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add option to isCriticalEdge

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31258 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-10-28 06:58:17 +00:00
parent 0997fadc37
commit b57de3328d
2 changed files with 14 additions and 4 deletions
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3
include/llvm/Transforms/Utils/BasicBlockUtils.h
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@ -57,7 +57,8 @@ void RemoveSuccessor(TerminatorInst *TI, unsigned SuccNum);
/// Critical edges are edges from a block with multiple successors to a block
/// with multiple predecessors.
///
bool isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum);
bool isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum,
bool AllowIdenticalEdges = false);
/// SplitCriticalEdge - If this edge is a critical edge, insert a new node to
/// split the critical edge. This will update DominatorSet, ImmediateDominator,

15
lib/Transforms/Utils/BreakCriticalEdges.cpp
View File

@ -84,7 +84,8 @@ bool BreakCriticalEdges::runOnFunction(Function &F) {
// Critical edges are edges from a block with multiple successors to a block
// with multiple predecessors.
//
bool llvm::isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum) {
bool llvm::isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum,
bool AllowIdenticalEdges) {
assert(SuccNum < TI->getNumSuccessors() && "Illegal edge specification!");
if (TI->getNumSuccessors() == 1) return false;
@ -93,8 +94,16 @@ bool llvm::isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum) {
// If there is more than one predecessor, this is a critical edge...
assert(I != E && "No preds, but we have an edge to the block?");
const BasicBlock *FirstPred = *I;
++I; // Skip one edge due to the incoming arc from TI.
return I != E;
if (!AllowIdenticalEdges)
return I != E;
// If AllowIdenticalEdges is true, then we allow this edge to be considered
// non-critical iff all preds come from TI's block.
for (; I != E; ++I)
if (*I != FirstPred) return true;
return false;
}
// SplitCriticalEdge - If this edge is a critical edge, insert a new node to
@ -106,7 +115,7 @@ bool llvm::isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum) {
//
bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P,
bool MergeIdenticalEdges) {
if (!isCriticalEdge(TI, SuccNum)) return false;
if (!isCriticalEdge(TI, SuccNum, MergeIdenticalEdges)) return false;
BasicBlock *TIBB = TI->getParent();
BasicBlock *DestBB = TI->getSuccessor(SuccNum);