Mercurial > hg > index.cgi
diff docs/manual/x628.html @ 347:330a66a0f45a
Document the forwardrefmax pragma
Since the forwardrefmax is useful for combatting huge assembly times in many
sources, actually document it so people can find it.
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Thu, 09 Apr 2015 12:51:02 -0600 |
| parents | 507f442dc71e |
| children |
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--- a/docs/manual/x628.html Thu Apr 09 12:36:07 2015 -0600 +++ b/docs/manual/x628.html Thu Apr 09 12:51:02 2015 -0600 @@ -17,7 +17,7 @@ HREF="x564.html"><LINK REL="NEXT" TITLE="LWLINK" -HREF="c727.html"></HEAD +HREF="c734.html"></HEAD ><BODY CLASS="SECTION" BGCOLOR="#FFFFFF" @@ -59,7 +59,7 @@ ALIGN="right" VALIGN="bottom" ><A -HREF="c727.html" +HREF="c734.html" ACCESSKEY="N" >Next</A ></TD @@ -341,6 +341,37 @@ yet evaluate to a constant value at the point where the conditional appears, the assembler will still complain about a non constant condition.</P ></DD +><DT +>forwardrefmax</DT +><DD +><P +>This pragma will disable forward reference optimization completely. +Ordinarily, LWASM will attempt to select the shortest possible addressing +mode for forward references. However, in many source files, especially +those not using the PCR relative addressing modes, this optimization is +pointless since the assembler will almost certainly settle on a 16 bit +offset or address. If all variables in the direct page are defined before +the main body of the code, the benefit of forward reference optimization +almost certainly vanishes completely. However, the cost of doing that +optimization remains and can result in a very long assembly time.</P +><P +>Enabling this pragma will cause all forward references to use the +maximum offset or address size, much the same has EDTASM and other pure +two pass assemblers do. The side effect is that all line lengths and +symbol values are fully resolved after the initial parsing pass and the +amount of work to resolve everything becomes almost nil.</P +><P +>While this pragma can be applied selectively to sections of source +code (use *PRAGMA if doing so and compatibility with other assemblers +is desired), it is likely more useful when provided as a command line +pragma.</P +><P +>It should be noted that the presence or absence of this pragma +will not change the correctness of the generated code unless cycle counts +or byte counts are critical (which they usually are not). It also will +not override the operand size override prefixes (< and >). It only +applies when the assembler is left to guess what the operand size is.</P +></DD ></DL ></DIV ><P @@ -394,7 +425,7 @@ ALIGN="right" VALIGN="top" ><A -HREF="c727.html" +HREF="c734.html" ACCESSKEY="N" >Next</A ></TD