5 files changed, 49 insertions, 41 deletions
diff --git a/lib/Transforms/NaCl/CMakeLists.txt b/lib/Transforms/NaCl/CMakeLists.txt
index 1ca8e3d59e..5d630bb111 100644
--- a/lib/Transforms/NaCl/CMakeLists.txt
+++ b/lib/Transforms/NaCl/CMakeLists.txt
@@ -4,6 +4,7 @@ add_llvm_library(LLVMTransformsNaCl
   ExpandGetElementPtr.cpp
   ExpandTls.cpp
   ExpandTlsConstantExpr.cpp
+  ExpandUtils.cpp
   ExpandVarArgs.cpp
   GlobalCleanup.cpp
   StripMetadata.cpp
diff --git a/lib/Transforms/NaCl/ExpandConstantExpr.cpp b/lib/Transforms/NaCl/ExpandConstantExpr.cpp
index 5ff47cb00c..2856a9d7e4 100644
--- a/lib/Transforms/NaCl/ExpandConstantExpr.cpp
+++ b/lib/Transforms/NaCl/ExpandConstantExpr.cpp
@@ -63,31 +63,12 @@ static bool expandInstruction(Instruction *Inst) {
     return false;
 
   bool Modified = false;
-  if (PHINode *PN = dyn_cast<PHINode>(Inst)) {
-    // PHI nodes require special treatment.  A incoming block may be
-    // listed twice, but its incoming values must match so they must
-    // be converted only once.
-    std::map<BasicBlock*,Value*> Converted;
-    for (unsigned OpNum = 0; OpNum < Inst->getNumOperands(); OpNum++) {
-      if (ConstantExpr *Expr =
-          dyn_cast<ConstantExpr>(Inst->getOperand(OpNum))) {
-        Modified = true;
-        BasicBlock *Incoming = PN->getIncomingBlock(OpNum);
-        if (Converted.count(Incoming) == 0) {
-          Converted[Incoming] = expandConstantExpr(Incoming->getTerminator(),
-                                                   Expr);
-        }
-        Inst->setOperand(OpNum, Converted[Incoming]);
-      }
-    }
-    return Modified;
-  }
-
   for (unsigned OpNum = 0; OpNum < Inst->getNumOperands(); OpNum++) {
     if (ConstantExpr *Expr =
         dyn_cast<ConstantExpr>(Inst->getOperand(OpNum))) {
       Modified = true;
-      Inst->setOperand(OpNum, expandConstantExpr(Inst, Expr));
+      Use *U = &Inst->getOperandUse(OpNum);
+      PhiSafeReplaceUses(U, expandConstantExpr(PhiSafeInsertPt(U), Expr));
     }
   }
   return Modified;
diff --git a/lib/Transforms/NaCl/ExpandTls.cpp b/lib/Transforms/NaCl/ExpandTls.cpp
index 929b2e0a15..53e1c92a96 100644
--- a/lib/Transforms/NaCl/ExpandTls.cpp
+++ b/lib/Transforms/NaCl/ExpandTls.cpp
@@ -250,15 +250,8 @@ static void rewriteTlsVars(Module &M, std::vector<VarInfo> *TlsVars,
        ++VarInfo) {
     GlobalVariable *Var = VarInfo->TlsVar;
     while (!Var->use_empty()) {
-      Instruction *U = cast<Instruction>(*Var->use_begin());
-      Instruction *InsertPt = U;
-      if (PHINode *PN = dyn_cast<PHINode>(InsertPt)) {
-        // We cannot insert instructions before a PHI node, so insert
-        // before the incoming block's terminator.  Note that if the
-        // terminator is conditional, this could be suboptimal,
-        // because we might be calling ReadTpFunc unnecessarily.
