LLVM :: Assembler regression test failures

[bryanpkc]

Two regression tests are currently failing on the release_100 candidate (PR #1):

Failing Tests (2):
    LLVM :: Assembler/invalid-diglobalvariable-empty-name.ll
    LLVM :: Assembler/invalid-diglobalvariable-missing-name.ll

They are caused by the following commits:

• flang-compiler/llvm@5c217c2
• flang-compiler/llvm@e35c28b

Reverting these commits allow the regression tests to pass.

At -O3 -g, Flang will generate a DIGlobalVariable named _BLNK_ for an unnamed COMMON block, so it is not clear to me why we need to allow an empty or missing name in a DIGlobalVariable.

@schweitzpgi Do you have an example program that breaks without these commits?

[schweitzpgi]

No, I don’t have one at hand.

I don’t believe that a (fake) name is actually required by ELF and the reasoning was that some tools may want to create anonymous symbols. Obviously, using fake symbol names will get around the existing LLVM imposed restrictions.

-- Eric

From: Bryan Chan [email protected] Sent: Tuesday, August 25, 2020 7:53 AM To: flang-compiler/classic-flang-llvm-project [email protected] Cc: Eric Schweitz [email protected]; Mention [email protected] Subject: [flang-compiler/classic-flang-llvm-project] LLVM :: Assembler regression test failures (#2)

Two regression tests are currently failing:

Failing Tests (2):

LLVM :: Assemberl/invalid-diglobalvariable-empty-name.ll

LLVM :: Assemberl/invalid-diglobalvariable-missing-name.ll

They are caused by the following commits:

• flang-compiler/llvm@5c217c2https://github.com/flang-compiler/llvm/commit/5c217c2
• flang-compiler/llvm@e35c28bhttps://github.com/flang-compiler/llvm/commit/e35c28b

Reverting these commits allow the regression tests to pass.

At -O3 -g, Flang will generate a DIGlobalVariable named BLNK for an unnamed COMMON block, so it is not clear to me why we need to allow an empty or missing name in a DIGlobalVariable.

@schweitzpgihttps://github.com/schweitzpgi Do you have an example program that breaks without these commits?

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[kiranchandramohan]

@bryanpkc @shivaramaarao @alokkrsharma We are trying to reduce the delta with upstream llvm and find that the commits mentioned above by @bryanpkc change the name field of GlobalVariables to be empty and optional (https://github.com/flang-compiler/classic-flang-llvm-project/blame/release_13x/llvm/lib/AsmParser/LLParser.cpp#L4960). Is there any plan to either upstream this change or alternatively remove this change and adjust flang accordingly?

[jinisusan]

Once Alok's https://github.com/flang-compiler/flang/pull/1228 (to remove the DIGlobalVariable metadata associated with the common block) is merged, we can remove this difference wrt upstream llvm.