From 86441169da23959c81d8648c3dfdc7a0bb8d2225 Mon Sep 17 00:00:00 2001 From: Manman Ren Date: Thu, 10 Jan 2013 01:10:10 +0000 Subject: [PATCH] Stack Alignment: throw error if we can't satisfy the minimal alignment requirement when creating stack objects in MachineFrameInfo. Add CreateStackObjectWithMinAlign to throw error when the minimal alignment can't be achieved and to clamp the alignment when the preferred alignment can't be achieved. Same is true for CreateVariableSizedObject. Will not emit error in CreateSpillStackObject or CreateStackObject. As long as callers of CreateStackObject do not assume the object will be aligned at the requested alignment, we should not have miscompile since later optimizations which look at the object's alignment will have the correct information. rdar://12713765 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172027 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/CodeGen/MachineFrameInfo.h | 19 ++++++-- lib/CodeGen/MachineFunction.cpp | 48 ++++++++++++------- .../SelectionDAG/FunctionLoweringInfo.cpp | 3 +- .../SelectionDAG/SelectionDAGBuilder.cpp | 3 +- .../ARM/alloc-no-stack-realign-error.ll | 19 ++++++++ test/CodeGen/ARM/alloc-no-stack-realign.ll | 2 +- 6 files changed, 70 insertions(+), 24 deletions(-) create mode 100644 test/CodeGen/ARM/alloc-no-stack-realign-error.ll diff --git a/include/llvm/CodeGen/MachineFrameInfo.h b/include/llvm/CodeGen/MachineFrameInfo.h index 93d77287d7c..0748b9ab24a 100644 --- a/include/llvm/CodeGen/MachineFrameInfo.h +++ b/include/llvm/CodeGen/MachineFrameInfo.h @@ -493,11 +493,23 @@ public: return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL; } + /// CreateStackObjectWithMinAlign - Create a new statically sized stack + /// object, returning a nonnegative identifier to represent it. This function + /// takes a preferred alignment and a minimal alignment. + /// + int CreateStackObjectWithMinAlign(uint64_t Size, unsigned PrefAlignment, + unsigned MinAlignment, bool isSS, + bool MayNeedSP = false, const AllocaInst *Alloca = 0); + /// CreateStackObject - Create a new statically sized stack object, returning - /// a nonnegative identifier to represent it. + /// a nonnegative identifier to represent it. Will not emit an error when + /// Alignment can't be satisfied. /// int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSS, - bool MayNeedSP = false, const AllocaInst *Alloca = 0); + bool MayNeedSP = false, const AllocaInst *Alloca = 0) { + return CreateStackObjectWithMinAlign(Size, Alignment, 0, isSS, + MayNeedSP, Alloca); + } /// CreateSpillStackObject - Create a new statically sized stack object that /// represents a spill slot, returning a nonnegative identifier to represent @@ -517,7 +529,8 @@ public: /// variable sized object is created, whether or not the index returned is /// actually used. /// - int CreateVariableSizedObject(unsigned Alignment); + int CreateVariableSizedObject(unsigned PrefAlignment, unsigned MinAlignment, + const AllocaInst *Alloca = 0); /// getCalleeSavedInfo - Returns a reference to call saved info vector for the /// current function. diff --git a/lib/CodeGen/MachineFunction.cpp b/lib/CodeGen/MachineFunction.cpp index 9647e83e24c..3d7d20d4160 100644 --- a/lib/CodeGen/MachineFunction.cpp +++ b/lib/CodeGen/MachineFunction.cpp @@ -473,24 +473,32 @@ void MachineFrameInfo::ensureMaxAlignment(unsigned Align) { } /// clampStackAlignment - Clamp the alignment if requested and emit a warning. -static inline unsigned clampStackAlignment(bool ShouldClamp, unsigned Align, - unsigned StackAlign) { - if (!ShouldClamp || Align <= StackAlign) - return Align; - DEBUG(dbgs() << "Warning: requested alignment " << Align - << " exceeds the stack alignment " << StackAlign - << " when stack realignment is off" << '\n'); +static inline unsigned clampStackAlignment(bool ShouldClamp, unsigned PrefAlign, + unsigned MinAlign, unsigned StackAlign, + const AllocaInst *Alloca = 0) { + if (!ShouldClamp || PrefAlign <= StackAlign) + return PrefAlign; + if (Alloca && MinAlign > StackAlign) + Alloca->getParent()->getContext().emitError(Alloca, + "Requested Minimal Alignment exceeds the Stack Alignment!"); + else + assert(MinAlign <= StackAlign && + "Requested Minimal Alignment exceeds the Stack Alignment!"); return StackAlign; } -/// CreateStackObject - Create a new statically sized stack object, returning -/// a nonnegative identifier to represent it. +/// CreateStackObjectWithMinAlign - Create a new statically sized stack +/// object, returning a nonnegative identifier to represent it. This function +/// takes a preferred alignment and a minimal alignment. /// -int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment, - bool isSS, bool MayNeedSP, const AllocaInst *Alloca) { +int MachineFrameInfo::CreateStackObjectWithMinAlign(uint64_t Size, + unsigned PrefAlignment, unsigned MinAlignment, + bool isSS, bool MayNeedSP, const