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Finegrainify namespacification 

Fix bug: LoopSimplify/2003-12-10-ExitBlocksProblem.ll

llvm-svn: 10373
This commit is contained in:
Chris Lattner 2003-12-10 17:20:35 +00:00
parent 679b49d7f5
commit 7710f2f49e
1 changed files with 21 additions and 22 deletions
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39
llvm/lib/Transforms/Scalar/LoopSimplify.cpp
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@ -17,8 +17,9 @@
//
// Loop exit-block insertion guarantees that all exit blocks from the loop
// (blocks which are outside of the loop that have predecessors inside of the
// loop) are dominated by the loop header. This simplifies transformations such
// as store-sinking that are built into LICM.
// loop) only have predecessors from inside of the loop (and are thus dominated
// by the loop header). This simplifies transformations such as store-sinking
// that are built into LICM.
//
// This pass also guarantees that loops will have exactly one backedge.
//
@ -42,12 +43,11 @@
#include "Support/SetOperations.h"
#include "Support/Statistic.h"
#include "Support/DepthFirstIterator.h"
namespace llvm {
using namespace llvm;
namespace {
Statistic<>
NumInserted("loopsimplify", "Number of pre-header blocks inserted");
NumInserted("loopsimplify", "Number of pre-header or exit blocks inserted");
struct LoopSimplify : public FunctionPass {
virtual bool runOnFunction(Function &F);
@ -81,8 +81,8 @@ namespace {
}
// Publically exposed interface to pass...
const PassInfo *LoopSimplifyID = X.getPassInfo();
Pass *createLoopSimplifyPass() { return new LoopSimplify(); }
const PassInfo *llvm::LoopSimplifyID = X.getPassInfo();
Pass *llvm::createLoopSimplifyPass() { return new LoopSimplify(); }
/// runOnFunction - Run down all loops in the CFG (recursively, but we could do
/// it in any convenient order) inserting preheaders...
@ -111,18 +111,20 @@ bool LoopSimplify::ProcessLoop(Loop *L) {
Changed = true;
}
// Regardless of whether or not we added a preheader to the loop we must
// guarantee that the preheader dominates all exit nodes. If there are any
// exit nodes not dominated, split them now.
DominatorSet &DS = getAnalysis<DominatorSet>();
BasicBlock *Header = L->getHeader();
for (unsigned i = 0, e = L->getExitBlocks().size(); i != e; ++i)
if (!DS.dominates(Header, L->getExitBlocks()[i])) {
RewriteLoopExitBlock(L, L->getExitBlocks()[i]);
assert(DS.dominates(Header, L->getExitBlocks()[i]) &&
"RewriteLoopExitBlock failed?");
// Next, check to make sure that all exit nodes of the loop only have
// predecessors that are inside of the loop. This check guarantees that the
// loop preheader/header will dominate the exit blocks. If the exit block has
// predecessors from outside of the loop, split the edge now.
for (unsigned i = 0, e = L->getExitBlocks().size(); i != e; ++i) {
BasicBlock *ExitBlock = L->getExitBlocks()[i];
for (pred_iterator PI = pred_begin(ExitBlock), PE = pred_end(ExitBlock);
PI != PE; ++PI)
if (!L->contains(*PI)) {
RewriteLoopExitBlock(L, ExitBlock);
NumInserted++;
Changed = true;
break;
}
}
// The preheader may have more than two predecessors at this point (from the
@ -342,8 +344,6 @@ void LoopSimplify::InsertPreheaderForLoop(Loop *L) {
void LoopSimplify::RewriteLoopExitBlock(Loop *L, BasicBlock *Exit) {
DominatorSet &DS = getAnalysis<DominatorSet>();
assert(!DS.dominates(L->getHeader(), Exit) &&
"Loop already dominates exit block??");
assert(std::find(L->getExitBlocks().begin(), L->getExitBlocks().end(), Exit)
!= L->getExitBlocks().end() && "Not a current exit block!");
@ -576,4 +576,3 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
}
}
} // End llvm namespace