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extend.texi (Size of an asm): Really move node to its position.

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* doc/extend.texi (Size of an asm): Really move node to its position.

From-SVN: r210577
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Uros Bizjak 2014-05-18 09:17:06 +02:00
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commit db2687a001
1 changed files with 22 additions and 22 deletions
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gcc/doc/extend.texi
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@ -7267,28 +7267,6 @@ output of the assembler instruction directly into a particular register.
specified for that operand in the @code{asm}.)
@end itemize
@node Size of an asm
@subsection Size of an @code{asm}
Some targets require that GCC track the size of each instruction used
in order to generate correct code. Because the final length of the
code produced by an @code{asm} statement is only known by the
assembler, GCC must make an estimate as to how big it will be. It
does this by counting the number of instructions in the pattern of the
@code{asm} and multiplying that by the length of the longest
instruction supported by that processor. (When working out the number
of instructions, it assumes that any occurrence of a newline or of
whatever statement separator character is supported by the assembler --
typically @samp{;} --- indicates the end of an instruction.)
Normally, GCC's estimate is adequate to ensure that correct
code is generated, but it is possible to confuse the compiler if you use
pseudo instructions or assembler macros that expand into multiple real
instructions, or if you use assembler directives that expand to more
space in the object file than is needed for a single instruction.
If this happens then the assembler may produce a diagnostic saying that
a label is unreachable.
@menu
* Global Reg Vars::
* Local Reg Vars::
@ -7467,6 +7445,28 @@ register int *result asm ("r0");
asm ("sysint" : "=r" (result) : "0" (p1), "r" (p2));
@end smallexample
@node Size of an asm
@subsection Size of an @code{asm}
Some targets require that GCC track the size of each instruction used
in order to generate correct code. Because the final length of the
code produced by an @code{asm} statement is only known by the
assembler, GCC must make an estimate as to how big it will be. It
does this by counting the number of instructions in the pattern of the
@code{asm} and multiplying that by the length of the longest
instruction supported by that processor. (When working out the number
of instructions, it assumes that any occurrence of a newline or of
whatever statement separator character is supported by the assembler --
typically @samp{;} --- indicates the end of an instruction.)
Normally, GCC's estimate is adequate to ensure that correct
code is generated, but it is possible to confuse the compiler if you use
pseudo instructions or assembler macros that expand into multiple real
instructions, or if you use assembler directives that expand to more
space in the object file than is needed for a single instruction.
If this happens then the assembler may produce a diagnostic saying that
a label is unreachable.
@node Alternate Keywords
@section Alternate Keywords
@cindex alternate keywords