If the pointer was loaded/stored before the null check, the check
is redundant and can be removed. For now the optimizers do not
remove the nullptr check, see https://gcc.godbolt.org/z/H2r5GG.
The patch allows to use more nonnull constraints. Also, it found
one more optimization in some PowerPC test. This is my first llvm
review, I am free to any comments.
Differential Revision: https://reviews.llvm.org/D71177
This is a resubmission of bbb29738b5 that
was reverted due to clang tests failures. It includes the fix and
additional IR tests for the missed case.
Summary:
In case when all incoming values of a PHI are equal pointers, this
transformation inserts a definition of such a pointer right after
definition of the base pointer and replaces with this value both PHI and
all it's incoming pointers. Primary goal of this transformation is
canonicalization of this pattern in order to enable optimizations that
can't handle PHIs. Non-inbounds pointers aren't currently supported.
Reviewers: spatel, RKSimon, lebedev.ri, apilipenko
Reviewed By: apilipenko
Tags: #llvm
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D68128
In case when all incoming values of a PHI are equal pointers, this
transformation inserts a definition of such a pointer right after
definition of the base pointer and replaces with this value both PHI and
all it's incoming pointers. Primary goal of this transformation is
canonicalization of this pattern in order to enable optimizations that
can't handle PHIs. Non-inbounds pointers aren't currently supported.
Reviewers: spatel, RKSimon, lebedev.ri, apilipenko
Reviewed By: apilipenko
Tags: #llvm
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D68128
Nikita Popov