-        InsertPt = PN->getIncomingBlock(Var->use_begin())->getTerminator();
-      }
+      Use *U = &Var->use_begin().getUse();
+      Instruction *InsertPt = PhiSafeInsertPt(U);
       Value *RawThreadPtr = CallInst::Create(ReadTpFunc, "tls_raw", InsertPt);
       Value *TypedThreadPtr = new BitCastInst(RawThreadPtr, TemplatePtrType,
                                               "tls_struct", InsertPt);
@@ -279,7 +272,7 @@ static void rewriteTlsVars(Module &M, std::vector<VarInfo> *TlsVars,
           M.getContext(), APInt(32, VarInfo->TemplateIndex)));
       Value *TlsField = GetElementPtrInst::Create(TypedThreadPtr, Indexes,
                                                   "field", InsertPt);
-      U->replaceUsesOfWith(Var, TlsField);
+      PhiSafeReplaceUses(U, TlsField);
     }
     VarInfo->TlsVar->eraseFromParent();
   }
diff --git a/lib/Transforms/NaCl/ExpandTlsConstantExpr.cpp b/lib/Transforms/NaCl/ExpandTlsConstantExpr.cpp
index 51b21cbf2a..328e5e08e6 100644
--- a/lib/Transforms/NaCl/ExpandTlsConstantExpr.cpp
+++ b/lib/Transforms/NaCl/ExpandTlsConstantExpr.cpp
@@ -78,18 +78,11 @@ static void expandConstExpr(Constant *Expr) {
 
   if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Expr)) {
     while (!Expr->use_empty()) {
-      Instruction *U = cast<Instruction>(*Expr->use_begin());
-      Instruction *InsertPt = U;
-      if (PHINode *PN = dyn_cast<PHINode>(InsertPt)) {
-        // We cannot insert instructions before a PHI node, so insert
-        // before the incoming block's terminator.  This could be
-        // suboptimal if the terminator is a conditional.
-        InsertPt = PN->getIncomingBlock(Expr->use_begin())->getTerminator();
-      }
+      Use *U = &Expr->use_begin().getUse();
       Instruction *NewInst = CE->getAsInstruction();
-      NewInst->insertBefore(InsertPt);
+      NewInst->insertBefore(PhiSafeInsertPt(U));
       NewInst->setName("expanded");
-      U->replaceUsesOfWith(CE, NewInst);
+      PhiSafeReplaceUses(U, NewInst);
     }
   }
 }
diff --git a/lib/Transforms/NaCl/ExpandUtils.cpp b/lib/Transforms/NaCl/ExpandUtils.cpp
new file mode 100644
index 0000000000..0670ff75ce
--- /dev/null
+++ b/lib/Transforms/NaCl/ExpandUtils.cpp
@@ -0,0 +1,40 @@
+//===-- ExpandUtils.cpp - Helper functions for expansion passes -----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Transforms/NaCl.h"
+
+using namespace llvm;
+
+Instruction *llvm::PhiSafeInsertPt(Use *U) {
+  Instruction *InsertPt = cast<Instruction>(U->getUser());
+  if (PHINode *PN = dyn_cast<PHINode>(InsertPt)) {
+    // We cannot insert instructions before a PHI node, so insert
+    // before the incoming block's terminator.  This could be
+    // suboptimal if the terminator is a conditional.
+    InsertPt = PN->getIncomingBlock(*U)->getTerminator();
+  }
+  return InsertPt;
+}
+
+void llvm::PhiSafeReplaceUses(Use *U, Value *NewVal) {
+  if (PHINode *PN = dyn_cast<PHINode>(U->getUser())) {
+    // A PHI node can have multiple incoming edges from the same
+    // block, in which case all these edges must have the same
+    // incoming value.
+    BasicBlock *BB = PN->getIncomingBlock(*U);
+    for (unsigned I = 0; I < PN->getNumIncomingValues(); ++I) {
+      if (PN->getIncomingBlock(I) == BB)
+        PN->setIncomingValue(I, NewVal);
+    }
+  } else {
+    U->getUser()->replaceUsesOfWith(U->get(), NewVal);
+  }
+}