Vendor import of llvm release_32 branch r168974 (effectively, 3.2 RC2):

http://llvm.org/svn/llvm-project/llvm/branches/release_32@168974

1 files changed, 46 insertions, 10 deletions

diff --git a/lib/Analysis/Lint.cpp b/lib/Analysis/Lint.cpp
index 83bdf52..6d6d580 100644
--- a/lib/Analysis/Lint.cpp
+++ b/lib/Analysis/Lint.cpp
@@ -43,7 +43,7 @@
 #include "llvm/Analysis/Loads.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Assembly/Writer.h"
-#include "llvm/Target/TargetData.h"
+#include "llvm/DataLayout.h"
 #include "llvm/Target/TargetLibraryInfo.h"
 #include "llvm/Pass.h"
 #include "llvm/PassManager.h"
@@ -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();
@@ -411,14 +411,50 @@ void Lint::visitMemoryReference(Instruction &I,
             "Undefined behavior: Branch to non-blockaddress", &I);
   }
 
+  // Check for buffer overflows and misalignment.
   if (TD) {
-    if (Align == 0 && Ty) Align = TD->getABITypeAlignment(Ty);
+    // 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 (!AI->isArrayAllocation() && ATy->isSized())
+          BaseSize = TD->getTypeAllocSize(ATy);
+        BaseAlign = AI->getAlignment();
+        if (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 (GTy->isSized())
+            BaseSize = TD->getTypeAllocSize(GTy);
+          BaseAlign = GV->getAlignment();
+          if (BaseAlign == 0 && GTy->isSized())
+            BaseAlign = TD->getABITypeAlignment(GTy);
+        }
+      }
 
-    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))),
+      // 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 (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 +506,7 @@ 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;