Fixes https://github.com/llvm/llvm-project/issues/170051
The previous implementation allows splitting the successor if it's the
loop header, regardless of whether the terminator of `this` is
analyzable.
This addresses a performance issue for our downstream GPU target that
sets requiresStructuredCFG to true. The issue is that EarlyMachineLICM
pass does not hoist loop invariants because a critical edge is not
split.
The critical edge's destination a loop header. Splitting the critical
edge will not break structured CFG.
Add a nvptx test to demonstrate the issue since the target also
requires structured CFG.
---------
Co-authored-by: Matt Arsenault <arsenm2@gmail.com>
Post-RA machine sinking could sink a copy of sub-register into
a successor. However, the sub-register might not be removed from the
live-in bitmask of its super register in successor and then a later
pass, e.g, if-converter, may add an implicit use of the register from
live-in resulting in an use of an undefined register. This change makes
sure subrange of live-ins from super register could be removed as well.
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.
Part of the coverage-tracking feature, following #107279.
In order for DebugLoc coverage testing to work, we firstly have to set
annotations for intentionally-empty DebugLocs, and secondly we have to
ensure that we do not drop these annotations as we propagate DebugLocs
throughout compilation. As the annotations exist as part of the DebugLoc
class, and not the underlying DILocation, they will not survive a
DebugLoc->DILocation->DebugLoc roundtrip. Therefore this patch modifies
a number of places in the compiler to propagate DebugLocs directly
rather than via the underlying DILocation. This has no effect on the
output of normal builds; it only ensures that during coverage builds, we
do not drop incorrectly annotations and therefore create false
positives.
The bulk of these changes are in replacing
DILocation::getMergedLocation(s) with a DebugLoc equivalent, and in
changing the IRBuilder to store a DebugLoc directly rather than storing
DILocations in its general Metadata array. We also use a new function,
`DebugLoc::orElse`, which selects the "best" DebugLoc out of a pair
(valid location > annotated > empty), preferring the current DebugLoc on
a tie - this encapsulates the existing behaviour at a few sites where we
_may_ assign a DebugLoc to an existing instruction, while extending the
logic to handle annotation DebugLocs at the same time.
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.
- Move `MIPrinter` class to anonymous namespace, and remove it as a
friend of `MachineBasicBlock`.
- Move `canPredictBranchProbabilities` to `MachineBasicBlock` and change
it to use the new `BranchProbability::normalizeProbabilities` function
that accepts a range, and also to use `llvm::equal()` to check equality
of the two vectors.
- Use `ListSeparator` to print comma separate lists instead of manual
code to do that.
This relands commit #115111.
Use traditional way to update post dominator tree, i.e. break critical
edge splitting into insert, insert, delete sequence.
When splitting critical edges, the post dominator tree may change its
root node, and `setNewRoot` only works in normal dominator tree...
See
6c7e5827ed/llvm/include/llvm/Support/GenericDomTree.h (L684-L687)
Summary:
- Remove wrappers in `MachineDominatorTree`.
- Remove `MachineDominatorTree` update code in
`MachineBasicBlock::SplitCriticalEdge`.
- Use `MachineDomTreeUpdater` in passes which call
`MachineBasicBlock::SplitCriticalEdge` and preserve
`MachineDominatorTreeWrapperPass` or CFG analyses.
Commit abea99f65a97248974c02a5544eaf25fc4240056 introduced related
methods in 2014. Now we have SemiNCA based dominator tree in 2017 and
dominator tree updater, the solution adopted here seems a bit outdated.
- Add `LiveIntervalsAnalysis`.
- Add `LiveIntervalsPrinterPass`.
- Use `LiveIntervalsWrapperPass` in legacy pass manager.
- Use `std::unique_ptr` instead of raw pointer for `LICalc`, so
destructor and default move constructor can handle it correctly.
This would be the last analysis required by `PHIElimination`.
This reverts commit 0f8849349ae3d3f2f537ad6ab233a586fb39d375.
Resolve conflict in `MachinePostDominators.h` There is a conflict after
merging #96378, resolved in #96852. Both PRs modified
`MachinePostDominators.h` and triggered build failure.
This commit converts most of `DomTreeUpdater` into
`GenericDomTreeUpdater` class template, so IR and MIR can reuse some
codes.
There are some differences between interfaces of `BasicBlock` and
`MachineBasicBlock`, so subclasses still need to implement some
functions, like `forceFlushDeletedBB`.
