BoundsChecking: add a couple of simple tests and fix a bug in branch emition

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157329 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/BoundsChecking.cpp

@@ -62,6 +62,7 @@ namespace {
     unsigned Penalty;
 
     BasicBlock *getTrapBB();
+    void emitBranchToTrap(Value *Cmp = 0);
     ConstTriState computeAllocSize(Value *Alloc, uint64_t &Size,
                                    Value* &SizeValue);
     bool instrument(Value *Ptr, Value *Val);
@@ -94,6 +95,22 @@ BasicBlock *BoundsChecking::getTrapBB() {
 }
 
 
+/// emitBranchToTrap - emit a branch instruction to a trap block.
+/// If Cmp is non-null, perform a jump only if its value evaluates to true.
+void BoundsChecking::emitBranchToTrap(Value *Cmp) {
+  Instruction *Inst = Builder->GetInsertPoint();
+  BasicBlock *OldBB = Inst->getParent();
+  BasicBlock *Cont = OldBB->splitBasicBlock(Inst);
+  OldBB->getTerminator()->eraseFromParent();
+
+  // FIXME: add unlikely branch taken metadata?
+  if (Cmp)
+    BranchInst::Create(getTrapBB(), Cont, Cmp, OldBB);
+  else
+    BranchInst::Create(getTrapBB(), OldBB);
+}
+
+
 /// computeAllocSize - compute the object size allocated by an allocation
 /// site. Returns NotConst if the size is not constant (in SizeValue), Const if
 /// the size is constant (in Size), and Dunno if the size could not be
@@ -254,7 +271,7 @@ bool BoundsChecking::instrument(Value *Ptr, Value *InstVal) {
   if (!OffsetValue && ConstAlloc == Const) {
     if (Size < Offset || (Size - Offset) < NeededSize) {
       // Out of bounds
-      Builder->CreateBr(getTrapBB());
+      emitBranchToTrap();
       ++ChecksAdded;
       return true;
     }
@@ -278,13 +295,8 @@ bool BoundsChecking::instrument(Value *Ptr, Value *InstVal) {
   Value *Cmp1 = Builder->CreateICmpULT(SizeValue, OffsetValue);
   Value *Cmp2 = Builder->CreateICmpULT(ObjSize, NeededSizeVal);
   Value *Or = Builder->CreateOr(Cmp1, Cmp2);
+  emitBranchToTrap(Or);
 
-  // FIXME: add unlikely branch taken metadata?
-  Instruction *Inst = Builder->GetInsertPoint();
-  BasicBlock *OldBB = Inst->getParent();
-  BasicBlock *Cont = OldBB->splitBasicBlock(Inst);
-  OldBB->getTerminator()->eraseFromParent();
-  BranchInst::Create(getTrapBB(), Cont, Or, OldBB);
   ++ChecksAdded;
   return true;
 }

test/Transforms/BoundsChecking/simple.ll

@@ -0,0 +1,78 @@
+; RUN: opt < %s -boundschecking -S | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
+@.str = private constant [8 x i8] c"abcdefg\00"   ; <[8 x i8]*>
+
+declare noalias i8* @malloc(i64) nounwind
+declare noalias i8* @calloc(i64, i64) nounwind
+declare noalias i8* @realloc(i8* nocapture, i64) nounwind
+
+; CHECK: @f1
+define void @f1() nounwind {
+  %1 = tail call i8* @malloc(i64 32)
+  %2 = bitcast i8* %1 to i32*
+  %idx = getelementptr inbounds i32* %2, i64 2
+; CHECK-NOT: trap
+  store i32 3, i32* %idx, align 4
+  ret void
+}
+
+; CHECK: @f2
+define void @f2() nounwind {
+  %1 = tail call i8* @malloc(i64 32)
+  %2 = bitcast i8* %1 to i32*
+  %idx = getelementptr inbounds i32* %2, i64 8
+; CHECK: trap
+  store i32 3, i32* %idx, align 4
+  ret void
+}
+
+; CHECK: @f3
+define void @f3(i64 %x) nounwind {
+  %1 = tail call i8* @calloc(i64 4, i64 %x)
+  %2 = bitcast i8* %1 to i32*
+  %idx = getelementptr inbounds i32* %2, i64 8
+; CHECK-NEXT: mul i64 4, %
+; CHECK-NEXT: sub i64 {{.*}}, 32
+; CHECK-NEXT: icmp ult i64 {{.*}}, 32
+; CHECK-NEXT: icmp ult i64 {{.*}}, 4
+; CHECK-NEXT: or i1
+; CHECK: trap
+  store i32 3, i32* %idx, align 4
+  ret void
+}
+
+; CHECK: @f4
+define void @f4(i64 %x) nounwind {
+  %1 = tail call i8* @realloc(i8* null, i64 %x) nounwind
+  %2 = bitcast i8* %1 to i32*
+  %idx = getelementptr inbounds i32* %2, i64 8
+; CHECK: trap
+  %3 = load i32* %idx, align 4
+  ret void
+}
+
+; CHECK: @f5
+define void @f5(i64 %x) nounwind {
+  %idx = getelementptr inbounds [8 x i8]* @.str, i64 0, i64 %x
+; CHECK: trap
+  %1 = load i8* %idx, align 4
+  ret void
+}
+
+; CHECK: @f6
+define void @f6(i64 %x) nounwind {
+  %1 = alloca i128
+; CHECK-NOT: trap
+  %2 = load i128* %1, align 4
+  ret void
+}
+
+; CHECK: @f7
+define void @f7(i64 %x) nounwind {
+  %1 = alloca i128, i64 %x
+; CHECK: mul i64 16,
+; CHECK: trap
+  %2 = load i128* %1, align 4
+  ret void
+}