This patch fixes a missed optimization issue: predicate infos might be
lost in phi-use scenarios.
Due to the existence of and-chains, a phi-use might be associated with
multiple LN_Last predicate infos.
E.g.,
```cpp
// TWO LN_Last Predicate Info defs:
// 1. a >= 1
// 2. a < 2
if ( a < 1 || a >= 2) {
a = 1;
}
// PHI use of `a`
use(a)
```
However, previously, `popStackUntilDFSScope` reserved only ONE LN_Last
def for a phi use (i.e., reserve only one of `a >= 1` / `a < 2`),
although there might be multiple LN_Last defs for the same phi use.
This patch reserves the adjacent LN_Last defs if they are designated for
the same phi use.
These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
Replacing the argument with a no-op bitcast violates a verifier
constraint, even if only temporarily. Any replacement based on it
would result in a violation even after the copy has been removed.
Fixes https://github.com/llvm/llvm-project/issues/153013.
PredicateInfo needs some no-op to which the predicate can be attached.
Currently this is an ssa.copy intrinsic. This PR replaces it with a
no-op bitcast.
Using a bitcast is more efficient because we don't have the overhead of
an overloaded intrinsic. It also makes things slightly simpler overall.
These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
Currently predicates are allocated on the heap and tracked with an
intrusive list. Use a bump pointer allocator instead, which is more
efficient. The list is no longer needed, as we don't have to track
predicates for freeing.
The bump pointer allocator is provided as a parameter for PredicateInfo
to allow reusing the same allocator for all functions during IPSCCP.
This pass creates a lot of ssa.copy intrinsics, typically for a small
set of types. Determining the function type, performing intrinsic name
mangling and looking up the declaration has noticeable overhead in this
case.
Improve this by caching the declarations by type. I've made this a
separate map from CreatedDeclarations, which only tracks the
declarations that were newly inserted (but not pre-existing ones).
Def is only actually used during renaming, and having it in ValueDFS
causes unnecessary confusion. Remove it from ValueDFS and instead use a
separate StackEntry structure for renaming, which holds the ValueDFS and
the Def.
The order in which we collect the predicates does not matter, as they
will be sorted anyway. As such, avoid the expensive depth first walk
over the dominator tree and instead use plain iteration over the
function.
(To be a bit more precise, the predicates and uses for a specific value
are sorted, so this change has no impact on that. It can change the
order in which values are processed in the first place, but that order
is not semantically relevant.)
The comparison function for ValueDFS was confused in a number of ways.
Most significantly, it had a bunch of logic based on Def -- however, Def
is always null during sorting, it only gets set later. At this point
defs only have PInfo set.
Clean up the implementation to remove various dead code.
EdgeOnly indicates a phi def, which can already be identified by
LN_Last with non-null PInfo. Most of the code already reasons in
terms of LN_Last instead of EdgeOnly.
As far as I can tell, this set is pointless: It just represents whether
the target block has multiple predecessors, and the way it is
constructed and queried, we're not even reducing the number of
getSinglePredecessor() calls or something like that.
Previously, PredicateAssume was modified to materialize after the assume
statement rather than before it (See 353fa44). Update relevant comments
to match this.
Rename the function to reflect its correct behavior and to be consistent
with `Module::getOrInsertFunction`. This is also in preparation of
adding a new `Intrinsic::getDeclaration` that will have behavior similar
to `Module::getFunction` (i.e, just lookup, no creation).
This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
This is a second attempt to fix the EXPENSIVE_CHECKS issue that was mentioned In D91661#2875179 by @jroelofs.
(The first attempt was in D105983)
D91661 more or less completely reverted D49126 and by doing so also removed the cleanup logic of the created declarations and calls.
This patch is a replacement for D91661 (which must itself be reverted first). It replaces the custom declaration creation with the
generic version and shows the test impact. It also tracks the number of NamedValues to detect if a new prototype was added instead
of looking at the available users of a prototype.
Reviewed By: jroelofs
Differential Revision: https://reviews.llvm.org/D106147
This reverts commit 77080a1eb6061df2dcfae8ac84b85ad4d1e02031.
This change introduced issues detected with EXPENSIVE_CHECKS. Reverting to restore the
needed function cleanup. A next patch will then just improve on the name mangling.
Now that intrinsic name mangling can cope with unnamed types, the custom name mangling in PredicateInfo (introduced by D49126) can be removed.
(See D91250, D48541)
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D91661
This reverts commit b7d870eae7fdadcf10d0f177faa7409c2e37d776 and the
subsequent fix "[Polly] Fix build after AssumptionCache change (D96168)"
(commit e6810cab09fcbc87b6e5e4d226de0810e2f2ea38).
