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authorRoland McGrath <roland@gnu.org>2012-03-13 16:59:57 +0000
committerRoland McGrath <roland@gnu.org>2012-03-13 16:59:57 +0000
commitfa94de6b5c193ccfe743efa63720647f63417032 (patch)
tree6e2097f0183c1ad232e4f9650cd885a26de0c6c7 /gas/doc
parent46cb6474c3a9fae3dbe25f7f42a7d24217d0fb5c (diff)
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2012-03-12 Roland McGrath <mcgrathr@google.com> * config/tc-arm.c (arm_frag_max_var): New function. * config/tc-arm.h: Declare it. (md_frag_max_var): New macro. * config/tc-i386.c (i386_frag_max_var): New function. * config/tc-i386.h: Declare it. (md_frag_max_var): New macro. * doc/as.texinfo (Bundle directives): New node. (Pseudo Ops): Add it to the menu. * NEWS: Mention new feature. * read.c [md_frag_max_var] (HANDLE_BUNDLE): New macro. [HANDLE_BUNDLE] (bundle_align_p2): New variable. [HANDLE_BUNDLE] (bundle_lock_frchain, bundle_lock_frag): New variables. [HANDLE_BUNDLE] (start_bundle, pending_bundle_size, finish_bundle): New functions. (assemble_one): New function if [HANDLE_BUNDLE], #define directly to md_assembly if not. (read_a_source_file): Call assemble_one in place of md_assemble. (read_a_source_file) [HANDLE_BUNDLE]: Check for unterminated .bundle_lock at end of processing. [HANDLE_BUNDLE] (s_bundle_align_mode, s_bundle_lock, s_bundle_unlock): New functions. [HANDLE_BUNDLE] (potable): Add their entries. * read.h: Declare new functions. gas/testsuite/ 2012-03-12 Roland McGrath <mcgrathr@google.com> * gas/i386/bundle-bad.s: New file. * gas/i386/bundle-bad.d: New file. * gas/i386/bundle-bad.l: New file. * gas/i386/i386.exp: Run it. * gas/arm/bundle.s: New file. * gas/arm/bundle.d: New file. * gas/arm/bundle-lock.s: New file. * gas/arm/bundle-lock.d: New file. * gas/i386/bundle.s: New file. * gas/i386/bundle.d: New file. * gas/i386/x86-64-bundle.s: New file. * gas/i386/x86-64-bundle.d: New file. * gas/i386/bundle-lock.s: New file. * gas/i386/bundle-lock.d: New file. * gas/i386/i386.exp: Run them.
Diffstat (limited to 'gas/doc')
-rw-r--r--gas/doc/as.texinfo56
1 files changed, 55 insertions, 1 deletions
diff --git a/gas/doc/as.texinfo b/gas/doc/as.texinfo
index 45405b8..2f892e2 100644
--- a/gas/doc/as.texinfo
+++ b/gas/doc/as.texinfo
@@ -3970,6 +3970,7 @@ Some machine configurations provide additional directives.
* Ascii:: @code{.ascii "@var{string}"}@dots{}
* Asciz:: @code{.asciz "@var{string}"}@dots{}
* Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
+* Bundle directives:: @code{.bundle_align_mode @var{abs-expr}}, @code{.bundle_lock}, @code{.bundle_unlock}
* Byte:: @code{.byte @var{expressions}}
* CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
* Comm:: @code{.comm @var{symbol} , @var{length} }
@@ -4292,6 +4293,59 @@ filled in with the value 0x368d (the exact placement of the bytes depends upon
the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
undefined.
+@node Bundle directives
+@section @code{.bundle_align_mode @var{abs-expr}}
+@cindex @code{bundle_align_mode} directive
+@cindex bundle
+@cindex instruction bundle
+@cindex aligned instruction bundle
+@code{.bundle_align_mode} enables or disables @defn{aligned instruction
+bundle} mode. In this mode, sequences of adjacent instructions are grouped
+into fixed-sized @defn{bundles}. If the argument is zero, this mode is
+disabled (which is the default state). If the argument it not zero, it
+gives the size of an instruction bundle as a power of two (as for the
+@code{.p2align} directive, @pxref{P2align}).
+
+For some targets, it's an ABI requirement that no instruction may span a
+certain aligned boundary. A @defn{bundle} is simply a sequence of
+instructions that starts on an aligned boundary. For example, if
+@var{abs-expr} is @code{5} then the bundle size is 32, so each aligned
+chunk of 32 bytes is a bundle. When aligned instruction bundle mode is in
+effect, no single instruction may span a boundary between bundles. If an
+instruction would start too close to the end of a bundle for the length of
+that particular instruction to fit within the bundle, then the space at the
+end of that bundle is filled with no-op instructions so the instruction
+starts in the next bundle. As a corollary, it's an error if any single
+instruction's encoding is longer than the bundle size.
+
+@section @code{.bundle_lock} and @code{.bundle_unlock}
+@cindex @code{bundle_lock} directive
+@cindex @code{bundle_unlock} directive
+The @code{.bundle_lock} and directive @code{.bundle_unlock} directives
+allow explicit control over instruction bundle padding. These directives
+are only valid when @code{.bundle_align_mode} has been used to enable
+aligned instruction bundle mode. It's an error if they appear when
+@code{.bundle_align_mode} has not been used at all, or when the last
+directive was @w{@code{.bundle_align_mode 0}}.
+
+@cindex bundle-locked
+For some targets, it's an ABI requirement that certain instructions may
+appear only as part of specified permissible sequences of multiple
+instructions, all within the same bundle. A pair of @code{.bundle_lock}
+and @code{.bundle_unlock} directives define a @defn{bundle-locked}
+instruction sequence. For purposes of aligned instruction bundle mode, a
+sequence starting with @code{.bundle_lock} and ending with
+@code{.bundle_unlock} is treated as a single instruction. That is, the
+entire sequence must fit into a single bundle and may not span a bundle
+boundary. If necessary, no-op instructions will be inserted before the
+first instruction of the sequence so that the whole sequence starts on an
+aligned bundle boundary. It's an error if the sequence is longer than the
+bundle size.
+
+Bundle-locked sequences do not nest. It's an error if two
+@code{.bundle_lock} directives appear without an intervening
+@code{.bundle_unlock} directive.
+
@node Byte
@section @code{.byte @var{expressions}}
@@ -5521,7 +5575,7 @@ hence @emph{octa}-word for 16 bytes.
Set the location counter to @var{loc} in the absolute section. @var{loc} must
be an absolute expression. This directive may be useful for defining
symbols with absolute values. Do not confuse it with the @code{.org}
-directive.
+directive.
@node Org
@section @code{.org @var{new-lc} , @var{fill}}