necipfazil created this revision.
necipfazil added reviewers: rjmccall, rsmith, morehouse, kcc, llvm-commits,
cfe-commits.
necipfazil requested review of this revision.
Herald added a project: clang.
Create and add generalized type identifier metadata to indirect calls,
and to functions that may be target to indirect calls.
Type identifiers will be used by the back-end to construct the call
graph section to precisely represent the possible targets for indirect calls.
The type information is deliberately pulled from the front-end to have extra
precision since some type information is lost at IR, and to ensure
consistent type identifiers between object files compiled at different
times (as C/C++ standards require language-level types to match).
Original RFC: https://lists.llvm.org/pipermail/llvm-dev/2021-June/151044.html
Updated RFC: https://lists.llvm.org/pipermail/llvm-dev/2021-July/151739.html
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D105909
Files:
clang/lib/CodeGen/CGClass.cpp
clang/lib/CodeGen/CGExpr.cpp
clang/lib/CodeGen/CGExprCXX.cpp
clang/lib/CodeGen/CGObjCMac.cpp
clang/lib/CodeGen/CodeGenModule.cpp
clang/lib/CodeGen/CodeGenModule.h
clang/test/CodeGen/call-graph-section.c
Index: clang/test/CodeGen/call-graph-section.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/call-graph-section.c
@@ -0,0 +1,47 @@
+// Tests that we assign appropriate identifiers to indirect calls and targets.
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -fcall-graph-section -S \
+// RUN: -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=ITANIUM %s
+
+// RUN: %clang_cc1 -triple x86_64-pc-windows-msvc -fcall-graph-section -S \
+// RUN: -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=MS %s
+
+// CHECK: define {{(dso_local )?}}void @foo({{.*}} !type [[TVOID_GENERALIZED:![0-9]+]]
+void foo() {
+}
+
+// CHECK: define {{(dso_local )?}}void @bar({{.*}} !type [[TVOID_GENERALIZED:![0-9]+]]
+void bar() {
+ void (*fp)() = foo;
+ // CHECK: call {{.*}} !type [[TVOID_GENERALIZED:![0-9]+]]
+ return fp();
+}
+
+// CHECK: define {{(dso_local )?}}i32 @baz({{.*}} !type [[TPRIMITIVE_GENERALIZED:![0-9]+]]
+int baz(char a, float b, double c) {
+ return 1;
+}
+
+// CHECK: define {{(dso_local )?}}i32* @qux({{.*}} !type [[TPTR_GENERALIZED:![0-9]+]]
+int *qux(char *a, float *b, double *c) {
+ return 0;
+}
+
+// CHECK: define {{(dso_local )?}}void @corge({{.*}} !type [[TVOID_GENERALIZED:![0-9]+]]
+void corge() {
+ int (*fp_baz)(char, float, double) = baz;
+ // CHECK: call i32 {{.*}}, !type [[TPRIMITIVE_GENERALIZED:![0-9]+]]
+ fp_baz('a', .0f, .0);
+
+ int *(*fp_qux)(char *, float *, double *) = qux;
+ // CHECK: call i32* {{.*}}, !type [[TPTR_GENERALIZED:![0-9]+]]
+ fp_qux(0, 0, 0);
+}
+
+// ITANIUM-DAG: [[TVOID_GENERALIZED]] = !{{{.*}}!"_ZTSFvE.generalized"}
+// ITANIUM-DAG: [[TPRIMITIVE_GENERALIZED]] = !{{{.*}}!"_ZTSFicfdE.generalized"}
+// ITANIUM-DAG: [[TPTR_GENERALIZED]] = !{{{.*}}!"_ZTSFPvS_S_S_E.generalized"}
+// MS-DAG: [[TVOID_GENERALIZED]] = !{{{.*}}!"?6AX@Z.generalized"}
+// MS-DAG: [[TPRIMITIVE_GENERALIZED]] = !{{{.*}}!"?6AHDMN@Z.generalized"}
+// MS-DAG: [[TPTR_GENERALIZED]] = !{{{.*}}!"?6APEAXPEAX00@Z.generalized"}
+
Index: clang/lib/CodeGen/CodeGenModule.h
===================================================================
--- clang/lib/CodeGen/CodeGenModule.h
+++ clang/lib/CodeGen/CodeGenModule.h
@@ -1406,6 +1406,10 @@
void CreateFunctionTypeMetadataForIcall(const FunctionDecl *FD,
llvm::Function *F);
+ /// Create and attach type metadata to the given call.
+ void CreateFunctionTypeMetadataForIcall(const QualType &QT,
+ llvm::CallBase *CB);
+
/// Whether this function's return type has no side effects, and thus may
/// be trivially discarded if it is unused.
bool MayDropFunctionReturn(const ASTContext &Context, QualType ReturnType);
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -1873,8 +1873,9 @@
// In the cross-dso CFI mode with canonical jump tables, we want !type
// attributes on definitions only.
