arc: build libgcc in U-Boot

This way we may have very limited set of functions implemented so we
save some space.

Also it allows us to build U-Boot for any ARC core with the same one
toolchain because we don't rely on pre-built libgcc.

For example:
 * we may use little-endian toolchain but build U-Boot for ether
endianess
 * we may use non-multilibbed uClibc toolchain but build U-Boot for
whatever ARC CPU flavour that current GCC supports

Private libgcc built from generic C implementation contributes only 144
bytes to .text section so we don't see significant degradation of size:
--->8---
$ arc-linux-size u-boot.libgcc-prebuilt
   text	   data	    bss	    dec	    hex	filename
 222217	  24912	 214820	 461949	  70c7d	u-boot.libgcc-prebuilt

$ arc-linux-size u-boot.libgcc-private
   text	   data	    bss	    dec	    hex	filename
 222361	  24912	 214820	 462093	  70d0d	u-boot.libgcc-private
--->8---

Also I don't notice visible performance degradation compared to
pre-built libgcc (where at least "*div*" functions are had-written in
assembly) on typical operations of downloading 10Mb uImage over TFTP and
bootm.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

1 files changed, 226 insertions, 0 deletions

diff --git a/arch/arc/lib/_millicodethunk.S b/arch/arc/lib/_millicodethunk.S
new file mode 100644
index 0000000..b332416
--- /dev/null
+++ b/arch/arc/lib/_millicodethunk.S
@@ -0,0 +1,226 @@
+/*
+ * Copyright (C) 1995, 1997, 2007-2013 Free Software Foundation, Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+ /* ANSI concatenation macros.  */
+
+ #define CONCAT1(a, b) CONCAT2(a, b)
+ #define CONCAT2(a, b) a ## b
+
+ /* Use the right prefix for global labels.  */
+
+ #define SYM(x) CONCAT1 (__USER_LABEL_PREFIX__, x)
+
+#ifndef WORKING_ASSEMBLER
+#define abs_l abs
+#define asl_l asl
+#define mov_l mov
+#endif
+
+#define FUNC(X)         .type SYM(X),@function
+#define HIDDEN_FUNC(X)	FUNC(X)` .hidden X
+#define ENDFUNC0(X)     .Lfe_##X: .size X,.Lfe_##X-X
+#define ENDFUNC(X)      ENDFUNC0(X)
+
+	.section .text
+	.align 4
+	.global SYM(__st_r13_to_r15)
+	.global SYM(__st_r13_to_r16)
+	.global SYM(__st_r13_to_r17)
+	.global SYM(__st_r13_to_r18)
+	.global SYM(__st_r13_to_r19)
+	.global SYM(__st_r13_to_r20)
+	.global SYM(__st_r13_to_r21)
+	.global SYM(__st_r13_to_r22)
+	.global SYM(__st_r13_to_r23)
+	.global SYM(__st_r13_to_r24)
+	.global SYM(__st_r13_to_r25)
