[LLParser] Error out if a name is too long and gets renamed

Typically names longer than -non-global-value-max-name-size will just get renamed if there is a collision after truncating. This is fine since we typically don't reference Values by name.

However LLParser does reference Values by name, so report an error when that happens, otherwise weird issues can crop up if there are name collisions (e.g. verifier issues with the changed test case because we end up reusing the same block for `testz` and `testa`).

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D145282

diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 673a34e..8b8ba41 100644 (file)
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -3330,6 +3330,12 @@ Value *LLParser::PerFunctionState::getVal(const std::string &Name, Type *Ty,
   } else {
     FwdVal = new Argument(Ty, Name);
   }
+  if (FwdVal->getName() != Name) {
+    P.error(Loc, "name is too long which can result in name collisions, "
+                 "consider making the name shorter or "
+                 "increasing -non-global-value-max-name-size");
+    return nullptr;
+  }
 
   ForwardRefVals[Name] = std::make_pair(FwdVal, Loc);
   return FwdVal;

diff --git a/llvm/test/Assembler/non-global-value-max-name-size.ll b/llvm/test/Assembler/non-global-value-max-name-size.ll
index 4536ce2..dd56286 100644 (file)
--- a/llvm/test/Assembler/non-global-value-max-name-size.ll
+++ b/llvm/test/Assembler/non-global-value-max-name-size.ll
@@ -1,10 +1,15 @@
-; RUN: opt < %s -S -non-global-value-max-name-size=4
-; Test that local value name lookup works if the name is capped
+; RUN: opt < %s -S -non-global-value-max-name-size=5
+; RUN: not opt < %s -S -non-global-value-max-name-size=4 2>&1 | FileCheck %s
+
+; CHECK: name is too long
 
 define void @f() {
 bb0:
   br label %testz
 
 testz:
+  br label %testa
+
+testa:
   br label %testz
 }