[llvm-dev] PR36144: X86 Intel syntax and masm flavor

Mon Oct 22 14:07:56 PDT 2018


> On Oct 22, 2018, at 1:44 PM, Reid Kleckner <rnk at google.com> wrote:
> 
> 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.
Thanks, Reid!

> 
> On Mon, Oct 22, 2018 at 1:13 PM Gerolf Hoflehner <ghoflehner at apple.com <mailto:ghoflehner at apple.com>> wrote:
> 
> 
>> On Sep 12, 2018, at 1:48 PM, Reid Kleckner via llvm-dev <llvm-dev at lists.llvm.org <mailto: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 <mailto: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 .intel_syntax 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 <mailto: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)
>> 
>> .intel_syntax
>> 0:
>>   jmp 0b
>> 
>> 2)
>> 
>> .intel_syntax
>>   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 <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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