We can't consider variable safe if out-of-lifetime access is possible.
So if StackLifetime can't prove that the instruction always uses
the variable when it's still alive, we consider it unsafe.
Usually DominatorTree provides this info, but here we use
StackLifetime. The reason is that in the next patch StackLifetime
will be used for actual lifetime checks and we can avoid
forwarding the DominatorTree into this code.
We don't need process paramenters which marked as
byval as we are not going to pass interested allocas
without copying.
If we pass value into byval argument, we just handle that
as Load of corresponding type and stop that branch of analysis.
Summary:
Treat scalable allocas as if they have storage size of 0, and
scalable-typed memory accesses as if their range is unlimited.
This is not a proper support of scalable vector types in the analysis -
we can do better, but not today.
Reviewers: vitalybuka
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73394
Summary:
IPA is implemented as module pass which produce map from Function or Alias to
StackSafetyInfo for a single function.
From prototype by Evgenii Stepanov and Vlad Tsyrklevich.
Reviewers: eugenis, vlad.tsyrklevich, pcc, glider
Subscribers: hiraditya, mgrang, llvm-commits
Differential Revision: https://reviews.llvm.org/D54543
llvm-svn: 347611
Summary:
Analysis produces StackSafetyInfo which contains information with how allocas
and parameters were used in functions.
From prototype by Evgenii Stepanov and Vlad Tsyrklevich.
Reviewers: eugenis, vlad.tsyrklevich, pcc, glider
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D54504
llvm-svn: 347603
Vitaly Buka