RISC-V: Add dg-remove-option for z* extensions

This introduces testsuite support infra for removing extensions.
Since z* extensions don't have ordering requirements the logic for
adding/removing those extensions has also been consolidated.

This fixes RVWMO compile testcases failing on Ztso targets by removing
the extension from the -march string.

gcc/ChangeLog:

	* doc/sourcebuild.texi (dg-remove-option): Add documentation.
	(dg-add-option): Add documentation for riscv_{a,zaamo,zalrsc,ztso}

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/amo/amo-table-a-6-amo-add-1.c: Add dg-remove-options
	for ztso.
	* gcc.target/riscv/amo/amo-table-a-6-amo-add-2.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-amo-add-3.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-amo-add-4.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-amo-add-5.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-compare-exchange-1.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-compare-exchange-2.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-compare-exchange-3.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-compare-exchange-4.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-compare-exchange-5.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-compare-exchange-6.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-compare-exchange-7.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-fence-1.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-fence-2.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-fence-3.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-fence-4.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-fence-5.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-load-1.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-load-2.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-load-3.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-store-1.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-store-2.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-store-compat-3.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-subword-amo-add-1.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-subword-amo-add-2.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-subword-amo-add-3.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-subword-amo-add-4.c: Ditto.
	* gcc.target/riscv/amo/amo-table-a-6-subword-amo-add-5.c: Ditto.
	* gcc.target/riscv/amo/amo-zalrsc-amo-add-1.c: Replace manually
	specified -march string with dg-add/remove-options directives.
	* gcc.target/riscv/amo/amo-zalrsc-amo-add-2.c: Ditto.
	* gcc.target/riscv/amo/amo-zalrsc-amo-add-3.c: Ditto.
	* gcc.target/riscv/amo/amo-zalrsc-amo-add-4.c: Ditto.
	* gcc.target/riscv/amo/amo-zalrsc-amo-add-5.c: Ditto.
	* lib/target-supports-dg.exp: Add dg-remove-options.
	* lib/target-supports.exp: Add dg-remove-options and consolidate z*
	extension add/remove-option code.

Signed-off-by: Patrick O'Neill <patrick@rivosinc.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi
index e37fb85..c6bb41d 100644
--- a/gcc/doc/sourcebuild.texi
+++ b/gcc/doc/sourcebuild.texi
@@ -1015,6 +1015,7 @@ FIXME: discuss non-C testsuites here.
 * Selectors:: Selecting targets to which a test applies.
 * Effective-Target Keywords:: Keywords describing target attributes.
 * Add Options:: Features for @code{dg-add-options}
+* Remove Options:: Features for @code{dg-remove-options}
 * Require Support:: Variants of @code{dg-require-@var{support}}
 * Final Actions:: Commands for use in @code{dg-final}
 @end menu
@@ -1085,6 +1086,13 @@ default, or that don't provide them at all.  It must come after
 all @code{dg-options} directives.
 For supported values of @var{feature} see @ref{Add Options, ,}.
 
+@item @{ dg-remove-options @var{feature} @dots{} @}
+Remove any compiler options that are needed to access certain features.
+This directive does nothing on targets that disable the features by
+default, or that don't provide them at all.  It must come after
+all @code{dg-options} and @code{dg-add-options} directives.
+For supported values of @var{feature} see @ref{Remove Options, ,}.
+
 @item @{ dg-additional-options @var{options} [@{ target @var{selector} @}] @}
 This directive provides a list of compiler options, to be used
 if the target system matches @var{selector}, that are added to the default
@@ -3278,6 +3286,18 @@ compliance mode.
 @code{mips16} function attributes.
 Only MIPS targets support this feature, and only then in certain modes.
 
+@item riscv_a
+Add the 'A' extension to the -march string on RISC-V targets.
+
+@item riscv_zaamo
+Add the zaamo extension to the -march string on RISC-V targets.
+
+@item riscv_zalrsc
+Add the zalrsc extension to the -march string on RISC-V targets.
+
+@item riscv_ztso
+Add the ztso extension to the -march string on RISC-V targets.
+
 @item stack_size
 @anchor{stack_size_ao}
 Add the flags needed to define macro STACK_SIZE and set it to the stack size
@@ -3300,6 +3320,29 @@ a target, if any.  This requires the target to have an implementation of the
 Add the flags needed to enable support for weak undefined symbols.
 @end table
 
+@node Remove Options
+@subsection Features for @code{dg-remove-options}
+
+The supported values of @var{feature} for directive @code{dg-remove-options}
+are:
+
+@table @code
+@item riscv_a
+Remove the 'A' extension and all implied extensions from the -march string on
+RISC-V targets.
+
+@item riscv_zaamo
+Remove the zaamo extension from the -march string on RISC-V. If the 'A'
+extension is present downgrade it to zalrsc.
+
+@item riscv_zalrsc
+Remove the zalrsc extension from the -march string on RISC-V. If the 'A'
+extension is present downgrade it to zaamo.
+
+@item riscv_ztso
+Remove the ztso extension from the -march string on RISC-V targets.
+@end table
+
 @node Require Support
 @subsection Variants of @code{dg-require-@var{support}}