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Simplify this code: don't call AnalyzeBranch before doing simpler checks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90633 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -363,11 +363,6 @@ bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const {
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}
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bool MachineBasicBlock::canFallThrough() {
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MachineBasicBlock *TBB = 0, *FBB = 0;
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SmallVector<MachineOperand, 4> Cond;
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const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
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bool BranchUnAnalyzable = TII->AnalyzeBranch(*this, TBB, FBB, Cond, true);
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MachineFunction::iterator Fallthrough = this;
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++Fallthrough;
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// If FallthroughBlock is off the end of the function, it can't fall through.
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@ -378,16 +373,21 @@ bool MachineBasicBlock::canFallThrough() {
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if (!isSuccessor(Fallthrough))
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return false;
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// If we couldn't analyze the branch, examine the last instruction.
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// If the block doesn't end in a known control barrier, assume fallthrough
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// is possible. The isPredicable check is needed because this code can be
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// called during IfConversion, where an instruction which is normally a
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// Barrier is predicated and thus no longer an actual control barrier. This
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// is over-conservative though, because if an instruction isn't actually
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// predicated we could still treat it like a barrier.
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if (BranchUnAnalyzable)
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// Analyze the branches, if any, at the end of the block.
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MachineBasicBlock *TBB = 0, *FBB = 0;
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SmallVector<MachineOperand, 4> Cond;
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const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
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if (TII->AnalyzeBranch(*this, TBB, FBB, Cond, true)) {
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// If we couldn't analyze the branch, examine the last instruction.
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// If the block doesn't end in a known control barrier, assume fallthrough
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// is possible. The isPredicable check is needed because this code can be
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// called during IfConversion, where an instruction which is normally a
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// Barrier is predicated and thus no longer an actual control barrier. This
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// is over-conservative though, because if an instruction isn't actually
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// predicated we could still treat it like a barrier.
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return empty() || !back().getDesc().isBarrier() ||
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back().getDesc().isPredicable();
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}
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// If there is no branch, control always falls through.
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if (TBB == 0) return true;
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