These tests all follow the same pattern:
mov r2, r0
movs r0, #0
$CMP r2, r1
it eq
moveq r0, #1
bx lr
The first 'mov' can be eliminated by rematerializing 'movs r0, #0' below the
test instruction:
$CMP r0, r1
mov.w r0, #0
it eq
moveq r0, #1
bx lr
So far, only physreg coalescing can do that. The register allocators won't yet
split live ranges just to eliminate copies. They can learn, but this particular
problem is not likely to show up in real code. It only appears because r0 is
used for both the function argument and return value.
llvm-svn: 130858
comparison that would overflow.
- The other under/overflow cases can't actually happen because the immediates
which would trigger them are legal (so we don't enter this code), but
adjusted the style to make it clear the transform is always valid.
llvm-svn: 112053
Jakob Stoklund Olesen