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/IPO/ConstantMerge.cpp b/lib/Transforms/IPO/ConstantMerge.cpp
new file mode 100644
index 0000000..0c7ee59
--- /dev/null
+++ b/lib/Transforms/IPO/ConstantMerge.cpp
@@ -0,0 +1,116 @@
+//===- ConstantMerge.cpp - Merge duplicate global constants ---------------===//
+//
+// 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 defines the interface to a pass that merges duplicate global
+// constants together into a single constant that is shared. This is useful
+// because some passes (ie TraceValues) insert a lot of string constants into
+// the program, regardless of whether or not an existing string is available.
+//
+// Algorithm: ConstantMerge is designed to build up a map of available constants
+// and eliminate duplicates when it is initialized.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "constmerge"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
+
+STATISTIC(NumMerged, "Number of global constants merged");
+
+namespace {
+ struct VISIBILITY_HIDDEN ConstantMerge : public ModulePass {
+ static char ID; // Pass identification, replacement for typeid
+ ConstantMerge() : ModulePass((intptr_t)&ID) {}
+
+ // run - For this pass, process all of the globals in the module,
+ // eliminating duplicate constants.
+ //
+ bool runOnModule(Module &M);
+ };
+
+ char ConstantMerge::ID = 0;
+ RegisterPass<ConstantMerge>X("constmerge","Merge Duplicate Global Constants");
+}
+
+ModulePass *llvm::createConstantMergePass() { return new ConstantMerge(); }
+
+bool ConstantMerge::runOnModule(Module &M) {
+ // Map unique constant/section pairs to globals. We don't want to merge
+ // globals in different sections.
+ std::map<std::pair<Constant*, std::string>, GlobalVariable*> CMap;
+
+ // Replacements - This vector contains a list of replacements to perform.
+ std::vector<std::pair<GlobalVariable*, GlobalVariable*> > Replacements;
+
+ bool MadeChange = false;
+
+ // Iterate constant merging while we are still making progress. Merging two
+ // constants together may allow us to merge other constants together if the
+ // second level constants have initializers which point to the globals that
+ // were just merged.
+ while (1) {
+ // First pass: identify all globals that can be merged together, filling in
+ // the Replacements vector. We cannot do the replacement in this pass
+ // because doing so may cause initializers of other globals to be rewritten,
+ // invalidating the Constant* pointers in CMap.
+ //
+ for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
+ GVI != E; ) {
+ GlobalVariable *GV = GVI++;
+
+ // If this GV is dead, remove it.
+ GV->removeDeadConstantUsers();
+ if (GV->use_empty() && GV->hasInternalLinkage()) {
+ GV->eraseFromParent();
+ continue;
+ }
+
+ // Only process constants with initializers.
+ if (GV->isConstant() && GV->hasInitializer()) {
+ Constant *Init = GV->getInitializer();
+
+ // Check to see if the initializer is already known.
+ GlobalVariable *&Slot = CMap[std::make_pair(Init, GV->getSection())];
+
+ if (Slot == 0) { // Nope, add it to the map.
+ Slot = GV;
+ } else if (GV->hasInternalLinkage()) { // Yup, this is a duplicate!
+ // Make all uses of the duplicate constant use the canonical version.
+ Replacements.push_back(std::make_pair(GV, Slot));
+ } else if (GV->hasInternalLinkage()) {
+ // Make all uses of the duplicate constant use the canonical version.
+ Replacements.push_back(std::make_pair(Slot, GV));
+ Slot = GV;
+ }
+ }
+ }
+
+ if (Replacements.empty())
+ return MadeChange;
+ CMap.clear();
+
+ // Now that we have figured out which replacements must be made, do them all
+ // now. This avoid invalidating the pointers in CMap, which are unneeded
+ // now.
+ for (unsigned i = 0, e = Replacements.size(); i != e; ++i) {
+ // Eliminate any uses of the dead global...
+ Replacements[i].first->replaceAllUsesWith(Replacements[i].second);
+
+ // Delete the global value from the module...
+ M.getGlobalList().erase(Replacements[i].first);
+ }
+
+ NumMerged += Replacements.size();
+ Replacements.clear();
+ }
+}