Various additions and some small fixes.
From-SVN: r22468
This commit is contained in:
Dave Love
parent
d2a73f8ee2
commit
0b31330e26
423
gcc/f/g77.texi
423
gcc/f/g77.texi
@ -647,7 +647,7 @@ Jonathan Corbet
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@item
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Dr.@: Mark Fernyhough
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@item
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Takafumi Hayashi (The University of AIzu)---@email{takafumi@@u-aizu.ac.jp}
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Takafumi Hayashi (The University of Aizu)---@email{takafumi@@u-aizu.ac.jp}
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@item
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Kate Hedstrom
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@item
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@ -2638,8 +2638,28 @@ is @samp{-mno-align-double}, not @samp{-benign-double}.
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@item -ffloat-store
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@cindex IEEE conformance
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@cindex conformance, IEEE
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Might help a Fortran program that depends on exact IEEE conformance
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on some machines, but might slow down a program that doesn't.
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@cindex floating point precision
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Might help a Fortran program that depends on exact IEEE conformance on
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some machines, but might slow down a program that doesn't.
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This option is effective when the floating point unit is set to work in
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IEEE 854 `extended precision'---as it typically is on x86 and m68k GNU
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systems---rather than IEEE 754 double precision. @code{-ffloat-store}
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tries to remove the extra precision by spilling data from floating point
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registers into memory and this typically involves a big performance
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hit. However, it doesn't affect intermediate results, so that it is
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only partially effective. `Excess precision' is avoided in code like:
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@smallexample
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a = b + c
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d = a * e
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@end smallexample
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but not in code like:
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@smallexample
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d = (b + c) * e
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@end smallexample
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@xref{Floating point precision} for another, potentially better way of
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controlling the precision.
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@cindex -fforce-mem option
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@cindex options, -fforce-mem
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@ -2704,13 +2724,42 @@ Might improve performance on some code.
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@item -funroll-loops
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@cindex loops, unrolling
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@cindex unrolling loops
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Definitely improves performance on some code.
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@cindex loop optimization
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@c DL: fixme: Craig doesn't like `indexed' but f95 doesn't seem to
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@c provide a suitable term
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Typically improves performance on code using indexed @code{DO} loops by
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unrolling them and is probably generally appropriate for Fortran, though
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it is not turned on at any optimization level.
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Note that outer loop unrolling isn't done specifically; decisions about
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whether to unroll a loop are made on the basis of its instruction count.
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@c DL: Fixme: This should obviously go somewhere else...
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Also, no `loop discovery'@footnote{@dfn{loop discovery} refers to the
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process by which a compiler, or indeed any reader of a program,
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determines which portions of the program are more likely to be executed
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repeatedly as it is being run. Such discovery typically is done early
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when compiling using optimization techniques, so the ``discovered''
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loops get more attention---and more run-time resources, such as
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registers---from the compiler. It is easy to ``discover'' loops that are
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constructed out of looping constructs in the language
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(such as Fortran's @code{DO}). For some programs, ``discovering'' loops
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constructed out of lower-level constructs (such as @code{IF} and
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@code{GOTO}) can lead to generation of more optimal code
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than otherwise.} is done, so only loops written with @code{DO}
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benefit from loop optimizations, including---but not limited
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to---unrolling. Loops written with @code{IF} and @code{GOTO} will not
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be recognized as such. This option only unrolls indexed @code{DO}
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loops, not @code{DO WHILE} loops.
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@cindex -funroll-all-loops option
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@cindex options, -funroll-all-loops
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@cindex @code{DO WHILE}
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@item -funroll-all-loops
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@c DL: Is this really true? What _are_ the semantics of this option?
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Improves performance on some code.
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@c DL: Check my understanding of -funroll-all-loops v. -funroll-loops is correct.
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Probably improves performance on code using @code{DO WHILE} loops by
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unrolling them in addition to indexed @code{DO} loops. In the absence
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of @code{DO WHILE}, this option is equivalent to @code{-funroll-loops}
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but possibly slower.
