[Verifier] Make error message precise about which variable is being diagnosed.

NFCI.

Author: Yuanfang Chen

llvm/lib/IR/Verifier.cpp

@@ -735,8 +735,9 @@ void Verifier::visitGlobalVariable(const GlobalVariable &GV) {
           Value *V = Op->stripPointerCasts();
           Assert(isa<GlobalVariable>(V) || isa<Function>(V) ||
                      isa<GlobalAlias>(V),
-                 "invalid llvm.used member", V);
-          Assert(V->hasName(), "members of llvm.used must be named", V);
+                 Twine("invalid ") + GV.getName() + " member", V);
+          Assert(V->hasName(),
+                 Twine("members of ") + GV.getName() + " must be named", V);
         }
       }
     }

llvm/test/Verifier/llvm.used-invalid-init2.ll

@@ -2,6 +2,10 @@
 
 @a = global i8 42
 @llvm.used = appending global [2 x i8*] [i8* @a, i8* null], section "llvm.metadata"
+@llvm.compiler.used = appending global [2 x i8*] [i8* @a, i8* null], section "llvm.metadata"
 
 ; CHECK: invalid llvm.used member
 ; CHECK-NEXT: i8* null
+
+; CHECK: invalid llvm.compiler.used member
+; CHECK-NEXT: i8* null