[MC] Report locations for .symver errors

Author: MaskRay

llvm/include/llvm/MC/MCAssembler.h

@@ -211,7 +211,12 @@ class MCAssembler {
   handleFixup(const MCAsmLayout &Layout, MCFragment &F, const MCFixup &Fixup);
 
 public:
-  std::vector<std::pair<StringRef, const MCSymbol *>> Symvers;
+  struct Symver {
+    StringRef Name;
+    const MCSymbol *Sym;
+    SMLoc Loc;
+  };
+  std::vector<Symver> Symvers;
 
   /// Construct a new assembler instance.
   //

llvm/lib/MC/ELFObjectWriter.cpp

@@ -1258,9 +1258,9 @@ void ELFObjectWriter::executePostLayoutBinding(MCAssembler &Asm,
                                                const MCAsmLayout &Layout) {
   // The presence of symbol versions causes undefined symbols and
   // versions declared with @@@ to be renamed.
-  for (const std::pair<StringRef, const MCSymbol *> &P : Asm.Symvers) {
-    StringRef AliasName = P.first;
-    const auto &Symbol = cast<MCSymbolELF>(*P.second);
+  for (const MCAssembler::Symver &S : Asm.Symvers) {
+    StringRef AliasName = S.Name;
+    const auto &Symbol = cast<MCSymbolELF>(*S.Sym);
     size_t Pos = AliasName.find('@');
     assert(Pos != StringRef::npos);
 
@@ -1286,18 +1286,16 @@ void ELFObjectWriter::executePostLayoutBinding(MCAssembler &Asm,
     if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
       continue;
 
-    // FIXME: Get source locations for these errors or diagnose them earlier.
     if (Symbol.isUndefined() && Rest.startswith("@@") &&
         !Rest.startswith("@@@")) {
-      Asm.getContext().reportError(SMLoc(), "versioned symbol " + AliasName +
-                                                " must be defined");
+      Asm.getContext().reportError(S.Loc, "default version symbol " +
+                                              AliasName + " must be defined");
       continue;
     }
 
     if (Renames.count(&Symbol) && Renames[&Symbol] != Alias) {
-      Asm.getContext().reportError(
-          SMLoc(), llvm::Twine("multiple symbol versions defined for ") +
-                       Symbol.getName());
+      Asm.getContext().reportError(S.Loc, Twine("multiple versions for ") +
+                                              Symbol.getName());
       continue;
     }
 

llvm/lib/MC/MCELFStreamer.cpp

@@ -342,7 +342,8 @@ void MCELFStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
 
 void MCELFStreamer::emitELFSymverDirective(StringRef AliasName,
                                            const MCSymbol *Aliasee) {
-  getAssembler().Symvers.push_back({AliasName, Aliasee});
+  getAssembler().Symvers.push_back(
+      MCAssembler::Symver{AliasName, Aliasee, getStartTokLoc()});
 }
 
 void MCELFStreamer::emitLocalCommonSymbol(MCSymbol *S, uint64_t Size,

llvm/test/MC/ELF/invalid-symver.s

@@ -0,0 +1,12 @@
+# RUN: not llvm-mc -filetype=obj -triple=x86_64 %s -o /dev/null 2>&1 | FileCheck %s --implicit-check-not=error:
+
+# CHECK: {{.*}}.s:[[#@LINE+2]]:1: error: multiple versions for multi
+.symver multi, multi@1
+.symver multi, multi@2
+
+.symver equiv, equiv@1
+.symver equiv, equiv@1
+
+# CHECK: {{.*}}.s:[[#@LINE+1]]:1: error: default version symbol undefined@@v1 must be defined
+.symver undefined_2, undefined@@v1
+.long undefined_2