I am doing this for a few different reasons:
1. The code for manipulating successors was partially in TermInst (with
SILBasicBlock delegating to TermInst) and partly in SILBasicBlock itself. It
makes more sense to just be consistent and move all said functionality into
TermInst and just always delegate to SILBasicBlock.
2. I am preparing an API around gathering all critical edges. All of the
critical edge breaking APIs to take a TermInst. I wanted to use some of the
successor APIs, only to discover that we were not delegating to TermInst. By
moving said functionality onto TermInst itself and delegating, we have it in
both places.
rdar://31521023
introduce a common superclass, SILNode.
This is in preparation for allowing instructions to have multiple
results. It is also a somewhat more elegant representation for
instructions that have zero results. Instructions that are known
to have exactly one result inherit from a class, SingleValueInstruction,
that subclasses both ValueBase and SILInstruction. Some care must be
taken when working with SILNode pointers and testing for equality;
please see the comment on SILNode for more information.
A number of SIL passes needed to be updated in order to handle this
new distinction between SIL values and SIL instructions.
Note that the SIL parser is now stricter about not trying to assign
a result value from an instruction (like 'return' or 'strong_retain')
that does not produce any.
Static initializers are now represented by a list of literal and aggregate instructions in a SILGlobalVariable.
For details see SIL.rst.
This representation is cleaner than what we did so far (point to the initializer function and do some pattern matching).
One implication of that change is that now (a subset of) instructions not necessarily have a parent function.
Regarding the generated code it's a NFC.
Also the swift module format didn't change because so far we don't serializer global variables.
addNodeToList only needs to be implemented to override the default callback
behavior of ilist_trait_defaults<SILBasicBlock>. This implmentation in
ilist_traits<SILBasicBlock> is exactly the same as the default callback so is
unnecessary.
This iterator is not actually a SILSuccessorIterator since it is not iterating
over the "successors" of a block. Instead it is used to given the head of a CFG
edge, iterate over the CFG edge's predecessors using the double linked list
stored inside SILSuccessor.
This rename/refactor ties SILSuccessor closer to SILSuccessorIterator and makes
it clear what we are actually iterating over.
I reversed this loop's direction over the instruction list and forgot to change
the order of erasing an instruction with respect to advancing the iterator.
Thankfully ASAN is far smarter than I.
Converting between forward/reverse iterators makes the loop unreadable.
Add an iterator return value to BasicBlock::erase(SILInstruction*).
This commit does a few things:
1. It uses SwitchEnumBuilder so we are not re-inventing any wheels.
2. Instead of hacking around not putting in a destroy for .None on the fail
pass, just *do the right thing* and recognize that we have a binary case enum
and in such a case, just emit code for the other case rather than use a default
case (meaning no cleanup on .none).
rdar://31145255
There are a few different use cases here:
1. In Raw SIL, no return folding may not have been run yet implying that a call
to a no-return function /can/ have arbitrary control flow after it (consider
mandatory inlined functions). We need to recognize that the region of code that
is strictly post dominated by the no-return function is "transitively
unreachable" and thus leaking is ok from that point. *Footnote 1*.
2. In Canonical and Raw SIL, we must recognize that unreachables and no-return
functions constitute places where we are allowed to leak.
rdar://29791263
----
*Footnote 1*: The reason why this is done is since we want to emit unreachable
code diagnostics when we run no-return folding. By leaving in the relevant code,
we have preserved all of the SILLocations on that code allowing us to create
really nice diagnostics.
Separate formal lowered types from SIL types.
The SIL type of an argument will depend on the SIL module's conventions.
The module conventions are determined by the SIL stage and LangOpts.
Almost NFC, but specialized manglings are broken incidentally as a result of
fixes to the way passes handle book-keeping of aruments. The mangler is fixed in
the subsequent commit.
Otherwise, NFC is intended, but quite possible do to rewriting the logic in many
places.
Most of this involved sprinkling ValueOwnershipKind::Owned in many places. In
some of these places, I am sure I was too cavalier and I expect some of them to
be trivial. The verifier will help me to track those down.
On the other hand, I do expect there to be some places where we are willing to
accept guaranteed+trivial or owned+trivial. In those cases, I am going to
provide an aggregate ValueOwnershipKind that will then tell SILArgument that it
should disambiguate using the type. This will eliminate the ackwardness from
such code.
I am going to use a verifier to fix such cases.
This commit also begins the serialization of ValueOwnershipKind of arguments,
but does not implement parsing of value ownership kinds. That and undef are the
last places that we still use ValueOwnershipKind::Any.
rdar://29791263
This in the case of insertFunctionArgument requires a ValueOwnershipKind to be
specified since we use that for transformations of function argument lists that
are only correct after the transformation is complete. This only occurs in
FunctionSignatureOptimizations.
