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Fix internal compiler error on "var2 = var1 + 1" patterns This appears to be the correct fix. It was provided by Tormod Volden (debian.tormod@gmail.com). The final commit is substantially different from Tormod's submission mostly due to housecleaning (removing the old patches and updating the README). Tormod's comments follow. The original addhi_mem_1 "insn" instruction pattern /matches/ two memory operands, just with the /constraint/ that these are the same location. A pattern match tells the compiler "you should be able to use this, but you might have to work on it to meet the constraints". For typical constraints on registers the compiler can add "reloads", moving stuff between registers or from memory, until the constraints are met and the instruction can be used. However, in this case, no amount of reloads can make two memory locations the same if they already weren't, so the compiler breaks down and cries "unable to generate reloads". It seems this issue only appears if optimization is enabled. The proof is in gcc's reload.c and is left as an exercise to the reader. Limiting the matching pattern to identical memory operands avoids these situations, while allowing the common "var++" cases. References: The pattern/constraints difference is explained in https://gcc.gnu.org/onlinedocs/gccint/Simple-Constraints.html#index-other-register-constraints-3335
author William Astle <lost@l-w.ca>
date Tue, 29 Mar 2016 21:21:49 -0600
parents fc166b3bbae3
children
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>Chapter 5. Libraries and LWAR</H1
><P
>LWTOOLS also includes a tool for managing libraries. These are analogous to
the static libraries created with the "ar" tool on POSIX systems. Each library
file contains one or more object files. The linker will treat the object
files within a library as though they had been specified individually on
the command line except when resolving external references. External references
are looked up first within the object files within the library and then, if
not found, the usual lookup based on the order the files are specified on
the command line occurs.</P
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>The tool for creating these libary files is called LWAR.</P
><DIV
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><A
NAME="AEN1005"
>5.1. Command Line Options</A
></H1
><P
>The binary for LWAR is called "lwar". Note that the binary is in lower
case. The options lwar understands are listed below. For archive manipulation
options, the first non-option argument is the name of the archive. All other
non-option arguments are the names of files to operate on.</P
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><DL
><DT
><CODE
CLASS="OPTION"
>--add</CODE
>, <CODE
CLASS="OPTION"
>-a</CODE
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><DD
><P
>This option specifies that an archive is going to have files added to it.
If the archive does not already exist, it is created. New files are added
to the end of the archive.</P
></DD
><DT
><CODE
CLASS="OPTION"
>--create</CODE
>, <CODE
CLASS="OPTION"
>-c</CODE
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><DD
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>This option specifies that an archive is going to be created and have files
added to it. If the archive already exists, it is truncated.</P
></DD
><DT
><CODE
CLASS="OPTION"
>--merge</CODE
>, <CODE
CLASS="OPTION"
>-m</CODE
></DT
><DD
><P
>If specified, any files specified to be added to an archive will be checked
to see if they are archives themselves. If so, their constituent members are
added to the archive. This is useful for avoiding archives containing archives.</P
></DD
><DT
><CODE
CLASS="OPTION"
>--list</CODE
>, <CODE
CLASS="OPTION"
>-l</CODE
></DT
><DD
><P
>This will display a list of the files contained in the archive.</P
></DD
><DT
><CODE
CLASS="OPTION"
>--debug</CODE
>, <CODE
CLASS="OPTION"
>-d</CODE
></DT
><DD
><P
>This option increases the debugging level. It is only useful for LWTOOLS
developers.</P
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><DT
><CODE
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>--help</CODE
>, <CODE
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>-?</CODE
></DT
><DD
><P
>This provides a listing of command line options and a brief description
of each.</P
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><DT
><CODE
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>--usage</CODE
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><DD
><P
>This will display a usage summary
of each command line option.</P
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><DT
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>--version</CODE
>, <CODE
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></DT
><DD
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>This will display the version of LWLINK.
of each.</P
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