[WebAssembly] Basic support for Wasm object file encoding.
With the "wasm32-unknown-unknown-wasm" triple, this allows writing out
simple wasm object files, and is another step in a larger series toward
migrating from ELF to general wasm object support. Note that this code
and the binary format itself is still experimental.
llvm-svn: 296190
diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 6b4aef1..21431a1 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -1162,18 +1162,73 @@
// Wasm
//===----------------------------------------------------------------------===//
+static const Comdat *getWasmComdat(const GlobalValue *GV) {
+ const Comdat *C = GV->getComdat();
+ if (!C)
+ return nullptr;
+
+ if (C->getSelectionKind() != Comdat::Any)
+ report_fatal_error("Wasm COMDATs only support SelectionKind::Any, '" +
+ C->getName() + "' cannot be lowered.");
+
+ return C;
+}
+
MCSection *TargetLoweringObjectFileWasm::getExplicitSectionGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
llvm_unreachable("getExplicitSectionGlobal not yet implemented");
return nullptr;
}
+static MCSectionWasm *
+selectWasmSectionForGlobal(MCContext &Ctx, const GlobalObject *GO,
+ SectionKind Kind, Mangler &Mang,
+ const TargetMachine &TM, bool EmitUniqueSection,
+ unsigned Flags, unsigned *NextUniqueID) {
+ StringRef Group = "";
+ if (getWasmComdat(GO))
+ llvm_unreachable("comdat not yet supported for wasm");
+
+ bool UniqueSectionNames = TM.getUniqueSectionNames();
+ SmallString<128> Name = getSectionPrefixForGlobal(Kind);
+
+ if (const auto *F = dyn_cast<Function>(GO)) {
+ const auto &OptionalPrefix = F->getSectionPrefix();
+ if (OptionalPrefix)
+ Name += *OptionalPrefix;
+ }
+
+ if (EmitUniqueSection && UniqueSectionNames) {
+ Name.push_back('.');
+ TM.getNameWithPrefix(Name, GO, Mang, true);
+ }
+ unsigned UniqueID = MCContext::GenericSectionID;
+ if (EmitUniqueSection && !UniqueSectionNames) {
+ UniqueID = *NextUniqueID;
+ (*NextUniqueID)++;
+ }
+ return Ctx.getWasmSection(Name, /*Type=*/0, Flags,
+ Group, UniqueID);
+}
+
MCSection *TargetLoweringObjectFileWasm::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
+
+ if (Kind.isCommon())
+ report_fatal_error("mergable sections not supported yet on wasm");
+
+ // If we have -ffunction-section or -fdata-section then we should emit the
+ // global value to a uniqued section specifically for it.
+ bool EmitUniqueSection = false;
if (Kind.isText())
- return TextSection;
- assert(!Kind.isMetadata() && "metadata sections not yet implemented");
- return DataSection;
+ EmitUniqueSection = TM.getFunctionSections();
+ else
+ EmitUniqueSection = TM.getDataSections();
+ EmitUniqueSection |= GO->hasComdat();
+
+ return selectWasmSectionForGlobal(getContext(), GO, Kind, getMangler(), TM,
+ EmitUniqueSection, /*Flags=*/0,
+ &NextUniqueID);
}
bool TargetLoweringObjectFileWasm::shouldPutJumpTableInFunctionSection(