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@item -fno-move-all-movables
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@cindex -fno-move-all-movables option
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@ -4137,6 +4186,8 @@ Extensions to the ANSI FORTRAN 77 standard:
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* Control Statements::
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* Functions and Subroutines::
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* Scope and Classes of Names::
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* I/O::
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* Fortran 90 Features::
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@end menu
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@node Direction of Language Development
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@ -4593,7 +4644,7 @@ Otherwise, it is treated as an indicator of a continuation
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line.
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@item
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The exclamation point appears outside a character or hollerith
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The exclamation point appears outside a character or Hollerith
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constant.
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Otherwise, the exclamation point is considered part of the
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constant.
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@ -4612,7 +4663,7 @@ is permitted under the following conditions:
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@itemize @bullet
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@item
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The semicolon appears outside a character or hollerith
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The semicolon appears outside a character or Hollerith
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constant.
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Otherwise, the semicolon is considered part of the
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constant.
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@ -4671,6 +4722,7 @@ for the relevant aspects of GNU Fortran.)
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* Statement Labels::
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* Order::
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* INCLUDE::
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* Cpp-style directives::
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@end menu
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@node Character Set
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@ -4683,7 +4735,7 @@ Letters include uppercase letters (the twenty-six characters
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of the English alphabet) and lowercase letters (their lowercase
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equivalent).
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Generally, lowercase letters may be used in place of uppercase
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letters, though in character and hollerith constants, they
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letters, though in character and Hollerith constants, they
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are distinct.
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Special characters include:
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@ -5010,6 +5062,18 @@ An @code{INCLUDE} directive may be continued across multiple
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lines as if it were a statement.
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This permits long names to be used for @var{filename}.
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@node Cpp-style directives
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@subsection Cpp-style directives
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@cindex #
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@cindex preprocessor
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@code{cpp} output-style @code{#} directives @xref{C Preprocessor
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Output,,, cpp, The C Preprocessor}, are recognized by the compiler even
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when the preprocessor isn't run on the input (as it is when compiling
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@samp{.F} files). (Note the distinction between these @code{cpp}
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@code{#} @emph{output} directives and @code{#line} @emph{input}
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directives.)
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@node Data Types and Constants
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@section Data Types and Constants
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@ -5561,6 +5625,7 @@ is 11, and so on.)
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(Corresponds to Section 4.8 of ANSI X3.9-1978 FORTRAN 77.)
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@cindex double quoted character constants
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A character constant may be delimited by a pair of double quotes
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(@samp{"}) instead of apostrophes.
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In this case, an apostrophe within the constant represents
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@ -5684,6 +5749,27 @@ The @code{NAMELIST} statement, and related I/O constructs, are
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supported by the GNU Fortran language in essentially the same
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way as they are by @code{f2c}.
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This follows Fortran 90 with the restriction that on @code{NAMELIST}
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input, subscripts must have the form
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@smallexample
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@var{subscript} [ @code{:} @var{subscript} [ @code{:} @var{stride}]]
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@end smallexample
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i.e.@:
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@smallexample
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&xx x(1:3,8:10:2)=1,2,3,4,5,6/
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@end smallexample
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is allowed, but not, say,
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@smallexample
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&xx x(:3,8::2)=1,2,3,4,5,6/
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@end smallexample
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As an extension of the Fortran 90 form, @code{$} and @code{$END} may be
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used in place of @code{&} and @code{/} in @code{NAMELIST} input, so that
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@smallexample
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$&xx x(1:3,8:10:2)=1,2,3,4,5,6 $end
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@end smallexample
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could be used instead of the example above.
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@node DOUBLE COMPLEX
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@subsection @code{DOUBLE COMPLEX} Statement
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@cindex DOUBLE COMPLEX
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@ -5710,10 +5796,13 @@ for the relevant aspects of GNU Fortran.)
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@node DO WHILE
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@subsection DO WHILE
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@cindex DO WHILE
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@cindex DO
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@cindex MIL-STD 1753
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The @code{DO WHILE} statement, a feature of both the MIL-STD 1753 and
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Fortran 90 standards, is provided by the GNU Fortran language.
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The Fortran 90 ``do forever'' statement comprising just @code{DO} is
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also supported.
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@node END DO
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@subsection END DO
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@ -6501,6 +6590,115 @@ for the relevant aspects of GNU Fortran.)
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Underscores (@samp{_}) are accepted in symbol names after the first
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character (which must be a letter).
