Revert "[llvm] Support forward-referenced globals with dso_local_equivalent"

This reverts commit 411020a.

One of the tests here fails on some upstream builders:
https://lab.llvm.org/buildbot#builders/16/builds/35314

Author: PiJoules

llvm/include/llvm/AsmParser/LLParser.h

@@ -131,10 +131,6 @@ namespace llvm {
     /// function.
     PerFunctionState *BlockAddressPFS;
 
-    // References to dso_local_equivalent. The key is the global's ValID, the
-    // value is a placeholder value that will be replaced.
-    std::map<ValID, GlobalValue *> ForwardRefDSOLocalEquivalents;
-
     // Attribute builder reference information.
     std::map<Value*, std::vector<unsigned> > ForwardRefAttrGroups;
     std::map<unsigned, AttrBuilder> NumberedAttrBuilders;

llvm/lib/AsmParser/LLParser.cpp

@@ -215,31 +215,6 @@ bool LLParser::validateEndOfModule(bool UpgradeDebugInfo) {
     return error(ForwardRefBlockAddresses.begin()->first.Loc,
                  "expected function name in blockaddress");
 
-  // If there are entries in ForwardRefDSOLocalEquivalents at this point, they
-  // are references after the function was defined.  Resolve those now.
-  for (auto &Iter : ForwardRefDSOLocalEquivalents) {
-    GlobalValue *GV = nullptr;
-    const ValID &GVRef = Iter.first;
-    if (GVRef.Kind == ValID::t_GlobalName)
-      GV = M->getNamedValue(GVRef.StrVal);
-    else if (GVRef.UIntVal < NumberedVals.size())
-      GV = dyn_cast<GlobalValue>(NumberedVals[GVRef.UIntVal]);
-
-    if (!GV)
-      return error(GVRef.Loc, "unknown function '" + GVRef.StrVal +
-                                  "' referenced by dso_local_equivalent");
-
-    if (!GV->getValueType()->isFunctionTy())
-      return error(GVRef.Loc,
-                   "expected a function, alias to function, or ifunc "
-                   "in dso_local_equivalent");
-
-    auto *Equiv = DSOLocalEquivalent::get(GV);
-    Iter.second->replaceAllUsesWith(Equiv);
-    Iter.second->eraseFromParent();
-  }
-  ForwardRefDSOLocalEquivalents.clear();
-
   for (const auto &NT : NumberedTypes)
     if (NT.second.second.isValid())
       return error(NT.second.second,
@@ -3453,21 +3428,7 @@ bool LLParser::parseValID(ValID &ID, PerFunctionState *PFS, Type *ExpectedTy) {
       GV = M->getNamedValue(Fn.StrVal);
     }
 
-    if (!GV) {
-      // Make a placeholder global variable as a placeholder for this reference.
-      GlobalValue *&FwdRef = ForwardRefDSOLocalEquivalents
-                                 .try_emplace(std::move(Fn), nullptr)
-                                 .first->second;
-      if (!FwdRef) {
-        FwdRef = new GlobalVariable(*M, Type::getInt8Ty(Context), false,
-                                    GlobalValue::InternalLinkage, nullptr, "",
-                                    nullptr, GlobalValue::NotThreadLocal);
-      }
-
-      ID.ConstantVal = FwdRef;
-      ID.Kind = ValID::t_Constant;
-      return false;
-    }
+    assert(GV && "Could not find a corresponding global variable");
 
     if (!GV->getValueType()->isFunctionTy())
       return error(Fn.Loc, "expected a function, alias to function, or ifunc "