+	HIDDEN_FUNC(__st_r13_to_r15)
+	HIDDEN_FUNC(__st_r13_to_r16)
+	HIDDEN_FUNC(__st_r13_to_r17)
+	HIDDEN_FUNC(__st_r13_to_r18)
+	HIDDEN_FUNC(__st_r13_to_r19)
+	HIDDEN_FUNC(__st_r13_to_r20)
+	HIDDEN_FUNC(__st_r13_to_r21)
+	HIDDEN_FUNC(__st_r13_to_r22)
+	HIDDEN_FUNC(__st_r13_to_r23)
+	HIDDEN_FUNC(__st_r13_to_r24)
+	HIDDEN_FUNC(__st_r13_to_r25)
+	.align 4
+SYM(__st_r13_to_r25):
+	st r25, [sp,48]
+SYM(__st_r13_to_r24):
+	st r24, [sp,44]
+SYM(__st_r13_to_r23):
+	st r23, [sp,40]
+SYM(__st_r13_to_r22):
+	st r22, [sp,36]
+SYM(__st_r13_to_r21):
+	st r21, [sp,32]
+SYM(__st_r13_to_r20):
+	st r20, [sp,28]
+SYM(__st_r13_to_r19):
+	st r19, [sp,24]
+SYM(__st_r13_to_r18):
+	st r18, [sp,20]
+SYM(__st_r13_to_r17):
+	st r17, [sp,16]
+SYM(__st_r13_to_r16):
+	st r16, [sp,12]
+SYM(__st_r13_to_r15):
+#ifdef __ARC700__
+	st r15, [sp,8] ; minimum function size to avoid stall: 6 bytes.
+#else
+	st_s r15, [sp,8]
+#endif
+	st_s r14, [sp,4]
+	j_s.d [%blink]
+	st_s r13, [sp,0]
+	ENDFUNC(__st_r13_to_r15)
+	ENDFUNC(__st_r13_to_r16)
+	ENDFUNC(__st_r13_to_r17)
+	ENDFUNC(__st_r13_to_r18)
+	ENDFUNC(__st_r13_to_r19)
+	ENDFUNC(__st_r13_to_r20)
+	ENDFUNC(__st_r13_to_r21)
+	ENDFUNC(__st_r13_to_r22)
+	ENDFUNC(__st_r13_to_r23)
+	ENDFUNC(__st_r13_to_r24)
+	ENDFUNC(__st_r13_to_r25)
+
+	.section .text
+	.align 4
+;	==================================
+;	the loads
+
+	.global SYM(__ld_r13_to_r15)
+	.global SYM(__ld_r13_to_r16)
+	.global SYM(__ld_r13_to_r17)
+	.global SYM(__ld_r13_to_r18)
+	.global SYM(__ld_r13_to_r19)
+	.global SYM(__ld_r13_to_r20)
+	.global SYM(__ld_r13_to_r21)
+	.global SYM(__ld_r13_to_r22)
+	.global SYM(__ld_r13_to_r23)
+	.global SYM(__ld_r13_to_r24)
+	.global SYM(__ld_r13_to_r25)
+	HIDDEN_FUNC(__ld_r13_to_r15)
+	HIDDEN_FUNC(__ld_r13_to_r16)
+	HIDDEN_FUNC(__ld_r13_to_r17)
+	HIDDEN_FUNC(__ld_r13_to_r18)
+	HIDDEN_FUNC(__ld_r13_to_r19)
+	HIDDEN_FUNC(__ld_r13_to_r20)
+	HIDDEN_FUNC(__ld_r13_to_r21)
+	HIDDEN_FUNC(__ld_r13_to_r22)
+	HIDDEN_FUNC(__ld_r13_to_r23)
+	HIDDEN_FUNC(__ld_r13_to_r24)
+	HIDDEN_FUNC(__ld_r13_to_r25)
+SYM(__ld_r13_to_r25):
+	ld r25, [sp,48]
+SYM(__ld_r13_to_r24):
+	ld r24, [sp,44]
+SYM(__ld_r13_to_r23):
+	ld r23, [sp,40]
+SYM(__ld_r13_to_r22):
+	ld r22, [sp,36]
+SYM(__ld_r13_to_r21):
+	ld r21, [sp,32]
+SYM(__ld_r13_to_r20):
+	ld r20, [sp,28]
+SYM(__ld_r13_to_r19):
+	ld r19, [sp,24]
+SYM(__ld_r13_to_r18):
+	ld r18, [sp,20]
+SYM(__ld_r13_to_r17):
+	ld r17, [sp,16]
