don't use binutils 2.17

[oota-llvm.git] / docs / TestingGuide.html

diff --git a/docs/TestingGuide.html b/docs/TestingGuide.html
index 584b632e04c3b54e759cf4d0e6e886690f9786d3..f03adaaef64b0cdf326b27078e35114a473ceb88 100644 (file)
--- a/docs/TestingGuide.html
+++ b/docs/TestingGuide.html
@@ -329,6 +329,66 @@ location of these external programs is configured by the llvm-test
   ; RUN: llvm-dis < %s.bc-13 > %t2
   ; RUN: diff %t1 %t2
   </pre>
+
+  <p>As with a Unix shell, the RUN: lines permit pipelines and I/O redirection
+  to be used. However, the usage is slightly different than for Bash. To check
+  what's legal, see the documentation for the 
+  <a href="http://www.tcl.tk/man/tcl8.5/TclCmd/exec.htm#M2">Tcl exec</a>
+  command and the 
+  <a href="http://www.tcl.tk/man/tcl8.5/tutorial/Tcl26.html">tutorial</a>. 
+  The major differences are:</p>
+  <ul>
+    <li>You can't do <tt>2&gt;&amp;1</tt>. That will cause Tcl to write to a
+    file named <tt>&amp;1</tt>. Usually this is done to get stderr to go through
+    a pipe. You can do that in tcl with <tt>|&amp;</tt> so replace this idiom:
+    <tt>... 2&gt;&amp;1 | grep</tt> with <tt>... |&amp; grep</tt></li>
+    <li>You can only redirect to a file, not to another descriptor and not from
+    a here document.</li>
+    <li>tcl supports redirecting to open files with the @ syntax but you
+    shouldn't use that here.</li>
+  </ul>
+
+  <p>There are some quoting rules that you must pay attention to when writing
+  your RUN lines. In general nothing needs to be quoted. Tcl won't strip off any
+  ' or " so they will get passed to the invoked program. For example:</p>
+  <pre>
+     ... | grep 'find this string'
+  </pre>
+  <p>This will fail because the ' characters are passed to grep. This would
+  instruction grep to look for <tt>'find</tt> in the files <tt>this</tt> and
+  <tt>string'</tt>. To avoid this use curly braces to tell Tcl that it should
+  treat everything enclosed as one value. So our example would become:</p>
+  <pre>
+     ... | grep {find this string}
+  </pre>
+  <p>Additionally, the characters <tt>[</tt> and <tt>]</tt> are treated 
+  specially by Tcl. They tell Tcl to interpret the content as a command to
+  execute. Since these characters are often used in regular expressions this can
+  have disastrous results and cause the entire test run in a directory to fail.
+  For example, a common idiom is to look for some basicblock number:</p>
+  <pre>
+     ... | grep bb[2-8]
+  </pre>
+  <p>This, however, will cause Tcl to fail because its going to try to execute
+  a program named "2-8". Instead, what you want is this:</p>
+  <pre>
+     ... | grep {bb\[2-8\]}
+  </pre>
+  <p>Finally, if you need to pass the <tt>\</tt> character down to a program,
+  then it must be doubled. This is another Tcl special character. So, suppose
+  you had:
+  <pre>
+     ... | grep 'i32\*'
+  </pre>
+  <p>This will fail to match what you want (a pointer to i32). First, the
+  <tt>'</tt> do not get stripped off. Second, the <tt>\</tt> gets stripped off
+  by Tcl so what grep sees is: <tt>'i32*'</tt>. That's not likely to match
+  anything. To resolve this you must use <tt>\\</tt> and the <tt>{}</tt>, like
+  this:</p>
+  <pre>
+     ... | grep {i32\\*}
+  </pre>
+
 </div>
 
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