From c3fb03e289a5b1122ea98073ba3714f171bfbb0c Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sun, 29 Aug 2010 04:54:06 +0000
Subject: [PATCH] implement SSAUpdater::RewriteUseAfterInsertions, a helpful
 form of RewriteUse.

llvm-svn: 112409
---
 llvm/include/llvm/Transforms/Utils/SSAUpdater.h |  6 ++++++
 llvm/lib/Transforms/Utils/SSAUpdater.cpp        | 16 ++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/llvm/include/llvm/Transforms/Utils/SSAUpdater.h b/llvm/include/llvm/Transforms/Utils/SSAUpdater.h
index ca98466b3456..86ecb73df696 100644
--- a/llvm/include/llvm/Transforms/Utils/SSAUpdater.h
+++ b/llvm/include/llvm/Transforms/Utils/SSAUpdater.h
@@ -94,6 +94,12 @@ public:
   /// for the use's block will be considered to be below it.
   void RewriteUse(Use &U);
 
+  /// RewriteUseAfterInsertions - Rewrite a use, just like RewriteUse.  However,
+  /// this version of the method can rewrite uses in the same block as a
+  /// definition, because it assumes that all uses of a value are below any
+  /// inserted values.
+  void RewriteUseAfterInsertions(Use &U);
+
 private:
   Value *GetValueAtEndOfBlockInternal(BasicBlock *BB);
 
diff --git a/llvm/lib/Transforms/Utils/SSAUpdater.cpp b/llvm/lib/Transforms/Utils/SSAUpdater.cpp
index f4bdb527655a..9dc2a1ed38e9 100644
--- a/llvm/lib/Transforms/Utils/SSAUpdater.cpp
+++ b/llvm/lib/Transforms/Utils/SSAUpdater.cpp
@@ -205,6 +205,22 @@ void SSAUpdater::RewriteUse(Use &U) {
   U.set(V);
 }
 
+/// RewriteUseAfterInsertions - Rewrite a use, just like RewriteUse.  However,
+/// this version of the method can rewrite uses in the same block as a
+/// definition, because it assumes that all uses of a value are below any
+/// inserted values.
+void SSAUpdater::RewriteUseAfterInsertions(Use &U) {
+  Instruction *User = cast<Instruction>(U.getUser());
+  
+  Value *V;
+  if (PHINode *UserPN = dyn_cast<PHINode>(User))
+    V = GetValueAtEndOfBlock(UserPN->getIncomingBlock(U));
+  else
+    V = GetValueAtEndOfBlock(User->getParent());
+  
+  U.set(V);
+}
+
 /// PHIiter - Iterator for PHI operands.  This is used for the PHI_iterator
 /// in the SSAUpdaterImpl template.
 namespace {
-- 
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