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[SimplifyCFG] fix typos/formatting; NFC

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llvm-svn: 313671
This commit is contained in:
Sanjay Patel 2017-09-19 20:58:14 +00:00
parent d4ae470d2e
commit ca14697c2b
1 changed files with 22 additions and 24 deletions
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46
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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@ -5191,8 +5191,7 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
// string and lookup indices into that.
// Ignore switches with less than three cases. Lookup tables will not make
// them
// faster, so we don't analyze them.
// them faster, so we don't analyze them.
if (SI->getNumCases() < 3)
return false;
@ -5310,15 +5309,14 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
Builder.SetInsertPoint(LookupBB);
if (NeedMask) {
// Before doing the lookup we do the hole check.
// The LookupBB is therefore re-purposed to do the hole check
// and we create a new LookupBB.
// Before doing the lookup, we do the hole check. The LookupBB is therefore
// re-purposed to do the hole check, and we create a new LookupBB.
BasicBlock *MaskBB = LookupBB;
MaskBB->setName("switch.hole_check");
LookupBB = BasicBlock::Create(Mod.getContext(), "switch.lookup",
CommonDest->getParent(), CommonDest);
// Make the mask's bitwidth at least 8bit and a power-of-2 to avoid
// Make the mask's bitwidth at least 8-bit and a power-of-2 to avoid
// unnecessary illegal types.
uint64_t TableSizePowOf2 = NextPowerOf2(std::max(7ULL, TableSize - 1ULL));
APInt MaskInt(TableSizePowOf2, 0);
@ -5348,7 +5346,7 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
}
if (!DefaultIsReachable || GeneratingCoveredLookupTable) {
// We cached PHINodes in PHIs, to avoid accessing deleted PHINodes later,
// We cached PHINodes in PHIs. To avoid accessing deleted PHINodes later,
// do not delete PHINodes here.
SI->getDefaultDest()->removePredecessor(SI->getParent(),
/*DontDeleteUselessPHIs=*/true);
@ -5419,14 +5417,14 @@ static bool isSwitchDense(ArrayRef<int64_t> Values) {
return NumCases * 100 >= Range * MinDensity;
}
// Try and transform a switch that has "holes" in it to a contiguous sequence
// of cases.
//
// A switch such as: switch(i) {case 5: case 9: case 13: case 17:} can be
// range-reduced to: switch ((i-5) / 4) {case 0: case 1: case 2: case 3:}.
//
// This converts a sparse switch into a dense switch which allows better
// lowering and could also allow transforming into a lookup table.
/// Try to transform a switch that has "holes" in it to a contiguous sequence
/// of cases.
///
/// A switch such as: switch(i) {case 5: case 9: case 13: case 17:} can be
/// range-reduced to: switch ((i-5) / 4) {case 0: case 1: case 2: case 3:}.
///
/// This converts a sparse switch into a dense switch which allows better
/// lowering and could also allow transforming into a lookup table.
static bool ReduceSwitchRange(SwitchInst *SI, IRBuilder<> &Builder,
const DataLayout &DL,
const TargetTransformInfo &TTI) {
@ -5552,11 +5550,11 @@ bool SimplifyCFGOpt::SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder) {
if (ForwardSwitchConditionToPHI(SI))
return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
// The conversion from switch to lookup tables results in difficult
// to analyze code and makes pruning branches much harder.
// This is a problem of the switch expression itself can still be
// restricted as a result of inlining or CVP. There only apply this
// transformation during late steps of the optimisation chain.
// The conversion from switch to lookup tables results in difficult-to-analyze
// code and makes pruning branches much harder. This is a problem if the
// switch expression itself can still be restricted as a result of inlining or
// CVP. Therefore, only apply this transformation during late stages of the
// optimisation pipeline.
if (LateSimplifyCFG && SwitchToLookupTable(SI, Builder, DL, TTI))
return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
@ -5690,8 +5688,8 @@ bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI,
return true;
// If the Terminator is the only non-phi instruction, simplify the block.
// if LoopHeader is provided, check if the block or its successor is a loop
// header (This is for early invocations before loop simplify and
// If LoopHeader is provided, check if the block or its successor is a loop
// header. (This is for early invocations before loop simplify and
// vectorization to keep canonical loop forms for nested loops. These blocks
// can be eliminated when the pass is invoked later in the back-end.)
bool NeedCanonicalLoop =
@ -5702,8 +5700,8 @@ bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI,
!NeedCanonicalLoop && TryToSimplifyUncondBranchFromEmptyBlock(BB))
return true;
// If the only instruction in the block is a seteq/setne comparison
// against a constant, try to simplify the block.
// If the only instruction in the block is a seteq/setne comparison against a
// constant, try to simplify the block.
if (ICmpInst *ICI = dyn_cast<ICmpInst>(I))
if (ICI->isEquality() && isa<ConstantInt>(ICI->getOperand(1))) {
for (++I; isa<DbgInfoIntrinsic>(I); ++I)