This is a very easily misused API since it allows for users to leak instructions
if they are not careful. This commit removes this API and replaces the small
number of uses of this API with higher level APIs that accomplish the same task
without using removeFromParent(). There were no API users that specifically
required removeFromParent.
An example of one way we were using removeFromParent is to move a SILInstruction
to the front of a block. That does not require exposing an API like
removeFromParent()... we can just create a higher level API like the one added
in this commit: SILInstruction::moveFront(SILBasicBlock *).
rdar://31276565
At some point, pass definitions were heavily macro-ized. Pass
descriptive names were added in two places. This is not only redundant
but a source of confusion. You could waste a lot of time grepping for
the wrong string. I removed all the getName() overrides which, at
around 90 passes, was a fairly significant amount of code bloat.
Any pass that we want to be able to invoke by name from a tool
(sil-opt) or pipeline plan *should* have unique type name, enum value,
commend-line string, and name string. I removed a comment about the
various inliner passes that contradicted that.
Side note: We should be consistent with the policy that a pass is
identified by its type. We have a couple passes, LICM and CSE, which
currently violate that convention.
We hit an assert in AllocStackHoisting that is only triggered in a release lto
build.
Clang forwards the read of parent basic block of 'AssignedLoc' in the next
statement:
auto *EntryBB = AssignedLoc->getFunction()->getEntryBlock(); // read AssignedLoc->ParentBB
AssignedLoc->removeFromParent(); // writes AssignedLoc->ParentBB
To this read:
EntryBB->push_front(AssignedLoc); // read AssignedLoc->ParentBB and assert if non-null, *should reload*
As a temporary workaround outline code to prevent the miscompile.
rdar://29982182
Hoist alloc_stack instructions of 'generic' or resilient type to the entry
block. At the same time also perform a very simple stack coloring analysis.
This does not use a true liveness-analysis yet but rather employs some simple
conservative checks to see whether the live ranges of two alloc_stacks might
interfere.
AllocStackHoisting is an IRGen SIL pass. This allows for using IRGen's type
lowering information. Furthermore, hoisting and merging the alloc_stack
instructions this late does not interfere with SIL optimizations because the
resulting SIL never gets serialized.
