1#include "WebAssemblySortRegion.h"
2#include "WebAssemblyExceptionInfo.h"
3#include "llvm/CodeGen/MachineLoopInfo.h"
4
5using namespace llvm;
6using namespace WebAssembly;
7
8namespace llvm {
9namespace WebAssembly {
10template <>
11bool ConcreteSortRegion<MachineLoop>::isLoop() const {
12 return true;
13}
14} // end namespace WebAssembly
15} // end namespace llvm
16
17const SortRegion *SortRegionInfo::getRegionFor(const MachineBasicBlock *MBB) {
18 const auto *ML = MLI.getLoopFor(BB: MBB);
19 const auto *WE = WEI.getExceptionFor(MBB);
20 if (!ML && !WE)
21 return nullptr;
22 // We determine subregion relationship by domination of their headers, i.e.,
23 // if region A's header dominates region B's header, B is a subregion of A.
24 // WebAssemblyException contains BBs in all its subregions (loops or
25 // exceptions), but MachineLoop may not, because MachineLoop does not
26 // contain BBs that don't have a path to its header even if they are
27 // dominated by its header. So here we should use
28 // WE->contains(ML->getHeader()), but not ML->contains(WE->getHeader()).
29 if ((ML && !WE) || (ML && WE && WE->contains(MBB: ML->getHeader()))) {
30 // If the smallest region containing MBB is a loop
31 auto [It, Inserted] = LoopMap.try_emplace(Key: ML);
32 if (Inserted)
33 It->second = std::make_unique<ConcreteSortRegion<MachineLoop>>(args&: ML);
34 return It->second.get();
35 } else {
36 // If the smallest region containing MBB is an exception
37 auto [It, Inserted] = ExceptionMap.try_emplace(Key: WE);
38 if (Inserted)
39 It->second =
40 std::make_unique<ConcreteSortRegion<WebAssemblyException>>(args&: WE);
41 return It->second.get();
42 }
43}
44
45MachineBasicBlock *SortRegionInfo::getBottom(const SortRegion *R) {
46 if (R->isLoop())
47 return getBottom(ML: MLI.getLoopFor(BB: R->getHeader()));
48 else
49 return getBottom(WE: WEI.getExceptionFor(MBB: R->getHeader()));
50}
51
52MachineBasicBlock *SortRegionInfo::getBottom(const MachineLoop *ML) {
53 MachineBasicBlock *Bottom = ML->getHeader();
54 for (MachineBasicBlock *MBB : ML->blocks()) {
55 if (MBB->getNumber() > Bottom->getNumber())
56 Bottom = MBB;
57 // MachineLoop does not contain all BBs dominated by its header. BBs that
58 // don't have a path back to the loop header aren't included. But for the
59 // purpose of CFG sorting and stackification, we need a bottom BB among all
60 // BBs that are dominated by the loop header. So we check if there is any
61 // WebAssemblyException contained in this loop, and computes the most bottom
62 // BB of them all.
63 if (MBB->isEHPad()) {
64 MachineBasicBlock *ExBottom = getBottom(WE: WEI.getExceptionFor(MBB));
65 if (ExBottom->getNumber() > Bottom->getNumber())
66 Bottom = ExBottom;
67 }
68 }
69 return Bottom;
70}
71
72MachineBasicBlock *SortRegionInfo::getBottom(const WebAssemblyException *WE) {
73 MachineBasicBlock *Bottom = WE->getHeader();
74 for (MachineBasicBlock *MBB : WE->blocks())
75 if (MBB->getNumber() > Bottom->getNumber())
76 Bottom = MBB;
77 return Bottom;
78}
79