Fold the PPCISD shifts when presented with 0 inputs. This occurs for code
like:
long long test(long long X, int Y) {
return 1ULL << Y;
}
long long test2(long long X, int Y) {
return -1LL << Y;
}
which we used to compile to:
_test:
li r2, 1
subfic r3, r5, 32
li r4, 0
addi r6, r5, -32
srw r3, r2, r3
slw r4, r4, r5
slw r6, r2, r6
or r3, r4, r3
slw r4, r2, r5
or r3, r3, r6
blr
_test2:
li r2, -1
subfic r3, r5, 32
addi r6, r5, -32
srw r3, r2, r3
slw r4, r2, r5
slw r2, r2, r6
or r3, r4, r3
or r3, r3, r2
blr
Now we produce:
_test:
li r2, 1
addi r3, r5, -32
subfic r4, r5, 32
slw r3, r2, r3
srw r4, r2, r4
or r3, r4, r3
slw r4, r2, r5
blr
_test2:
li r2, -1
subfic r3, r5, 32
addi r6, r5, -32
srw r3, r2, r3
slw r4, r2, r5
slw r2, r2, r6
or r3, r4, r3
or r3, r3, r2
blr
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30479 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed