[llvm-commits] [llvm] r156585 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombine.h lib/Transforms/InstCombine/InstCombineAddSub.cpp lib/Transforms/InstCombine/InstCombineCalls.cpp test/Transforms/InstCombine/objsize.ll
Duncan Sands
baldrick at free.fr
Fri May 11 00:24:16 PDT 2012
Hi Nuno,
> objectsize: add support for GEPs with non-constant indexes
> add an additional parameter to InstCombiner::EmitGEPOffset() to force it to *not* emit operations with NUW flag
why? It seems strange - can you please explain.
Ciao, Duncan.
> Modified:
> llvm/trunk/lib/Transforms/InstCombine/InstCombine.h
> llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
> llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
> llvm/trunk/test/Transforms/InstCombine/objsize.ll
>
> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombine.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombine.h?rev=156585&r1=156584&r2=156585&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/InstCombine/InstCombine.h (original)
> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombine.h Thu May 10 18:17:35 2012
> @@ -226,7 +226,7 @@
> bool DoXform = true);
> Instruction *transformSExtICmp(ICmpInst *ICI, Instruction&CI);
> bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
> - Value *EmitGEPOffset(User *GEP);
> + Value *EmitGEPOffset(User *GEP, bool NoNUW = false);
>
> public:
> // InsertNewInstBefore - insert an instruction New before instruction Old
>
> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp?rev=156585&r1=156584&r2=156585&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp (original)
> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp Thu May 10 18:17:35 2012
> @@ -423,7 +423,8 @@
> /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
> /// code necessary to compute the offset from the base pointer (without adding
> /// in the base pointer). Return the result as a signed integer of intptr size.
> -Value *InstCombiner::EmitGEPOffset(User *GEP) {
> +/// If NoNUW is true, then the NUW flag is not used.
> +Value *InstCombiner::EmitGEPOffset(User *GEP, bool NoNUW) {
> TargetData&TD = *getTargetData();
> gep_type_iterator GTI = gep_type_begin(GEP);
> Type *IntPtrTy = TD.getIntPtrType(GEP->getContext());
> @@ -431,7 +432,7 @@
>
> // If the GEP is inbounds, we know that none of the addressing operations will
> // overflow in an unsigned sense.
> - bool isInBounds = cast<GEPOperator>(GEP)->isInBounds();
> + bool isInBounds = cast<GEPOperator>(GEP)->isInBounds()&& !NoNUW;
>
> // Build a mask for high order bits.
> unsigned IntPtrWidth = TD.getPointerSizeInBits();
>
> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp?rev=156585&r1=156584&r2=156585&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp (original)
> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp Thu May 10 18:17:35 2012
> @@ -173,7 +173,7 @@
> uint64_t Penalty, TargetData *TD,
> InstCombiner::BuilderTy *Builder) {
> if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Alloc)) {
> - if (GV->hasUniqueInitializer()) {
> + if (GV->hasDefinitiveInitializer()) {
> Constant *C = GV->getInitializer();
> Size = TD->getTypeAllocSize(C->getType());
> return 1;
> @@ -198,7 +198,8 @@
> if (Penalty< 2)
> return 2;
>
> - SizeValue = Builder->CreateMul(Builder->getInt64(Size), ArraySize);
> + SizeValue = ConstantInt::get(ArraySize->getType(), Size);
> + SizeValue = Builder->CreateMul(SizeValue, ArraySize);
> return 0;
>
> } else if (CallInst *MI = extractMallocCall(Alloc)) {
> @@ -320,22 +321,12 @@
>
> // Get to the real allocated thing and offset as fast as possible.
> Value *Op1 = II->getArgOperand(0)->stripPointerCasts();
> + GEPOperator *GEP;
>
> - uint64_t Offset = 0;
> - Value *OffsetValue;
> - bool ConstOffset = true;
> -
> - // Try to look through constant GEPs.
> - if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1)) {
> - if (!GEP->hasAllConstantIndices()) return 0;
> -
> - // Get the current byte offset into the thing. Use the original
> - // operand in case we're looking through a bitcast.
> - SmallVector<Value*, 8> Ops(GEP->idx_begin(), GEP->idx_end());
> - if (!GEP->getPointerOperandType()->isPointerTy())
> + if ((GEP = dyn_cast<GEPOperator>(Op1))) {
> + // check if we will be able to get the offset
> + if (!GEP->hasAllConstantIndices()&& Penalty< 2)
> return 0;
> - Offset = TD->getIndexedOffset(GEP->getPointerOperandType(), Ops);
> -
> Op1 = GEP->getPointerOperand()->stripPointerCasts();
> }
>
> @@ -349,28 +340,36 @@
> if (ConstAlloc == 2)
> return 0;
>
> - if (ConstOffset&& ConstAlloc) {
> + uint64_t Offset = 0;
> + Value *OffsetValue = 0;
> +
> + if (GEP) {
> + if (GEP->hasAllConstantIndices()) {
> + SmallVector<Value*, 8> Ops(GEP->idx_begin(), GEP->idx_end());
> + assert(GEP->getPointerOperandType()->isPointerTy());
> + Offset = TD->getIndexedOffset(GEP->getPointerOperandType(), Ops);
> + } else
> + OffsetValue = EmitGEPOffset(GEP, true /*NoNUW*/);
> + }
> +
> + if (!OffsetValue&& ConstAlloc) {
> if (Size< Offset) {
> // Out of bounds
> return ReplaceInstUsesWith(CI, ConstantInt::get(ReturnTy, 0));
> }
> return ReplaceInstUsesWith(CI, ConstantInt::get(ReturnTy, Size-Offset));
> + }
>
> - } else if (Penalty>= 2) {
> - if (ConstOffset)
> - OffsetValue = Builder->getInt64(Offset);
> - if (ConstAlloc)
> - SizeValue = Builder->getInt64(Size);
> -
> - Value *Val = Builder->CreateSub(SizeValue, OffsetValue);
> - Val = Builder->CreateTrunc(Val, ReturnTy);
> - // return 0 if there's an overflow
> - Value *Cmp = Builder->CreateICmpULT(SizeValue, OffsetValue);
> - Val = Builder->CreateSelect(Cmp, ConstantInt::get(ReturnTy, 0), Val);
> - return ReplaceInstUsesWith(CI, Val);
> -
> - } else
> - return 0;
> + if (!OffsetValue)
> + OffsetValue = ConstantInt::get(ReturnTy, Offset);
> + if (ConstAlloc)
> + SizeValue = ConstantInt::get(ReturnTy, Size);
> +
> + Value *Val = Builder->CreateSub(SizeValue, OffsetValue);
> + // return 0 if there's an overflow
> + Value *Cmp = Builder->CreateICmpULT(SizeValue, OffsetValue);
> + Val = Builder->CreateSelect(Cmp, ConstantInt::get(ReturnTy, 0), Val);
> + return ReplaceInstUsesWith(CI, Val);
> }
> case Intrinsic::bswap:
> // bswap(bswap(x)) -> x
>
> Modified: llvm/trunk/test/Transforms/InstCombine/objsize.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/objsize.ll?rev=156585&r1=156584&r2=156585&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstCombine/objsize.ll (original)
> +++ llvm/trunk/test/Transforms/InstCombine/objsize.ll Thu May 10 18:17:35 2012
> @@ -168,3 +168,28 @@
> ; CHECK-NEXT: ret i32 30
> ret i32 %objsize
> }
> +
> +; CHECK: @test9
> +define i32 @test9(i32 %x, i32 %y) nounwind {
> + %a = alloca [3 x [4 x double]], align 8
> + %1 = getelementptr inbounds [3 x [4 x double]]* %a, i32 0, i32 %x
> + %2 = getelementptr inbounds [4 x double]* %1, i32 0, i32 %y
> + %3 = bitcast double* %2 to i8*
> + %objsize = call i32 @llvm.objectsize.i32(i8* %3, i1 false, i32 2)
> + ret i32 %objsize
> +; CHECK-NEXT: shl i32 %x, 5
> +; CHECK-NEXT: shl i32 %y, 3
> +; CHECK-NEXT: add i32
> +; CHECK-NEXT: sub i32 96,
> +; CHECK-NEXT: icmp ugt i32 {{.*}}, 96
> +; CHECK-NEXT: select i1 {{.*}}, i32 0,
> +}
> +
> +; CHECK: @overflow
> +define i32 @overflow() {
> + %alloc = call noalias i8* @malloc(i32 21) nounwind
> + %gep = getelementptr inbounds i8* %alloc, i32 50
> + %objsize = call i32 @llvm.objectsize.i32(i8* %gep, i1 false, i32 0) nounwind readonly
> +; CHECK-NEXT: ret i32 0
> + ret i32 %objsize
> +}
>
>
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