- if (CodeGenOpts.SanitizeCfiCrossDso &&
- CodeGenOpts.SanitizeCfiCanonicalJumpTables) {
+ if ((CodeGenOpts.SanitizeCfiCrossDso &&
+ CodeGenOpts.SanitizeCfiCanonicalJumpTables) ||
+ CodeGenOpts.CallGraphSection) {
if (auto *FD = dyn_cast<FunctionDecl>(D)) {
// Skip available_externally functions. They won't be codegen'ed in the
// current module anyway.
@@ -2057,7 +2058,17 @@
void CodeGenModule::CreateFunctionTypeMetadataForIcall(const FunctionDecl *FD,
llvm::Function *F) {
- // Only if we are checking indirect calls.
+ bool EmittedMDIdGeneralized = false;
+ if (CodeGenOpts.CallGraphSection &&
+ (!F->hasLocalLinkage() ||
+ F->getFunction().hasAddressTaken(nullptr, /* IgnoreCallbackUses */ true,
+ /* IgnoreAssumeLikeCalls */ true,
+ /* IgnoreLLVMUsed */ false))) {
+ F->addTypeMetadata(0, CreateMetadataIdentifierGeneralized(FD->getType()));
+ EmittedMDIdGeneralized = true;
+ }
+
+ // Add additional metadata only if we are checking indirect calls with CFI.
if (!LangOpts.Sanitize.has(SanitizerKind::CFIICall))
return;
@@ -2068,7 +2079,9 @@
llvm::Metadata *MD = CreateMetadataIdentifierForType(FD->getType());
F->addTypeMetadata(0, MD);
- F->addTypeMetadata(0, CreateMetadataIdentifierGeneralized(FD->getType()));
+ // Add the generalized identifier if not added already.
+ if (!EmittedMDIdGeneralized)
+ F->addTypeMetadata(0, CreateMetadataIdentifierGeneralized(FD->getType()));
// Emit a hash-based bit set entry for cross-DSO calls.
if (CodeGenOpts.SanitizeCfiCrossDso)
@@ -2076,6 +2089,17 @@
F->addTypeMetadata(0, llvm::ConstantAsMetadata::get(CrossDsoTypeId));
}
+void CodeGenModule::CreateFunctionTypeMetadataForIcall(const QualType &QT,
+ llvm::CallBase *CB) {
+ // Only if needed for call graph section and only for indirect calls.
+ if (!(CodeGenOpts.CallGraphSection && CB && CB->isIndirectCall()))
+ return;
+
+ auto *MD = CreateMetadataIdentifierGeneralized(QT);
+ auto *MDN = llvm::MDNode::get(getLLVMContext(), MD);
+ CB->setMetadata(llvm::LLVMContext::MD_type, MDN);
+}
+
void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F,
bool IsIncompleteFunction,
bool IsThunk) {
@@ -2150,7 +2174,8 @@
// are non-canonical then we need type metadata in order to produce the local
// jump table.
if (!CodeGenOpts.SanitizeCfiCrossDso ||
- !CodeGenOpts.SanitizeCfiCanonicalJumpTables)
+ !CodeGenOpts.SanitizeCfiCanonicalJumpTables ||
+ CodeGenOpts.CallGraphSection)
CreateFunctionTypeMetadataForIcall(FD, F);
if (getLangOpts().OpenMP && FD->hasAttr<OMPDeclareSimdDeclAttr>())
Index: clang/lib/CodeGen/CGObjCMac.cpp
===================================================================
--- clang/lib/CodeGen/CGObjCMac.cpp
+++ clang/lib/CodeGen/CGObjCMac.cpp
@@ -2279,6 +2279,13 @@
CGCallee Callee = CGCallee::forDirect(BitcastFn);
RValue rvalue = CGF.EmitCall(MSI.CallInfo, Callee, Return, ActualArgs,
&CallSite);
+ // Set type identifier metadata of indirect calls for call graph section.
+ if (CGM.getCodeGenOpts().CallGraphSection && Method && CallSite &&
+ CallSite->isIndirectCall()) {
+ if (const auto *FnType = Method->getFunctionType()) {
+ CGM.CreateFunctionTypeMetadataForIcall(QualType(FnType, 0), CallSite);
+ }
+ }
// Mark the call as noreturn if the method is marked noreturn and the
// receiver cannot be null.
Index: clang/lib/CodeGen/CGExprCXX.cpp
===================================================================
--- clang/lib/CodeGen/CGExprCXX.cpp
+++ clang/lib/CodeGen/CGExprCXX.cpp
@@ -86,9 +86,17 @@
*this, MD, This, ImplicitParam, ImplicitParamTy, CE, Args, RtlArgs);
auto &FnInfo = CGM.getTypes().arrangeCXXMethodCall(
Args, FPT, CallInfo.ReqArgs, CallInfo.PrefixSize);
- return EmitCall(FnInfo, Callee, ReturnValue, Args, nullptr,
- CE && CE == MustTailCall,
- CE ? CE->getExprLoc() : SourceLocation());
+ llvm::CallBase *CallOrInvoke = nullptr;
+ auto Call = EmitCall(FnInfo, Callee, ReturnValue, Args, &CallOrInvoke,
+ CE && CE == MustTailCall,
+ CE ? CE->getExprLoc() : SourceLocation());
+
+ // Set type identifier metadata of indirect calls for call graph section.
