file header format. The standard format for the LLVM source tree looks like
this:</p>
+<div class="doc_code">
<pre>
//===-- llvm/Instruction.h - Instruction class definition -------*- C++ -*-===//
//
// base class for all of the VM instructions.
//
//===----------------------------------------------------------------------===//
-
</pre>
+</div>
<p>A few things to note about this particular format: The "<tt>-*- C++
-*-</tt>" string on the first line is there to tell Emacs that the source file
<p>Immediately after the <a href="#scf_commenting">header file comment</a> (and
include guards if working on a header file), the <a
-href="#hl_dontinclude">minimal</a> list of #includes required by the file should
-be listed. We prefer these #includes to be listed in this order:</p>
+href="#hl_dontinclude">minimal</a> list of <tt>#include</tt>s required by the
+file should be listed. We prefer these <tt>#include</tt>s to be listed in this
+order:</p>
<ol>
<li><a href="#mmheader">Main Module header</a></li>
<li><a href="#hl_privateheaders">Local/Private Headers</a></li>
- <li>llvm/*</li>
- <li>llvm/Analysis/*</li>
- <li>llvm/Assembly/*</li>
- <li>llvm/Bytecode/*</li>
- <li>llvm/CodeGen/*</li>
+ <li><tt>llvm/*</tt></li>
+ <li><tt>llvm/Analysis/*</tt></li>
+ <li><tt>llvm/Assembly/*</tt></li>
+ <li><tt>llvm/Bytecode/*</tt></li>
+ <li><tt>llvm/CodeGen/*</tt></li>
<li>...</li>
- <li>Support/*</li>
- <li>Config/*</li>
- <li>System #includes</li>
+ <li><tt>Support/*</tt></li>
+ <li><tt>Config/*</tt></li>
+ <li>System <tt>#includes</tt></li>
</ol>
<p>... and each catagory should be sorted by name.</p>
syntax of the code slightly. For example, an warning that annoys me occurs when
I write code like this:</p>
+<div class="doc_code">
<pre>
- if (V = getValue()) {
- ..
- }
+if (V = getValue()) {
+ ...
+}
</pre>
+</div>
<p><tt>gcc</tt> will warn me that I probably want to use the <tt>==</tt>
operator, and that I probably mistyped it. In most cases, I haven't, and I
really don't want the spurious errors. To fix this particular problem, I
rewrite the code like this:</p>
+<div class="doc_code">
<pre>
- if ((V = getValue())) {
- ..
- }
+if ((V = getValue())) {
+ ...
+}
</pre>
+</div>
<p>...which shuts <tt>gcc</tt> up. Any <tt>gcc</tt> warning that annoys you can
be fixed by massaging the code appropriately.</p>
helps the poor debugging make sense of why an assertion is being made and
enforced, and hopefully what to do about it. Here is one complete example:</p>
+<div class="doc_code">
<pre>
- inline Value *getOperand(unsigned i) {
- assert(i < Operands.size() && "getOperand() out of range!");
- return Operands[i];
- }
+inline Value *getOperand(unsigned i) {
+ assert(i < Operands.size() && "getOperand() out of range!");
+ return Operands[i];
+}
</pre>
+</div>
<p>Here are some examples:</p>
+<div class="doc_code">
<pre>
- assert(Ty->isPointerType() && "Can't allocate a non pointer type!");
+assert(Ty->isPointerType() && "Can't allocate a non pointer type!");
- assert((Opcode == Shl || Opcode == Shr) && "ShiftInst Opcode invalid!");
+assert((Opcode == Shl || Opcode == Shr) && "ShiftInst Opcode invalid!");
- assert(idx < getNumSuccessors() && "Successor # out of range!");
+assert(idx < getNumSuccessors() && "Successor # out of range!");
- assert(V1.getType() == V2.getType() && "Constant types must be identical!");
+assert(V1.getType() == V2.getType() && "Constant types must be identical!");
- assert(isa<PHINode>(Succ->front()) && "Only works on PHId BBs!");
+assert(isa<PHINode>(Succ->front()) && "Only works on PHId BBs!");
</pre>
+</div>
<p>You get the idea...</p>
<div class="doc_text">
-<p>Hard fast rule: Preincrement (++X) may be no slower than postincrement (X++)
-and could very well be a lot faster than it. Use preincrementation whenever
-possible.</p>
+<p>Hard fast rule: Preincrement (<tt>++X</tt>) may be no slower than
+postincrement (<tt>X++</tt>) and could very well be a lot faster than it. Use
+preincrementation whenever possible.</p>
<p>The semantics of postincrement include making a copy of the value being
incremented, returning it, and then preincrementing the "work value". For
</div>
-
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
<a name="hl_avoidendl">Avoid std::endl</a>
to the output stream specified. In addition to doing this, however, it also
flushes the output stream. In other words, these are equivalent:</p>
+<div class="doc_code">
<pre>
- std::cout << std::endl;
- std::cout << "\n" << std::flush;
+std::cout << std::endl;
+std::cout << '\n' << std::flush;
</pre>
+</div>
<p>Most of the time, you probably have no reason to flush the output stream, so
-it's better to use a literal <tt>"\n"</tt>.</p>
+it's better to use a literal <tt>'\n'</tt>.</p>
</div>
<div class="doc_text">
-<p>C++ is a powerful language. With a firm grasp on its capabilities, you can make
-write effective, consise, readable and maintainable code all at the same time.
-By staying consistent, you reduce the amount of special cases that need to be
-remembered. Reducing the total number of lines of code you write is a good way
-to avoid documentation, and avoid giving bugs a place to hide.</p>
+<p>C++ is a powerful language. With a firm grasp on its capabilities, you can
+make write effective, consise, readable and maintainable code all at the same
+time. By staying consistent, you reduce the amount of special cases that need
+to be remembered. Reducing the total number of lines of code you write is a
+good way to avoid documentation, and avoid giving bugs a place to hide.</p>
<p>For these reasons, come to know and love the contents of your local
<algorithm> header file. Know about <functional> and what it can do
projects / oota-llvm.git / commitdiff