Make macro checks ARMv8-M baseline proof

libgloss:

        * arm/Makefile.in: Add newlib/libc/machine/arm to the include path if
        newlib is present.
        * arm/arm.h: Include acle-compat.h.
        (THUMB_V7_V6M): Rename to ...
        (PREFER_THUMB): This.  Use ACLE macros __ARM_ARCH_ISA_ARM instead of
        __ARM_ARCH_6M__ to decide whether to define it.
        (THUMB1_ONLY): Define for Thumb-1 only targets.
        (THUMB_V7M_V6M): Rename to ...
        (THUMB_VXM): This.  Defined based on __ARM_ARCH_ISA_ARM, excluding
        ARMv7.
        * arm/crt0.S: Use THUMB1_ONLY rather than __ARM_ARCH_6M__,
        !__ARM_ARCH_ISA_ARM rather than THUMB_V7M_V6M for fp enabling, and
        PREFER_THUMB rather than THUMB_V7_V6M.  Rename other occurences of
        THUMB_V7M_V6M to THUMB_VXM.
        * arm/linux-crt0.c: Likewise.
        * arm/redboot-crt0.S: Likewise.
        * arm/swi.h: Likewise.
        * arm/trap.S: Likewise.

newlib:

        * libc/machine/arm/memcpy-stub.c: Use ACLE macros __ARM_ARCH_ISA_THUMB
        and __ARM_ARCH_ISA_ARM to check for Thumb-2 only targets rather than
        __ARM_ARCH and __ARM_ARCH_PROFILE.
        * libc/machine/arm/memcpy.S: Likewise.
        * libc/machine/arm/setjmp.S: Likewise for Thumb-1 only target and
        include acle-compat.h.
        * libc/machine/arm/strcmp.S: Likewise for Thumb-1 and Thumb-2 only
        target and include acle-compat.h.
        * libc/sys/arm/arm.h: Include acle-compat.h.
        (THUMB_V7_V6M): Rename to ...
        (PREFER_THUMB): This.  Use ACLE macro __ARM_ARCH_ISA_ARM instead of
        __ARM_ARCH_6M__ to decide whether to define it.
        (THUMB1_ONLY): Define for Thumb-1 only targets.
        (THUMB_V7M_V6M): Rename to ...
        (THUMB_VXM): This.  Defined based on __ARM_ARCH_ISA_ARM, excluding
        ARMv7.
        * libc/sys/arm/crt0.S: Use PREFER_THUMB rather than THUMB_V7_V6M and
        rename THUMB_V7M_V6M into THUMB_VXM.
        * libc/sys/arm/swi.h: Likewise.

newlib/libc/sys/arm/arm.h

@@ -29,25 +29,27 @@
 #ifndef _LIBGLOSS_ARM_H
 #define _LIBGLOSS_ARM_H
 
-/* __thumb2__ stands for thumb on armva7(A/R/M/EM) architectures,
-   __ARM_ARCH_6M__ stands for armv6-M(thumb only) architecture,
-   __ARM_ARCH_7M__ stands for armv7-M(thumb only) architecture.
-   __ARM_ARCH_7EM__ stands for armv7e-M(thumb only) architecture.
-   There are some macro combinations used many times in libgloss/arm,
-   like (__thumb2__ || (__thumb__ && __ARM_ARCH_6M__)), so factor
-   it out and use THUMB_V7_V6M instead, which stands for thumb on
-   v6-m/v7 arch as the combination does.  */
-#if defined(__thumb2__) || (defined(__thumb__) && defined(__ARM_ARCH_6M__))
-# define THUMB_V7_V6M
+#include "acle-compat.h"
+
+/* Checking for targets supporting only Thumb instructions (eg. ARMv6-M) or
+   supporting Thumb-2 instructions, whether ARM instructions are available or
+   not, is done many times in libgloss/arm.  So factor it out and use
+   PREFER_THUMB instead.  */
+#if __thumb2__ || (__thumb__ && !__ARM_ARCH_ISA_ARM)
+# define PREFER_THUMB
 #endif
 