+ if (CGM.getCodeGenOpts().CallGraphSection && CallOrInvoke &&
+ CallOrInvoke->isIndirectCall())
+ CGM.CreateFunctionTypeMetadataForIcall(MD->getType(), CallOrInvoke);
+
+ return Call;
}
RValue CodeGenFunction::EmitCXXDestructorCall(
@@ -112,9 +120,18 @@
CallArgList Args;
commonEmitCXXMemberOrOperatorCall(*this, DtorDecl, This, ImplicitParam,
ImplicitParamTy, CE, Args, nullptr);
- return EmitCall(CGM.getTypes().arrangeCXXStructorDeclaration(Dtor), Callee,
- ReturnValueSlot(), Args, nullptr, CE && CE == MustTailCall,
- CE ? CE->getExprLoc() : SourceLocation{});
+ llvm::CallBase *CallOrInvoke = nullptr;
+ auto Call =
+ EmitCall(CGM.getTypes().arrangeCXXStructorDeclaration(Dtor), Callee,
+ ReturnValueSlot(), Args, &CallOrInvoke, CE && CE == MustTailCall,
+ CE ? CE->getExprLoc() : SourceLocation{});
+
+ // Set type identifier metadata of indirect calls for call graph section.
+ if (CGM.getCodeGenOpts().CallGraphSection && CallOrInvoke &&
+ CallOrInvoke->isIndirectCall())
+ CGM.CreateFunctionTypeMetadataForIcall(DtorDecl->getType(), CallOrInvoke);
+
+ return Call;
}
RValue CodeGenFunction::EmitCXXPseudoDestructorExpr(
@@ -471,10 +488,18 @@
// And the rest of the call args
EmitCallArgs(Args, FPT, E->arguments());
- return EmitCall(CGM.getTypes().arrangeCXXMethodCall(Args, FPT, required,
- /*PrefixSize=*/0),
- Callee, ReturnValue, Args, nullptr, E == MustTailCall,
- E->getExprLoc());
+ llvm::CallBase *CallOrInvoke = nullptr;
+ auto Call = EmitCall(CGM.getTypes().arrangeCXXMethodCall(Args, FPT, required,
+ /*PrefixSize=*/0),
+ Callee, ReturnValue, Args, &CallOrInvoke,
+ E == MustTailCall, E->getExprLoc());
+
+ // Set type identifier metadata of indirect calls for call graph section.
+ if (CGM.getCodeGenOpts().CallGraphSection && CallOrInvoke &&
+ CallOrInvoke->isIndirectCall())
+ CGM.CreateFunctionTypeMetadataForIcall(QualType(FPT, 0), CallOrInvoke);
+
+ return Call;
}
RValue
Index: clang/lib/CodeGen/CGExpr.cpp
===================================================================
--- clang/lib/CodeGen/CGExpr.cpp
+++ clang/lib/CodeGen/CGExpr.cpp
@@ -5311,6 +5311,11 @@
CalleeDecl);
}
+ // Set type identifier metadata of indirect calls for call graph section.
+ if (CGM.getCodeGenOpts().CallGraphSection && CallOrInvoke &&
+ CallOrInvoke->isIndirectCall())
+ CGM.CreateFunctionTypeMetadataForIcall(QualType(FnType, 0), CallOrInvoke);
+
return Call;
}
Index: clang/lib/CodeGen/CGClass.cpp
===================================================================
--- clang/lib/CodeGen/CGClass.cpp
+++ clang/lib/CodeGen/CGClass.cpp
@@ -2182,7 +2182,13 @@
const CGFunctionInfo &Info = CGM.getTypes().arrangeCXXConstructorCall(
Args, D, Type, ExtraArgs.Prefix, ExtraArgs.Suffix, PassPrototypeArgs);
CGCallee Callee = CGCallee::forDirect(CalleePtr, GlobalDecl(D, Type));
- EmitCall(Info, Callee, ReturnValueSlot(), Args, nullptr, false, Loc);
+ llvm::CallBase *CallOrInvoke = nullptr;
+ EmitCall(Info, Callee, ReturnValueSlot(), Args, &CallOrInvoke, false, Loc);
+
+ // Set type identifier metadata of indirect calls for call graph section.
+ if (CGM.getCodeGenOpts().CallGraphSection && CallOrInvoke &&
+ CallOrInvoke->isIndirectCall())
+ CGM.CreateFunctionTypeMetadataForIcall(D->getType(), CallOrInvoke);
// Generate vtable assumptions if we're constructing a complete object
// with a vtable. We don't do this for base subobjects for two reasons:
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