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@node I/O
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@section I/O
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@cindex dollar sign
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A dollar sign at the end of an output format specification suppresses
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the newline at the end of the output.
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@cindex <> edit descriptor
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@cindex edit descriptor, <>
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Edit descriptors in @code{FORMAT} statements may contain compile-time
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@code{INTEGER} constant expressions in angle brackets, such as
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@smallexample
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10 FORMAT (I<WIDTH>)
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@end smallexample
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The @code{OPEN} specifier @code{NAME=} is equivalent to @code{FILE=}.
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These Fortran 90 features are supported:
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@itemize @bullet
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@item
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@cindex Z edit descriptor
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@cindex edit descriptor, Z
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The @code{Z} edit descriptor is supported.
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@item
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The @code{FILE=} specifier may be omitted in an @code{OPEN} statement if
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@code{STATUS='SCRATCH'} is supplied. The @code{STATUS='REPLACE'}
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specifier is supported.
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@end itemize
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@node Fortran 90 Features
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@section Fortran 90 Features
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@cindex Fortran 90
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For convenience this section collects a list (probably incomplete) of
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the Fortran 90 features supported by the GNU Fortran language, even if
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they are documented elsewhere.
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@c makeinfo 1.68 objects to the nested parens
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@ifnotinfo
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@xref{Characters Lines Sequence,,{Characters, Lines, and Execution Sequence}},
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@end ifnotinfo
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@ifinfo
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@xref{Characters Lines Sequence},
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@end ifinfo
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for information on additional fixed source form lexical issues. In
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addition, the free source form is supported through the
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@cindex @samp{-ffree-form}
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@samp{-ffree-form} option. @xref{Fortran 90} for other Fortran 90
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features be turned on by the
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@cindex @samp{-ff90}
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@samp{-ff90} option. @xref{Table of Intrinsic Functions} for
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information on the Fortran 90 intrinsics available.
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@table @asis
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@item Automatic arrays in procedures
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@item Character assignments
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@cindex character assignments
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In character assignments, the variable being assigned may occur on the
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right hand side of the assignment.
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@item Character strings
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@cindex double quoted character constants
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Strings may have zero length and substrings of character constants are
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permitted. Character constants may be enclosed in double quotes
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(@code{"}) as well as single quotes. @xref{Character Type}.
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@item Construct names
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(Symbolic tags on blocks.) @xref{Construct Names }.
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@item @code{CYCLE} and @code{EXIT}
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@xref{CYCLE and EXIT,,The @code{CYCLE} and @code{EXIT} Statements}.
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@item @code{DOUBLE COMPLEX}
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@xref{DOUBLE COMPLEX,,@code{DOUBLE COMPLEX} Statement
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}.
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@item @code{DO WHILE}
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@xref{DO WHILE}.
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@item @code{END} decoration
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@xref{Statements}.
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@item @code{END DO}
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@xref{END DO}.
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@item @code{KIND}
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@item @code{IMPLICIT NONE}
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@item @code{INCLUDE} statements
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@xref{INCLUDE}.
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@item List directed and namelist i/o on internal files
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@item Binary, octal and hexadecimal constants
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These are supported more generally than required by Fortran 90.
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@xref{Integer Type}.
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@item @code{NAMELIST}
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@xref{NAMELIST}.
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@item @code{OPEN} specifiers
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@code{STATUS='REPLACE'} is supported.
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@item Relational operators
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The operators @code{<}, @code{<=}, @code{==}, @code{/=}, @code{>} and
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@code{>=} may be used instead of @code{.LT.}, @code{.LE.}, @code{.EQ.},
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@code{.NE.}, @code{.GT.} and @code{.GE.} respectively.
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@item @code{SELECT CASE}
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Not fully implemented. @xref{SELECT CASE on CHARACTER Type,,
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@code{SELECT CASE} on @code{CHARACTER} Type}.
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@item Specification statements
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A limited subset of the Fortran 90 syntax and semantics for variable
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declarations is supported, including @code{KIND}. @xref{Kind Notation}.
