From 8786754cc3d6a93357283af9976ec3bb8fe78abb Mon Sep 17 00:00:00 2001 From: Peter Collingbourne Date: Fri, 9 Dec 2016 01:10:11 +0000 Subject: [PATCH] WholeProgramDevirt: Teach the pass to handle structs of arrays. This will become necessary in some cases once D22296 lands. llvm-svn: 289165 --- llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp | 45 +++++++++---------- .../WholeProgramDevirt/bad-read-from-vtable.ll | 24 ++++++++-- .../{non-aggregate-vtable.ll => pointer-vtable.ll} | 2 +- .../Transforms/WholeProgramDevirt/soa-vtable.ll | 52 ++++++++++++++++++++++ 4 files changed, 96 insertions(+), 27 deletions(-) rename llvm/test/Transforms/WholeProgramDevirt/{non-aggregate-vtable.ll => pointer-vtable.ll} (96%) create mode 100644 llvm/test/Transforms/WholeProgramDevirt/soa-vtable.ll diff --git a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp index 9c80a2a..844cc0f 100644 --- a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp +++ b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp @@ -293,7 +293,7 @@ struct DevirtModule { void buildTypeIdentifierMap( std::vector &Bits, DenseMap> &TypeIdMap); - Constant *getValueAtOffset(Constant *I, uint64_t Offset); + Constant *getPointerAtOffset(Constant *I, uint64_t Offset); bool tryFindVirtualCallTargets(std::vector &TargetsForSlot, const std::set &TypeMemberInfos, @@ -383,36 +383,36 @@ void DevirtModule::buildTypeIdentifierMap( } } -Constant *DevirtModule::getValueAtOffset(Constant *I, uint64_t Offset) { +Constant *DevirtModule::getPointerAtOffset(Constant *I, uint64_t Offset) { + if (I->getType()->isPointerTy()) { + if (Offset == 0) + return I; + return nullptr; + } + const DataLayout &DL = M.getDataLayout(); - unsigned Op; if (auto *C = dyn_cast(I)) { const StructLayout *SL = DL.getStructLayout(C->getType()); - if (Offset >= SL->getSizeInBytes()) return nullptr; - Op = SL->getElementContainingOffset(Offset); - - if (Offset != SL->getElementOffset(Op)) - return nullptr; - - } else if (auto *C = dyn_cast(I)) { + unsigned Op = SL->getElementContainingOffset(Offset); + return getPointerAtOffset(cast(I->getOperand(Op)), + Offset - SL->getElementOffset(Op)); + } + if (auto *C = dyn_cast(I)) { ArrayType *VTableTy = C->getType(); uint64_t ElemSize = DL.getTypeAllocSize(VTableTy->getElementType()); - if (Offset % ElemSize != 0) - return nullptr; - - Op = Offset / ElemSize; - + unsigned Op = Offset / ElemSize; if (Op >= C->getNumOperands()) return nullptr; - } else - return nullptr; - return cast(I->getOperand(Op)); + return getPointerAtOffset(cast(I->getOperand(Op)), + Offset % ElemSize); + } + return nullptr; } bool DevirtModule::tryFindVirtualCallTargets( @@ -422,13 +422,12 @@ bool DevirtModule::tryFindVirtualCallTargets( if (!TM.Bits->GV->isConstant()) return false; - Constant *I = TM.Bits->GV->getInitializer(); - Value *V = getValueAtOffset(I, TM.Offset + ByteOffset); - - if (!V) + Constant *Ptr = getPointerAtOffset(TM.Bits->GV->getInitializer(), + TM.Offset + ByteOffset); + if (!Ptr) return false; - auto Fn = dyn_cast(V->stripPointerCasts()); + auto Fn = dyn_cast(Ptr->stripPointerCasts()); if (!Fn) return false; diff --git a/llvm/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll b/llvm/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll index 97445ef..4885be7 100644 --- a/llvm/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll +++ b/llvm/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll @@ -3,14 +3,15 @@ target datalayout = "e-p:64:64" target triple = "x86_64-unknown-linux-gnu" -@vt = global [2 x i8*] [i8* zeroinitializer, i8* bitcast (void (i8*)* @vf to i8*)], !type !0 +@vt1 = global [2 x i8*] [i8* zeroinitializer, i8* bitcast (void (i8*)* @vf to i8*)], !type !0 +@vt2 = global i8* bitcast (void (i8*)* @vf to i8*), !type !1 define void @vf(i8* %this) { ret void } -; CHECK: