Changes in directory llvm/lib/CodeGen:
BranchFolding.cpp updated: 1.11 -> 1.12
---
Log message:
Reenable this pass, fixing the bugs in it.
It now correctly deletes unreachable blocks and blocks that are empty.
---
Diffs of the changes: (+32 -23)
BranchFolding.cpp | 55 +++++++++++++++++++++++++++++++-----------------------
1 files changed, 32 insertions(+), 23 deletions(-)
Index: llvm/lib/CodeGen/BranchFolding.cpp
diff -u llvm/lib/CodeGen/BranchFolding.cpp:1.11
llvm/lib/CodeGen/BranchFolding.cpp:1.12
--- llvm/lib/CodeGen/BranchFolding.cpp:1.11 Fri Oct 13 19:30:06 2006
+++ llvm/lib/CodeGen/BranchFolding.cpp Tue Oct 17 12:13:52 2006
@@ -18,6 +18,7 @@
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/ADT/STLExtras.h"
@@ -36,39 +37,39 @@
FunctionPass *llvm::createBranchFoldingPass() { return new BranchFolder(); }
+/// RemoveDeadBlock - Remove the specified dead machine basic block from the
+/// function, updating the CFG.
+static void RemoveDeadBlock(MachineBasicBlock *MBB) {
+ assert(MBB->pred_empty() && "MBB must be dead!");
+ MachineFunction *MF = MBB->getParent();
+ // drop all successors.
+ while (!MBB->succ_empty())
+ MBB->removeSuccessor(MBB->succ_end()-1);
+ // Remove the block.
+ MF->getBasicBlockList().erase(MBB);
+}
+
bool BranchFolder::runOnMachineFunction(MachineFunction &MF) {
TII = MF.getTarget().getInstrInfo();
if (!TII) return false;
-
- // DISABLED FOR NOW.
- return false;
-
//MF.dump();
bool EverMadeChange = false;
MadeChange = true;
while (MadeChange) {
MadeChange = false;
- for (MachineFunction::iterator MBB = ++MF.begin(), E = MF.end(); MBB != E;
- ++MBB)
- OptimizeBlock(MBB);
- // If branches were folded away somehow, do a quick scan and delete any
dead
- // blocks.
- if (MadeChange) {
- for (MachineFunction::iterator I = ++MF.begin(), E = MF.end(); I != E; )
{
- MachineBasicBlock *MBB = I++;
- // Is it dead?
- if (MBB->pred_empty()) {
- // drop all successors.
- while (!MBB->succ_empty())
- MBB->removeSuccessor(MBB->succ_end()-1);
- MF.getBasicBlockList().erase(MBB);
- }
+ for (MachineFunction::iterator I = ++MF.begin(), E = MF.end(); I != E; ) {
+ MachineBasicBlock *MBB = I++;
+ OptimizeBlock(MBB);
+
+ // If it is dead, remove it.
+ if (MBB->pred_empty()) {
+ RemoveDeadBlock(MBB);
+ MadeChange = true;
}
- }
-
+ }
EverMadeChange |= MadeChange;
}
@@ -115,14 +116,22 @@
MachineFunction::iterator FallThrough = next(MBB);
- if (FallThrough != MBB->getParent()->end()) {
+ if (FallThrough == MBB->getParent()->end()) {
+ // TODO: Simplify preds to not branch here if possible!
+ } else {
+ // Rewrite all predecessors of the old block to go to the fallthrough
+ // instead.
while (!MBB->pred_empty()) {
MachineBasicBlock *Pred = *(MBB->pred_end()-1);
ReplaceUsesOfBlockWith(Pred, MBB, FallThrough, TII);
}
+
+ // If MBB was the target of a jump table, update jump tables to go to the
+ // fallthrough instead.
+ MBB->getParent()->getJumpTableInfo()->ReplaceMBBInJumpTables(MBB,
+
FallThrough);
MadeChange = true;
}
- // TODO: CHANGE STUFF TO NOT BRANCH HERE!
return;
}
_______________________________________________
llvm-commits mailing list
llvm-commits@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