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(@code{KIND} is of limited usefulness in the absence of the
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@code{KIND}-related intrinsics, since these intrinsics permit writing
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more widely portable code.) An example of supported @code{KIND} usage
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is:
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@smallexample
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INTEGER (KIND=1) :: FOO=1, BAR=2
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CHARACTER (LEN=3) FOO
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@end smallexample
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@code{PARAMETER} and @code{DIMENSION} attributes aren't supported.
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@end table
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@node Other Dialects
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@chapter Other Dialects
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@ -8341,7 +8539,7 @@ prototype information.
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@code{#include} this in the C which has to call
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the Fortran routines to make sure you get it right.
|
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|
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@xref{Arrays,,Arrays (DIMENSION}, for information on the differences
|
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@xref{Arrays,,Arrays (DIMENSION)}, for information on the differences
|
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between the way Fortran (including compilers like @code{g77}) and
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C handle arrays.
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@ -9813,7 +10011,7 @@ The meaning of a @code{DO} loop in Fortran is precisely specified
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in the Fortran standard@dots{}and is quite different from what
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many programmers might expect.
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In particular, Fortran @code{DO} loops are implemented as if
|
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In particular, Fortran indexed @code{DO} loops are implemented as if
|
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the number of trips through the loop is calculated @emph{before}
|
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the loop is entered.
|
||||
|
||||
@ -9997,6 +10195,8 @@ tracking down bugs in such programs.
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||||
* Aliasing Assumed To Work::
|
||||
* Output Assumed To Flush::
|
||||
* Large File Unit Numbers::
|
||||
* Floating point precision::
|
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* Inconsistent Calling Sequences::
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@end menu
|
||||
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@node Not My Type
|
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@ -10414,6 +10614,62 @@ open by a running program.
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Information on how to increase these limits should be found
|
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in your system's documentation.
|
||||
|
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@node Floating point precision
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@subsection Floating point precision
|
||||
|
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@cindex IEEE 754
|
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@cindex IEEE conformance
|
||||
@cindex conformance, IEEE
|
||||
@cindex floating point precision
|
||||
If your program depends on exact IEEE 754 floating point handling it may
|
||||
help on some systems---specifically x86 or m68k hardware---to use
|
||||
the @code{-ffloat-store} option or to reset the precision flag on the
|
||||
floating point unit @xref{Optimize Options}.
|
||||
|
||||
However, it might be better simply to put the FPU into double precision
|
||||
mode and not take the performance hit of @code{-ffloat-store}. On x86
|
||||
and m68k GNU systems you can do this with a technique similar to that
|
||||
for turning on floating point exceptions @xref{Floating-point Exception
|
||||
Handling}. The control word could be set to double precision by
|
||||
replacing the @code{__setfpucw} call with one like this:
|
||||
@smallexample
|
||||
__setfpucw ((_FPU_DEFAULT & ~_FPU_EXTENDED) | _FPU_DOUBLE);
|
||||
@end smallexample
|
||||
(It is not clear whether this has any effect on the operation of the GNU
|
||||
maths library, but we have no evidence of it causing trouble.)
|
||||
|
||||
Some targets (such as the Alpha) may need special options for full IEEE
|
||||
conformance @xref{Submodel Options,,Hardware Models and
|
||||
Configurations,gcc,Using and Porting GNU CC}.
|
||||
|
||||
@node Inconsistent Calling Sequences
|
||||
@subsection Inconsistent Calling Sequences
|
||||
|
||||
@pindex ftnchek
|
||||
@cindex floating point errors
|
||||
@cindex x86 FPU stack
|
||||
Code containing inconsistent calling sequences in the same file is
|
||||
normally rejected @xref{GLOBALS}. (Use, say, @code{ftnchek} to ensure
|
||||
consistency across source files
|
||||
@c makeinfo 1.68 objects to the nested parens
|
||||
@ifinfo
|
||||
@xref{f2c Skeletons and Prototypes}.)
|
||||
@end ifinfo
|
||||
@ifnotinfo
|
||||
@xref{f2c Skeletons and Prototypes,,
|
||||
{Generating Skeletons and Prototypes with @code{f2c}}}.)
