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166ce9a607
When it was first created, CFGSort only made sure BBs in each
`MachineLoop` are sorted together. After we added exception support,
CFGSort now also sorts BBs in each `WebAssemblyException`, which
represents a `catch` block, together, and
`Region` class was introduced to be a thin wrapper for both
`MachineLoop` and `WebAssemblyException`.
But how we compute those loops and exceptions is different.
`MachineLoopInfo` is constructed using the standard loop computation
algorithm in LLVM; the definition of loop is "a set of BBs that are
dominated by a loop header and have a path back to the loop header". So
even if some BBs are semantically contained by a loop in the original
program, or in other words dominated by a loop header, if they don't
have a path back to the loop header, they are not considered a part of
the loop. For example, if a BB is dominated by a loop header but
contains `call abort()` or `rethrow`, it wouldn't have a path back to
the header, so it is not included in the loop.
But `WebAssemblyException` is wasm-specific data structure, and its
algorithm is simple: a `WebAssemblyException` consists of an EH pad and
all BBs dominated by the EH pad. So this scenario is possible: (This is
also the situation in the newly added test in cfg-stackify-eh.ll)
```
Loop L: header, A, ehpad, latch
Exception E: ehpad, latch, B
```
(B contains `abort()`, so it does not have a path back to the loop
header, so it is not included in L.)
And it is sorted in this order:
```
header
A
ehpad
latch
B
```
And when CFGStackify places `end_loop` or `end_try` markers, it
previously used `WebAssembly::getBottom()`, which returns the latest BB
in the sorted order, and placed the marker there. So in this case the
marker placements will be like this:
```
loop
header
try
A
catch
ehpad
latch
end_loop <-- misplaced!
B
end_try
```
in which nesting between the loop and the exception is not correct.
`end_loop` marker has to be placed after `B`, and also after `end_try`.
Maybe the fundamental way to solve this problem is to come up with our
own algorithm for computing loop region too, in which we include all BBs
dominated by a loop header in a loop. But this takes a lot more effort.
The only thing we need to fix is actually, `getBottom()`. If we make it
return the right BB, which means in case of a loop, the latest BB of the
loop itself and all exceptions contained in there, we are good.
This renames `Region` and `RegionInfo` to `SortRegion` and
`SortRegionInfo` and extracts them into their own file. And add
`getBottom` to `SortRegionInfo` class, from which it can access
`WebAssemblyExceptionInfo`, so that it can compute a correct bottom
block for loops.
Reviewed By: dschuff
Differential Revision: https://reviews.llvm.org/D84724
67 lines
2.1 KiB
CMake
67 lines
2.1 KiB
CMake
set(LLVM_TARGET_DEFINITIONS WebAssembly.td)
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tablegen(LLVM WebAssemblyGenAsmMatcher.inc -gen-asm-matcher)
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tablegen(LLVM WebAssemblyGenAsmWriter.inc -gen-asm-writer)
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tablegen(LLVM WebAssemblyGenDAGISel.inc -gen-dag-isel)
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tablegen(LLVM WebAssemblyGenDisassemblerTables.inc -gen-disassembler)
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tablegen(LLVM WebAssemblyGenFastISel.inc -gen-fast-isel)
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tablegen(LLVM WebAssemblyGenInstrInfo.inc -gen-instr-info)
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tablegen(LLVM WebAssemblyGenMCCodeEmitter.inc -gen-emitter)
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tablegen(LLVM WebAssemblyGenRegisterInfo.inc -gen-register-info)
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tablegen(LLVM WebAssemblyGenSubtargetInfo.inc -gen-subtarget)
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add_public_tablegen_target(WebAssemblyCommonTableGen)
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add_llvm_target(WebAssemblyCodeGen
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WebAssemblyAddMissingPrototypes.cpp
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WebAssemblyArgumentMove.cpp
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WebAssemblyAsmPrinter.cpp
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WebAssemblyCFGStackify.cpp
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WebAssemblyCFGSort.cpp
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WebAssemblyDebugFixup.cpp
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WebAssemblyDebugValueManager.cpp
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WebAssemblyLateEHPrepare.cpp
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WebAssemblyExceptionInfo.cpp
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WebAssemblyExplicitLocals.cpp
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WebAssemblyFastISel.cpp
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WebAssemblyFixBrTableDefaults.cpp
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WebAssemblyFixIrreducibleControlFlow.cpp
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WebAssemblyFixFunctionBitcasts.cpp
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WebAssemblyFrameLowering.cpp
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WebAssemblyISelDAGToDAG.cpp
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WebAssemblyISelLowering.cpp
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WebAssemblyInstrInfo.cpp
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WebAssemblyLowerBrUnless.cpp
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WebAssemblyLowerEmscriptenEHSjLj.cpp
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WebAssemblyLowerGlobalDtors.cpp
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WebAssemblyMachineFunctionInfo.cpp
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WebAssemblyMCInstLower.cpp
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WebAssemblyOptimizeLiveIntervals.cpp
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WebAssemblyOptimizeReturned.cpp
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WebAssemblyPeephole.cpp
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WebAssemblyPrepareForLiveIntervals.cpp
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WebAssemblyRegisterInfo.cpp
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WebAssemblyRegColoring.cpp
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WebAssemblyRegNumbering.cpp
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WebAssemblyRegStackify.cpp
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WebAssemblyReplacePhysRegs.cpp
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WebAssemblyRuntimeLibcallSignatures.cpp
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WebAssemblySelectionDAGInfo.cpp
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WebAssemblySetP2AlignOperands.cpp
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WebAssemblySortRegion.cpp
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WebAssemblyMemIntrinsicResults.cpp
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WebAssemblySubtarget.cpp
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WebAssemblyTargetMachine.cpp
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WebAssemblyTargetObjectFile.cpp
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WebAssemblyTargetTransformInfo.cpp
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WebAssemblyUtilities.cpp
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DEPENDS
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intrinsics_gen
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)
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add_subdirectory(AsmParser)
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add_subdirectory(Disassembler)
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add_subdirectory(MCTargetDesc)
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add_subdirectory(TargetInfo)
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