reload.c (find_reloads): Handle constraint letters marked by EXTRA_ADDRESS_CONSTRAINT and...

	* reload.c (find_reloads): Handle constraint letters marked by
	EXTRA_ADDRESS_CONSTRAINT and EXTRA_MEMORY_CONSTRAINT.
	(alternative_allows_memconst): Likewise.
	* reload1.c (maybe_fix_stack_asms): Likewise.
	* recog.c (asm_operand_ok, preprocess_constraints,
	constrain_operands): Likewise.
	* regclass.c (record_operand_costs, record_reg_classes): Likewise.
	* local-alloc.c (block_alloc, requires_inout): Likewise.
	* stmt.c (parse_output_constraint, parse_input_constraint): Likewise.

	* defaults.h (EXTRA_MEMORY_CONSTRAINT): Provide a default.
	(EXTRA_ADDRESS_CONSTRAINT): Likewise.
	* doc/tm.texi: Document these two new target macros.

	* config/s390/s390.c (s390_expand_plus_operand): Accept already
	valid operands.
	(q_constraint): New function.
	config/s390/s390-protos.h (q_constraint): Declare it.
	config/s390/s390.h (EXTRA_CONSTRAINT): Use it.
	(EXTRA_MEMORY_CONSTRAINT): New macro.

	* config/s390/s390.md: Throughout the machine description,
	replace all instances of the constraint combinations 'Qo'
	or 'oQ' with simply 'Q'.

From-SVN: r56291

1 files changed, 38 insertions, 0 deletions

diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index d13b53e..064120d 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -2614,6 +2614,44 @@ letter @samp{Q} is defined as representing a memory address that does
 a @samp{Q} constraint on the input and @samp{r} on the output.  The next
 alternative specifies @samp{m} on the input and a register class that
 does not include r0 on the output.
+
+@findex EXTRA_MEMORY_CONSTRAINT
+@item EXTRA_MEMORY_CONSTRAINT (@var{c})
+A C expression that defines the optional machine-dependent constraint
+letters, amongst those accepted by @code{EXTRA_CONSTRAINT}, that should
+be treated like memory constraints by the reload pass.
+
+It should return 1 if the operand type represented by the constraint 
+letter @var{c} comprises a subset of all memory references including
+all those whose address is simply a base register.  This allows the reload 
+pass to reload an operand, if it does not directly correspond to the operand 
+type of @var{c}, by copying its address into a base register.
+
+For example, on the S/390, some instructions do not accept arbitrary
+memory references, but only those that do not make use of an index
+register.  The constraint letter @samp{Q} is defined via
+@code{EXTRA_CONSTRAINT} as representing a memory address of this type.
+If the letter @samp{Q} is marked as @code{EXTRA_MEMORY_CONSTRAINT},
+a @samp{Q} constraint can handle any memory operand, because the
+reload pass knows it can be reloaded by copying the memory address
+into a base register if required.  This is analogous to the way
+a @samp{o} constraint can handle any memory operand.
+
+@findex EXTRA_ADDRESS_CONSTRAINT
+@item EXTRA_ADDRESS_CONSTRAINT (@var{c})
+A C expression that defines the optional machine-dependent constraint
+letters, amongst those accepted by @code{EXTRA_CONSTRAINT}, that should
+be treated like address constraints by the reload pass.
+
+It should return 1 if the operand type represented by the constraint 
+letter @var{c} comprises a subset of all memory addresses including
+all those that consist of just a base register.  This allows the reload 
+pass to reload an operand, if it does not directly correspond to the operand 
+type of @var{c}, by copying it into a base register.
+
+Any constraint marked as @code{EXTRA_ADDRESS_CONSTRAINT} can only
+be used with the @code{address_operand} predicate.  It is treated 
+analogously to the @samp{p} constraint.
 @end table
 
 @node Stack and Calling