define void @unaligned -define void @unaligned(i8* %obj) { +; CHECK: define void @unaligned1 +define void @unaligned1(i8* %obj) { %vtableptr = bitcast i8* %obj to [1 x i8*]** %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr %vtablei8 = bitcast [1 x i8*]* %vtable to i8* @@ -25,6 +26,22 @@ define void @unaligned(i8* %obj) { ret void } +; CHECK: define void @unaligned2 +define void @unaligned2(i8* %obj) { + %vtableptr = bitcast i8* %obj to [1 x i8*]** + %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr + %vtablei8 = bitcast [1 x i8*]* %vtable to i8* + %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid2") + call void @llvm.assume(i1 %p) + %fptrptr = getelementptr i8, i8* %vtablei8, i32 1 + %fptrptr_casted = bitcast i8* %fptrptr to i8** + %fptr = load i8*, i8** %fptrptr_casted + %fptr_casted = bitcast i8* %fptr to void (i8*)* + ; CHECK: call void % + call void %fptr_casted(i8* %obj) + ret void +} + ; CHECK: define void @outofbounds define void @outofbounds(i8* %obj) { %vtableptr = bitcast i8* %obj to [1 x i8*]** @@ -61,3 +78,4 @@ declare i1 @llvm.type.test(i8*, metadata) declare void @llvm.assume(i1) !0 = !{i32 0, !"typeid"} +!1 = !{i32 0, !"typeid2"} diff --git a/llvm/test/Transforms/WholeProgramDevirt/non-aggregate-vtable.ll b/llvm/test/Transforms/WholeProgramDevirt/pointer-vtable.ll similarity index 96% rename from llvm/test/Transforms/WholeProgramDevirt/non-aggregate-vtable.ll rename to llvm/test/Transforms/WholeProgramDevirt/pointer-vtable.ll index e9c2db7..5e76a5a 100644 --- a/llvm/test/Transforms/WholeProgramDevirt/non-aggregate-vtable.ll +++ b/llvm/test/Transforms/WholeProgramDevirt/pointer-vtable.ll @@ -19,7 +19,7 @@ define void @call(i8* %obj) { %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0 %fptr = load i8*, i8** %fptrptr %fptr_casted = bitcast i8* %fptr to void (i8*)* - ; CHECK: call void % + ; CHECK: call void @vf( call void %fptr_casted(i8* %obj) ret void } diff --git a/llvm/test/Transforms/WholeProgramDevirt/soa-vtable.ll b/llvm/test/Transforms/WholeProgramDevirt/soa-vtable.ll new file mode 100644 index 0000000..3b6afc5 --- /dev/null +++ b/llvm/test/Transforms/WholeProgramDevirt/soa-vtable.ll @@ -0,0 +1,52 @@ +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s + +target datalayout = "e-p:64:64" +target triple = "x86_64-unknown-linux-gnu" + +%vtTy = type { [2 x void (i8*)*], [2 x void (i8*)*] } + +@vt = constant %vtTy { [2 x void (i8*)*] [void (i8*)* null, void (i8*)* @vf1], [2 x void (i8*)*] [void (i8*)* null, void (i8*)* @vf2] }, !type !0, !type !1 + +define void @vf1(i8* %this) { + ret void +} + +define void @vf2(i8* %this) { + ret void +} + +; CHECK: define void @call1 +define void @call1(i8* %obj) { + %vtableptr = bitcast i8* %obj to [1 x i8*]** + %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr + %vtablei8 = bitcast [1 x i8*]* %vtable to i8* + %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid1") + call void @llvm.assume(i1 %p) + %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0 + %fptr = load i8*, i8** %fptrptr + %fptr_casted = bitcast i8* %fptr to void (i8*)* + ; CHECK: call void @vf1( + call void %fptr_casted(i8* %obj) + ret void +} + +; CHECK: define void @call2 +define void @call2(i8* %obj) { + %vtableptr = bitcast i8* %obj to [1 x i8*]** + %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr + %vtablei8 = bitcast [1 x i8*]* %vtable to i8* + %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid2") + call void @llvm.assume(i1 %p) + %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0 + %fptr = load i8*, i8** %fptrptr + %fptr_casted = bitcast i8* %fptr to void (i8*)* + ; CHECK: call void @vf2( + call void %fptr_casted(i8* %obj) + ret void +} + +declare i1 @llvm.type.test(i8*, metadata) +declare void @llvm.assume(i1) + +!0 = !{i32 8, !"typeid1"} +!1 = !{i32 24, !"typeid2"} -- 2.7.4