File libgcc-riscv-div.patch of Package gcc7

From 485b0a0039a29cf046fe97c7d72aefe49275b141 Mon Sep 17 00:00:00 2001
From: Nelson Chu <nelson.chu@sifive.com>
Date: Mon, 29 Nov 2021 04:48:20 -0800
Subject: [PATCH] RISC-V: jal cannot refer to a default visibility symbol for
 shared object.

This is the original binutils bugzilla report,
https://sourceware.org/bugzilla/show_bug.cgi?id=28509

And this is the first version of the proposed binutils patch,
https://sourceware.org/pipermail/binutils/2021-November/118398.html

After applying the binutils patch, I get the the unexpected error when
building libgcc,

/scratch/nelsonc/riscv-gnu-toolchain/riscv-gcc/libgcc/config/riscv/div.S:42:
/scratch/nelsonc/build-upstream/rv64gc-linux/build-install/riscv64-unknown-linux-gnu/bin/ld: relocation R_RISCV_JAL against `__udivdi3' which may bind externally can not be used when making a shared object; recompile with -fPIC

Therefore, this patch add an extra hidden alias symbol for __udivdi3, and
then use HIDDEN_JUMPTARGET to target a non-preemptible symbol instead.
The solution is similar to glibc as follows,
https://sourceware.org/git/?p=glibc.git;a=commit;h=68389203832ab39dd0dbaabbc4059e7fff51c29b

libgcc/ChangeLog:

	* config/riscv/div.S: Add the hidden alias symbol for __udivdi3, and
	then use HIDDEN_JUMPTARGET to target it since it is non-preemptible.
	* config/riscv/riscv-asm.h: Added new macros HIDDEN_JUMPTARGET and
	HIDDEN_DEF.
---
 libgcc/config/riscv/div.S | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/libgcc/config/riscv/div.S b/libgcc/config/riscv/div.S
index 63d542e846c..2d43a48a302 100644
--- a/libgcc/config/riscv/div.S
+++ b/libgcc/config/riscv/div.S
@@ -23,6 +23,14 @@ a copy of the GCC Runtime Library Exception along with this program;
 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 <http://www.gnu.org/licenses/>.  */
 
+#define FUNC_ALIAS(X,Y)		\
+	.globl X;		\
+	X = Y
+#define CONCAT1(a, b)		CONCAT2(a, b)
+#define CONCAT2(a, b)		a ## b
+#define HIDDEN_JUMPTARGET(X)	CONCAT1(__hidden_, X)
+#define HIDDEN_DEF(X)		FUNC_ALIAS(HIDDEN_JUMPTARGET(X), X);     \
+				.hidden HIDDEN_JUMPTARGET(X)
   .text
   .align 2
 
@@ -39,7 +47,7 @@ __udivsi3:
   sll    a0, a0, 32
   sll    a1, a1, 32
   move   t0, ra
-  jal    __udivdi3
+  jal    HIDDEN_JUMPTARGET(__udivdi3)
   sext.w a0, a0
   jr     t0
 
@@ -51,7 +59,7 @@ __umodsi3:
   srl    a0, a0, 32
   srl    a1, a1, 32
   move   t0, ra
-  jal    __udivdi3
+  jal    HIDDEN_JUMPTARGET(__udivdi3)
   sext.w a0, a1
   jr     t0
 
@@ -96,12 +104,13 @@ __udivdi3:
   bnez  a3, .L3
 .L5:
   ret
+HIDDEN_DEF (__udivdi3)
 
   .globl __umoddi3
 __umoddi3:
   /* Call __udivdi3(a0, a1), then return the remainder, which is in a1.  */
   move  t0, ra
-  jal   __udivdi3
+  jal   HIDDEN_JUMPTARGET(__udivdi3)
   move  a0, a1
   jr    t0
 
@@ -110,12 +119,12 @@ __umoddi3:
   neg   a0, a0
   bgez  a1, .L12      /* Compute __udivdi3(-a0, a1), then negate the result.  */
   neg   a1, a1
-  j     __udivdi3     /* Compute __udivdi3(-a0, -a1).  */
+  j     HIDDEN_JUMPTARGET(__udivdi3)     /* Compute __udivdi3(-a0, -a1).  */
 .L11:                 /* Compute __udivdi3(a0, -a1), then negate the result.  */
   neg   a1, a1
 .L12:
   move  t0, ra
-  jal   __udivdi3
+  jal   HIDDEN_JUMPTARGET(__udivdi3)
   neg   a0, a0
   jr    t0
 
@@ -125,7 +134,7 @@ __moddi3:
   bltz   a1, .L31
   bltz   a0, .L32
 .L30:
-  jal    __udivdi3    /* The dividend is not negative.  */
+  jal    HIDDEN_JUMPTARGET(__udivdi3)    /* The dividend is not negative.  */
   move   a0, a1
   jr     t0
 .L31:
@@ -133,7 +142,7 @@ __moddi3:
   bgez   a0, .L30
 .L32:
   neg    a0, a0
-  jal    __udivdi3    /* The dividend is hella negative.  */
+  jal    HIDDEN_JUMPTARGET(__udivdi3)    /* The dividend is hella negative.  */
   neg    a0, a1
   jr     t0
 
-- 
2.40.1