[mlir][LLVMIR] Fix identified structs with same name

[aengelke]

Summary

Different identified struct types may have the same name ("").
Previously, these were deduplicated based on their name, which caused
an assertion failure when nesting identified structs:

%0 = type { %1 }
%1 = type { i8 }
declare void @fn(%0)

[gysit]

Thanks for fixing this bug!

LGTM and feel free to implement the file check nit comment if it works.

mlir/test/Target/LLVMIR/Import/global-struct.ll

5

nit: Would the above file check lines work as well? That way it seems a bit clearer the names have to be different.

[aengelke]

Thanks for the suggestion, I took it with a minor fix to work around greedy regex matching.

mlir/lib/Target/LLVMIR/TypeFromLLVM.cpp

if (type->isLiteral()) {
       translateTypes(type->subtypes(), subtypes);
       return LLVM::LLVMStructType::getLiteral(&context, subtypes,
                                               type->isPacked());
     }
 
     if (type->isOpaque())
       return LLVM::LLVMStructType::getOpaque(type->getName(), &context);
 
-    LLVM::LLVMStructType translated =
-        LLVM::LLVMStructType::getIdentified(&context, type->getName());
-    knownTranslations.try_emplace(type, translated);
+    // With opaque pointers, types in LLVM can't be recursive anymore. Note that
+    // using getIdentified is not possible, as type names in LLVM are not
+    // guaranteed to be unique.
     translateTypes(type->subtypes(), subtypes);
-    LogicalResult bodySet = translated.setBody(subtypes, type->isPacked());
-    assert(succeeded(bodySet) &&
-           "could not set the body of an identified struct");
-    (void)bodySet;
+    LLVM::LLVMStructType translated = LLVM::LLVMStructType::getNewIdentified(
+        &context, type->getName(), subtypes, type->isPacked());
+    knownTranslations.try_emplace(type, translated);
     return translated;
   }
 
   /// Translates the given fixed-vector type.
   Type translate(llvm::FixedVectorType *type) {
     return LLVM::getFixedVectorType(translateType(type->getElementType()),
                                     type->getNumElements());
   }

mlir/test/Target/LLVMIR/Import/global-struct.ll

+; RUN: mlir-translate --import-llvm %s | FileCheck %s
+
+; Ensure both structs have different names.
+; CHECK: llvm.func @fn(!llvm.struct<"[[NAME:[^"]*]]",
+; CHECK-NOT: struct<"[[NAME]]",
+%0 = type { %1 }
+%1 = type { i8 }
+declare void @fn(%0)