AllocaInst *Alloca) { assert(Size != 0 && "Cannot allocate zero size stack objects!"); - Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption, - Alignment, TFI.getStackAlignment()); + unsigned Alignment = clampStackAlignment( + !TFI.isStackRealignable() || !RealignOption, + PrefAlignment, MinAlignment, + TFI.getStackAlignment(), Alloca); Objects.push_back(StackObject(Size, Alignment, 0, false, isSS, MayNeedSP, Alloca)); int Index = (int)Objects.size() - NumFixedObjects - 1; @@ -506,7 +514,8 @@ int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment, int MachineFrameInfo::CreateSpillStackObject(uint64_t Size, unsigned Alignment) { Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption, - Alignment, TFI.getStackAlignment()); + Alignment, 0, + TFI.getStackAlignment()); CreateStackObject(Size, Alignment, true, false); int Index = (int)Objects.size() - NumFixedObjects - 1; ensureMaxAlignment(Alignment); @@ -518,10 +527,13 @@ int MachineFrameInfo::CreateSpillStackObject(uint64_t Size, /// variable sized object is created, whether or not the index returned is /// actually used. /// -int MachineFrameInfo::CreateVariableSizedObject(unsigned Alignment) { +int MachineFrameInfo::CreateVariableSizedObject(unsigned PrefAlignment, + unsigned MinAlignment, const AllocaInst *Alloca) { HasVarSizedObjects = true; - Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption, - Alignment, TFI.getStackAlignment()); + unsigned Alignment = clampStackAlignment( + !TFI.isStackRealignable() || !RealignOption, + PrefAlignment, MinAlignment, + TFI.getStackAlignment(), Alloca); Objects.push_back(StackObject(0, Alignment, 0, false, false, true, 0)); ensureMaxAlignment(Alignment); return (int)Objects.size()-NumFixedObjects-1; @@ -542,7 +554,7 @@ int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset, unsigned StackAlign = TFI.getStackAlignment(); unsigned Align = MinAlign(SPOffset, StackAlign); Align = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption, - Align, TFI.getStackAlignment()); + Align, 0, TFI.getStackAlignment()); Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable, /*isSS*/ false, /*NeedSP*/ false, diff --git a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp index b46edad7a3d..229c50be9a1 100644 --- a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp +++ b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp @@ -95,7 +95,8 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) { (TySize >= 8 && isa(Ty) && cast(Ty)->getElementType()->isIntegerTy(8))); StaticAllocaMap[AI] = - MF->getFrameInfo()->CreateStackObject(TySize, Align, false, + MF->getFrameInfo()->CreateStackObjectWithMinAlign(TySize, Align, + AI->getAlignment(), false, MayNeedSP, AI); } diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index 8c22db35cb1..ee98b00e2b5 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -3259,7 +3259,8 @@ void SelectionDAGBuilder::visitAlloca(const AllocaInst &I) { // Inform the Frame Information that we have just allocated a variable-sized // object. - FuncInfo.MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1); + FuncInfo.MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1, + I.getAlignment(), &I); } void SelectionDAGBuilder::visitLoad(const LoadInst &I) { diff --git a/test/CodeGen/ARM/alloc-no-stack-realign-error.ll b/test/CodeGen/ARM/alloc-no-stack-realign-error.ll new file mode 100644 index 00000000000..96c00174dba --- /dev/null +++ b/test/CodeGen/ARM/alloc-no-stack-realign-error.ll @@ -0,0 +1,19 @@ +; RUN: llc < %s -mtriple=armv7-apple-ios -O0 -realign-stack=0 2>&1 | FileCheck %s + +; rdar://12713765 +@T3_retval = common global <16 x float> zeroinitializer, align 16 + +; If alignment for alloc is smaller than or equal to stack alignment, but the +; preferred type alignment is bigger, the alignment will be clamped. +; If alignment for alloca is bigger than stack alignment, the compiler +; will emit an error. +define void @test(<16 x float>* noalias sret %agg.result) nounwind ssp { +entry: +; CHECK: Requested Minimal Alignment exceeds the Stack Alignment! + %retval = alloca <16 x float>, align 16 + %0 = load <16 x float>* @T3_retval, align 16 + store <16 x float> %0, <16 x float>* %retval + %1 = load <16 x float>* %retval + store <16 x float> %1, <16 x float>* %agg.result, align 16 + ret void +} diff --git a/test/CodeGen/ARM/alloc-no-stack-realign.ll b/test/CodeGen/ARM/alloc-no-stack-realign.ll index 273041dee34..94adc9c67de 100644 --- a/test/CodeGen/ARM/alloc-no-stack-realign.ll +++ b/test/CodeGen/ARM/alloc-no-stack-realign.ll @@ -39,7 +39,7 @@ entry: ; NO-REALIGN: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #16 ; NO-REALIGN: vst1.64 ; NO-REALIGN: vst1.64 - %retval = alloca <16 x float>, align 16 + %retval = alloca <16 x float>, align 4 %0 = load <16 x float>* @T3_retval, align 16 store <16 x float> %0, <16 x float>* %retval %1 = load <16 x float>* %retval