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<h4 class="subsection">17.7.5 Registers That Form a Stack</h4>
<p>There are special features to handle computers where some of the
“registers” form a stack. Stack registers are normally written by
pushing onto the stack, and are numbered relative to the top of the
stack.
<p>Currently, GCC can only handle one group of stack-like registers, and
they must be consecutively numbered. Furthermore, the existing
support for stack-like registers is specific to the 80387 floating
point coprocessor. If you have a new architecture that uses
stack-like registers, you will need to do substantial work on
<samp><span class="file">reg-stack.c</span></samp> and write your machine description to cooperate
with it, as well as defining these macros.
<div class="defun">
— Macro: <b>STACK_REGS</b><var><a name="index-STACK_005fREGS-4094"></a></var><br>
<blockquote><p>Define this if the machine has any stack-like registers.
</p></blockquote></div>
<div class="defun">
— Macro: <b>STACK_REG_COVER_CLASS</b><var><a name="index-STACK_005fREG_005fCOVER_005fCLASS-4095"></a></var><br>
<blockquote><p>This is a cover class containing the stack registers. Define this if
the machine has any stack-like registers.
</p></blockquote></div>
<div class="defun">
— Macro: <b>FIRST_STACK_REG</b><var><a name="index-FIRST_005fSTACK_005fREG-4096"></a></var><br>
<blockquote><p>The number of the first stack-like register. This one is the top
of the stack.
</p></blockquote></div>
<div class="defun">
— Macro: <b>LAST_STACK_REG</b><var><a name="index-LAST_005fSTACK_005fREG-4097"></a></var><br>
<blockquote><p>The number of the last stack-like register. This one is the bottom of
the stack.
</p></blockquote></div>
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