forked from OSchip/llvm-project
[WPD] Avoid noalias assumptions in unique return value optimization
Summary: Changes the type of the @__typeid_.*_unique_member imports we generate for unique return value optimization from i8 to [0 x i8]. This prevents assuming that these imports do not alias, such as when two unique return values occur in the same vtable. Fixes PR45393. Reviewers: tejohnson, pcc Reviewed By: pcc Subscribers: aganea, hiraditya, rnk, george.burgess.iv, dblaikie, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D77421
This commit is contained in:
Bob Haarman
parent
314f00a034
commit
cc5c58889e
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@ -500,6 +500,10 @@ struct DevirtModule {
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IntegerType *Int32Ty;
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IntegerType *Int64Ty;
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IntegerType *IntPtrTy;
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/// Sizeless array type, used for imported vtables. This provides a signal
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/// to analyzers that these imports may alias, as they do for example
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/// when multiple unique return values occur in the same vtable.
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ArrayType *Int8Arr0Ty;
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bool RemarksEnabled;
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function_ref<OptimizationRemarkEmitter &(Function *)> OREGetter;
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@ -529,6 +533,7 @@ struct DevirtModule {
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Int32Ty(Type::getInt32Ty(M.getContext())),
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Int64Ty(Type::getInt64Ty(M.getContext())),
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IntPtrTy(M.getDataLayout().getIntPtrType(M.getContext(), 0)),
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Int8Arr0Ty(ArrayType::get(Type::getInt8Ty(M.getContext()), 0)),
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RemarksEnabled(areRemarksEnabled()), OREGetter(OREGetter) {
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assert(!(ExportSummary && ImportSummary));
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FunctionsToSkip.init(SkipFunctionNames);
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@ -1415,7 +1420,8 @@ void DevirtModule::exportConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
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Constant *DevirtModule::importGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
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StringRef Name) {
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Constant *C = M.getOrInsertGlobal(getGlobalName(Slot, Args, Name), Int8Ty);
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Constant *C =
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M.getOrInsertGlobal(getGlobalName(Slot, Args, Name), Int8Arr0Ty);
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auto *GV = dyn_cast<GlobalVariable>(C);
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if (GV)
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GV->setVisibility(GlobalValue::HiddenVisibility);
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@ -1457,8 +1463,8 @@ void DevirtModule::applyUniqueRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
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for (auto &&Call : CSInfo.CallSites) {
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IRBuilder<> B(Call.CS.getInstruction());
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Value *Cmp =
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B.CreateICmp(IsOne ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
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B.CreateBitCast(Call.VTable, Int8PtrTy), UniqueMemberAddr);
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B.CreateICmp(IsOne ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE, Call.VTable,
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B.CreateBitCast(UniqueMemberAddr, Call.VTable->getType()));
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Cmp = B.CreateZExt(Cmp, Call.CS->getType());
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Call.replaceAndErase("unique-ret-val", FnName, RemarksEnabled, OREGetter,
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Cmp);
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@ -0,0 +1,17 @@
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---
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TypeIdMap:
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_ZTS1C:
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WPDRes:
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16:
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Kind: Indir
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ResByArg:
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'':
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Kind: UniqueRetVal
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Info: 1
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24:
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Kind: Indir
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ResByArg:
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'':
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Kind: UniqueRetVal
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Info: 1
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...
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@ -11,10 +11,10 @@
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target datalayout = "e-p:64:64"
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target triple = "x86_64-unknown-linux-gnu"
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; VCP-X86: @__typeid_typeid1_0_1_byte = external hidden global i8, !absolute_symbol !0
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; VCP-X86: @__typeid_typeid1_0_1_bit = external hidden global i8, !absolute_symbol !1
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; VCP-X86: @__typeid_typeid2_8_3_byte = external hidden global i8, !absolute_symbol !0
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; VCP-X86: @__typeid_typeid2_8_3_bit = external hidden global i8, !absolute_symbol !1
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; VCP-X86: @__typeid_typeid1_0_1_byte = external hidden global [0 x i8], !absolute_symbol !0
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; VCP-X86: @__typeid_typeid1_0_1_bit = external hidden global [0 x i8], !absolute_symbol !1
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; VCP-X86: @__typeid_typeid2_8_3_byte = external hidden global [0 x i8], !absolute_symbol !0
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; VCP-X86: @__typeid_typeid2_8_3_bit = external hidden global [0 x i8], !absolute_symbol !1
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; Test cases where the argument values are known and we can apply virtual
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; constant propagation.
