[llvm-dev] PR36144: X86 Intel syntax and masm flavor (original) (raw)

Reid Kleckner via llvm-dev llvm-dev at lists.llvm.org
Mon Oct 22 13:44:13 PDT 2018

After looking more closely at the patch in question, I again think it should be reverted.

The patch sets a boolean to indicate that inline asm is being parsed in three places now:

  1. true when parsing intel inline asm
  2. true when .intel_syntax directives are encountered (BUG!)
  3. false when .att_syntax is encountered

We should only set this to true when parsing inline asm, clearly. I sent my second email after I saw place 1 when re-reading the patch and thought, oh, everything is working as intended. I'll go ahead and do it, since it is clearly wrong. .intel_syntax should not imply IsParsingInlineAsm.

On Mon, Oct 22, 2018 at 1:13 PM Gerolf Hoflehner <ghoflehner at apple.com> wrote:

On Sep 12, 2018, at 1:48 PM, Reid Kleckner via llvm-dev <_ _llvm-dev at lists.llvm.org> wrote: Sorry, I spoke too soon. This only happens for intel style inline assembly in LLVM IR. I don't have a good suggestion. Why is it relevant that the issue is contained? The 0b support in MS asm shouldn’t break the general intel assembly syntax. On Wed, Sep 12, 2018 at 1:44 PM Reid Kleckner <rnk at google.com> wrote: I think we should revert r301390 just on principle from looking at the code. If I understand correctly, it flips the bit for "is parsing inline asm" to true when encountering a plain .intelsyntax directive. That's just wrong.

On Wed, Sep 12, 2018 at 6:34 AM Francis Visoiu Mistrih via llvm-dev <_ _llvm-dev at lists.llvm.org> wrote:

Hi,

We have a significant regression since llvm 5.0.0 in the x86 assembler. The following snippets fail: 1) .intelsyntax 0: jmp 0b 2) .intelsyntax and edi, 0b010101 when running through llvm-mc -arch x86-64. This regression was introduced in r301390, which was driven by PR27884. I think https://llvm.org/PR36144 describes this very well, and I think we should get this fixed, since it's a pretty basic thing to support in the assembler. Here are a few solutions to this: 1) Introduce a new asm dialect/flavor/style to assemble masm files. 2) Only set the flags based on the target triple. Also suggested in PR27884. 3) Only set the flags based on a new command line flag. Let me know if any other solution comes to mind. While we get this issue fixed, is it reasonable to revert r301390? Thanks, -- Francis

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