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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 566660ef3b4d
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>Chapter 4. LWLINK</H1
><P
>The LWTOOLS linker is called LWLINK. This chapter documents the various features
of the linker.</P
><DIV
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><H1
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><A
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>4.1. Command Line Options</A
></H1
><P
>The binary for LWLINK is called "lwlink". Note that the binary is in lower
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><DT
><CODE
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>--decb</CODE
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><DD
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>Selects the DECB output format target. This is equivalent to <CODE
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><DT
><CODE
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>This option specifies the name of the output file. If not specified, the
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><CODE
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>--script=FILE</CODE
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><P
>This option allows specifying a linking script to override the linker's
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><CODE
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><CODE
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>--library-path=DIR</CODE
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>-L DIR</CODE
></DT
><DD
><P
>Add DIR to the library search path.</P
></DD
><DT
><CODE
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>--debug</CODE
>, <CODE
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>-d</CODE
></DT
><DD
><P
>This option increases the debugging level. It is only useful for LWTOOLS
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><DT
><CODE
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>--help</CODE
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></DT
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><P
>This provides a listing of command line options and a brief description
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></DT
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><P
>This will display a usage summary
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><DT
><CODE
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>--version</CODE
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><DD
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>This will display the version of LWLINK.</P
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