[CIR][CodeGen] Introduce CIR CXXSpecialMember attribute #1711

bruteforceboy · 2025-06-23T13:58:37Z

I think this one is self-explanatory, so I will not write much 🙂‍

Adding this attribute helps in optimizations like #1653, and using the attribute it's easy to create operations like cir.std.vector.ctor/cir.std.vector.dtor by just modifying IdiomRecognizer a bit. I believe it will also be useful for future optimizations. Finally, I updated quite a number of tests so they now reflect this attribute.

Please, let me know if you see any issues.

bcardosolopes

Thanks for adding more of the building blocks here. In the future it'd be nice to have a representation for struct/class more closer to C++ and it will probably be easier to extract this type of information, but to prevent over engineering early, it feels right to incrementally add pieces that can enable us to better analyze C++ code and make transformations easier to write.

Can you look into changing LifetimeChecker.cpp to use this attribute instead of the current AST approach?

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

clang/test/CIR/CodeGen/String.cpp

clang/lib/CIR/CodeGen/CIRGenCall.cpp

bcardosolopes · 2025-06-23T21:53:46Z

(@andykaylor @erichkeane @dkolsen-pgi in case you have any extra thoughts here)

andykaylor

Do we also want to set this attribute on cir.func definitions/declarations?

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

clang/lib/CIR/CodeGen/CIRGenCall.cpp

clang/lib/CIR/CodeGen/CIRGenExprCXX.cpp

clang/test/CIR/CodeGen/String.cpp

github-actions · 2025-06-25T10:54:26Z

✅ With the latest revision this PR passed the C/C++ code formatter.

bruteforceboy · 2025-06-25T11:06:45Z

A few updates:

The attribute is now attached to the FuncOp (like ctor<type>) instead of the call
The attribute now stores Type instead of a string
I updated LifetimeChecker.cpp to make use of this attribute instead of the AST approach
I added a couple of traits for the ctor attribute, and I think we can extend as necessary in the future
CIR_CXXCtorDtor is now CIR_CXXSpecialMember
Updated a couple of tests to reflect the ctor/dtor attribute.

cc: @bcardosolopes, @erichkeane, @andykaylor

erichkeane

1 comment, else seems reasonable, I'm happy when the others are.

clang/lib/CIR/CodeGen/CIRGenFunction.cpp

clang/test/CIR/CodeGen/ctor-alias.cpp

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

clang/include/clang/CIR/Dialect/IR/CIROps.td

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

bcardosolopes

Thanks for the update, one more round of suggestions

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

clang/include/clang/CIR/Dialect/IR/CIROps.td

clang/lib/CIR/CodeGen/CIRGenModule.cpp

bcardosolopes

Thanks for the updates, one more round!

bcardosolopes · 2025-07-03T21:14:58Z

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -3661,7 +3661,8 @@ def FuncOp : CIR_Op<"func", [
    OptionalAttr<GlobalCtorAttr>:$global_ctor,
    OptionalAttr<GlobalDtorAttr>:$global_dtor,
    OptionalAttr<ArrayAttr>:$annotations,
-    OptionalAttr<AnyASTFunctionDeclAttr>:$ast
+    OptionalAttr<AnyASTFunctionDeclAttr>:$ast,
+    OptionalAttr<CIR_CXXSpecialMemberAttr>:$cxx_special_member


Please move this before the ast one.

bcardosolopes · 2025-07-03T21:18:46Z

clang/lib/CIR/Dialect/IR/CIRDialect.cpp

@@ -2618,6 +2619,55 @@ ParseResult cir::FuncOp::parse(OpAsmParser &parser, OperationState &state) {
      state.addAttribute(annotationsNameAttr, annotations);
  }

+  // Add CXXSpecialMember attributes.
+  if (mlir::succeeded(parser.parseOptionalKeyword("ctor"))) {


Both ctor and dtor already have defined printer/parsers, you shouldn't need to add the logic again here. Have you found any problems while using parseOptionalAttribute?

I had problems using parseOptionalAttribute because of the custom print format I was going for: ctor<Type>. I have updated both the parsing and printing a bit now, so all these don't need to be repeated. Now the attribute looks like cxx_special_member<#cir.cxx_ctor<Type>>, and parsing is much neater now.

bruteforceboy requested review from lanza and bcardosolopes as code owners June 23, 2025 13:58

bcardosolopes reviewed Jun 23, 2025

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andykaylor reviewed Jun 24, 2025

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erichkeane reviewed Jun 24, 2025

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add CXXCtorDtor attribute

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bruteforceboy force-pushed the cxx-ctor-dtor branch from 68ff6ef to 8c7235c Compare June 25, 2025 10:51

Merge remote-tracking branch 'origin/main' into cxx-ctor-dtor

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update

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bruteforceboy force-pushed the cxx-ctor-dtor branch from 77c8851 to d4c51f3 Compare June 25, 2025 11:47

erichkeane reviewed Jun 25, 2025

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add curleys

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bruteforceboy changed the title ~~[CIR][CodeGen] Introduce CIR CXXCtorDtor attribute~~ [CIR][CodeGen] Introduce CIR CXXSpecialMember attribute Jun 25, 2025

bcardosolopes reviewed Jun 26, 2025

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bruteforceboy added 2 commits June 27, 2025 13:10

review comments & add cir-opt

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Merge remote-tracking branch 'origin/main' into cxx-ctor-dtor

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bruteforceboy force-pushed the cxx-ctor-dtor branch from ab65415 to c1f8a62 Compare June 27, 2025 11:48

update test & improve parsing

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bruteforceboy force-pushed the cxx-ctor-dtor branch from c1f8a62 to f6aaa4d Compare June 27, 2025 12:01

bcardosolopes reviewed Jul 1, 2025

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bruteforceboy added 3 commits July 3, 2025 14:58

apply review comments

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Merge remote-tracking branch 'origin/main' into cxx-ctor-dtor

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update dialect

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bcardosolopes reviewed Jul 3, 2025

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bruteforceboy added 2 commits July 4, 2025 16:10

update printing/parsing

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Merge remote-tracking branch 'origin/main' into cxx-ctor-dtor

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[CIR][CodeGen] Introduce CIR CXXSpecialMember attribute #1711

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[CIR][CodeGen] Introduce CIR CXXSpecialMember attribute #1711

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