[ORC][JITLink] Add jitlink::Scope::SideEffectsOnly, use it in ORC Platforms.

SideEffectsOnly is a new jitlink::Scope value that corresponds to the
JITSymbolFlags::MaterializationSideEffectsOnly flag: Symbols with this scope
can be looked up (and form part of the initial interface of a LinkGraph) but
never actually resolve to an address (so can only be looked up with a
WeaklyReferencedSymbol lookup).

Previously ObjectLinkingLayer implicitly treated JITLink symbols as having this
scope, regardless of a Symbol's actual scope, if the
MaterializationSideEffectsOnly flag was set on the corresponding symbol in the
MaterializationResponsibility object. Using an explicit scope in JITLink for
this (1) allows JITLink plugins to identify and correctly handle
side-effects-only symbols, and (2) allows raw LinkGraphs to define
side-effects-only symbols without clients having to manually modify their
`MaterializationUnit::Interface`.

4 files changed, 11 insertions, 11 deletions

diff --git a/llvm/lib/ExecutionEngine/Orc/COFFPlatform.cpp b/llvm/lib/ExecutionEngine/Orc/COFFPlatform.cpp
index 007e18e..9d655c2 100644
--- a/llvm/lib/ExecutionEngine/Orc/COFFPlatform.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/COFFPlatform.cpp
@@ -76,7 +76,7 @@ public:
     // Init symbol is __ImageBase symbol.
     auto &ImageBaseSymbol = G->addDefinedSymbol(
         HeaderBlock, 0, *R->getInitializerSymbol(), HeaderBlock.getSize(),
-        jitlink::Linkage::Strong, jitlink::Scope::Default, false, true);
+        jitlink::Linkage::Strong, jitlink::Scope::SideEffectsOnly, false, true);
 
     addImageBaseRelocationEdge(HeaderBlock, ImageBaseSymbol);
 
diff --git a/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp b/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp
index 431c649..44d282f 100644
--- a/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp
@@ -197,7 +197,7 @@ public:
         8, 0);
     auto &DSOHandleSymbol = G->addDefinedSymbol(
         DSOHandleBlock, 0, *R->getInitializerSymbol(), DSOHandleBlock.getSize(),
-        jitlink::Linkage::Strong, jitlink::Scope::Default, false, true);
+        jitlink::Linkage::Strong, jitlink::Scope::SideEffectsOnly, false, true);
     DSOHandleBlock.addEdge(EdgeKind, 0, DSOHandleSymbol, 0);
 
     ENP.getObjectLinkingLayer().emit(std::move(R), std::move(G));
diff --git a/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp b/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
index 3e02beb..1b18a4d 100644
--- a/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
@@ -1001,9 +1001,9 @@ Error MachOPlatform::MachOPlatformPlugin::preserveImportantSections(
       // to the first block.
       if (!InitSym) {
         auto &B = **InitSection->blocks().begin();
-        InitSym = &G.addDefinedSymbol(B, 0, *InitSymName, B.getSize(),
-                                      jitlink::Linkage::Strong,
-                                      jitlink::Scope::Default, false, true);
+        InitSym = &G.addDefinedSymbol(
+            B, 0, *InitSymName, B.getSize(), jitlink::Linkage::Strong,
+            jitlink::Scope::SideEffectsOnly, false, true);
       }
 
       // Add keep-alive edges to anonymous symbols in all other init blocks.
diff --git a/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp b/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
index c1c5540..c5342c4 100644
--- a/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
@@ -65,6 +65,8 @@ JITSymbolFlags getJITSymbolFlagsForSymbol(Symbol &Sym) {
 
   if (Sym.getScope() == Scope::Default)
     Flags |= JITSymbolFlags::Exported;
+  else if (Sym.getScope() == Scope::SideEffectsOnly)
+    Flags |= JITSymbolFlags::MaterializationSideEffectsOnly;
 
   if (Sym.isCallable())
     Flags |= JITSymbolFlags::Callable;
@@ -236,7 +238,7 @@ public:
 
     SymbolMap InternedResult;
     for (auto *Sym : G.defined_symbols())
-      if (Sym->getScope() != Scope::Local) {
+      if (Sym->getScope() < Scope::SideEffectsOnly) {
         auto InternedName = ES.intern(Sym->getName());
         auto Ptr = getJITSymbolPtrForSymbol(*Sym, G.getTargetTriple());
         auto Flags = getJITSymbolFlagsForSymbol(*Sym);
@@ -249,7 +251,7 @@ public:
       }
 
     for (auto *Sym : G.absolute_symbols())
-      if (Sym->getScope() != Scope::Local) {
+      if (Sym->getScope() < Scope::SideEffectsOnly) {
         auto InternedName = ES.intern(Sym->getName());
         auto Ptr = getJITSymbolPtrForSymbol(*Sym, G.getTargetTriple());
         auto Flags = getJITSymbolFlagsForSymbol(*Sym);
@@ -281,11 +283,9 @@ public:
         // If this is a materialization-side-effects only symbol then bump
         // the counter and remove in from the result, otherwise make sure that
         // it's defined.
-        if (Flags.hasMaterializationSideEffectsOnly()) {
+        if (Flags.hasMaterializationSideEffectsOnly())
           ++NumMaterializationSideEffectsOnlySymbols;
-          InternedResult.erase(Sym);
-          continue;
-        } else if (I == InternedResult.end())
+        else if (I == InternedResult.end())
           MissingSymbols.push_back(Sym);
         else if (Layer.OverrideObjectFlags)
           I->second.setFlags(Flags);