[llvm-commits] [llvm] r90633 - /llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp
Dan Gohman
gohman at apple.com
Fri Dec 4 16:32:59 PST 2009
Author: djg
Date: Fri Dec 4 18:32:59 2009
New Revision: 90633
URL: http://llvm.org/viewvc/llvm-project?rev=90633&view=rev
Log:
Simplify this code: don't call AnalyzeBranch before doing simpler checks.
Modified:
llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp
Modified: llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp?rev=90633&r1=90632&r2=90633&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp Fri Dec 4 18:32:59 2009
@@ -363,11 +363,6 @@
}
bool MachineBasicBlock::canFallThrough() {
- MachineBasicBlock *TBB = 0, *FBB = 0;
- SmallVector<MachineOperand, 4> Cond;
- const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
- bool BranchUnAnalyzable = TII->AnalyzeBranch(*this, TBB, FBB, Cond, true);
-
MachineFunction::iterator Fallthrough = this;
++Fallthrough;
// If FallthroughBlock is off the end of the function, it can't fall through.
@@ -378,16 +373,21 @@
if (!isSuccessor(Fallthrough))
return false;
- // If we couldn't analyze the branch, examine the last instruction.
- // If the block doesn't end in a known control barrier, assume fallthrough
- // is possible. The isPredicable check is needed because this code can be
- // called during IfConversion, where an instruction which is normally a
- // Barrier is predicated and thus no longer an actual control barrier. This
- // is over-conservative though, because if an instruction isn't actually
- // predicated we could still treat it like a barrier.
- if (BranchUnAnalyzable)
+ // Analyze the branches, if any, at the end of the block.
+ MachineBasicBlock *TBB = 0, *FBB = 0;
+ SmallVector<MachineOperand, 4> Cond;
+ const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
+ if (TII->AnalyzeBranch(*this, TBB, FBB, Cond, true)) {
+ // If we couldn't analyze the branch, examine the last instruction.
+ // If the block doesn't end in a known control barrier, assume fallthrough
+ // is possible. The isPredicable check is needed because this code can be
+ // called during IfConversion, where an instruction which is normally a
+ // Barrier is predicated and thus no longer an actual control barrier. This
+ // is over-conservative though, because if an instruction isn't actually
+ // predicated we could still treat it like a barrier.
return empty() || !back().getDesc().isBarrier() ||
back().getDesc().isPredicable();
+ }
// If there is no branch, control always falls through.
if (TBB == 0) return true;
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