|
||||
@end ifnotinfo
|
||||
|
||||
Mysterious errors, which may appear to be code generation problems, can
|
||||
appear specifically on the x86 architecture with some such
|
||||
inconsistencies. On x86 hardware, floating point return values of
|
||||
functions are placed on the floating point unit's register stack, not
|
||||
the normal stack. Thus calling a @code{REAL} or @code{DOUBLE PRECISION}
|
||||
@code{FUNCTION} as some other sort of procedure, or vice versa,
|
||||
scrambles the floating point stack. This may break unrelated code
|
||||
executed later. Similarly if, say, external C routines are written
|
||||
incorrectly.
|
||||
|
||||
@node Overly Convenient Options
|
||||
@section Overly Convenient Command-line Options
|
||||
@cindex overly convenient options
|
||||
@ -11251,6 +11507,25 @@ instead of converting them to double precision first.
|
||||
This would tend to result in output that is more consistent
|
||||
with that produced by some other Fortran implementations.
|
||||
|
||||
A useful source of information on floating point computation is David
|
||||
Goldberg, `What Every Computer Scientist Should Know About
|
||||
Floating-Point Arithmetic', Computing Surveys, 23, March 1991, pp.@:
|
||||
5--48. At the time of writing this is available online under
|
||||
@uref{http://docs.sun.com} and there is a supplemented version at
|
||||
@uref{http://www.validgh.com/}. Information related to the IEEE 754
|
||||
floating point standard by a leading light can be found at
|
||||
@uref{http://http.cs.berkeley.edu/%7Ewkahan/ieee754status }; see also
|
||||
slides from the short course referenced from
|
||||
@uref{http://http.cs.berkeley.edu/%7Efateman/}.
|
||||
@uref{http://www.suburbia.net/%7Ebillm/floating-point/} has a brief
|
||||
guide to IEEE 754, a somewhat x86 GNU/Linux-specific FAQ and library
|
||||
code for GNU/Linux x86 systems.
|
||||
@c xref would be different between editions:
|
||||
The GNU C library provides routines for controlling the FPU, and other
|
||||
documentation about this.
|
||||
|
||||
@xref{Floating point precision}, regarding IEEE 754 conformance.
|
||||
|
||||
@include bugs.texi
|
||||
|
||||
@node Missing Features
|
||||
@ -11312,6 +11587,7 @@ Better diagnostics:
|
||||
Run-time facilities:
|
||||
* Uninitialized Variables at Run Time::
|
||||
* Bounds Checking at Run Time::
|
||||
* Portable Unformatted Files::
|
||||
|
||||
Debugging:
|
||||
* Labels Visible to Debugger::
|
||||
@ -11653,6 +11929,7 @@ code to specify explicit assembler code.
|
||||
@subsection Q Edit Descriptor
|
||||
@cindex FORMAT statement
|
||||
@cindex Q edit descriptor
|
||||
@cindex edit descriptor, Q
|
||||
|
||||
The @code{Q} edit descriptor in @code{FORMAT}s isn't supported.
|
||||
(This is meant to get the number of characters remaining in an input record.)
|
||||
@ -11730,6 +12007,25 @@ the @code{OPEN}, @code{CLOSE}, and @code{INQUIRE} statements.
|
||||
These extensions are easy to add to @code{g77} itself, but
|
||||
require much more work on @code{libg2c}.
|
||||
|
||||
@cindex FORM='PRINT'
|
||||
@cindex ANS carriage control
|
||||
@cindex carraige control
|
||||
@pindex asa
|
||||
@pindex fpr
|
||||
@code{g77} doesn't support @code{FORM='PRINT'} or an equivalent to
|
||||
translate the traditional `carraige control' characters in column 1 of
|
||||
output to use backspaces, carriage returns and the like. However
|
||||
programs exist to translate them in output files (or standard output).
|
||||
These are typically called either @code{fpr} or @code{asa}. You can get
|
||||
a version of @code{asa} from
|
||||
@uref{ftp://sunsite.unc.edu/pub/Linux/devel/lang/fortran} for GNU
|
||||
systems which will probably build easily on other systems.
|
||||
Alternatively, @code{fpr} is in BSD distributions in various archive
|
||||
sites.
|
||||
|
||||
I think both programs can either be used in a pipeline.
