https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108049
Bug ID: 108049
Summary: s390: Compiler adds extra zero extend after xoring 2
zero extended values
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: jens.seifert at de dot ibm.com
Target Milestone: ---
Same issue for PPC: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107949
extern unsigned char magic1[256];
unsigned int hash(const unsigned char inp[4])
{
const unsigned long long INIT = 0x1ULL;
unsigned long long h1 = INIT;
h1 = magic1[((unsigned long long)inp[0]) ^ h1];
h1 = magic1[((unsigned long long)inp[1]) ^ h1];
h1 = magic1[((unsigned long long)inp[2]) ^ h1];
h1 = magic1[((unsigned long long)inp[3]) ^ h1];
return h1;
}
hash(unsigned char const*):
llgc %r4,1(%r2) <= zero extends to 64-bit
lgrl %r1,.LC0
llgc %r3,0(%r2) <= zero extends to 64-bit
xilf %r3,1
llgc %r3,0(%r3,%r1)
xr %r3,%r4 <= should be 64-bit xor
llgc %r4,2(%r2) <= zero extends to 64-bit
llgcr %r3,%r3 <= unnecessary
llgc %r2,3(%r2)
llgc %r3,0(%r3,%r1)
xr %r3,%r4 <= should be 64-bit xor
llgcr %r3,%r3 <= unnecessary
llgc %r3,0(%r3,%r1) <= zero extends to 64-bit
xrk %r2,%r3,%r2 <= should be 64-bit xor
llgcr %r2,%r2 <= unnecessary
llgc %r2,0(%r2,%r1)
br %r14
Smaller sample:
unsigned long long tiny2(const unsigned char *inp)
{
unsigned long long a = inp[0];
unsigned long long b = inp[1];
return a ^ b;
}
tiny2(unsigned char const*):
llgc %r1,0(%r2)
llgc %r2,1(%r2)
xrk %r2,%r1,%r2
llgcr %r2,%r2
br %r14
