop
std 31,-8(1)
For either of them, the "before" nops only take effects when it's entered from
global entry, both are counted as five insns in global entry area, there is no
differences from these two perspectives. I'd like to go with 1) if no
objections.