Internal label names never occur in the symbol table, so when using an
object streamer, there's no point in constructing these names and then
adding them to hash tables -- they are never visible in the output.
It's not possible to reuse createTempSymbol, because on BPF has a
different prefix for globals and basic blocks right now.
Prepare for new pass manager version of `MachineDominatorTreeAnalysis`.
We may need a machine dominator tree version of `DomTreeUpdater` to
handle `SplitCriticalEdge` in some CodeGen passes.
Some small changes to recomputeLiveIns() to improve performance:
- Instead of copying the list of old live-ins, and then clearing
them, a new method swaps the list for an empty one.
- getLiveIns() now returns a constant reference to the list
As result, the list-data is never copied. Depending on the
implementation
details of the vector container, it can also save calls to allocate
and deallocate memory.
I see a small improvement on CTMark with these changes.
---------
Co-authored-by: Nikita Popov <github@npopov.com>
In SplitCriticalEdge, DebugLoc of the branch instruction in new created
MBB was set to empty. It should be set and we can find proper DebugLoc
for it in most cases. This patch set it to non empty merged DebugLoc of
current MBB branches.
We adjust the insertion point at the BB top for spills/copies during RA
to ensure they are placed after the exec restore instructions required
for the divergent control flow execution. This is, however, required
only for the vector operations. The insertions for scalar registers can
still go to the BB top.
Add subrange tracking and handling for LiveIntervals during PHI
elimination.
This requires extending MachineBasicBlock::SplitCriticalEdge to also
update subrange intervals.
28b9126879
introduced the path cloning format in the basic-block-sections profile.
This PR validates and applies path clonings.
A path cloning is valid if all of these conditions hold:
1. All bb ids in the path are mapped to existing blocks.
2. Each two consecutive bb ids in the path have a successor relationship
in the CFG.
3. The path does not include a block with indirect branches, except
possibly as the last block.
Applying a path cloning involves cloning all blocks in the path (except
the first one) and setting up their branches.
Once all clonings are applied, the cluster information is used to guide
block layout in the modified function.
Follow up fix for #68786 to address that MachineFunction handleInsertion
is actually called before a new instruction has been inserted into the
block. Hence new instructions must be recorded and SlotIndex updates
performed after the delegate call.
Remove use after free when attempting to update SlotIndexes in
MachineBasicBlock::SplitCriticalEdge.
Use MachineFunction delegate mechanism to capture target specific
manipulations of branch instructions and update SlotIndexes.
Temporal divergence that was present in input or introduced in IR
transforms, like code-sinking or LICM, is handled in SIFixSGPRCopies
by changing sgpr source instr to vgpr instr.
After 5b657f5, that moved LICM after AMDGPUCodeGenPrepare,
machine-sinking can introduce temporal divergence by sinking
instructions outside of the cycle.
Add isSafeToSink callback in TargetInstrInfo.
Add handling for subrange updates in LiveInterval preservation.
This requires extending MachineBasicBlock::SplitCriticalEdge
to also update subrange intervals.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D158144
This patch removes the `getBBIDOrNumber` which was introduced to allow emitting version 1.
Reviewed By: shenhan
Differential Revision: https://reviews.llvm.org/D158299
Record the call frame size on entry to each basic block. This is usually
zero except when a basic block has been split in the middle of a call
sequence.
This simplifies PEI::replaceFrameIndices which previously had to visit
basic blocks in a specific order and had special handling for
unreachable blocks. More importantly it paves the way for an equally
simple implementation of a backwards version of replaceFrameIndices,
which is required to fully convert PrologEpilogInserter to backwards
register scavenging, which is preferred because it does not rely on
accurate kill flags.
Differential Revision: https://reviews.llvm.org/D156113
Record the SP adjustment on entry to each basic block. This is almost
always zero except on targets like ARM which can split a basic block in
the middle of a call sequence.
This simplifies PEI::replaceFrameIndices which previously had to visit
basic blocks in a specific order and had special handling for
unreachable blocks. More importantly it paves the way for an equally
simple implementation of a backwards version of replaceFrameIndices,
which is required to fully convert PrologEpilogInserter to backwards
register scavenging, which is preferred because it does not rely on
accurate kill flags.
Differential Revision: https://reviews.llvm.org/D154281
In preparation for removing the `#include "llvm/ADT/StringExtras.h"`
from the header to source file of `llvm/Support/Error.h`, first add in
all the missing includes that were previously included transitively
through this header.
