PNaCl: Fix ExpandTls to handle a couple of corner cases involving PHI nodes

ExpandTls's use of replaceUsesOfWith() didn't work for PHI nodes
containing the same Constant twice (which needs to work for same or
differing incoming BasicBlocks).  The same applies to
ExpandTlsConstantExpr.

I noticed this while implementing ExpandConstantExpr.

Fix this and factor out some common code that all three passes can
use.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=2837
TEST=test/Transforms/NaCl/*.ll

Review URL: https://codereview.chromium.org/13128002

1 files changed, 2 insertions, 21 deletions

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;