|
||||
|
||||
|
||||
@node ENCODE and DECODE
|
||||
@subsection @code{ENCODE} and @code{DECODE}
|
||||
@cindex ENCODE statement
|
||||
@ -11865,11 +12161,13 @@ END
|
||||
@cindex NaN values
|
||||
|
||||
The @code{gcc} backend and, consequently, @code{g77}, currently provides no
|
||||
control over whether or not floating-point exceptions are trapped or
|
||||
general control over whether or not floating-point exceptions are trapped or
|
||||
ignored.
|
||||
(Ignoring them typically results in NaN values being
|
||||
propagated in systems that conform to IEEE 754.)
|
||||
The behaviour is inherited from the system-dependent startup code.
|
||||
The behaviour is normally inherited from the system-dependent startup
|
||||
code, though some targets, such as the Alpha, have code generation
|
||||
options which change the behaviour.
|
||||
|
||||
Most systems provide some C-callable mechanism to change this; this can
|
||||
be invoked at startup using @code{gcc}'s @code{constructor} attribute.
|
||||
@ -11879,13 +12177,21 @@ on an x86-based GNU system:
|
||||
|
||||
@smallexample
|
||||
#include <fpu_control.h>
|
||||
void __attribute__ ((constructor))
|
||||
trapfpe () @{
|
||||
(void) __setfpucw (_FPU_DEFAULT &
|
||||
~(_FPU_MASK_IM | _FPU_MASK_ZM | _FPU_MASK_OM));
|
||||
static void __attribute__ ((constructor))
|
||||
trapfpe ()
|
||||
@{
|
||||
__setfpucw (_FPU_DEFAULT &
|
||||
~(_FPU_MASK_IM | _FPU_MASK_ZM | _FPU_MASK_OM));
|
||||
@}
|
||||
@end smallexample
|
||||
|
||||
A convenient trick is to compile this something like:
|
||||
@smallexample
|
||||
gcc -o libtrapfpe.a trapfpe.c
|
||||
@end smallexample
|
||||
and then use it by adding @code{-trapfpe} to the @code{g77} command line
|
||||
when linking.
|
||||
|
||||
@node Nonportable Conversions
|
||||
@subsection Nonportable Conversions
|
||||
@cindex nonportable conversions
|
||||
@ -12099,6 +12405,76 @@ in a fashion similar to @code{f2c}.
|
||||
Note that @code{g77} already warns about references to out-of-bounds
|
||||
elements of arrays when it detects these at compile time.
|
||||
|
||||
@node Portable Unformatted Files
|
||||
@subsection Portable Unformatted Files
|
||||
|
||||
@cindex unformatted files
|
||||
@cindex file formats
|
||||
@cindex binary data
|
||||
@cindex byte ordering
|
||||
@code{g77} has no facility for exchanging unformatted files with systems
|
||||
using different number formats---even differing only in endianness (byte
|
||||
order)---or written by other compilers. Some compilers provide
|
||||
facilities at least for doing byte-swapping during unformatted I/O.
|
||||
|
||||
It is unrealistic to expect to cope with exchanging unformatted files
|
||||
with arbitrary other compiler runtimes, but the @code{g77} runtime
|
||||
should at least be able to read files written by @code{g77} on systems
|
||||
with different number formats, particularly if they differ only in byte
|
||||
order.
|
||||
|
||||
In case you do need to write a program to translate to or from
|
||||
@code{g77} (@code{libf2c}) unformatted files, they are written as
|
||||
follows:
|
||||
@table @asis
|
||||
@item Sequential
|
||||
Unformatted sequential records consist of
|
||||
@enumerate
|
||||
@item
|
||||
A number giving the length of the record contents;
|
||||
@item
|
||||
the length of record contents again (for backspace).
|
||||
@end enumerate
|
||||
The record length is of C type
|
||||
@code{long}; this means that it is 8 bytes on 64-bit systems such as
|
||||
Alpha GNU/Linux and 4 bytes on other systems, such as x86 GNU/Linux.
|
||||
Consequently such files cannot be exchanged between 64-bit and 32-bit
|
||||
systems, even with the same basic number format.
|
||||
@item Direct access
|
||||
Unformatted direct access files form a byte stream of length
|
||||
@var{records}*@var{recl} bytes, where @var{records} is the maximum
|
||||
record number (@code{REC=@var{records}}) written and @var{recl} is the
|
||||
record length in bytes specified in the @code{OPEN} statement
|
||||
(@code{RECL=@var{recl}}). Data appear in the records as determined by
|
||||
the relevant @code{WRITE} statement. Dummy records with arbitrary
|
||||
contents appear in the file in place of records which haven't been
|
||||
written.
