[ImplicitNullChecks] Check for rewrite of register used in 'test' instruction
The following code pattern:
mov %rax, %rcx
test %rax, %rax
%rax = ....
je throw_npe
mov(%rcx), %r9
mov(%rax), %r10
gets transformed into the following incorrect code after implicit null check pass:
mov %rax, %rcx
%rax = ....
faulting_load_op("movl (%rax), %r10", throw_npe)
mov(%rcx), %r9
For implicit null check pass, if the register that is checked for null value (ie, the register used in the 'test' instruction) is written into before the condition jump, we should avoid doing the optimization.
Patch by Surya Kumari Jangala!
Differential Revision: https://reviews.llvm.org/D48627
Reviewed By: skatkov
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@336241 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed