MSP430: Don't generate 430X insns when handling data in the lower memory region

gcc/ChangeLog:

2019-10-07  Jozef Lawrynowicz  <jozef.l@mittosystems.com>

	* config.in: Regenerate.
	* config/msp430/constraints.md: Fix docstring for "Ys" constraint.
	Add new "Yx" constraint.
	* config/msp430/driver-msp430.c (msp430_propagate_region_opt): New spec
	function.
	* config/msp430/msp430-protos.h (msp430_op_not_in_high_mem): New
	prototype.
	* config/msp430/msp430.c (msp430_option_override): Allow the lower
	code/data region to be selected in the small memory model.
	(msp430_section_attr): Don't warn if the "section" and "lower"
	attributes are used together.
	(msp430_handle_generic_attribute): Likewise.
	(msp430_var_in_low_mem): New function.
	(TARGET_ENCODE_SECTION_INFO): Define.
	(msp430_encode_section_info): New function.
	(gen_prefix): Return early in the small memory model.
	Require TARGET_USE_LOWER_REGION_PREFIX to be set before adding the
	".lower" prefix if -m{code,data}-region=lower have been passed.
	(msp430_output_aligned_decl_common): Emit common symbols when
	-mdata-region=lower is passed unless TARGET_USE_LOWER_REGION_PREFIX is
	set. 
	(TARGET_ASM_FILE_END): Define.
	(msp430_file_end): New function.
	(msp430_do_not_relax_short_jumps): Allow relaxation when
	function will be in the lower region.
	(msp430_op_not_in_high_mem): New function.
	(msp430_print_operand): Check "msp430_op_not_in_high_mem" for
	the 'X' operand selector. 
	Clarify comment for 'x' operand selector.
	* config/msp430/msp430.h (LINK_SPEC): Propagate
	-m{code,data}-region to the linker via spec function
	msp430_propagate_region_opt.
	(msp430_propagate_region_opt): New prototype.
	(EXTRA_SPEC_FUNCTIONS): Add msp430_propagate_region_opt.
	(SYMBOL_FLAG_LOW_MEM): Define.
	* config/msp430/msp430.md (addsipsi3): Add missing "%X" operand
	selector.
	(zero_extendqihi2): Fix operand number used by "%X" selector.
	(zero_extendqisi2): Likewise.
	(zero_extendhisi2): Likewise.
	(movqi): Use "Yx" constraint in place of "%X" operand selector.
	(movhi): Likewise.
	(addqi3): Likewise.
	(addhi3): Likewise.
	(addsi3): Likewise.
	(addhi3_cy): Likewise.
	(addchi4_cy): Likewise.
	(subqi3): Likewise.
	(subhi3): Likewise.
	(subsi3): Likewise.
	(bic<mode>3): Likewise.
	(and<mode>3): Likewise.
	(ior<mode>3): Likewise.
	(xor<mode>3): Likewise.
	(slli_1): Add missing "%X" operand selector.
	(slll_1): Likewise.
	(slll_2): Likewise.
	(srai_1): Likewise.
	(sral_1): Likewise.
	(sral_2): Likewise.
	(srli_1): Likewise.
	(srll_1): Likewise.
	(cbranchqi4_real): Use "Yx" constraint in place of "%X" operand
	selector.
	(cbranchhi4_real): Likewise.
	(cbranchqi4_reversed): Likewise.
	(cbranchhi4_reversed): Likewise.
	(*bitbranch<mode>4): Likewise.
	(*bitbranch<mode>4_z): Remove unnecessary "%x" operand selector.
	* config/msp430/msp430.opt (mcode-region=): Set default to
	MSP430_REGION_LOWER. Improve docstring.
	(mdata-region=): Likewise.
	(muse-lower-region-prefix): New option.
	* config/msp430/t-msp430 (MULTILIB_OPTIONS): Add
	mdata-region=none multilib. 
	(MULTILIB_MATCHES): Set mdata-region={upper,either} to match
	mdata-region=none multilib. 
	MULTILIB_EXCEPTIONS: Remove.
	MULTILIB_REQUIRED: Define.
	* configure: Regenerate.
	* configure.ac: Define HAVE_AS_GNU_ATTRIBUTE and
	HAVE_AS_MSPABI_ATTRIBUTE if GAS version >= 2.33.50.
	* doc/extend.texi: Clarify comment for {upper,lower,either}
	function attributes.
	Add separate description for "lower" variable attribute.

gcc/testsuite/ChangeLog:

2019-10-07  Jozef Lawrynowicz  <jozef.l@mittosystems.com>

	* gcc.target/msp430/430x-insns.c: New test.
	* gcc.target/msp430/data-attributes-2.c: Remove dg-warning
	directives for conflicts between the "section" and "lower" attributes.
	* gcc.target/msp430/msp430.exp
	(check_effective_target_msp430_region_not_lower): New.
	(check_effective_target_msp430_region_lower): New.
	* gcc.target/msp430/object-attributes-430.c: New test.
	* gcc.target/msp430/object-attributes-default.c: New test.
	* gcc.target/msp430/object-attributes-mlarge-any-region.c: New test.
	* gcc.target/msp430/object-attributes-mlarge.c: New test.

From-SVN: r276665

1 files changed, 20 insertions, 5 deletions

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 64fccfe..7e37c5c 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -5206,7 +5206,7 @@ On the MSP430 target these attributes can be used to specify whether
 the function or variable should be placed into low memory, high
 memory, or the placement should be left to the linker to decide.  The
 attributes are only significant if compiling for the MSP430X
-architecture.
+architecture in the large memory model.
 
 The attributes work in conjunction with a linker script that has been
 augmented to specify where to place sections with a @code{.lower} and
@@ -7537,15 +7537,30 @@ value will be retained across resets.  The linker script being used to
 create the application should ensure that persistent data is correctly
 placed.
 
-@item lower
-@itemx upper
+@item upper
 @itemx either
-@cindex @code{lower} variable attribute, MSP430 
 @cindex @code{upper} variable attribute, MSP430 
 @cindex @code{either} variable attribute, MSP430 
 These attributes are the same as the MSP430 function attributes of the
 same name (@pxref{MSP430 Function Attributes}).  
-These attributes can be applied to both functions and variables.
+
+@item lower
+@cindex @code{lower} variable attribute, MSP430
+This option behaves mostly the same as the MSP430 function attribute of the
+same name (@pxref{MSP430 Function Attributes}), but it has some additional
+functionality.
+
+If @option{-mdata-region=}@{@code{upper,either,none}@} has been passed, or
+the @code{section} attribute is applied to a variable, the compiler will
+generate 430X instructions to handle it.  This is because the compiler has
+to assume that the variable could get placed in the upper memory region
+(above address 0xFFFF).  Marking the variable with the @code{lower} attribute
+informs the compiler that the variable will be placed in lower memory so it
+is safe to use 430 instructions to handle it.
+
+In the case of the @code{section} attribute, the section name given
+will be used, and the @code{.lower} prefix will not be added.
+
 @end table
 
 @node Nvidia PTX Variable Attributes