IR: Add COMDATs to the IR
This new IR facility allows us to represent the object-file semantic of
a COMDAT group.
COMDATs allow us to tie together sections and make the inclusion of one
dependent on another. This is required to implement features like MS
ABI VFTables and optimizing away certain kinds of initialization in C++.
This functionality is only representable in COFF and ELF, Mach-O has no
similar mechanism.
Differential Revision: http://reviews.llvm.org/D4178
llvm-svn: 211920
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 398e3d5..87d26b1 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -106,6 +106,7 @@
enum PrefixType {
GlobalPrefix,
+ ComdatPrefix,
LabelPrefix,
LocalPrefix,
NoPrefix
@@ -119,6 +120,7 @@
switch (Prefix) {
case NoPrefix: break;
case GlobalPrefix: OS << '@'; break;
+ case ComdatPrefix: OS << '$'; break;
case LabelPrefix: break;
case LocalPrefix: OS << '%'; break;
}
@@ -1165,8 +1167,15 @@
}
void AssemblyWriter::init() {
- if (TheModule)
- TypePrinter.incorporateTypes(*TheModule);
+ if (!TheModule)
+ return;
+ TypePrinter.incorporateTypes(*TheModule);
+ for (const Function &F : *TheModule)
+ if (const Comdat *C = F.getComdat())
+ Comdats.insert(C);
+ for (const GlobalVariable &GV : TheModule->globals())
+ if (const Comdat *C = GV.getComdat())
+ Comdats.insert(C);
}
@@ -1308,6 +1317,15 @@
printTypeIdentities();
+ // Output all comdats.
+ if (!Comdats.empty())
+ Out << '\n';
+ for (const Comdat *C : Comdats) {
+ printComdat(C);
+ if (C != Comdats.back())
+ Out << '\n';
+ }
+
// Output all globals.
if (!M->global_empty()) Out << '\n';
for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
@@ -1470,6 +1488,10 @@
PrintEscapedString(GV->getSection(), Out);
Out << '"';
}
+ if (GV->hasComdat()) {
+ Out << ", comdat ";
+ PrintLLVMName(Out, GV->getComdat()->getName(), ComdatPrefix);
+ }
if (GV->getAlignment())
Out << ", align " << GV->getAlignment();
@@ -1506,10 +1528,19 @@
writeOperand(Aliasee, !isa<ConstantExpr>(Aliasee));
}
+ if (GA->hasComdat()) {
+ Out << ", comdat ";
+ PrintLLVMName(Out, GA->getComdat()->getName(), ComdatPrefix);
+ }
+
printInfoComment(*GA);
Out << '\n';
}
+void AssemblyWriter::printComdat(const Comdat *C) {
+ C->print(Out);
+}
+
void AssemblyWriter::printTypeIdentities() {
if (TypePrinter.NumberedTypes.empty() &&
TypePrinter.NamedTypes.empty())
@@ -1647,6 +1678,10 @@
PrintEscapedString(F->getSection(), Out);
Out << '"';
}
+ if (F->hasComdat()) {
+ Out << " comdat ";
+ PrintLLVMName(Out, F->getComdat()->getName(), ComdatPrefix);
+ }
if (F->getAlignment())
Out << " align " << F->getAlignment();
if (F->hasGC())
@@ -2158,6 +2193,31 @@
W.printNamedMDNode(this);
}
+void Comdat::print(raw_ostream &ROS) const {
+ PrintLLVMName(ROS, getName(), ComdatPrefix);
+ ROS << " = comdat ";
+
+ switch (getSelectionKind()) {
+ case Comdat::Any:
+ ROS << "any";
+ break;
+ case Comdat::ExactMatch:
+ ROS << "exactmatch";
+ break;
+ case Comdat::Largest:
+ ROS << "largest";
+ break;
+ case Comdat::NoDuplicates:
+ ROS << "noduplicates";
+ break;
+ case Comdat::SameSize:
+ ROS << "samesize";
+ break;
+ }
+
+ ROS << '\n';
+}
+
void Type::print(raw_ostream &OS) const {
TypePrinting TP;
TP.print(const_cast<Type*>(this), OS);
@@ -2241,5 +2301,8 @@
// Module::dump() - Allow printing of Modules from the debugger.
void Module::dump() const { print(dbgs(), nullptr); }
+// \brief Allow printing of Comdats from the debugger.
+void Comdat::dump() const { print(dbgs()); }
+
// NamedMDNode::dump() - Allow printing of NamedMDNodes from the debugger.
void NamedMDNode::dump() const { print(dbgs()); }