+SYM(__ld_r13_to_r16):
+	ld r16, [sp,12]
+SYM(__ld_r13_to_r15):
+#ifdef __ARC700__
+	ld r15, [sp,8] ; minimum function size to avoid stall: 6 bytes.
+#else
+	ld_s r15, [sp,8]
+#endif
+	ld_s r14, [sp,4]
+	j_s.d [%blink]
+	ld_s r13, [sp,0]
+	ENDFUNC(__ld_r13_to_r15)
+	ENDFUNC(__ld_r13_to_r16)
+	ENDFUNC(__ld_r13_to_r17)
+	ENDFUNC(__ld_r13_to_r18)
+	ENDFUNC(__ld_r13_to_r19)
+	ENDFUNC(__ld_r13_to_r20)
+	ENDFUNC(__ld_r13_to_r21)
+	ENDFUNC(__ld_r13_to_r22)
+	ENDFUNC(__ld_r13_to_r23)
+	ENDFUNC(__ld_r13_to_r24)
+	ENDFUNC(__ld_r13_to_r25)
+
+	.global SYM(__ld_r13_to_r14_ret)
+	.global SYM(__ld_r13_to_r15_ret)
+	.global SYM(__ld_r13_to_r16_ret)
+	.global SYM(__ld_r13_to_r17_ret)
+	.global SYM(__ld_r13_to_r18_ret)
+	.global SYM(__ld_r13_to_r19_ret)
+	.global SYM(__ld_r13_to_r20_ret)
+	.global SYM(__ld_r13_to_r21_ret)
+	.global SYM(__ld_r13_to_r22_ret)
+	.global SYM(__ld_r13_to_r23_ret)
+	.global SYM(__ld_r13_to_r24_ret)
+	.global SYM(__ld_r13_to_r25_ret)
+	HIDDEN_FUNC(__ld_r13_to_r14_ret)
+	HIDDEN_FUNC(__ld_r13_to_r15_ret)
+	HIDDEN_FUNC(__ld_r13_to_r16_ret)
+	HIDDEN_FUNC(__ld_r13_to_r17_ret)
+	HIDDEN_FUNC(__ld_r13_to_r18_ret)
+	HIDDEN_FUNC(__ld_r13_to_r19_ret)
+	HIDDEN_FUNC(__ld_r13_to_r20_ret)
+	HIDDEN_FUNC(__ld_r13_to_r21_ret)
+	HIDDEN_FUNC(__ld_r13_to_r22_ret)
+	HIDDEN_FUNC(__ld_r13_to_r23_ret)
+	HIDDEN_FUNC(__ld_r13_to_r24_ret)
+	HIDDEN_FUNC(__ld_r13_to_r25_ret)
+	.section .text
+	.align 4
+SYM(__ld_r13_to_r25_ret):
+	ld r25, [sp,48]
+SYM(__ld_r13_to_r24_ret):
+	ld r24, [sp,44]
+SYM(__ld_r13_to_r23_ret):
+	ld r23, [sp,40]
+SYM(__ld_r13_to_r22_ret):
+	ld r22, [sp,36]
+SYM(__ld_r13_to_r21_ret):
+	ld r21, [sp,32]
+SYM(__ld_r13_to_r20_ret):
+	ld r20, [sp,28]
+SYM(__ld_r13_to_r19_ret):
+	ld r19, [sp,24]
+SYM(__ld_r13_to_r18_ret):
+	ld r18, [sp,20]
+SYM(__ld_r13_to_r17_ret):
+	ld r17, [sp,16]
+SYM(__ld_r13_to_r16_ret):
+	ld r16, [sp,12]
+SYM(__ld_r13_to_r15_ret):
+	ld r15, [sp,8]
+SYM(__ld_r13_to_r14_ret):
+	ld blink,[sp,r12]
+	ld_s r14, [sp,4]
+	ld.ab r13, [sp,r12]
+	j_s.d [%blink]
+	add_s sp,sp,4
+	ENDFUNC(__ld_r13_to_r14_ret)
+	ENDFUNC(__ld_r13_to_r15_ret)
+	ENDFUNC(__ld_r13_to_r16_ret)
+	ENDFUNC(__ld_r13_to_r17_ret)
+	ENDFUNC(__ld_r13_to_r18_ret)
+	ENDFUNC(__ld_r13_to_r19_ret)
+	ENDFUNC(__ld_r13_to_r20_ret)
+	ENDFUNC(__ld_r13_to_r21_ret)
+	ENDFUNC(__ld_r13_to_r22_ret)
+	ENDFUNC(__ld_r13_to_r23_ret)
+	ENDFUNC(__ld_r13_to_r24_ret)
+	ENDFUNC(__ld_r13_to_r25_ret)