[InstCombine, SCCP] Consolidate code used to remove instructions
InstCombine and SCCP both want to remove dead code in a very particular
way but using identical means to do so. Share the code between the two.
No functionality change is intended.
llvm-svn: 258653
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 0ccd79a..329a1f1 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3012,24 +3012,9 @@
if (Visited.count(&*BB))
continue;
- // Delete the instructions backwards, as it has a reduced likelihood of
- // having to update as many def-use and use-def chains.
- Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
- while (EndInst != BB->begin()) {
- // Delete the next to last instruction.
- Instruction *Inst = &*--EndInst->getIterator();
- if (!Inst->use_empty() && !Inst->getType()->isTokenTy())
- Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
- if (Inst->isEHPad() || Inst->getType()->isTokenTy()) {
- EndInst = Inst;
- continue;
- }
- if (!isa<DbgInfoIntrinsic>(Inst)) {
- ++NumDeadInst;
- MadeIRChange = true;
- }
- Inst->eraseFromParent();
- }
+ unsigned NumDeadInstInBB = removeAllNonTerminatorAndEHPadInstructions(&*BB);
+ MadeIRChange |= NumDeadInstInBB > 0;
+ NumDeadInst += NumDeadInstInBB;
}
return MadeIRChange;
diff --git a/llvm/lib/Transforms/Scalar/SCCP.cpp b/llvm/lib/Transforms/Scalar/SCCP.cpp
index 4b18679..902fbdf 100644
--- a/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -1568,25 +1568,8 @@
DEBUG(dbgs() << " BasicBlock Dead:" << *BB);
++NumDeadBlocks;
- // Check to see if there are non-terminating instructions to delete.
- if (isa<TerminatorInst>(BB->begin()))
- return;
-
- // Delete the instructions backwards, as it has a reduced likelihood of having
- // to update as many def-use and use-def chains.
- Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
- while (EndInst != BB->begin()) {
- // Delete the next to last instruction.
- Instruction *Inst = &*--EndInst->getIterator();
- if (!Inst->use_empty())
- Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
- if (Inst->isEHPad()) {
- EndInst = Inst;
- continue;
- }
- BB->getInstList().erase(Inst);
- ++NumInstRemoved;
- }
+ unsigned NumRemovedInBB = removeAllNonTerminatorAndEHPadInstructions(BB);
+ NumInstRemoved += NumRemovedInBB;
}
// runOnFunction() - Run the Sparse Conditional Constant Propagation algorithm,
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index ed941a7..d2ac989 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1222,6 +1222,27 @@
Deref, Offset);
}
+unsigned llvm::removeAllNonTerminatorAndEHPadInstructions(BasicBlock *BB) {
+ unsigned NumDeadInst = 0;
+ // Delete the instructions backwards, as it has a reduced likelihood of
+ // having to update as many def-use and use-def chains.
+ Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
+ while (EndInst != BB->begin()) {
+ // Delete the next to last instruction.
+ Instruction *Inst = &*--EndInst->getIterator();
+ if (!Inst->use_empty() && !Inst->getType()->isTokenTy())
+ Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
+ if (Inst->isEHPad() || Inst->getType()->isTokenTy()) {
+ EndInst = Inst;
+ continue;
+ }
+ if (!isa<DbgInfoIntrinsic>(Inst))
+ ++NumDeadInst;
+ Inst->eraseFromParent();
+ }
+ return NumDeadInst;
+}
+
void llvm::changeToUnreachable(Instruction *I, bool UseLLVMTrap) {
BasicBlock *BB = I->getParent();
// Loop over all of the successors, removing BB's entry from any PHI