Fix a nasty problem on two-address machines in the following situation:
store EAX -> [ss#0]
[ss#0] += 1
...
use(EAX)
In this case, it is not valid to rewrite this as:
store EAX -> [ss#0]
EAX += 1
store EAX -> [ss#0] ;;; this would also delete the store above
...
use(EAX)
... because EAX is not a dead at that point. Keep track of which registers
we are allowed to clobber, and which ones we aren't, and don't clobber the
ones we're not supposed to. :)
This should resolve the issues on X86 last night.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25948 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed