Changes in directory llvm/lib/Transforms/Scalar:
LCSSA.cpp updated: 1.10 -> 1.11
---
Log message:
Fix a bug in Phi-noded insertion. Also, update some comments to reflect what's
actually going on.
---
Diffs of the changes: (+21 -12)
LCSSA.cpp | 33 +++++++++++++++++++++------------
1 files changed, 21 insertions(+), 12 deletions(-)
Index: llvm/lib/Transforms/Scalar/LCSSA.cpp
diff -u llvm/lib/Transforms/Scalar/LCSSA.cpp:1.10
llvm/lib/Transforms/Scalar/LCSSA.cpp:1.11
--- llvm/lib/Transforms/Scalar/LCSSA.cpp:1.10 Thu Jun 1 01:07:40 2006
+++ llvm/lib/Transforms/Scalar/LCSSA.cpp Sat Jun 3 18:22:50 2006
@@ -36,9 +36,7 @@
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Support/CFG.h"
#include <algorithm>
-#include <cassert>
#include <map>
-#include <vector>
using namespace llvm;
@@ -69,7 +67,6 @@
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
AU.addRequired<LoopInfo>();
- AU.addPreserved<LoopInfo>();
AU.addRequired<DominatorTree>();
AU.addRequired<DominanceFrontier>();
}
@@ -137,6 +134,10 @@
++NumLCSSA; // We are applying the transformation
std::map<BasicBlock*, Instruction*> Phis;
+
+ // Add the base instruction to the Phis list. This makes tracking down
+ // the dominating values easier when we're filling in Phi nodes. This will
+ // be removed later, before we perform use replacement.
Phis[Instr->getParent()] = Instr;
// Phi nodes that need to be IDF-processed
@@ -150,12 +151,19 @@
Phis[*BBI] = phi;
}
+ // Phi nodes that need to have their incoming values filled.
+ std::vector<PHINode*> needIncomingValues;
+
// Calculate the IDF of these LCSSA Phi nodes, inserting new Phi's where
// necessary. Keep track of these new Phi's in Phis.
while (!workList.empty()) {
PHINode *CurPHI = workList.back();
workList.pop_back();
+ // Even though we've removed this Phi from the work list, we still need
+ // to fill in its incoming values.
+ needIncomingValues.push_back(CurPHI);
+
// Get the current Phi's DF, and insert Phi nodes. Add these new
// nodes to our worklist.
DominanceFrontier::const_iterator it = DF->find(CurPHI->getParent());
@@ -172,14 +180,14 @@
}
}
}
-
- // Get the predecessor blocks of the current Phi, and use them to hook up
- // the operands of the current Phi to any members of DFPhis that dominate
- // it. This is a nop for the Phis inserted directly in the exit blocks,
- // since they are not dominated by any members of DFPhis.
- for (pred_iterator PI = pred_begin(CurPHI->getParent()),
- E = pred_end(CurPHI->getParent()); PI != E; ++PI)
- CurPHI->addIncoming(getValueDominatingBlock(*PI, Phis),
+ }
+
+ // Fill in all Phis we've inserted that need their incoming values filled in.
+ for (std::vector<PHINode*>::iterator IVI = needIncomingValues.begin(),
+ IVE = needIncomingValues.end(); IVI != IVE; ++IVI) {
+ for (pred_iterator PI = pred_begin((*IVI)->getParent()),
+ E = pred_end((*IVI)->getParent()); PI != E; ++PI)
+ (*IVI)->addIncoming(getValueDominatingBlock(*PI, Phis),
*PI);
}
@@ -197,7 +205,8 @@
Uses.push_back(use);
}
- // Deliberately remove the initial instruction from Phis set.
+ // Deliberately remove the initial instruction from Phis set. It would mess
+ // up use-replacement.
Phis.erase(Instr->getParent());
for (std::vector<Instruction*>::iterator II = Uses.begin(), IE = Uses.end();
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