It's not necessary to do rounding for alloca operations when the requested
alignment is equal to the stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/ConstantProp.cpp b/lib/Transforms/Scalar/ConstantProp.cpp
new file mode 100644
index 0000000..3308e33
--- /dev/null
+++ b/lib/Transforms/Scalar/ConstantProp.cpp
@@ -0,0 +1,90 @@
+//===- ConstantProp.cpp - Code to perform Simple Constant Propagation -----===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements constant propagation and merging:
+//
+// Specifically, this:
+// * Converts instructions like "add int 1, 2" into 3
+//
+// Notice that:
+// * This pass has a habit of making definitions be dead. It is a good idea
+// to to run a DIE pass sometime after running this pass.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "constprop"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Constant.h"
+#include "llvm/Instruction.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/InstIterator.h"
+#include "llvm/ADT/Statistic.h"
+#include <set>
+using namespace llvm;
+
+STATISTIC(NumInstKilled, "Number of instructions killed");
+
+namespace {
+ struct VISIBILITY_HIDDEN ConstantPropagation : public FunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+ ConstantPropagation() : FunctionPass((intptr_t)&ID) {}
+
+ bool runOnFunction(Function &F);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ }
+ };
+
+ char ConstantPropagation::ID = 0;
+ RegisterPass<ConstantPropagation> X("constprop",
+ "Simple constant propagation");
+}
+
+FunctionPass *llvm::createConstantPropagationPass() {
+ return new ConstantPropagation();
+}
+
+
+bool ConstantPropagation::runOnFunction(Function &F) {
+ // Initialize the worklist to all of the instructions ready to process...
+ std::set<Instruction*> WorkList;
+ for(inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i) {
+ WorkList.insert(&*i);
+ }
+ bool Changed = false;
+
+ while (!WorkList.empty()) {
+ Instruction *I = *WorkList.begin();
+ WorkList.erase(WorkList.begin()); // Get an element from the worklist...
+
+ if (!I->use_empty()) // Don't muck with dead instructions...
+ if (Constant *C = ConstantFoldInstruction(I)) {
+ // Add all of the users of this instruction to the worklist, they might
+ // be constant propagatable now...
+ for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
+ UI != UE; ++UI)
+ WorkList.insert(cast<Instruction>(*UI));
+
+ // Replace all of the uses of a variable with uses of the constant.
+ I->replaceAllUsesWith(C);
+
+ // Remove the dead instruction.
+ WorkList.erase(I);
+ I->getParent()->getInstList().erase(I);
+
+ // We made a change to the function...
+ Changed = true;
+ ++NumInstKilled;
+ }
+ }
+ return Changed;
+}