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[WinEH] Make collectFuncletMembers non-recursive

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Use a worklist for the pre-order DFS instead of using recursion.
No functionality change is intended.

llvm-svn: 258521
This commit is contained in:
David Majnemer 2016-01-22 18:49:50 +00:00
parent d50c4b11ba
commit 0533388931
1 changed files with 22 additions and 24 deletions
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46
lib/CodeGen/Analysis.cpp
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@ -654,32 +654,30 @@ bool llvm::canBeOmittedFromSymbolTable(const GlobalValue *GV) {
static void collectFuncletMembers(
DenseMap<const MachineBasicBlock *, int> &FuncletMembership, int Funclet,
const MachineBasicBlock *MBB) {
// Add this MBB to our funclet.
auto P = FuncletMembership.insert(std::make_pair(MBB, Funclet));
SmallVector<const MachineBasicBlock *, 16> Worklist = {MBB};
while (!Worklist.empty()) {
const MachineBasicBlock *Visiting = Worklist.pop_back_val();
// Don't follow blocks which start new funclets.
if (Visiting->isEHPad() && Visiting != MBB)
continue;
// Don't revisit blocks.
if (!P.second) {
assert(P.first->second == Funclet && "MBB is part of two funclets!");
return;
// Add this MBB to our funclet.
auto P = FuncletMembership.insert(std::make_pair(Visiting, Funclet));
// Don't revisit blocks.
if (!P.second) {
assert(P.first->second == Funclet && "MBB is part of two funclets!");
continue;
}
// Returns are boundaries where funclet transfer can occur, don't follow
// successors.
if (Visiting->isReturnBlock())
continue;
for (const MachineBasicBlock *Succ : Visiting->successors())
Worklist.push_back(Succ);
}
bool IsReturn = false;
int NumTerminators = 0;
for (const MachineInstr &MI : MBB->terminators()) {
IsReturn |= MI.isReturn();
++NumTerminators;
}
assert((!IsReturn || NumTerminators == 1) &&
"Expected only one terminator when a return is present!");
// Returns are boundaries where funclet transfer can occur, don't follow
// successors.
if (IsReturn)
return;
for (const MachineBasicBlock *SMBB : MBB->successors())
if (!SMBB->isEHPad())
collectFuncletMembers(FuncletMembership, Funclet, SMBB);
}
DenseMap<const MachineBasicBlock *, int>