#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/Support/Allocator.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLowering.h"
STATISTIC(UncondBranchTakenFreq,
"Potential frequency of taking unconditional branches");
+static cl::opt<unsigned> AlignAllBlock("align-all-blocks",
+ cl::desc("Force the alignment of all "
+ "blocks in the function."),
+ cl::init(0), cl::Hidden);
+
namespace {
class BlockChain;
/// \brief Type for our function-wide basic block -> block chain mapping.
const TargetInstrInfo *TII;
/// \brief A handle to the target's lowering info.
- const TargetLowering *TLI;
+ const TargetLoweringBase *TLI;
/// \brief Allocator and owner of BlockChain structures.
///
Cond.clear();
MachineBasicBlock *TBB = 0, *FBB = 0; // For AnalyzeBranch.
if (!TII->AnalyzeBranch(*PrevBB, TBB, FBB, Cond)) {
+ // The "PrevBB" is not yet updated to reflect current code layout, so,
+ // o. it may fall-through to a block without explict "goto" instruction
+ // before layout, and no longer fall-through it after layout; or
+ // o. just opposite.
+ //
+ // AnalyzeBranch() may return erroneous value for FBB when these two
+ // situations take place. For the first scenario FBB is mistakenly set
+ // NULL; for the 2nd scenario, the FBB, which is expected to be NULL,
+ // is mistakenly pointing to "*BI".
+ //
+ bool needUpdateBr = true;
+ if (!Cond.empty() && (!FBB || FBB == *BI)) {
+ PrevBB->updateTerminator();
+ needUpdateBr = false;
+ Cond.clear();
+ TBB = FBB = 0;
+ if (TII->AnalyzeBranch(*PrevBB, TBB, FBB, Cond)) {
+ // FIXME: This should never take place.
+ TBB = FBB = 0;
+ }
+ }
+
// If PrevBB has a two-way branch, try to re-order the branches
// such that we branch to the successor with higher weight first.
if (TBB && !Cond.empty() && FBB &&
DebugLoc dl; // FIXME: this is nowhere
TII->RemoveBranch(*PrevBB);
TII->InsertBranch(*PrevBB, FBB, TBB, Cond, dl);
+ needUpdateBr = true;
}
- PrevBB->updateTerminator();
+ if (needUpdateBr)
+ PrevBB->updateTerminator();
}
}
}
// Align this block if the layout predecessor's edge into this block is
- // cold relative to the block. When this is true, othe predecessors make up
+ // cold relative to the block. When this is true, other predecessors make up
// all of the hot entries into the block and thus alignment is likely to be
// important.
BranchProbability LayoutProb = MBPI->getEdgeProbability(LayoutPred, *BI);
BlockToChain.clear();
ChainAllocator.DestroyAll();
+ if (AlignAllBlock)
+ // Align all of the blocks in the function to a specific alignment.
+ for (MachineFunction::iterator FI = F.begin(), FE = F.end();
+ FI != FE; ++FI)
+ FI->setAlignment(AlignAllBlock);
+
// We always return true as we have no way to track whether the final order
// differs from the original order.
return true;