RISC-V: Add -malign-data= option.

	gcc/
	Ilia Diachkov  <ilia.diachkov@optimitech.com>
	* config/riscv/riscv-opts.h (struct riscv_align_data): New.
	* config/riscv/riscv.c (riscv_constant_alignment): Use
	riscv_align_data_type.
	* config/riscv/riscv.h (RISCV_EXPAND_ALIGNMENT): New.
	(DATA_ALIGNMENT): Use RISCV_EXPAND_ALIGNMENT.
	(LOCAL_ALIGNMENT): Use RISCV_EXPAND_ALIGNMENT.
	* config/riscv/riscv.opt (malign-data): New.
	* doc/invoke.texi (RISC-V Options): Document -malign-data=.

From-SVN: r273714

gcc/ChangeLog

+2019-07-22  Ilia Diachkov  <ilia.diachkov@optimitech.com>
+
+	* config/riscv/riscv-opts.h (struct riscv_align_data): New.
+	* config/riscv/riscv.c (riscv_constant_alignment): Use
+	riscv_align_data_type.
+	* config/riscv/riscv.h (RISCV_EXPAND_ALIGNMENT): New.
+	(DATA_ALIGNMENT): Use RISCV_EXPAND_ALIGNMENT.
+	(LOCAL_ALIGNMENT): Use RISCV_EXPAND_ALIGNMENT.
+	* config/riscv/riscv.opt (malign-data): New.
+	* doc/invoke.texi (RISC-V Options): Document -malign-data=.
+
 2019-07-02  Giuliano Belinassi  <giuliano.belinassi@usp.br>
 
 	* cgraph.c (dump_graphviz): New function.

gcc/config/riscv/riscv-opts.h

@@ -46,4 +46,9 @@ enum riscv_microarchitecture_type {
 };
 extern enum riscv_microarchitecture_type riscv_microarchitecture;
 
+enum riscv_align_data {
+  riscv_align_data_type_xlen,
+  riscv_align_data_type_natural
+};
+
 #endif /* ! GCC_RISCV_OPTS_H */

gcc/config/riscv/riscv.c

@@ -4904,7 +4904,8 @@ riscv_can_change_mode_class (machine_mode, machine_mode, reg_class_t rclass)
 static HOST_WIDE_INT
 riscv_constant_alignment (const_tree exp, HOST_WIDE_INT align)
 {
-  if (TREE_CODE (exp) == STRING_CST || TREE_CODE (exp) == CONSTRUCTOR)
+  if ((TREE_CODE (exp) == STRING_CST || TREE_CODE (exp) == CONSTRUCTOR)
+      && (riscv_align_data_type == riscv_align_data_type_xlen))
     return MAX (align, BITS_PER_WORD);
   return align;
 }

gcc/config/riscv/riscv.h

@@ -168,6 +168,13 @@ along with GCC; see the file COPYING3.  If not see
    mode that should actually be used.  We allow pairs of registers.  */
 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (TARGET_64BIT ? TImode : DImode)
 
+/* DATA_ALIGNMENT and LOCAL_ALIGNMENT common definition.  */
+#define RISCV_EXPAND_ALIGNMENT(COND, TYPE, ALIGN)			\
+  (((COND) && ((ALIGN) < BITS_PER_WORD)					\
+    && (TREE_CODE (TYPE) == ARRAY_TYPE					\
+	|| TREE_CODE (TYPE) == UNION_TYPE				\
+	|| TREE_CODE (TYPE) == RECORD_TYPE)) ? BITS_PER_WORD : (ALIGN))
+
 /* If defined, a C expression to compute the alignment for a static
    variable.  TYPE is the data type, and ALIGN is the alignment that
    the object would ordinarily have.  The value of this macro is used
@@ -181,17 +188,15 @@ along with GCC; see the file COPYING3.  If not see
    that copy constants to character arrays can be done inline.  */
 
 #define DATA_ALIGNMENT(TYPE, ALIGN)						\
-  ((((ALIGN) < BITS_PER_WORD)						\
-    && (TREE_CODE (TYPE) == ARRAY_TYPE					\
-	|| TREE_CODE (TYPE) == UNION_TYPE				\
-	|| TREE_CODE (TYPE) == RECORD_TYPE)) ? BITS_PER_WORD : (ALIGN))
+  RISCV_EXPAND_ALIGNMENT (riscv_align_data_type == riscv_align_data_type_xlen,	\
+			  TYPE, ALIGN)
 
 /* We need this for the same reason as DATA_ALIGNMENT, namely to cause
    character arrays to be word-aligned so that `strcpy' calls that copy
    constants to character arrays can be done inline, and 'strcmp' can be
    optimised to use word loads. */
 #define LOCAL_ALIGNMENT(TYPE, ALIGN) \
-  DATA_ALIGNMENT (TYPE, ALIGN)
+  RISCV_EXPAND_ALIGNMENT (true, TYPE, ALIGN)
 
 /* Define if operations between registers always perform the operation
    on the full register even if a narrower mode is specified.  */

gcc/config/riscv/riscv.opt

@@ -131,3 +131,17 @@ Mask(RVE)
 mriscv-attribute
 Target Report Var(riscv_emit_attribute_p) Init(-1)
 Emit RISC-V ELF attribute.
+
+malign-data=
+Target RejectNegative Joined Var(riscv_align_data_type) Enum(riscv_align_data) Init(riscv_align_data_type_xlen)
+Use the given data alignment.
+
+Enum
+Name(riscv_align_data) Type(enum riscv_align_data)
+Known data alignment choices (for use with the -malign-data= option):
+
+EnumValue
+Enum(riscv_align_data) String(xlen) Value(riscv_align_data_type_xlen)
+
+EnumValue
+Enum(riscv_align_data) String(natural) Value(riscv_align_data_type_natural)

gcc/doc/invoke.texi

@@ -1068,7 +1068,8 @@ See RS/6000 and PowerPC Options.
 -mcmodel=medlow  -mcmodel=medany @gol
 -mexplicit-relocs  -mno-explicit-relocs @gol
 -mrelax  -mno-relax @gol
--mriscv-attribute  -mmo-riscv-attribute}
+-mriscv-attribute  -mmo-riscv-attribute @gol
+-malign-data=@var{type}}
 
 @emph{RL78 Options}
 @gccoptlist{-msim  -mmul=none  -mmul=g13  -mmul=g14  -mallregs @gol
@@ -24039,6 +24040,13 @@ linker relaxations.
 @itemx -mno-emit-attribute
 Emit (do not emit) RISC-V attribute to record extra information into ELF
 objects.  This feature requires at least binutils 2.32.
+
+@item -malign-data=@var{type}
+@opindex malign-data
+Control how GCC aligns variables and constants of array, structure, or union
+types.  Supported values for @var{type} are @samp{xlen} which uses x register
+width as the alignment value, and @samp{natural} which uses natural alignment.
+@samp{xlen} is the default.
 @end table
 
 @node RL78 Options