[PATCH] D16230: isSafeToLoadUnconditionally cleanup

[Artur Pilipenko via llvm-commits]

apilipenko created this revision.
apilipenko added reviewers: hfinkel, reames.
apilipenko added a subscriber: llvm-commits.

GlobalVariable/AllocaInst cases are handled by isDerferenceableAndAlignedPointer function.

http://reviews.llvm.org/D16230

Files:
  lib/Analysis/Loads.cpp

Index: lib/Analysis/Loads.cpp
===================================================================
--- lib/Analysis/Loads.cpp
+++ lib/Analysis/Loads.cpp
@@ -76,48 +76,9 @@
   if (isDereferenceableAndAlignedPointer(V, Align, DL, ScanFrom, DT, TLI))
     return true;
 
-  int64_t ByteOffset = 0;
-  Value *Base = V;
-  Base = GetPointerBaseWithConstantOffset(V, ByteOffset, DL);
-
-  if (ByteOffset < 0) // out of bounds
-    return false;
-
-  Type *BaseType = nullptr;
-  unsigned BaseAlign = 0;
-  if (const AllocaInst *AI = dyn_cast<AllocaInst>(Base)) {
-    // An alloca is safe to load from as load as it is suitably aligned.
-    BaseType = AI->getAllocatedType();
-    BaseAlign = AI->getAlignment();
-  } else if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(Base)) {
-    // Global variables are not necessarily safe to load from if they are
-    // overridden. Their size may change or they may be weak and require a test
-    // to determine if they were in fact provided.
-    if (!GV->mayBeOverridden()) {
-      BaseType = GV->getType()->getElementType();
-      BaseAlign = GV->getAlignment();
-    }
-  }
-
   PointerType *AddrTy = cast<PointerType>(V->getType());
   uint64_t LoadSize = DL.getTypeStoreSize(AddrTy->getElementType());
 
-  // If we found a base allocated type from either an alloca or global variable,
-  // try to see if we are definitively within the allocated region. We need to
-  // know the size of the base type and the loaded type to do anything in this
-  // case.
-  if (BaseType && BaseType->isSized()) {
-    if (BaseAlign == 0)
-      BaseAlign = DL.getPrefTypeAlignment(BaseType);
-
-    if (Align <= BaseAlign) {
-      // Check if the load is within the bounds of the underlying object.
-      if (ByteOffset + LoadSize <= DL.getTypeAllocSize(BaseType) &&
-          ((ByteOffset % Align) == 0))
-        return true;
-    }
-  }
-
   // Otherwise, be a little bit aggressive by scanning the local block where we
   // want to check to see if the pointer is already being loaded or stored
   // from/to.  If so, the previous load or store would have already trapped,


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