[nios2] [1/7] Add -march=, -mbmx, -mcdx flags

[Sandra Loosemore <sandra at codesourcery dot com>]

This patch adds command-line options to select the new R2 variants of
the Nios II architecture.  Aside from checking for conflicting
options, the only thing that this patch does with the new flags is pass
-march= through to the assembler.

The -mbmx and -mcdx options will enable code generation for the
optional BMX and CDX R2 extensions in subsequent patches in this
series.  The instructions added by the third optional R2 extension,
MPX (multiprocessor), are only emitted by explicit intrinsics added in
part 7 of the series, so there doesn't need to be an option for that
one.

This patch is sufficient to compile programs correctly for R2 provided
that they don't use load/store IO instructions (fixed in part 2) or
nested functions (fixed in part 3).

Committed as r225791.

-Sandra

2015-07-14  Sandra Loosemore  <sandra@codesourcery.com>
	    Cesar Philippidis  <cesar@codesourcery.com>
	    Chung-Lin Tang  <cltang@codesourcery.com>

	gcc/
	* config/nios2/nios2.opt (march, mbmx, mcdx): New options.
	* config/nios2/nios2-opts.h (enum nios2_arch_type): New enum for
	Nios II architecture level.
	* config/nios2/nios2.h (TARGET_ARCH_R2): New define.
	(TARGET_CPU_CPP_BUILTINS): Add definition of __nios2_arch__ symbol.
	(OPTION_DEFAULT_SPECS): Define.
	(ASM_SPEC): Add -march= spec strings.
	* config/nios2/nios2.c (nios2_option_override): Check for
	conflicts involving new options.
	* config.gcc (nios2*-*-*): Support --with-arch=.
	* doc/invoke.texi (Option Summary, Nios II Options): Document
	-march=, -mbmx,	and -mcdx.

Index: gcc/config/nios2/nios2.opt
===================================================================
--- gcc/config/nios2/nios2.opt	(revision 225786)
+++ gcc/config/nios2/nios2.opt	(working copy)
@@ -565,4 +565,24 @@ mcustom-round=
 Target Report RejectNegative Joined UInteger Var(nios2_custom_round) Init(-1)
 Integer id (N) of round custom instruction
 
+march=
+Target RejectNegative Joined Enum(nios2_arch_type) Var(nios2_arch_option) Init(ARCH_R1)
+Specify the name of the target architecture.
 
+Enum
+Name(nios2_arch_type) Type(enum nios2_arch_type)
+Valid Nios II ISA levels (for -march):
+
+EnumValue
+Enum(nios2_arch_type) String(r1) Value(ARCH_R1)
+
+EnumValue
+Enum(nios2_arch_type) String(r2) Value(ARCH_R2)
+
+mbmx
+Target Report Mask(HAS_BMX)
+Enable generation of R2 BMX instructions
+
+mcdx
+Target Report Mask(HAS_CDX)
+Enable generation of R2 CDX instructions
Index: gcc/config/nios2/nios2-opts.h
===================================================================
--- gcc/config/nios2/nios2-opts.h	(revision 225786)
+++ gcc/config/nios2/nios2-opts.h	(working copy)
@@ -77,5 +77,12 @@ enum nios2_ccs_code
   CCS_BUILTIN_CALL
 };
 
+/* Supported Nios II Architectures.  */
+enum nios2_arch_type
+{
+  ARCH_R1=1,
+  ARCH_R2
+};
+
 #endif
 
Index: gcc/config/nios2/nios2.h
===================================================================
--- gcc/config/nios2/nios2.h	(revision 225786)
+++ gcc/config/nios2/nios2.h	(working copy)
@@ -23,6 +23,9 @@
 #ifndef GCC_NIOS2_H
 #define GCC_NIOS2_H
 
+/* Indicate R2 ISA level support.  */
+#define TARGET_ARCH_R2 (nios2_arch_option == ARCH_R2)
+
 /* FPU insn codes declared here.  */
 #include "config/nios2/nios2-opts.h"
 
@@ -36,7 +39,9 @@
         builtin_define_std ("nios2_big_endian");    \
       else                                          \
         builtin_define_std ("nios2_little_endian"); \
-    }                                               \
+      builtin_define_with_int_value (		    \
+        "__nios2_arch__", (int) nios2_arch_option); \
+    }						    \
   while (0)
 
 /* We're little endian, unless otherwise specified by defining
@@ -50,14 +55,17 @@
 # define TARGET_DEFAULT (MASK_HAS_MUL | TARGET_ENDIAN_DEFAULT)
 #endif
 
+#define OPTION_DEFAULT_SPECS \
+  {"arch", "%{!march=*:%{!mcpu=*:-march=%(VALUE)}}" }
+
 #define CC1_SPEC "%{G*}"
 