It caused indeterminism in the output, such that e.g. the
polly-x86_64-linux buildbot failed accasionally.
PR49043 exposed a problem when it comes to RAUW llvm.assumes. While
D96106 would fix it for GVNSink, it seems a more general concern. To
avoid future problems this patch moves away from the vector of weak
reference model used in the assumption cache. Instead, we track the
llvm.assume calls with a callback handle which will remove itself from
the cache if the call is deleted.
Fixes PR49043.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D96168
Branch/assume conditions in PredicateInfo are currently handled in
a rather ad-hoc manner, with some arbitrary limitations. For example,
an `and` of two `icmp`s will be handled, but an `and` of an `icmp`
and some other condition will not. That also includes the case where
more than two conditions and and'ed together.
This patch makes the handling more general by looking through and/ors
up to a limit and considering all kinds of conditions (though operands
will only be taken for cmps of course).
Differential Revision: https://reviews.llvm.org/D94447
As long as RenamedOp is not guaranteed to be accurate, we cannot
assert here and should just return false. This was already done
for the other conditions in this function.
Fixes https://bugs.llvm.org/show_bug.cgi?id=46814.
Both users of predicteinfo (NewGVN and SCCP) are interested in
getting a cmp constraint on the predicated value. They currently
implement separate logic for this. This patch adds a common method
for this in PredicateBase.
This enables a missing bit of PredicateInfo handling in SCCP: Now
the predicate on the condition itself is also used. For switches
it means we know that the switched-on value is the same as the case
value. For assumes/branches we know that the condition is true or
false.
Differential Revision: https://reviews.llvm.org/D83640
This fixes warnings raised by Clang's new -Wsuggest-override, in preparation for enabling that warning in the LLVM build. This patch also removes the virtual keyword where redundant, but only in places where doing so improves consistency within a given file. It also removes a couple unnecessary virtual destructor declarations in derived classes where the destructor inherited from the base class is already virtual.
Differential Revision: https://reviews.llvm.org/D83709
Place the ssa.copy instructions for assumes after the assume,
instead of before it. Both options are valid, but placing them
afterwards prevents assumes from being replaced with assume(true).
This fixes https://bugs.llvm.org/show_bug.cgi?id=37541 in NewGVN
and will avoid a similar issue in SCCP when we handle more
predicate infos.
Differential Revision: https://reviews.llvm.org/D83631
OriginalOp of a predicate always refers to the original IR
value that was renamed. So for nested predicates of the same value, it
will always refer to the original IR value.
For the use in SCCP however, we need to find the renamed value that is
currently used in the condition associated with the predicate. This
patch adds a new RenamedOp field to do exactly that.
NewGVN currently relies on the existing behavior to merge instruction
metadata. A test case to check for exactly that has been added in
195fa4bfae10.
Reviewers: efriedma, davide, nikic
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D78133
The recently added Instruction::comesBefore can be used instead of
OrderedInstructions.
Reviewers: rnk, nikic, efriedma
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D78452
When running IPSCCP on a module with many small functions, memory
usage is dominated by PredicateInfo, which is a huge structure
(partially due to some unfortunate nested SmallVector use). However,
most of it is actually only temporary state needed to build
predicate info, and does not need to be retained after initial
construction.
This patch factors out the predicate building logic and state
into a separate PrediceInfoBuilder, with the extra bonus that
it does not need to live in the header anymore.
Differential Revision: https://reviews.llvm.org/D78326
This file lists every pass in LLVM, and is included by Pass.h, which is
very popular. Every time we add, remove, or rename a pass in LLVM, it
caused lots of recompilation.
I found this fact by looking at this table, which is sorted by the
number of times a file was changed over the last 100,000 git commits
multiplied by the number of object files that depend on it in the
current checkout:
recompiles touches affected_files header
342380 95 3604 llvm/include/llvm/ADT/STLExtras.h
314730 234 1345 llvm/include/llvm/InitializePasses.h
307036 118 2602 llvm/include/llvm/ADT/APInt.h
213049 59 3611 llvm/include/llvm/Support/MathExtras.h
170422 47 3626 llvm/include/llvm/Support/Compiler.h
162225 45 3605 llvm/include/llvm/ADT/Optional.h
158319 63 2513 llvm/include/llvm/ADT/Triple.h
140322 39 3598 llvm/include/llvm/ADT/StringRef.h
137647 59 2333 llvm/include/llvm/Support/Error.h
131619 73 1803 llvm/include/llvm/Support/FileSystem.h
Before this change, touching InitializePasses.h would cause 1345 files
to recompile. After this change, touching it only causes 550 compiles in
an incremental rebuild.
Reviewers: bkramer, asbirlea, bollu, jdoerfert
Differential Revision: https://reviews.llvm.org/D70211
