Split mem2reg promotion into two parts: a function which does the work, and
a pass which wraps the function. This allows other passes to use the functionality
llvm-svn: 5610
diff --git a/llvm/lib/Transforms/Scalar/Mem2Reg.cpp b/llvm/lib/Transforms/Scalar/Mem2Reg.cpp
new file mode 100644
index 0000000..6fbb43f
--- /dev/null
+++ b/llvm/lib/Transforms/Scalar/Mem2Reg.cpp
@@ -0,0 +1,59 @@
+//===- Mem2Reg.cpp - The -mem2reg pass, a wrapper around the Utils lib ----===//
+//
+// This pass is a simple pass wrapper around the PromoteMemToReg function call
+// exposed by the Utils library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/PromoteMemToReg.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/iMemory.h"
+#include "llvm/Function.h"
+#include "Support/Statistic.h"
+
+namespace {
+ Statistic<> NumPromoted("mem2reg", "Number of alloca's promoted");
+
+ struct PromotePass : public FunctionPass {
+ // runOnFunction - To run this pass, first we calculate the alloca
+ // instructions that are safe for promotion, then we promote each one.
+ //
+ virtual bool runOnFunction(Function &F);
+
+ // getAnalysisUsage - We need dominance frontiers
+ //
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<DominanceFrontier>();
+ AU.setPreservesCFG();
+ }
+ };
+
+ RegisterOpt<PromotePass> X("mem2reg", "Promote Memory to Register");
+} // end of anonymous namespace
+
+bool PromotePass::runOnFunction(Function &F) {
+ std::vector<AllocaInst*> Allocas;
+
+ BasicBlock &BB = F.getEntryNode(); // Get the entry node for the function
+
+ // Find allocas that are safe to promote, by looking at all instructions in
+ // the entry node
+ for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(&*I)) // Is it an alloca?
+ if (isAllocaPromotable(AI))
+ Allocas.push_back(AI);
+
+ if (!Allocas.empty()) {
+ PromoteMemToReg(Allocas, getAnalysis<DominanceFrontier>());
+ NumPromoted += Allocas.size();
+ return true;
+ }
+ return false;
+}
+
+// createPromoteMemoryToRegister - Provide an entry point to create this pass.
+//
+Pass *createPromoteMemoryToRegister() {
+ return new PromotePass();
+}