commit 94e8e0cfbe13cdbdf7addc6e36df863cab92e4c9
author Chris Lattner <sabre@nondot.org> Sat Jan 15 07:25:29 2011 +0000
committer Chris Lattner <sabre@nondot.org> Sat Jan 15 07:25:29 2011 +0000
tree 98f51b117a90652f64838caa862d98cbebdfe687
parent 7579609bfe0d915b6c2d8dc094a132d793ec8855

Now that instruction optzns can update the iterator as they go, we can 
have objectsize folding recursively simplify away their result when it
folds.  It is important to catch this here, because otherwise we won't
eliminate the cross-block values at isel and other times.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123524 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/CodeGenPrepare.cpp

diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index ae82787..921cec8 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -42,6 +42,7 @@
 #include "llvm/Support/PatternMatch.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/IRBuilder.h"
+#include "llvm/Support/ValueHandle.h"
 using namespace llvm;
 using namespace llvm::PatternMatch;
 
@@ -634,8 +635,18 @@
     bool Min = (cast<ConstantInt>(II->getArgOperand(1))->getZExtValue() == 1);
     const Type *ReturnTy = CI->getType();
     Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL);    
-    CI->replaceAllUsesWith(RetVal);
-    CI->eraseFromParent();
+    
+    // Substituting this can cause recursive simplifications, which can
+    // invalidate our iterator.  Use a WeakVH to hold onto it in case this
+    // happens.
+    WeakVH IterHandle(CurInstIterator);
+    
+    ReplaceAndSimplifyAllUses(CI, RetVal, TLI ? TLI->getTargetData() : 0, DT);
+
+    // If the iterator instruction was recursively deleted, start over at the
+    // start of the block.
+    if (IterHandle != CurInstIterator)
+      CurInstIterator = BB->begin();
     return true;
   }
 
@@ -653,6 +664,7 @@
   CodeGenPrepareFortifiedLibCalls Simplifier;
   return Simplifier.fold(CI, TD);
 }
+
 //===----------------------------------------------------------------------===//
 // Memory Optimization
 //===----------------------------------------------------------------------===//
@@ -1076,14 +1088,8 @@
   SunkAddrs.clear();
 
   CurInstIterator = BB.begin();
-  for (BasicBlock::iterator E = BB.end(); CurInstIterator != E; ) {
-    Instruction *I = CurInstIterator++;
-
-    if (CallInst *CI = dyn_cast<CallInst>(I))
-      MadeChange |= OptimizeCallInst(CI);
-    else
-      MadeChange |= OptimizeInst(I);
-  }
+  for (BasicBlock::iterator E = BB.end(); CurInstIterator != E; )
+    MadeChange |= OptimizeInst(CurInstIterator++);
 
   return MadeChange;
 }