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@ -34,7 +34,7 @@ define i32 @call1(i8* %obj) #0 {
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; SINGLE-IMPL: call i32 bitcast (void ()* @singleimpl1 to i32 (i8*, i32)*)
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%result = call i32 %fptr_casted(i8* %obj, i32 1)
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; UNIFORM-RET-VAL: ret i32 42
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; VCP-X86: [[GEP1:%.*]] = getelementptr i8, i8* [[VT1]], i32 ptrtoint (i8* @__typeid_typeid1_0_1_byte to i32)
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; VCP-X86: [[GEP1:%.*]] = getelementptr i8, i8* [[VT1]], i32 ptrtoint ([0 x i8]* @__typeid_typeid1_0_1_byte to i32)
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; VCP-ARM: [[GEP1:%.*]] = getelementptr i8, i8* [[VT1]], i32 42
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; VCP: [[BC1:%.*]] = bitcast i8* [[GEP1]] to i32*
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; VCP: [[LOAD1:%.*]] = load i32, i32* [[BC1]]
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@ -85,13 +85,13 @@ define i1 @call3(i8* %obj) #0 {
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cont:
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%fptr_casted = bitcast i8* %fptr to i1 (i8*, i32)*
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%result = call i1 %fptr_casted(i8* %obj, i32 3)
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; UNIQUE-RET-VAL0: icmp ne i8* %vtablei8, @__typeid_typeid2_8_3_unique_member
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; UNIQUE-RET-VAL1: icmp eq i8* %vtablei8, @__typeid_typeid2_8_3_unique_member
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; UNIQUE-RET-VAL0: icmp ne i8* %vtablei8, getelementptr inbounds ([0 x i8], [0 x i8]* @__typeid_typeid2_8_3_unique_member, i32 0, i32 0)
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; UNIQUE-RET-VAL1: icmp eq i8* %vtablei8, getelementptr inbounds ([0 x i8], [0 x i8]* @__typeid_typeid2_8_3_unique_member, i32 0, i32 0)
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; VCP: [[VT2:%.*]] = bitcast {{.*}} to i8*
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; VCP-X86: [[GEP2:%.*]] = getelementptr i8, i8* [[VT2]], i32 ptrtoint (i8* @__typeid_typeid2_8_3_byte to i32)
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; VCP-X86: [[GEP2:%.*]] = getelementptr i8, i8* [[VT2]], i32 ptrtoint ([0 x i8]* @__typeid_typeid2_8_3_byte to i32)
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; VCP-ARM: [[GEP2:%.*]] = getelementptr i8, i8* [[VT2]], i32 43
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; VCP: [[LOAD2:%.*]] = load i8, i8* [[GEP2]]
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; VCP-X86: [[AND2:%.*]] = and i8 [[LOAD2]], ptrtoint (i8* @__typeid_typeid2_8_3_bit to i8)
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; VCP-X86: [[AND2:%.*]] = and i8 [[LOAD2]], ptrtoint ([0 x i8]* @__typeid_typeid2_8_3_bit to i8)
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; VCP-ARM: [[AND2:%.*]] = and i8 [[LOAD2]], -128
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; VCP: [[ICMP2:%.*]] = icmp ne i8 [[AND2]], 0
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; VCP: ret i1 [[ICMP2]]
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@ -0,0 +1,59 @@
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; Test for PR45393: Two virtual functions that return unique i1 values
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; in the same vtable. Both calls are optimized to a comparison of
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; this's vptr against the address of the vtable. When nesting these
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; checks, LLVM would previously assume the nested check always fails,
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; but that assumption does not hold if both checks refer to the same vtable.
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; This tests checks that this case is handled correctly.
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;
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; RUN: opt -S -wholeprogramdevirt -wholeprogramdevirt-summary-action=import \
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; RUN: -wholeprogramdevirt-read-summary=%p/Inputs/unique-retval-same-vtable.yaml \
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; RUN: -O2 -o - %s | FileCheck %s
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;
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; Check that C::f() contains both possible return values.
