X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FLint.cpp;h=9393508a9e67edbdde900ae20180f92a0b866659;hb=55ec2218c448ef9e0d09b5534885b6d2a9786a73;hp=83bdf5286ad7deab58b6f728de82d384563fa02d;hpb=26c8dcc692fb2addd475446cfff24d6a4e958bca;p=oota-llvm.git

diff --git a/lib/Analysis/Lint.cpp b/lib/Analysis/Lint.cpp
index 83bdf5286ad..9393508a9e6 100644
--- a/lib/Analysis/Lint.cpp
+++ b/lib/Analysis/Lint.cpp
@@ -34,26 +34,26 @@
 // 
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Analysis/Passes.h"
+#include "llvm/Analysis/Lint.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Analysis/Dominators.h"
-#include "llvm/Analysis/Lint.h"
+#include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/Loads.h"
+#include "llvm/Analysis/Passes.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Assembly/Writer.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Target/TargetLibraryInfo.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/InstVisitor.h"
 #include "llvm/Pass.h"
 #include "llvm/PassManager.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/Function.h"
 #include "llvm/Support/CallSite.h"
 #include "llvm/Support/Debug.h"
-#include "llvm/Support/InstVisitor.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/STLExtras.h"
+#include "llvm/Target/TargetLibraryInfo.h"
 using namespace llvm;
 
 namespace {
@@ -103,7 +103,7 @@ namespace {
     Module *Mod;
     AliasAnalysis *AA;
     DominatorTree *DT;
-    TargetData *TD;
+    DataLayout *TD;
     TargetLibraryInfo *TLI;
 
     std::string Messages;
@@ -177,7 +177,7 @@ bool Lint::runOnFunction(Function &F) {
   Mod = F.getParent();
   AA = &getAnalysis<AliasAnalysis>();
   DT = &getAnalysis<DominatorTree>();
-  TD = getAnalysisIfAvailable<TargetData>();
+  TD = getAnalysisIfAvailable<DataLayout>();
   TLI = &getAnalysis<TargetLibraryInfo>();
   visit(F);
   dbgs() << MessagesStr.str();
@@ -411,16 +411,50 @@ void Lint::visitMemoryReference(Instruction &I,
             "Undefined behavior: Branch to non-blockaddress", &I);
   }
 
-  if (TD) {
-    if (Align == 0 && Ty) Align = TD->getABITypeAlignment(Ty);
-
-    if (Align != 0) {
-      unsigned BitWidth = TD->getTypeSizeInBits(Ptr->getType());
-      APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
-      ComputeMaskedBits(Ptr, KnownZero, KnownOne, TD);
-      Assert1(!(KnownOne & APInt::getLowBitsSet(BitWidth, Log2_32(Align))),
-              "Undefined behavior: Memory reference address is misaligned", &I);
+  // Check for buffer overflows and misalignment.
+  // Only handles memory references that read/write something simple like an
+  // alloca instruction or a global variable.
+  int64_t Offset = 0;
+  if (Value *Base = GetPointerBaseWithConstantOffset(Ptr, Offset, TD)) {
+    // OK, so the access is to a constant offset from Ptr.  Check that Ptr is
+    // something we can handle and if so extract the size of this base object
+    // along with its alignment.
+    uint64_t BaseSize = AliasAnalysis::UnknownSize;
+    unsigned BaseAlign = 0;
+
+    if (AllocaInst *AI = dyn_cast<AllocaInst>(Base)) {
+      Type *ATy = AI->getAllocatedType();
+      if (TD && !AI->isArrayAllocation() && ATy->isSized())
+        BaseSize = TD->getTypeAllocSize(ATy);
+      BaseAlign = AI->getAlignment();
+      if (TD && BaseAlign == 0 && ATy->isSized())
+        BaseAlign = TD->getABITypeAlignment(ATy);
+    } else if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Base)) {
+      // If the global may be defined differently in another compilation unit
+      // then don't warn about funky memory accesses.
+      if (GV->hasDefinitiveInitializer()) {
+        Type *GTy = GV->getType()->getElementType();
+        if (TD && GTy->isSized())
+          BaseSize = TD->getTypeAllocSize(GTy);
+        BaseAlign = GV->getAlignment();
+        if (TD && BaseAlign == 0 && GTy->isSized())
+          BaseAlign = TD->getABITypeAlignment(GTy);
+      }
     }
+
+    // Accesses from before the start or after the end of the object are not
+    // defined.
+    Assert1(Size == AliasAnalysis::UnknownSize ||
+            BaseSize == AliasAnalysis::UnknownSize ||
+            (Offset >= 0 && Offset + Size <= BaseSize),
+            "Undefined behavior: Buffer overflow", &I);
+
+    // Accesses that say that the memory is more aligned than it is are not
+    // defined.
+    if (TD && Align == 0 && Ty && Ty->isSized())
+      Align = TD->getABITypeAlignment(Ty);
+    Assert1(!BaseAlign || Align <= MinAlign(BaseAlign, Offset),
+            "Undefined behavior: Memory reference address is misaligned", &I);
   }
 }
 
@@ -470,7 +504,7 @@ void Lint::visitShl(BinaryOperator &I) {
             "Undefined result: Shift count out of range", &I);
 }
 
-static bool isZero(Value *V, TargetData *TD) {
+static bool isZero(Value *V, DataLayout *TD) {
   // Assume undef could be zero.
   if (isa<UndefValue>(V)) return true;