When calculating whether a value can safely overflow for use by an
icmp, we weren't checking that the value couldn't wrap around. To do
this we need the icmp to be using a constant, as well as the incoming
add or sub.
bugzilla report: https://bugs.llvm.org/show_bug.cgi?id=39060
Differential Revision: https://reviews.llvm.org/D52463
llvm-svn: 343092
Enabling ARMCodeGenPrepare by default caused a whole load of
failures. This is due to zexts and truncs not being handled properly.
ZExts are messy so it's just easier to disable for now and truncs
are allowed only as 'sinks'. I still need to figure out why allowing
them as 'sources' causes so many failures. The other main changes are
that we are explicit in the types that we converting to, it's now
always 'TypeSize'. Type support is also now performed while checking
for valid opcodes as it unnecessarily complicated having the checks
are different stages.
I've moved the tests around too, so we have the zext and truncs in
their own file as well as the overflowing opcode tests.
Differential Revision: https://reviews.llvm.org/D50518
llvm-svn: 339432
Sam Parker