On the other hand, createFunctionArgument is only used to construct completely
new argument lists, so we can instead just rely on the function we are in rather
than require the user to pass it in.
rdar://29791263
We preserve the current behavior of assuming Any ownership always and use
default arguments to hide this change most of the time. There are asserts now in
the SILBasicBlock::{create,replace,insert}{PHI,Function}Argument to ensure that
the people can only create SILFunctionArguments in entry blocks and
SILPHIArguments in non-entry blocks. This will ensure that the code in tree
maintains the API distinction even if we are not using the full distinction in
between the two.
Once the verifier is finished being upstreamed, I am going to audit the
createPHIArgument cases for the proper ownership. This is b/c I will be able to
use the verifier to properly debug the code. At that point, I will also start
serializing/printing/parsing the ownershipkind of SILPHIArguments, but lets take
things one step at a time and move incrementally.
In the process, I also discovered a CSE bug. I am not sure how it ever worked.
Basically we replace an argument with a new argument type but return the uses of
the old argument to refer to the old argument instead of a new argument.
rdar://29671437
For a long time, we have:
1. Created methods on SILArgument that only work on either function arguments or
block arguments.
2. Created code paths in the compiler that only allow for "function"
SILArguments or "block" SILArguments.
This commit refactors SILArgument into two subclasses, SILPHIArgument and
SILFunctionArgument, separates the function and block APIs onto the subclasses
(leaving the common APIs on SILArgument). It also goes through and changes all
places in the compiler that conditionalize on one of the forms of SILArgument to
just use the relevant subclass. This is made easier by the relevant APIs not
being on SILArgument anymore. If you take a quick look through you will see that
the API now expresses a lot more of its intention.
The reason why I am performing this refactoring now is that SILFunctionArguments
have a ValueOwnershipKind defined by the given function's signature. On the
other hand, SILBlockArguments have a stored ValueOwnershipKind. Rather than
store ValueOwnershipKind in both instances and in the function case have a dead
variable, I decided to just bite the bullet and fix this.
rdar://29671437
This was already done for getSuccessorBlocks() to distinguish getting successor
blocks from getting the full list of SILSuccessors via getSuccessors(). This
commit just makes all of the successor/predecessor code follow that naming
convention.
Some examples:
getSingleSuccessor() => getSingleSuccessorBlock().
isSuccessor() => isSuccessorBlock().
getPreds() => getPredecessorBlocks().
Really, IMO, we should consider renaming SILSuccessor to a more verbose name so
that it is clear that it is more of an internal detail of SILBasicBlock's
implementation rather than something that one should consider as apart of one's
mental model of the IR when one really wants to be thinking about predecessor
and successor blocks. But that is not what this commit is trying to change, it
is just trying to eliminate a bit of technical debt by making the naming
conventions here consistent.
Before this commit all code relating to handling arguments in SILBasicBlock had
somewhere in the name BB. This is redundant given that the class's name is
already SILBasicBlock. This commit drops those names.
Some examples:
getBBArg() => getArgument()
BBArgList => ArgumentList
bbarg_begin() => args_begin()
This eliminates all inline creation of SILBasicBlock via placement new.
There are a few reasons to do this:
1. A SILBasicBlock is always created with a parent function. This commit
formalizes this into the SILBasicBlock API by only allowing for SILFunctions to
create SILBasicBlocks. This is implemented via the type system by making all
SILBasicBlock constructors private. Since SILFunction is a friend of
SILBasicBlock, SILFunction can still create a SILBasicBlock without issue.
2. Since all SILBasicBlocks will be created in only a few functions, it becomes
very easy to determine using instruments the amount of memory being allocated
for SILBasicBlocks by simply inverting the call tree in Allocations.
With LTO+PGO, normal inlining can occur if profitable so there shouldn't be
overhead that we care about in shipping compilers.
This just runs a transform range on getSuccessor()'s ArrayRef<SILSuccessor> so
one does not need to always call Successor.getBB() when iterating over successor
blocks. Instead the transform range does that call for you.
I also updated some loops to use this new SILBasicBlock method to make sure that
the code is tested out by tests that are already in tree. All these places
should be functionally the same albeit a bit cleaner.
Use malloc/free for allocating/freeing SIL instructions instead of using the BumpPtrAllocator. This allows for memory reuse and significantly reduces the memory footprint of the compiler.
For example, a peak memory usage during a compilation of the standard library and StdlibUnitTest is reduced by 25%-30%. The performance of the compiler seems to be not affected by this change, i.e. no slowdown is measured.
The use-after-free issues reported by build bots are fixed now.
rdar://23303031
Hubris is my name. = /. I put in a verifier check to make sure that we can
properly look up some value and if we have two blocks related via a non-local
successor chain, the first is a CFG level successor of the second.
Swift SVN r32759
