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-rw-r--r--lib/Transforms/Utils/Local.cpp147
1 files changed, 12 insertions, 135 deletions
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index 4db3a72..08e1808 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -16,7 +16,6 @@
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/MemoryBuiltins.h"
@@ -44,8 +43,6 @@
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
-STATISTIC(NumRemoved, "Number of unreachable basic blocks removed");
-
//===----------------------------------------------------------------------===//
// Local constant propagation.
//
@@ -1124,153 +1121,33 @@ bool llvm::replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
return true;
}
-/// changeToUnreachable - Insert an unreachable instruction before the specified
-/// instruction, making it and the rest of the code in the block dead.
-static void changeToUnreachable(Instruction *I, bool UseLLVMTrap) {
- BasicBlock *BB = I->getParent();
- // Loop over all of the successors, removing BB's entry from any PHI
- // nodes.
- for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
- (*SI)->removePredecessor(BB);
-
- // Insert a call to llvm.trap right before this. This turns the undefined
- // behavior into a hard fail instead of falling through into random code.
- if (UseLLVMTrap) {
- Function *TrapFn =
- Intrinsic::getDeclaration(BB->getParent()->getParent(), Intrinsic::trap);
- CallInst *CallTrap = CallInst::Create(TrapFn, "", I);
- CallTrap->setDebugLoc(I->getDebugLoc());
- }
- new UnreachableInst(I->getContext(), I);
-
- // All instructions after this are dead.
- BasicBlock::iterator BBI = I, BBE = BB->end();
- while (BBI != BBE) {
- if (!BBI->use_empty())
- BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
- BB->getInstList().erase(BBI++);
- }
-}
-
-/// changeToCall - Convert the specified invoke into a normal call.
-static void changeToCall(InvokeInst *II) {
- SmallVector<Value*, 8> Args(II->op_begin(), II->op_end() - 3);
- CallInst *NewCall = CallInst::Create(II->getCalledValue(), Args, "", II);
- NewCall->takeName(II);
- NewCall->setCallingConv(II->getCallingConv());
- NewCall->setAttributes(II->getAttributes());
- NewCall->setDebugLoc(II->getDebugLoc());
- II->replaceAllUsesWith(NewCall);
-
- // Follow the call by a branch to the normal destination.
- BranchInst::Create(II->getNormalDest(), II);
-
- // Update PHI nodes in the unwind destination
- II->getUnwindDest()->removePredecessor(II->getParent());
- II->eraseFromParent();
-}
-
-static bool markAliveBlocks(BasicBlock *BB,
- SmallPtrSet<BasicBlock*, 128> &Reachable) {
-
+bool llvm::removeUnreachableBlocks(Function &F) {
+ SmallPtrSet<BasicBlock*, 16> Reachable;
SmallVector<BasicBlock*, 128> Worklist;
- Worklist.push_back(BB);
- Reachable.insert(BB);
- bool Changed = false;
+ Worklist.push_back(&F.getEntryBlock());
+ Reachable.insert(&F.getEntryBlock());
do {
- BB = Worklist.pop_back_val();
-
- // Do a quick scan of the basic block, turning any obviously unreachable
- // instructions into LLVM unreachable insts. The instruction combining pass
- // canonicalizes unreachable insts into stores to null or undef.
- for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E;++BBI){
- if (CallInst *CI = dyn_cast<CallInst>(BBI)) {
- if (CI->doesNotReturn()) {
- // If we found a call to a no-return function, insert an unreachable
- // instruction after it. Make sure there isn't *already* one there
- // though.
- ++BBI;
- if (!isa<UnreachableInst>(BBI)) {
- // Don't insert a call to llvm.trap right before the unreachable.
- changeToUnreachable(BBI, false);
- Changed = true;
- }
- break;
- }
- }
-
- // Store to undef and store to null are undefined and used to signal that
- // they should be changed to unreachable by passes that can't modify the
- // CFG.
- if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
- // Don't touch volatile stores.
- if (SI->isVolatile()) continue;
-
- Value *Ptr = SI->getOperand(1);
-
- if (isa<UndefValue>(Ptr) ||
- (isa<ConstantPointerNull>(Ptr) &&
- SI->getPointerAddressSpace() == 0)) {
- changeToUnreachable(SI, true);
- Changed = true;
- break;
- }
- }
- }
-
- // Turn invokes that call 'nounwind' functions into ordinary calls.
- if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
- Value *Callee = II->getCalledValue();
- if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
- changeToUnreachable(II, true);
- Changed = true;
- } else if (II->doesNotThrow()) {
- if (II->use_empty() && II->onlyReadsMemory()) {
- // jump to the normal destination branch.
- BranchInst::Create(II->getNormalDest(), II);
- II->getUnwindDest()->removePredecessor(II->getParent());
- II->eraseFromParent();
- } else
- changeToCall(II);
- Changed = true;
- }
- }
-
- Changed |= ConstantFoldTerminator(BB, true);
+ BasicBlock *BB = Worklist.pop_back_val();
for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
if (Reachable.insert(*SI))
Worklist.push_back(*SI);
} while (!Worklist.empty());
- return Changed;
-}
-
-/// removeUnreachableBlocksFromFn - Remove blocks that are not reachable, even
-/// if they are in a dead cycle. Return true if a change was made, false
-/// otherwise.
-bool llvm::removeUnreachableBlocks(Function &F) {
- SmallPtrSet<BasicBlock*, 128> Reachable;
- bool Changed = markAliveBlocks(F.begin(), Reachable);
- // If there are unreachable blocks in the CFG...
if (Reachable.size() == F.size())
- return Changed;
+ return false;
assert(Reachable.size() < F.size());
- NumRemoved += F.size()-Reachable.size();
-
- // Loop over all of the basic blocks that are not reachable, dropping all of
- // their internal references...
- for (Function::iterator BB = ++F.begin(), E = F.end(); BB != E; ++BB) {
- if (Reachable.count(BB))
+ for (Function::iterator I = llvm::next(F.begin()), E = F.end(); I != E; ++I) {
+ if (Reachable.count(I))
continue;
- for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
+ for (succ_iterator SI = succ_begin(I), SE = succ_end(I); SI != SE; ++SI)
if (Reachable.count(*SI))
- (*SI)->removePredecessor(BB);
- BB->dropAllReferences();
+ (*SI)->removePredecessor(I);
+ I->dropAllReferences();
}
- for (Function::iterator I = ++F.begin(); I != F.end();)
+ for (Function::iterator I = llvm::next(F.begin()), E=F.end(); I != E;)
if (!Reachable.count(I))
I = F.getBasicBlockList().erase(I);
else
generated by cgit v1.1 at 2025-01-09 19:00:20 +0000