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; CHECK-LABEL: define {{.*}} @_ZNK1C1fEv
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; CHECK-NOT: }
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; CHECK: 20074028
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; CHECK-NOT: }
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; CHECK: 1008434
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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%class.C = type { i32 (...)** }
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define hidden i32 @_ZNK1C1fEv(%class.C* %this) {
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entry:
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%0 = bitcast %class.C* %this to i1 (%class.C*)***
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%vtable = load i1 (%class.C*)**, i1 (%class.C*)*** %0
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%1 = bitcast i1 (%class.C*)** %vtable to i8*
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%2 = tail call i1 @llvm.type.test(i8* %1, metadata !"_ZTS1C")
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tail call void @llvm.assume(i1 %2)
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%vfn = getelementptr inbounds i1 (%class.C*)*, i1 (%class.C*)** %vtable, i64 2
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%3 = load i1 (%class.C*)*, i1 (%class.C*)** %vfn
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%call = tail call zeroext i1 %3(%class.C* %this)
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br i1 %call, label %if.then, label %return
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if.then:
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%vtable2 = load i1 (%class.C*)**, i1 (%class.C*)*** %0
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%4 = bitcast i1 (%class.C*)** %vtable2 to i8*
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%5 = tail call i1 @llvm.type.test(i8* %4, metadata !"_ZTS1C")
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tail call void @llvm.assume(i1 %5)
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%vfn3 = getelementptr inbounds i1 (%class.C*)*, i1 (%class.C*)** %vtable2, i64 3
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%6 = load i1 (%class.C*)*, i1 (%class.C*)** %vfn3
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; The method being called here and the method being called before
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; the branch above both return true in the same vtable and only that
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; vtable. Therefore, if this call is reached, we must select
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; 20074028. Earlier versions of LLVM mistakenly concluded that
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; this code *never* selects 200744028.
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%call4 = tail call zeroext i1 %6(%class.C* nonnull %this)
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%. = select i1 %call4, i32 20074028, i32 3007762
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br label %return
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return:
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%retval.0 = phi i32 [ %., %if.then ], [ 1008434, %entry ]
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ret i32 %retval.0
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}
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declare i1 @llvm.type.test(i8*, metadata)
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declare void @llvm.assume(i1)
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@ -20,15 +20,13 @@ define i1 @vf1(i8* %this) readnone {
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define i1 @call1(i8* %obj) {
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%vtableptr = bitcast i8* %obj to [1 x i8*]**
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%vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
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; CHECK: {{.*}} = bitcast [1 x i8*]* {{.*}} to i8*
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; CHECK: [[VT1:%[^ ]*]] = bitcast [1 x i8*]* {{.*}} to i8*
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%vtablei8 = bitcast [1 x i8*]* %vtable to i8*
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%p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid1")
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call void @llvm.assume(i1 %p)
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%fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
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%fptr = load i8*, i8** %fptrptr
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%fptr_casted = bitcast i8* %fptr to i1 (i8*)*
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; CHECK: [[RES1:%[^ ]*]] = icmp eq i8* [[VT1]], bitcast ([1 x i8*]* @vt3 to i8*)
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; CHECK: [[RES1:%[^ ]*]] = icmp eq [1 x i8*]* %vtable, @vt3
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%result = call i1 %fptr_casted(i8* %obj)
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; CHECK: ret i1 [[RES1]]
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ret i1 %result
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@ -38,7 +36,6 @@ define i1 @call1(i8* %obj) {
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define i32 @call2(i8* %obj) {
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%vtableptr = bitcast i8* %obj to [1 x i8*]**
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%vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
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; CHECK: [[VT2:%[^ ]*]] = bitcast [1 x i8*]* {{.*}} to i8*
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%vtablei8 = bitcast [1 x i8*]* %vtable to i8*
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%p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid2")
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call void @llvm.assume(i1 %p)
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@ -46,7 +43,7 @@ define i32 @call2(i8* %obj) {
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%fptr = load i8*, i8** %fptrptr
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; Intentional type mismatch to test zero extend.
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%fptr_casted = bitcast i8* %fptr to i32 (i8*)*
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; CHECK: [[RES2:%[^ ]*]] = icmp ne i8* [[VT1]], bitcast ([1 x i8*]* @vt2 to i8*)
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; CHECK: [[RES2:%[^ ]*]] = icmp ne [1 x i8*]* %vtable, @vt2
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%result = call i32 %fptr_casted(i8* %obj)
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; CHECK: [[ZEXT2:%[^ ]*]] = zext i1 [[RES2]] to i32
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; CHECK: ret i32 [[ZEXT2:%[^ ]*]]
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