in function cryptcompress_truncate() from reiserfs4 patch
compiler uses __cmpdi2 for old_size vs new_size (64 bit) comparision:
result = (old_size < new_size ? cryptcompress_append_hole(inode, new_size) :
prune_cryptcompress(inode, new_size, update_sd, aidx));
in another case for simple foo() method gcc inlines __cmpdi2 equivalent:
int foo(long long x, long long y) { return (x < y); }
foo: cmpw 7,5,3
li 0,0
bgt- 7,.L3
cmplw 6,6,4
beq- 7,.L6
.L2: mr 3,0
blr
.L6: ble- 6,.L2
.L3: li 0,1
mr 3,0
blr
what decides which variant is chosen?
is it possible to force inlining?
# gcc-4.0.0+pr20973+pr21173
--
Summary: unnecessary __cmpdi2 usage?
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: other
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: pluto at pld-linux dot org
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i686-pld-linux
GCC host triplet: i686-pld-linux
GCC target triplet: ppc-pld-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21237
