[AArch64] Add a "GP strictness" operand to SVE FP unspecs

[AArch64] Add a "GP strictness" operand to SVE FP unspecs

This patch makes the SVE unary, binary and ternary FP unspecs
take a new "GP strictness" operand that indicates whether the
predicate has to be taken literally, or whether it is valid to
make extra lanes active (up to and including using a PTRUE).

This again is laying the groundwork for the ACLE patterns,
in which the value can depend on the FP command-line flags.

At the moment it's only needed for addition, subtraction and
multiplication, which have unpredicated forms that can only
be used when operating on all lanes is safe.  But in future
it might be useful for optimising predicate usage.

The strict mode requires extra alternatives for addition,
subtraction and multiplication, but I've left those for the
main ACLE patch.

2019-08-14  Richard Sandiford  <richard.sandiford@arm.com>
	    Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>

gcc/
	* config/aarch64/aarch64.md (SVE_RELAXED_GP, SVE_STRICT_GP): New
	constants.
	* config/aarch64/predicates.md (aarch64_sve_gp_strictness): New
	predicate.
	* config/aarch64/aarch64-protos.h (aarch64_sve_pred_dominates_p):
	Declare.
	* config/aarch64/aarch64.c (aarch64_sve_pred_dominates_p): New
	function.
	* config/aarch64/aarch64-sve.md: Add a block comment about the
	handling of predicated FP operations.
	(<SVE_COND_FP_UNARY:optab><SVE_F:mode>2, add<SVE_F:mode>3)
	(sub<SVE_F:mode>3, mul<SVE_F:mode>3, div<SVE_F:mode>3)
	(<SVE_COND_FP_MAXMIN_PUBLIC:optab><SVE_F:mode>3)
	(<SVE_COND_FP_MAXMIN_PUBLIC:maxmin_uns><SVE_F:mode>3)
	(<SVE_COND_FP_TERNARY:optab><SVE_F:mode>4): Add an SVE_RELAXED_GP
	operand.
	(cond_<SVE_COND_FP_BINARY:optab><SVE_F:mode>)
	(cond_<SVE_COND_FP_TERNARY:optab><SVE_F:mode>): Add an SVE_STRICT_GP
	operand.
	(*<SVE_COND_FP_UNARY:optab><SVE_F:mode>2)
	(*cond_<SVE_COND_FP_BINARY:optab><SVE_F:mode>_2)
	(*cond_<SVE_COND_FP_BINARY:optab><SVE_F:mode>_3)
	(*cond_<SVE_COND_FP_BINARY:optab><SVE_F:mode>_any)
	(*fabd<SVE_F:mode>3, *div<SVE_F:mode>3)
	(*<SVE_COND_FP_MAXMIN_PUBLIC:optab><SVE_F:mode>3)
	(*<SVE_COND_FP_TERNARY:optab><SVE_F:mode>4)
	(*cond_<SVE_COND_FP_TERNARY:optab><SVE_F:mode>_2)
	(*cond_<SVE_COND_FP_TERNARY:optab><SVE_F:mode>_4)
	(*cond_<SVE_COND_FP_TERNARY:optab><SVE_F:mode>_any): Match the
	strictness operands.  Use aarch64_sve_pred_dominates_p to check
	whether the predicate on the conditional operation is suitable
	for merging.  Split patterns into the canonical equal-predicate form.
	(*add<SVE_F:mode>3, *sub<SVE_F:mode>3, *mul<SVE_F:mode>3): Likewise.
	Restrict the unpredicated alternatives to SVE_RELAXED_GP.

Co-Authored-By: Kugan Vivekanandarajah <kuganv@linaro.org>
From-SVN: r274418