Rebased PNaCl localmods in LLVM to 223109

lib/Transforms/NaCl/ExpandConstantExpr.cpp

+//===- ExpandConstantExpr.cpp - Convert ConstantExprs to Instructions------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass expands out ConstantExprs into Instructions.
+//
+// Note that this only converts ConstantExprs that are referenced by
+// Instructions.  It does not convert ConstantExprs that are used as
+// initializers for global variables.
+//
+// This simplifies the language so that the PNaCl translator does not
+// need to handle ConstantExprs as part of a stable wire format for
+// PNaCl.
+//
+//===----------------------------------------------------------------------===//
+
+#include <map>
+
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/NaCl.h"
+
+using namespace llvm;
+
+static bool expandInstruction(Instruction *Inst);
+
+namespace {
+  // This is a FunctionPass because our handling of PHI nodes means
+  // that our modifications may cross BasicBlocks.
+  struct ExpandConstantExpr : public FunctionPass {
+    static char ID; // Pass identification, replacement for typeid
+    ExpandConstantExpr() : FunctionPass(ID) {
+      initializeExpandConstantExprPass(*PassRegistry::getPassRegistry());
+    }
+
+    virtual bool runOnFunction(Function &Func);
+  };
+}
+
+char ExpandConstantExpr::ID = 0;
+INITIALIZE_PASS(ExpandConstantExpr, "expand-constant-expr",
+                "Expand out ConstantExprs into Instructions",
+                false, false)
+
+static Value *expandConstantExpr(Instruction *InsertPt, ConstantExpr *Expr) {
+  Instruction *NewInst = Expr->getAsInstruction();
+  NewInst->insertBefore(InsertPt);
+  NewInst->setName("expanded");
+  expandInstruction(NewInst);
+  return NewInst;
+}
+
+static bool expandInstruction(Instruction *Inst) {
+  // A landingpad can only accept ConstantExprs, so it should remain
+  // unmodified.
+  if (isa<LandingPadInst>(Inst))
+    return false;
+
+  bool Modified = false;
+  for (unsigned OpNum = 0; OpNum < Inst->getNumOperands(); OpNum++) {
+    if (ConstantExpr *Expr =
+        dyn_cast<ConstantExpr>(Inst->getOperand(OpNum))) {
+      Modified = true;
+      Use *U = &Inst->getOperandUse(OpNum);
+      PhiSafeReplaceUses(U, expandConstantExpr(PhiSafeInsertPt(U), Expr));
+    }
+  }
+  return Modified;
+}
+
+bool ExpandConstantExpr::runOnFunction(Function &Func) {
+  bool Modified = false;
+  for (llvm::Function::iterator BB = Func.begin(), E = Func.end();
+       BB != E;
+       ++BB) {
+    for (BasicBlock::InstListType::iterator Inst = BB->begin(), E = BB->end();
+         Inst != E;
+         ++Inst) {
+      Modified |= expandInstruction(Inst);
+    }
+  }
+  return Modified;
+}
+
+FunctionPass *llvm::createExpandConstantExprPass() {
+  return new ExpandConstantExpr();
+}