* rtl.texi (SET, CLOBBER): Document PARALLEL as SET_DEST possibility.

	* flow.c (mark_set_1, case PARALLEL): Don't require BLKmode, allow
	element to be null, and always expect an EXPR_LIST.
	* rtlanal.c (reg_overlap_mentioned_p, note_stores): Likewise.
	* sched-deps.c (sched_analyze_1): Likewise.
	* sched-rgn.c (check_live_1, update_live_1): Likewise.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@39141 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 13 insertions, 4 deletions

diff --git a/gcc/rtl.texi b/gcc/rtl.texi
index 0e9d8c48652..4cb0eb7014b 100644
--- a/gcc/rtl.texi
+++ b/gcc/rtl.texi
@@ -1923,8 +1923,8 @@ the operands of these.
 @item (set @var{lval} @var{x})
 Represents the action of storing the value of @var{x} into the place
 represented by @var{lval}.  @var{lval} must be an expression
-representing a place that can be stored in: @code{reg} (or
-@code{subreg} or @code{strict_low_part}), @code{mem}, @code{pc} or
+representing a place that can be stored in: @code{reg} (or @code{subreg}
+or @code{strict_low_part}), @code{mem}, @code{pc}, @code{parallel}, or
 @code{cc0}.@refill
 
 If @var{lval} is a @code{reg}, @code{subreg} or @code{mem}, it has a
@@ -1950,6 +1950,14 @@ The latter case represents a ``test'' instruction.  The expression
 @code{(set (cc0) (compare (reg:@var{m} @var{n}) (const_int 0)))}.
 Use the former expression to save space during the compilation.
 
+If @var{lval} is a @code{parallel}, it is used to represent the case of
+a function returning a structure in multiple registers.  Each element
+of the @code{paralllel} is an @code{expr_list} whose first operand is a
+@code{reg} and whose second operand is a @code{const_int} representing the
+offset (in bytes) into the structure at which the data in that register
+corresponds.  The first element may be null to indicate that the structure
+is also passed partly in memory.
+
 @cindex jump instructions and @code{set}
 @cindex @code{if_then_else} usage
 If @var{lval} is @code{(pc)}, we have a jump instruction, and the
@@ -2006,7 +2014,7 @@ addressed.
 @item (clobber @var{x})
 Represents the storing or possible storing of an unpredictable,
 undescribed value into @var{x}, which must be a @code{reg},
-@code{scratch} or @code{mem} expression.
+@code{scratch}, @code{parallel} or @code{mem} expression.
 
 One place this is used is in string instructions that store standard
 values into particular hard registers.  It may not be worth the
@@ -2015,7 +2023,8 @@ inform the compiler that the registers will be altered, lest it
 attempt to keep data in them across the string instruction.
 
 If @var{x} is @code{(mem:BLK (const_int 0))}, it means that all memory
-locations must be presumed clobbered.
+locations must be presumed clobbered.  If @var{x} is a @code{parallel},
+it has the same meaning as a @code{parallel} in a @code{set} expression.
 
 Note that the machine description classifies certain hard registers as
 ``call-clobbered''.  All function call instructions are assumed by