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[ScopBuilder] Simplify main statement flag in buildEqivClassBlockStmts. NFC. 

When reading code in ScopBuilder::buildEqivClassBlockStmts, I think the
main statement flag computation can be simplified, here is the patch.
It's based on two simple facts that:

  1. Instruction won't be removed once it's inserted into UnionFind.
  2. Main statement must be set if there is non-trivial statement besides the last one.

The patch also saves std::find call.

Patch by bin.narwal <bin.narwal@gmail.com>

Differential Revision: https://reviews.llvm.org/D66477

llvm-svn: 369972
This commit is contained in:
Michael Kruse 2019-08-26 21:31:47 +00:00
parent ba3d40a145
commit 88fd2d0123
1 changed files with 7 additions and 11 deletions
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18
polly/lib/Analysis/ScopBuilder.cpp
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@ -2095,7 +2095,7 @@ void ScopBuilder::buildEqivClassBlockStmts(BasicBlock *BB) {
// shouldModelInst() repeatedly.
SmallVector<Instruction *, 32> ModeledInsts;
EquivalenceClasses<Instruction *> UnionFind;
Instruction *MainInst = nullptr;
Instruction *MainInst = nullptr, *MainLeader = nullptr;
for (Instruction &Inst : *BB) {
if (!shouldModelInst(&Inst, L))
continue;
@ -2129,6 +2129,8 @@ void ScopBuilder::buildEqivClassBlockStmts(BasicBlock *BB) {
if (LeaderIt == UnionFind.member_end())
continue;
if (&Inst == MainInst)
MainLeader = *LeaderIt;
std::vector<Instruction *> &InstList = LeaderToInstList[*LeaderIt];
InstList.push_back(&Inst);
}
@ -2136,19 +2138,11 @@ void ScopBuilder::buildEqivClassBlockStmts(BasicBlock *BB) {
// Finally build the statements.
int Count = 0;
long BBIdx = scop->getNextStmtIdx();
bool MainFound = false;
for (auto &Instructions : reverse(LeaderToInstList)) {
std::vector<Instruction *> &InstList = Instructions.second;
// If there is no main instruction, make the first statement the main.
bool IsMain;
if (MainInst)
IsMain = std::find(InstList.begin(), InstList.end(), MainInst) !=
InstList.end();
else
IsMain = (Count == 0);
if (IsMain)
MainFound = true;
bool IsMain = (MainInst ? MainLeader == Instructions.first : Count == 0);
std::reverse(InstList.begin(), InstList.end());
std::string Name = makeStmtName(BB, BBIdx, Count, IsMain);
@ -2159,8 +2153,10 @@ void ScopBuilder::buildEqivClassBlockStmts(BasicBlock *BB) {
// Unconditionally add an epilogue (last statement). It contains no
// instructions, but holds the PHI write accesses for successor basic blocks,
// if the incoming value is not defined in another statement if the same BB.
// The epilogue becomes the main statement only if there is no other
// statement that could become main.
// The epilogue will be removed if no PHIWrite is added to it.
std::string EpilogueName = makeStmtName(BB, BBIdx, Count, !MainFound, true);
std::string EpilogueName = makeStmtName(BB, BBIdx, Count, Count == 0, true);
scop->addScopStmt(BB, EpilogueName, L, {});
}