From 0d984ef719f04aefa6983bd3723982b7024ca58e Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Thu, 21 Mar 2002 06:22:23 +0000
Subject: [PATCH] Fix the: test/Regression/Other/2002-03-20-LevelRaiseCrash.ll
 bug.  It turned out that almost always the result of the add was the same as
 the GEP that would be generated.  In this case, however, it wasn't, so bad
 things happened.

llvm-svn: 1929
---
 llvm/lib/Transforms/LevelRaise.cpp | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/Transforms/LevelRaise.cpp b/llvm/lib/Transforms/LevelRaise.cpp
index 2eafcf05ee85..de647935666e 100644
--- a/llvm/lib/Transforms/LevelRaise.cpp
+++ b/llvm/lib/Transforms/LevelRaise.cpp
@@ -62,6 +62,7 @@ static inline bool isReinterpretingCast(const CastInst *CI) {
 static bool HandleCastToPointer(BasicBlock::iterator BI,
                                 const PointerType *DestPTy) {
   CastInst *CI = cast<CastInst>(*BI);
+  if (CI->use_empty()) return false;
 
   // Scan all of the uses, looking for any uses that are not add
   // instructions.  If we have non-adds, do not make this transformation.
@@ -86,18 +87,36 @@ static bool HandleCastToPointer(BasicBlock::iterator BI,
   // If we have a getelementptr capability... transform all of the 
   // add instruction uses into getelementptr's.
   while (!CI->use_empty()) {
-    Instruction *I = cast<Instruction>(*CI->use_begin());
+    BinaryOperator *I = cast<BinaryOperator>(*CI->use_begin());
     assert(I->getOpcode() == Instruction::Add && I->getNumOperands() == 2 &&
            "Use is not a valid add instruction!");
     
     // Get the value added to the cast result pointer...
     Value *OtherPtr = I->getOperand((I->getOperand(0) == CI) ? 1 : 0);
 
-    GetElementPtrInst *GEP = new GetElementPtrInst(OtherPtr, Indices);
+    Instruction *GEP = new GetElementPtrInst(OtherPtr, Indices, I->getName());
     PRINT_PEEPHOLE1("cast-add-to-gep:i", I);
-    
-    // Replace the old add instruction with the shiny new GEP inst
-    ReplaceInstWithInst(I, GEP);
+
+    if (GEP->getType() == I->getType()) {
+      // Replace the old add instruction with the shiny new GEP inst
+      ReplaceInstWithInst(I, GEP);
+    } else {
+      // If the type produced by the gep instruction differs from the original
+      // add instruction type, insert a cast now.
+      //
+
+      // Insert the GEP instruction before the old add instruction... and get an
+      // iterator to point at the add instruction...
+      BasicBlock::iterator GEPI = InsertInstBeforeInst(GEP, I)+1;
+
+      PRINT_PEEPHOLE1("cast-add-to-gep:o", GEP);
+      CastInst *CI = new CastInst(GEP, I->getType());
+      GEP = CI;
+
+      // Replace the old add instruction with the shiny new GEP inst
+      ReplaceInstWithInst(I->getParent()->getInstList(), GEPI, GEP);
+    }
+
     PRINT_PEEPHOLE1("cast-add-to-gep:o", GEP);
   }
   return true;