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[MC] Fix accidentally eating the newline when handling a comment char at the end of the line. #165129

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Merged
merged 2 commits into from
Oct 26, 2025
Merged

[MC] Fix accidentally eating the newline when handling a comment char at the end of the line. #165129

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f528592
[MC] Fix accidentally eating the newline when handling a comment char…
aemerson Oct 26, 2025
60e5cff
clang-format
aemerson Oct 26, 2025
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9 changes: 8 additions & 1 deletion llvm/lib/MC/MCParser/AsmLexer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -835,7 +835,14 @@ AsmToken AsmLexer::LexToken() {
}

if (isAtStartOfComment(TokStart)) {
CurPtr += MAI.getCommentString().size() - 1;
StringRef CommentString = MAI.getCommentString();
// For multi-char comment strings, advance CurPtr only if we matched the
// full string. This stops us from accidentally eating the newline if the
// current line ends in a single comment char.
if (CommentString.size() > 1 &&
StringRef(TokStart, CommentString.size()) == CommentString) {
CurPtr += CommentString.size() - 1;
}
return LexLineComment();
}

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10 changes: 10 additions & 0 deletions llvm/test/MC/AsmParser/comments-x86-darwin-eol-dropped.s
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@@ -0,0 +1,10 @@
// RUN: llvm-mc -triple i386-apple-darwin %s 2>&1 | FileCheck %s
.p2align 3
// CHECK: .p2align 3
test:
// CHECK-LABEL: test:
// CHECK: pushl %ebp
// CHECK: movl %esp, %ebp
# Check that the following line's comment # doesn't drop the movl after
pushl %ebp #
movl %esp, %ebp