|
||||
@end table
|
||||
|
||||
Thus for exchanging a sequential or direct access unformatted file
|
||||
between big- and little-endian 32-bit systems using IEEE 754 floating
|
||||
point it would be sufficient to reverse the bytes in consecutive words
|
||||
in the file @emph{iff} only @code{REAL*4}, @code{COMPLEX},
|
||||
@code{INTEGER*4} and/or @code{LOGICAL*4} data have been written to it by
|
||||
@code{g77}.
|
||||
|
||||
If necessary, it is possible to do byte-oriented i/o with @code{g77}'s
|
||||
@code{FGETC} and @code{FPUTC} intrinsics. Byte-swapping can be done in
|
||||
Fortran by equivalencing larger sized variables to an @code{INTEGER*1}
|
||||
array or a set of scalars.
|
||||
|
||||
@cindex HDF
|
||||
@cindex PDB
|
||||
If you need to exchange binary data between arbitrary system and
|
||||
compiler variations, we recommend using a portable binary format with
|
||||
Fortran bindings, such as NCSA's HDF (@uref{http://hdf.ncsa.uiuc.edu/})
|
||||
or PACT's PDB@footnote{No, not @emph{that} one.}
|
||||
(@uref{http://www.llnl.gov/def_sci/pact/pact_homepage.html}). (Unlike,
|
||||
say, CDF or XDR, HDF-like systems write in the native number formats and
|
||||
only incur overhead when they are read on a system with a different
|
||||
format.) A future @code{g77} runtime library should use such
|
||||
techniques.
|
||||
|
||||
@node Labels Visible to Debugger
|
||||
@subsection Labels Visible to Debugger
|
||||
|
||||
@ -13499,6 +13875,8 @@ are passed via this mechanism.
|
||||
If you want to contribute to @code{g77} by doing research,
|
||||
design, specification, documentation, coding, or testing,
|
||||
the following information should give you some ideas.
|
||||
More relevant information might be available from
|
||||
@uref{ftp://alpha.gnu.org/gnu/g77/projects/}.
|
||||
|
||||
@menu
|
||||
* Efficiency:: Make @code{g77} itself compile code faster.
|
||||
@ -14377,7 +14755,7 @@ Consecutive keywords must be separated by spaces, so
|
||||
@samp{REALX,Y} is not valid, while @samp{REAL X,Y} is.
|
||||
There are no comment lines per se, but @samp{!} starts a
|
||||
comment anywhere in a line (other than within a character or
|
||||
hollerith constant).
|
||||
Hollerith constant).
|
||||
|
||||
@xref{Source Form}, for more information.
|
||||
|
||||
@ -14453,7 +14831,7 @@ someone examining the source file itself.
|
||||
Examples of errors resulting from preprocessor macro expansion
|
||||
include exceeding the line-length limit, improperly starting,
|
||||
terminating, or incorporating the apostrophe or double-quote in
|
||||
a character constant, improperly forming a hollerith constant,
|
||||
a character constant, improperly forming a Hollerith constant,
|
||||
and so on.
|
||||
|
||||
@xref{Overall Options,,Options Controlling the Kind of Output},
|
||||
@ -14526,8 +14904,11 @@ based on @code{gcc}.
|
||||
(It does not occur in @code{egcs}.)
|
||||
|
||||
On AIX 4.1, @code{g77} might not build with the native (non-GNU) tools
|
||||
due to a linker bug in coping with the @samp{-bbigtoc} option
|
||||
which leads to a @samp{Relocation overflow} error.
|
||||
due to a linker bug in coping with the @samp{-bbigtoc} option which
|
||||
leads to a @samp{Relocation overflow} error. The GNU linker is not
|
||||
recommended on current AIX versions, though; it was developed under a
|
||||
now-unsupported version. This bug is said to be fixed by `update PTF
|
||||
U455193 for APAR IX75823'.
|
||||
|
||||
Compiling with @samp{-mminimal-toc}
|
||||
might solve this problem, e.g.@: by adding
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user