 #if TARGET_ENDIAN_DEFAULT == 0
-# define ASM_SPEC "%{!meb:-EL} %{meb:-EB}"
+# define ASM_SPEC "%{!meb:-EL} %{meb:-EB} %{march=*:-march=%*}"
 # define LINK_SPEC_ENDIAN "%{!meb:-EL} %{meb:-EB}"
 # define MULTILIB_DEFAULTS { "EL" }
 #else
-# define ASM_SPEC "%{!mel:-EB} %{mel:-EL}"
+# define ASM_SPEC "%{!mel:-EB} %{mel:-EL} %{march=*:-march=%*}"
 # define LINK_SPEC_ENDIAN "%{!mel:-EB} %{mel:-EL}"
 # define MULTILIB_DEFAULTS { "EB" }
 #endif
Index: gcc/config/nios2/nios2.c
===================================================================
--- gcc/config/nios2/nios2.c	(revision 225787)
+++ gcc/config/nios2/nios2.c	(working copy)
@@ -1078,6 +1078,19 @@ nios2_option_override (void)
   if (!TARGET_HAS_MUL && TARGET_HAS_MULX)
     target_flags &= ~MASK_HAS_MULX;
 
+  /* Optional BMX and CDX instructions only make sense for R2.  */
+  if (!TARGET_ARCH_R2)
+    {
+      if (TARGET_HAS_BMX)
+	error ("BMX instructions are only supported with R2 architecture");
+      if (TARGET_HAS_CDX)
+	error ("CDX instructions are only supported with R2 architecture");
+    }
+
+  /* R2 is little-endian only.  */
+  if (TARGET_ARCH_R2 && TARGET_BIG_ENDIAN)
+    error ("R2 architecture is little-endian only");
+
   /* Initialize default FPU configurations.  */
   nios2_init_fpu_configs ();
 
Index: gcc/config.gcc
===================================================================
--- gcc/config.gcc	(revision 225786)
+++ gcc/config.gcc	(working copy)
@@ -4052,6 +4052,19 @@ case "${target}" in
 		esac
 		;;
 
+	nios2*-*-*)
+		supported_defaults="arch"
+			case "$with_arch" in
+			"" | r1 | r2)
+				# OK
+				;;
+			*)
+				echo "Unknown arch used in --with-arch=$with_arch" 1>&2
+				exit 1
+				;;
+			esac
+		;;
+
 	powerpc*-*-* | rs6000-*-*)
 		supported_defaults="abi cpu cpu_32 cpu_64 float tune tune_32 tune_64 advance_toolchain"
 
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 225786)
+++ gcc/doc/invoke.texi	(working copy)
@@ -857,7 +857,8 @@ Objective-C and Objective-C++ Dialects}.
 -mhw-mul -mno-hw-mul -mhw-mulx -mno-hw-mulx -mno-hw-div -mhw-div @gol
 -mcustom-@var{insn}=@var{N} -mno-custom-@var{insn} @gol
 -mcustom-fpu-cfg=@var{name} @gol
--mhal -msmallc -msys-crt0=@var{name} -msys-lib=@var{name}}
+-mhal -msmallc -msys-crt0=@var{name} -msys-lib=@var{name} @gol
+-march=@var{arch} -mbmx -mno-bmx -mcdx -mno-cdx}
 
 @emph{Nvidia PTX Options}
 @gccoptlist{-m32 -m64 -mmainkernel}
@@ -18500,6 +18501,15 @@ small data section.
 Generate little-endian (default) or big-endian (experimental) code,
 respectively.
 
+@item -march=@var{arch}
+@opindex march
+This specifies the name of the target Nios II architecture.  GCC uses this
+name to determine what kind of instructions it can emit when generating
+assembly code.  Permissible names are: @samp{r1}, @samp{r2}.
+
+The preprocessor macro @code{__nios2_arch__} is available to programs,
+with value 1 or 2, indicating the targeted ISA level.
+
 @item -mbypass-cache
 @itemx -mno-bypass-cache
 @opindex mno-bypass-cache
@@ -18538,6 +18548,15 @@ Enable or disable emitting @code{mul}, @
 instructions by the compiler. The default is to emit @code{mul}
 and not emit @code{div} and @code{mulx}.
 
+@item -mbmx
+@itemx -mno-bmx
+@itemx -mcdx
+@itemx -mno-cdx
+Enable or disable generation of Nios II R2 BMX (bit manipulation) and
+CDX (code density) instructions.  Enabling these instructions also
+requires @option{-march=r2}.  Since these instructions are optional
+extensions to the R2 architecture, the default is not to emit them.
+
 @item -mcustom-@var{insn}=@var{N}
 @itemx -mno-custom-@var{insn}
 @opindex mcustom-@var{insn}