There are some calls to functions like `__alloca` that are missing
a regmask operand that clobbers the FP registers. __alloca
only updates EAX and ESP so this isn't wrong. Becuase there is
no regmask the register allocator won't spill the FP registers
across the call. Assuming we want to preserve the FP stack for
these calls, we need to handle this is in the FP stackifier.
We might want to add a proper regmask operand to the code that
creates these calls, but we'd still need this change to the FP
stackifier if we preserve the FP stack.
The test is kind of long, but bugpoint wasn't able to reduce it