llvm/test/CodeGen/X86/dso_local_equivalent.ll

@@ -97,121 +97,3 @@ define void @call_dso_local_ifunc_func() {
   call void dso_local_equivalent @dso_local_ifunc_func()
   ret void
 }
-
-;; PR57815
-;; Ensure dso_local_equivalent works the exact same way as the previous
-;; examples but with forward-referenced symbols.
-
-; CHECK: call_forward_func:
-; CHECK:   callq forward_extern_func@PLT
-define void @call_forward_func() {
-  call void dso_local_equivalent @forward_extern_func()
-  ret void
-}
-
-; CHECK: call_forward_hidden_func:
-; CHECK:   callq forward_hidden_func{{$}}
-define void @call_forward_hidden_func() {
-  call void dso_local_equivalent @forward_hidden_func()
-  ret void
-}
-
-; CHECK: call_forward_protected_func:
-; CHECK:   callq forward_protected_func{{$}}
-define void @call_forward_protected_func() {
-  call void dso_local_equivalent @forward_protected_func()
-  ret void
-}
-
-; CHECK: call_forward_dso_local_func:
-; CHECK:   callq forward_dso_local_func{{$}}
-define void @call_forward_dso_local_func() {
-  call void dso_local_equivalent @forward_dso_local_func()
-  ret void
-}
-
-; CHECK: call_forward_internal_func:
-; CHECK:   callq forward_internal_func{{$}}
-define void @call_forward_internal_func() {
-  call void dso_local_equivalent @forward_internal_func()
-  ret void
-}
-
-declare hidden void @forward_hidden_func()
-declare protected void @forward_protected_func()
-declare dso_local void @forward_dso_local_func()
-define internal void @forward_internal_func() {
-entry:
-  ret void
-}
-define private void @forward_private_func() {
-entry:
-  ret void
-}
-
-; CHECK: call_forward_alias_func:
-; CHECK:   callq forward_alias_func@PLT
-define void @call_forward_alias_func() {
-  call void dso_local_equivalent @forward_alias_func()
-  ret void
-}
-
-; CHECK: call_forward_dso_local_alias_func:
-; CHECK:   callq .Lforward_dso_local_alias_func$local{{$}}
-define void @call_forward_dso_local_alias_func() {
-  call void dso_local_equivalent @forward_dso_local_alias_func()
-  ret void
-}
-
-define void @forward_aliasee_func() {
-entry:
-  ret void
-}
-
-@forward_alias_func = alias void (), ptr @forward_aliasee_func
-@forward_dso_local_alias_func = dso_local alias void (), ptr @forward_aliasee_func
-
-; If an ifunc is not dso_local already, then we should still emit a stub for it
-; to ensure it will be dso_local.
-; CHECK: call_forward_ifunc_func:
-; CHECK:   callq forward_ifunc_func@PLT
-define void @call_forward_ifunc_func() {
-  call void dso_local_equivalent @forward_ifunc_func()
-  ret void
-}
-
-; CHECK: call_forward_dso_local_ifunc_func:
-; CHECK:   callq forward_dso_local_ifunc_func{{$}}
-define void @call_forward_dso_local_ifunc_func() {
-  call void dso_local_equivalent @forward_dso_local_ifunc_func()
-  ret void
-}
-
-@forward_ifunc_func = ifunc void (), ptr @resolver
-@forward_dso_local_ifunc_func = dso_local ifunc void (), ptr @resolver
-
-;; Test "no-named" variables
-; CHECK: call_no_name_hidden:
-; CHECK:   callq __unnamed_{{[0-9]+}}{{$}}
-define void @call_no_name_hidden() {
-  call void dso_local_equivalent @0()
-  ret void
-}
-
-; CHECK: call_no_name_extern:
-; CHECK:   callq __unnamed_{{[0-9]+}}@PLT
-define void @call_no_name_extern() {
-  call void dso_local_equivalent @1()
-  ret void
-}
-
-declare hidden void @0()
-declare void @1()
-
-;; Note that we keep this at the very end because llc emits this after all the
-;; functions.
-; CHECK: const:
-; CHECK:   .long   forward_extern_func@PLT
-@const = constant i32 trunc (i64 ptrtoint (ptr dso_local_equivalent @forward_extern_func to i64) to i32)
-
-declare void @forward_extern_func()