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Remove copied preheader insertion logic from PPCCTRLoops

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Now that the preheader insertion logic in LoopSimplify is externally exposed,
use it, and remove the copy-and-pasted version.

No functionality change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182300 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel 2013-05-20 16:47:10 +00:00
parent fc32605ff3
commit 08f92c98ac
1 changed files with 3 additions and 85 deletions
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88
lib/Target/PowerPC/PPCCTRLoops.cpp
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@ -44,6 +44,7 @@
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/LoopSimplify.h"
#include "llvm/Target/TargetLibraryInfo.h"
#include "PPCTargetMachine.h"
#include "PPC.h"
@ -101,14 +102,9 @@ namespace {
}
private:
// FIXME: Copied from LoopSimplify.
BasicBlock *InsertPreheaderForLoop(Loop *L);
void PlaceSplitBlockCarefully(BasicBlock *NewBB,
SmallVectorImpl<BasicBlock*> &SplitPreds,
Loop *L);
bool mightUseCTR(const Triple &TT, BasicBlock *BB);
bool convertToCTRLoop(Loop *L);
private:
PPCTargetMachine *TM;
LoopInfo *LI;
@ -464,7 +460,7 @@ bool PPCCTRLoops::convertToCTRLoop(Loop *L) {
// the CTR register because some such uses might be reordered by the
// selection DAG after the mtctr instruction).
if (!Preheader || mightUseCTR(TT, Preheader))
Preheader = InsertPreheaderForLoop(L);
Preheader = InsertPreheaderForLoop(L, this);
if (!Preheader)
return MadeChange;
@ -512,84 +508,6 @@ bool PPCCTRLoops::convertToCTRLoop(Loop *L) {
return MadeChange;
}
// FIXME: Copied from LoopSimplify.
BasicBlock *PPCCTRLoops::InsertPreheaderForLoop(Loop *L) {
BasicBlock *Header = L->getHeader();
// Compute the set of predecessors of the loop that are not in the loop.
SmallVector<BasicBlock*, 8> OutsideBlocks;
for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
PI != PE; ++PI) {
BasicBlock *P = *PI;
if (!L->contains(P)) { // Coming in from outside the loop?
// If the loop is branched to from an indirect branch, we won't
// be able to fully transform the loop, because it prohibits
// edge splitting.
if (isa<IndirectBrInst>(P->getTerminator())) return 0;
// Keep track of it.
OutsideBlocks.push_back(P);
}
}
// Split out the loop pre-header.
BasicBlock *PreheaderBB;
if (!Header->isLandingPad()) {
PreheaderBB = SplitBlockPredecessors(Header, OutsideBlocks, ".preheader",
this);
} else {
SmallVector<BasicBlock*, 2> NewBBs;
SplitLandingPadPredecessors(Header, OutsideBlocks, ".preheader",
".split-lp", this, NewBBs);
PreheaderBB = NewBBs[0];
}
PreheaderBB->getTerminator()->setDebugLoc(
Header->getFirstNonPHI()->getDebugLoc());
DEBUG(dbgs() << "Creating pre-header "
<< PreheaderBB->getName() << "\n");
// Make sure that NewBB is put someplace intelligent, which doesn't mess up
// code layout too horribly.
PlaceSplitBlockCarefully(PreheaderBB, OutsideBlocks, L);
return PreheaderBB;
}
void PPCCTRLoops::PlaceSplitBlockCarefully(BasicBlock *NewBB,
SmallVectorImpl<BasicBlock*> &SplitPreds,
Loop *L) {
// Check to see if NewBB is already well placed.
Function::iterator BBI = NewBB; --BBI;
for (unsigned i = 0, e = SplitPreds.size(); i != e; ++i) {
if (&*BBI == SplitPreds[i])
return;
}
// If it isn't already after an outside block, move it after one. This is
// always good as it makes the uncond branch from the outside block into a
// fall-through.
// Figure out *which* outside block to put this after. Prefer an outside
// block that neighbors a BB actually in the loop.
BasicBlock *FoundBB = 0;
for (unsigned i = 0, e = SplitPreds.size(); i != e; ++i) {
Function::iterator BBI = SplitPreds[i];
if (++BBI != NewBB->getParent()->end() &&
L->contains(BBI)) {
FoundBB = SplitPreds[i];
break;
}
}
// If our heuristic for a *good* bb to place this after doesn't find
// anything, just pick something. It's likely better than leaving it within
// the loop.
if (!FoundBB)
FoundBB = SplitPreds[0];
NewBB->moveAfter(FoundBB);
}
#ifndef NDEBUG
static bool clobbersCTR(const MachineInstr *MI) {
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {