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Fix up PHI nodes correctly in the presence of unreachable BBs, part two. Also

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delete a newed pointer, and improve readability a little bit.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79411 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2009-08-19 07:16:57 +00:00
parent 5371aa2a1c
commit 08368ce984
2 changed files with 52 additions and 7 deletions
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37
lib/Transforms/Utils/SSI.cpp
View File

@ -226,10 +226,9 @@ void SSI::rename(BasicBlock *BB) {
for (BasicBlock::iterator begin = BB_succ->begin(),
notPhi = BB_succ->getFirstNonPHI(); begin != *notPhi; ++begin) {
Instruction *I = begin;
PHINode *PN;
PHINode *PN = dyn_cast<PHINode>(I);
int position;
if ((PN = dyn_cast<PHINode>(I)) && ((position
= getPositionPhi(PN)) != -1)) {
if (PN && ((position = getPositionPhi(PN)) != -1)) {
PN->addIncoming(value_stack[position].back(), BB);
}
}
@ -254,6 +253,8 @@ void SSI::rename(BasicBlock *BB) {
}
}
}
delete defined;
}
/// Substitute any use in this instruction for the last definition of
@ -307,16 +308,16 @@ bool SSI::dominateAny(BasicBlock *BB, Instruction *value) {
/// as an operand of another phi function used in the same BasicBlock,
/// LLVM looks this as an error. So on the second phi, the first phi is called
/// P and the BasicBlock it incomes is B. This P will be replaced by the value
/// it has for BasicBlock B.
/// it has for BasicBlock B. It also includes undef values for predecessors
/// that were not included in the phi.
///
void SSI::fixPhis() {
for (SmallPtrSet<PHINode *, 1>::iterator begin = phisToFix.begin(),
end = phisToFix.end(); begin != end; ++begin) {
PHINode *PN = *begin;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i < e; ++i) {
PHINode *PN_father;
if ((PN_father = dyn_cast<PHINode>(PN->getIncomingValue(i))) &&
PN->getParent() == PN_father->getParent() &&
PHINode *PN_father = dyn_cast<PHINode>(PN->getIncomingValue(i));
if (PN_father && PN->getParent() == PN_father->getParent() &&
!DT_->dominates(PN->getParent(), PN->getIncomingBlock(i))) {
BasicBlock *BB = PN->getIncomingBlock(i);
int pos = PN_father->getBasicBlockIndex(BB);
@ -324,6 +325,28 @@ void SSI::fixPhis() {
}
}
}
for (DenseMapIterator<PHINode *, unsigned> begin = phis.begin(),
end = phis.end(); begin != end; ++begin) {
PHINode *PN = begin->first;
BasicBlock *BB = PN->getParent();
pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
SmallVector<BasicBlock*, 8> Preds(PI, PE);
for (unsigned size = Preds.size();
PI != PE && PN->getNumIncomingValues() != size; ++PI) {
bool found = false;
for (unsigned i = 0, pn_end = PN->getNumIncomingValues();
i < pn_end; ++i) {
if (PN->getIncomingBlock(i) == *PI) {
found = true;
break;
}
}
if (!found) {
PN->addIncoming(UndefValue::get(PN->getType()), *PI);
}
}
}
}
/// Return which variable (position on the vector of variables) this phi

22
test/Transforms/SSI/2009-08-19-UnreachableBB2.ll Normal file
View File

@ -0,0 +1,22 @@
; RUN: llvm-as < %s | opt -ssi-everything -disable-output
define void @foo() {
entry:
%tmp0 = load i64* undef, align 4 ; <i64> [#uses=3]
br i1 undef, label %end_stmt_playback, label %bb16
readJournalHdr.exit: ; No predecessors!
br label %end_stmt_playback
bb16: ; preds = %bb7
%tmp1 = icmp slt i64 0, %tmp0 ; <i1> [#uses=1]
br i1 %tmp1, label %bb16, label %bb17
bb17: ; preds = %bb16
store i64 %tmp0, i64* undef, align 4
br label %end_stmt_playback
end_stmt_playback: ; preds = %bb17, %readJournalHdr.exit, %bb6, %bb2
store i64 %tmp0, i64* undef, align 4
ret void
}