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| author | Craig Burley <craig@jcb-sc.com> | 1999-04-19 22:42:00 +0000 |
|---|---|---|
| committer | Craig Burley <burley@gcc.gnu.org> | 1999-04-19 18:42:00 -0400 |
| commit | 1a5cfb80ec443e8e274f1ae7535eb1d2f2285e02 (patch) | |
| tree | 7ede6d1fa2d788c937ba2fc1d42d156a31cfc90a | |
| parent | bded05359b10cb1d7ff4f2c980ff83b5d4660ee9 (diff) | |
| download | gcc-1a5cfb80ec443e8e274f1ae7535eb1d2f2285e02.zip gcc-1a5cfb80ec443e8e274f1ae7535eb1d2f2285e02.tar.gz gcc-1a5cfb80ec443e8e274f1ae7535eb1d2f2285e02.tar.bz2 | |
clarify -malign-double situation
From-SVN: r26555
| -rw-r--r-- | gcc/f/ChangeLog | 4 | ||||
| -rw-r--r-- | gcc/f/bugs.texi | 38 | ||||
| -rw-r--r-- | gcc/f/news.texi | 6 |
3 files changed, 11 insertions, 37 deletions
diff --git a/gcc/f/ChangeLog b/gcc/f/ChangeLog index 8cfae68..fb17af4 100644 --- a/gcc/f/ChangeLog +++ b/gcc/f/ChangeLog @@ -1,3 +1,7 @@ +Tue Apr 20 01:38:57 1999 Craig Burley <craig@jcb-sc.com> + + * bugs.texi, news.texi: Clarify -malign-double situation. + Tue Apr 20 01:15:25 1999 Craig Burley <craig@jcb-sc.com> * stb.c (ffestb_R5282_): Convert DATA repeat count diff --git a/gcc/f/bugs.texi b/gcc/f/bugs.texi index 3d4e791..c9a486c 100644 --- a/gcc/f/bugs.texi +++ b/gcc/f/bugs.texi @@ -9,7 +9,7 @@ @c in the standalone derivations of this file (e.g. BUGS). @set copyrights-bugs 1995-1999 -@set last-update-bugs 1999-04-17 +@set last-update-bugs 1999-04-20 @include root.texi @@ -265,42 +265,6 @@ of specifications of alignment requirements and preferences for targets, and front ends like @code{g77} should take advantage of this when it becomes available. -@cindex alignment -@cindex double-precision performance -@cindex -malign-double -@item -The x86 target's @samp{-malign-double} option -no longer reliably aligns double-precision variables and arrays -when they are placed in the stack frame. - -This can significantly reduce the performance of some applications, -even on a run-to-run basis -(that is, performance measurements can vary fairly widely -depending on whether frequently used variables are properly aligned, -and that can change from one program run to the next, -even from one procedure call to the next). - -Versions 0.5.22 and earlier of @code{g77} -included a patch to @code{gcc} that enabled this, -but that patch has been deemed an improper (probably buggy) one -for version 2.8 of @code{gcc} and for @code{egcs}. - -Note that version 1.1 of @code{egcs} -aligns double-precision variables and arrays -when they are in static storage -even if @samp{-malign-double} is not specified. - -There is ongoing investigation into -how to make @samp{-malign-double} work properly, -also into how to make it unnecessary to get -all double-precision variables and arrays aligned -when such alignment would not violate -the relevant specifications for processor -and inter-procedural interfaces. - -For a suite of programs to test double-precision alignment, -see @uref{ftp://alpha.gnu.org/gnu/g77/align/}. - @cindex complex performance @cindex aliasing @item diff --git a/gcc/f/news.texi b/gcc/f/news.texi index 52d03d6..37acb1c 100644 --- a/gcc/f/news.texi +++ b/gcc/f/news.texi @@ -225,6 +225,12 @@ now reliably aligns @emph{all} double-precision variables and arrays on Intel x86 targets. @item +Even without the @samp{-malign-double} option, +@code{g77} reliably aligns local double-precision variables +that are not in @code{EQUIVALENCE} areas +and not @code{SAVE}'d. + +@item A substantial portion of the @code{g77} front end's code-generation component was rewritten. It now generates code using facilities more robustly supported |