Anirudh Prasad 129d906140 [AsmParser][ms][X86] Fix possible misbehaviour in parsing of special tokens at start of string. ... - Previously, https://reviews.llvm.org/D72680 introduced a new attribute called `AllowSymbolAtNameStart` (in relation to the MAsmParser changes) in `MCAsmInfo.h` which (according to the comment in the header) allows the following behaviour: ``` /// This is true if the assembler allows $ @ ? characters at the start of /// symbol names. Defaults to false. ``` - However, the usage of this field in AsmLexer.cpp doesn't seem completely accurate* for a couple of reasons. ``` default: if (MAI.doesAllowSymbolAtNameStart()) { // Handle Microsoft-style identifier: [a-zA-Z_$.@?][a-zA-Z0-9_$.@#?]* if (!isDigit(CurChar) && isIdentifierChar(CurChar, MAI.doesAllowAtInName(), AllowHashInIdentifier)) return LexIdentifier(); } ``` 1. The Dollar and At tokens, when occurring at the start of the string, are treated as separate tokens (AsmToken::Dollar and AsmToken::At respectively) and not lexed as an Identifier. 2. I'm not too sure why `MAI.doesAllowAtInName()` is used when `AllowAtInIdentifier` could be used. For X86 platforms, afaict, this shouldn't be an issue, since the `CommentString` attribute isn't "@". (alternatively the call to the setter can be set anywhere else as needed). The `AllowAtInName` does have an additional important meaning, but in the context of AsmLexer, shouldn't mean anything different compared to `AllowAtInIdentifier` My proposal is the following: - Introduce 3 new fields called `AllowQuestionTokenAtStartOfString`, `AllowDollarTokenAtStartOfString` and `AllowAtTokenAtStartOfString` in MCAsmInfo.h which will encapsulate the previously documented behaviour of "allowing $, @, ? characters at the start of symbol names") - Introduce these fields where "$", "@" are lexed, and treat them as identifiers depending on whether `Allow[Dollar|At]TokenAtStartOfString` is set. - For the sole case of "?", append it to the existing logic for treating a "default" token as an Identifier. z/OS (HLASM) will also make use of some of these fields in follow up patches. completely accurate* - This was based on the comments and the intended behaviour the code. I might have completely misinterpreted it, and if that is the case my sincere apologies. We can close this patch if necessary, if there are no changes to be made :) Depends on https://reviews.llvm.org/D99374 Reviewed By: Jonathan.Crowther Differential Revision: https://reviews.llvm.org/D99889		2021-04-21 10:21:09 -04:00
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AMDGPU
SystemZ	[AsmParser][ms][X86] Fix possible misbehaviour in parsing of special tokens at start of string.	2021-04-21 10:21:09 -04:00
CMakeLists.txt
Disassembler.cpp
DwarfLineTables.cpp
MCDisassemblerTest.cpp
MCInstPrinter.cpp
StringTableBuilderTest.cpp	[MC] Adjust StringTableBuilder for linked Mach-O binaries	2020-10-22 19:19:41 -07:00
TargetRegistry.cpp