-/* The (__ARM_ARCH_7EM__ || __ARM_ARCH_7M__ || __ARM_ARCH_6M__) combination
-   stands for cortex-M profile architectures, which don't support ARM state.
-   Factor it out and use THUMB_V7M_V6M instead.  */
-#if defined(__ARM_ARCH_7M__)     \
-    || defined(__ARM_ARCH_7EM__) \
-    || defined(__ARM_ARCH_6M__)
-# define THUMB_V7M_V6M
+/* Processor only capable of executing Thumb-1 instructions.  */
+#if __ARM_ARCH_ISA_THUMB == 1 && !__ARM_ARCH_ISA_ARM
+# define THUMB1_ONLY
+#endif
+
+/* M profile architectures.  This is a different set of architectures than
+   those not having ARM ISA because it does not contain ARMv7.  This macro is
+   necessary to test which architectures use bkpt as semihosting interface from
+   architectures using svc.  */
+#if !__ARM_ARCH_ISA_ARM && !__ARM_ARCH_7__
+# define THUMB_VXM
 #endif
 
 /* Defined if this target supports the BLX Rm instruction.  */

newlib/libc/sys/arm/crt0.S

@@ -44,7 +44,7 @@
 /* .text is used instead of .section .text so it works with arm-aout too.  */
 	.text
 	.syntax unified
-#ifdef THUMB_V7_V6M
+#ifdef PREFER_THUMB
 	.thumb
 .macro FUNC_START name
 	.global \name
@@ -99,7 +99,7 @@
 	/*  Issue Angel SWI to read stack info.  */
 	movs	r0, #AngelSWI_Reason_HeapInfo
 	adr	r1, .LC0	/*  Point at ptr to 4 words to receive data.  */
-#ifdef THUMB_V7M_V6M
+#ifdef THUMB_VXM
 	bkpt	AngelSWI
 #elif defined(__thumb2__)
 	/*  We are in thumb mode for startup on armv7 architectures.  */
@@ -176,7 +176,7 @@
 		 have somehow missed it below (in which case it gets the same
 		 value as FIQ - not ideal, but better than nothing).  */
 	mov	sp, r3
-#ifdef THUMB_V7_V6M
+#ifdef PREFER_THUMB
 	/* XXX Fill in stack assignments for interrupt modes.  */
 #else
 	mrs	r2, CPSR
@@ -239,7 +239,7 @@
 	subs	a3, a3, a1		/* Third arg: length of block.  */
 	
 
-#if defined(__thumb__) && !defined(THUMB_V7_V6M)
+#if __thumb__ && !defined(PREFER_THUMB)
 	/* Enter Thumb mode...  */
 	add	a4, pc, #1	/* Get the address of the Thumb block.  */
 	bx	a4		/* Go there and start Thumb decoding.  */
@@ -278,7 +278,7 @@ __change_mode:
 #else
 	movs	r0, #AngelSWI_Reason_GetCmdLine
 	adr	r1, .LC30	/* Space for command line.  */
-#ifdef THUMB_V7M_V6M
+#ifdef THUMB_VXM
 	bkpt	AngelSWI
 #else
  	AngelSWIAsm	AngelSWI
@@ -404,7 +404,7 @@ __change_mode:
 
 	bl	FUNCTION (exit)		/* Should not return.  */
 
-#if defined(__thumb__) && !defined(THUMB_V7_V6M)
+#if __thumb__ && !defined(PREFER_THUMB)
 	/* Come out of Thumb mode.  This code should be redundant.  */
 	mov	a4, pc
 	bx	a4

newlib/libc/sys/arm/swi.h

@@ -36,7 +36,7 @@
 #define AngelSWI 			AngelSWI_ARM
 #endif
 /* For thumb only architectures use the BKPT instruction instead of SWI.  */
-#ifdef THUMB_V7M_V6M
+#ifdef THUMB_VXM
 #define AngelSWIInsn			"bkpt"
 #define AngelSWIAsm			bkpt
 #else