[PATCH] D141313: LangRef: Add !associated to list of preserved global metadata

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: MaskRay, morehouse, pcc, vitalybuka.
Herald added subscribers: jdoerfert, hiraditya.
Herald added a project: All.
arsenm requested review of this revision.
Herald added a subscriber: wdng.
Herald added a project: LLVM.

https://reviews.llvm.org/D141313

Files:
  llvm/docs/LangRef.rst
  llvm/lib/IR/Verifier.cpp
  llvm/test/Verifier/associated-metadata.ll


Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -5406,9 +5406,10 @@
 Unlike instructions, global objects (functions and global variables) may have
 multiple metadata attachments with the same identifier.
 
-A transformation is required to drop any metadata attachment that it does not
-know or know it can't preserve. Currently there is an exception for metadata
-attachment to globals for ``!func_sanitize``, ``!type`` and ``!absolute_symbol`` which can't be
+A transformation is required to drop any metadata attachment that it
+does not know or know it can't preserve. Currently there is an
+exception for metadata attachment to globals for ``!func_sanitize``,
+``!type``, ``!absolute_symbol`` and ``!associated`` which can't be
 unconditionally dropped unless the global is itself deleted.
 
 Metadata attached to a module using named metadata may not be dropped, with
Index: llvm/test/Verifier/associated-metadata.ll
===================================================================
--- llvm/test/Verifier/associated-metadata.ll
+++ llvm/test/Verifier/associated-metadata.ll
@@ -20,6 +20,16 @@
 ; CHECK-NEXT: !3 = !{}
 @associated.empty = external addrspace(1) constant [8 x i8], !associated !3
 
+; CHECK: associated metadata must have a global value
+; CHECK-NEXT: ptr addrspace(1) @associated.null.metadata
+; CHECK-NEXT: !4 = !{null}
+ at associated.null.metadata = external addrspace(1) constant [8 x i8], !associated !4
+
+; CHECK: global values should not associate to themselves
+; CHECK-NEXT: ptr @associated.self
+; CHECK-NEXT: !5 = !{ptr @associated.self}
+ at associated.self = external constant [8 x i8], !associated !5
+
 @gv.decl0 = external constant [8 x i8]
 @gv.decl1 = external constant [8 x i8]
 
@@ -27,3 +37,5 @@
 !1 = !{float 1.000000e+00}
 !2 = !{ptr @gv.decl0, ptr @gv.decl1}
 !3 = !{}
+!4 = !{null}
+!5 = !{ptr @associated.self}
Index: llvm/lib/IR/Verifier.cpp
===================================================================
--- llvm/lib/IR/Verifier.cpp
+++ llvm/lib/IR/Verifier.cpp
@@ -658,7 +658,7 @@
       Check(Associated->getNumOperands() == 1,
             "associated metadata must have one operand", &GV, Associated);
       const Metadata *Op = Associated->getOperand(0).get();
-      Check(Op, "missing associated global", GO, Associated);
+      Check(Op, "associated metadata must have a global value", GO, Associated);
 
       const auto *VM = dyn_cast_or_null<ValueAsMetadata>(Op);
       Check(VM, "associated metadata must be ValueAsMetadata", GO,
@@ -671,6 +671,9 @@
         Check(isa<GlobalObject>(Stripped) || isa<Constant>(Stripped),
               "associated metadata must point to a GlobalObject", GO,
               Stripped);
+        Check(Stripped != VM->getValue(),
+              "global values should not associate to themselves", GO,
+              Associated);
       }
     }
   }


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