[ORC] Add weak symbol support to defineMaterializing, fix for PR40074.
The MaterializationResponsibility::defineMaterializing method allows clients to
add new definitions that are in the process of being materialized to the JIT.
This patch adds support to defineMaterializing for symbols with weak linkage
where the new definitions may be rejected if another materializer concurrently
defines the same symbol. If a weak symbol is rejected it will not be added to
the MaterializationResponsibility's responsibility set. Clients can check for
membership in the responsibility set via the
MaterializationResponsibility::getSymbols() method before resolving any
such weak symbols.
This patch also adds code to RTDyldObjectLinkingLayer to tag COFF comdat symbols
introduced during codegen as weak, on the assumption that these are COFF comdat
constants. This fixes http://llvm.org/PR40074.
diff --git a/llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp b/llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp
index a92264c..ff8289a 100644
--- a/llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp
@@ -7,6 +7,7 @@
//===----------------------------------------------------------------------===//
#include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
+#include "llvm/Object/COFF.h"
namespace {
@@ -160,6 +161,39 @@
std::set<StringRef> &InternalSymbols) {
SymbolFlagsMap ExtraSymbolsToClaim;
SymbolMap Symbols;
+
+ // Hack to support COFF constant pool comdats introduced during compilation:
+ // (See http://llvm.org/PR40074)
+ if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(&Obj)) {
+ auto &ES = getExecutionSession();
+
+ // For all resolved symbols that are not already in the responsibilty set:
+ // check whether the symbol is in a comdat section and if so mark it as
+ // weak.
+ for (auto &Sym : COFFObj->symbols()) {
+ if (Sym.getFlags() & object::BasicSymbolRef::SF_Undefined)
+ continue;
+ auto Name = Sym.getName();
+ if (!Name)
+ return Name.takeError();
+ auto I = Resolved.find(*Name);
+
+ // Skip unresolved symbols, internal symbols, and symbols that are
+ // already in the responsibility set.
+ if (I == Resolved.end() || InternalSymbols.count(*Name) ||
+ R.getSymbols().count(ES.intern(*Name)))
+ continue;
+ auto Sec = Sym.getSection();
+ if (!Sec)
+ return Sec.takeError();
+ if (*Sec == COFFObj->section_end())
+ continue;
+ auto &COFFSec = *COFFObj->getCOFFSection(**Sec);
+ if (COFFSec.Characteristics & COFF::IMAGE_SCN_LNK_COMDAT)
+ I->second.setFlags(I->second.getFlags() | JITSymbolFlags::Weak);
+ }
+ }
+
for (auto &KV : Resolved) {
// Scan the symbols and add them to the Symbols map for resolution.
@@ -184,10 +218,17 @@
Symbols[InternedName] = JITEvaluatedSymbol(KV.second.getAddress(), Flags);
}
- if (!ExtraSymbolsToClaim.empty())
+ if (!ExtraSymbolsToClaim.empty()) {
if (auto Err = R.defineMaterializing(ExtraSymbolsToClaim))
return Err;
+ // If we claimed responsibility for any weak symbols but were rejected then
+ // we need to remove them from the resolved set.
+ for (auto &KV : ExtraSymbolsToClaim)
+ if (KV.second.isWeak() && !R.getSymbols().count(KV.first))
+ Symbols.erase(KV.first);
+ }
+
if (auto Err = R.notifyResolved(Symbols)) {
R.failMaterialization();
return Err;