<html>
<head>
<base href="https://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Preprocessor falls for a trick code during macro expansion"
href="https://llvm.org/bugs/show_bug.cgi?id=26920">26920</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Preprocessor falls for a trick code during macro expansion
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Frontend
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>viniciustinti@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16028" name="attach_16028" title="Preprocessor tricky code">attachment 16028</a> <a href="attachment.cgi?id=16028&action=edit" title="Preprocessor tricky code">[details]</a></span>
Preprocessor tricky code
The preprocessor is tricked to insert an extra space during macro expansion in
the following code:
// clang -E asm.S -o -
#define CONCAT(a,b) a##b
#define XMM(i) CONCAT(%xmm, i)
.macro foo n
x = XMM(\n)
.endm
Instead of emitting '%xmm\n' it emits '%xmm \n'.
Even weird if one define 'XMM(i)' as 'CONCAT(%xmm,i)' without a leading space
on 'i' it emits '%xmm\n'.
At least I dont expect such a change impact on codegen.
The line that triggers it is:
// <a href="https://github.com/llvm-mirror/clang/blob/master/lib/Lex/TokenLexer.cpp#L186">https://github.com/llvm-mirror/clang/blob/master/lib/Lex/TokenLexer.cpp#L186</a>
...
if (i != 0 && !Tokens[i-1].is(tok::hashhash) && CurTok.hasLeadingSpace())
NextTokGetsSpace = true;
...</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>