Pass around function pointers as CGCallees, not bare llvm::Value*s.

The intention here is to make it easy to write frontend-assisted CFI
systems by propagating extra information in the CGCallee.

llvm-svn: 324377

1 files changed, 36 insertions, 31 deletions

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 2792636c7fe..dc60b1d2ed9 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -280,9 +280,9 @@ public:
   llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
                                         CharUnits VPtrOffset) override;
 
-  llvm::Value *getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,
-                                         Address This, llvm::Type *Ty,
-                                         SourceLocation Loc) override;
+  CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,
+                                     Address This, llvm::Type *Ty,
+                                     SourceLocation Loc) override;
 
   llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF,
                                          const CXXDestructorDecl *Dtor,
@@ -1651,42 +1651,47 @@ llvm::GlobalVariable *ItaniumCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
   return VTable;
 }
 
-llvm::Value *ItaniumCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
-                                                      GlobalDecl GD,
-                                                      Address This,
-                                                      llvm::Type *Ty,
-                                                      SourceLocation Loc) {
+CGCallee ItaniumCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
+                                                  GlobalDecl GD,
+                                                  Address This,
+                                                  llvm::Type *Ty,
+                                                  SourceLocation Loc) {
   GD = GD.getCanonicalDecl();
   Ty = Ty->getPointerTo()->getPointerTo();
   auto *MethodDecl = cast<CXXMethodDecl>(GD.getDecl());
   llvm::Value *VTable = CGF.GetVTablePtr(This, Ty, MethodDecl->getParent());
 
   uint64_t VTableIndex = CGM.getItaniumVTableContext().getMethodVTableIndex(GD);
-  if (CGF.ShouldEmitVTableTypeCheckedLoad(MethodDecl->getParent()))
-    return CGF.EmitVTableTypeCheckedLoad(
+  llvm::Value *VFunc;
+  if (CGF.ShouldEmitVTableTypeCheckedLoad(MethodDecl->getParent())) {
+    VFunc = CGF.EmitVTableTypeCheckedLoad(
         MethodDecl->getParent(), VTable,
         VTableIndex * CGM.getContext().getTargetInfo().getPointerWidth(0) / 8);
-
-  CGF.EmitTypeMetadataCodeForVCall(MethodDecl->getParent(), VTable, Loc);
-
-  llvm::Value *VFuncPtr =
-      CGF.Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfn");
-  auto *VFuncLoad =
-      CGF.Builder.CreateAlignedLoad(VFuncPtr, CGF.getPointerAlign());
-
-  // Add !invariant.load md to virtual function load to indicate that
-  // function didn't change inside vtable.
-  // It's safe to add it without -fstrict-vtable-pointers, but it would not
-  // help in devirtualization because it will only matter if we will have 2
-  // the same virtual function loads from the same vtable load, which won't
-  // happen without enabled devirtualization with -fstrict-vtable-pointers.
-  if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
-      CGM.getCodeGenOpts().StrictVTablePointers)
-    VFuncLoad->setMetadata(
-        llvm::LLVMContext::MD_invariant_load,
-        llvm::MDNode::get(CGM.getLLVMContext(),
-                          llvm::ArrayRef<llvm::Metadata *>()));
-  return VFuncLoad;
+  } else {
+    CGF.EmitTypeMetadataCodeForVCall(MethodDecl->getParent(), VTable, Loc);
+
+    llvm::Value *VFuncPtr =
+        CGF.Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfn");
+    auto *VFuncLoad =
+        CGF.Builder.CreateAlignedLoad(VFuncPtr, CGF.getPointerAlign());
+
+    // Add !invariant.load md to virtual function load to indicate that
+    // function didn't change inside vtable.
+    // It's safe to add it without -fstrict-vtable-pointers, but it would not
+    // help in devirtualization because it will only matter if we will have 2
+    // the same virtual function loads from the same vtable load, which won't
+    // happen without enabled devirtualization with -fstrict-vtable-pointers.
+    if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
+        CGM.getCodeGenOpts().StrictVTablePointers)
+      VFuncLoad->setMetadata(
+          llvm::LLVMContext::MD_invariant_load,
+          llvm::MDNode::get(CGM.getLLVMContext(),
+                            llvm::ArrayRef<llvm::Metadata *>()));
+    VFunc = VFuncLoad;
+  }
+
+  CGCallee Callee(MethodDecl, VFunc);
+  return Callee;
 }
 
 llvm::Value *ItaniumCXXABI::EmitVirtualDestructorCall(