RISC-V: Fix riscv g++ testsuite EH failures.

This fixes some EH failures for the medany code model in the g++ testsuite.
The problem is that the assembler is computing some values in the eh_frame
section as constants, that instead should have had relocs to be resolved by
the linker.  This happens in output_cfi_insn in the DW_CFA_advance_loc case
where it compares label frags and immediately simplifies if they are the
same.  We can fix that by forcing a new frag after every instruction
that the linker can reduce in size.  I've also added a testcase to verify
the fix.  This was tested with binutils make check, and gcc/g++ make checks on
qemu for medlow and medany code models.

	gas/
	* config/tc-riscv.c (append_insn): Call frag_wane and frag_new at
	end for linker optimizable relocs.
	* testsuite/gas/riscv/eh-relocs.d: New.
	* testsuite/gas/riscv/eh-relocs.s: New.
	* testsuite/gas/riscv/riscv.exp: Run eh-relocs test.

3 files changed, 24 insertions, 0 deletions

diff --git a/gas/testsuite/gas/riscv/eh-relocs.d b/gas/testsuite/gas/riscv/eh-relocs.d
new file mode 100644
index 0000000..94fa143
--- /dev/null
+++ b/gas/testsuite/gas/riscv/eh-relocs.d
@@ -0,0 +1,12 @@
+#as:
+#objdump: --section=.eh_frame -r
+
+.*:[ 	]+file format .*
+
+RELOCATION RECORDS FOR .*
+.*
+0+1c R_RISCV_32_PCREL.*
+0+20 R_RISCV_ADD32.*
+0+20 R_RISCV_SUB32.*
+0+25 R_RISCV_SET6.*
+0+25 R_RISCV_SUB6.*
diff --git a/gas/testsuite/gas/riscv/eh-relocs.s b/gas/testsuite/gas/riscv/eh-relocs.s
new file mode 100644
index 0000000..4e96e7e
--- /dev/null
+++ b/gas/testsuite/gas/riscv/eh-relocs.s
@@ -0,0 +1,11 @@
+	.text
+	.align	2
+	.globl	_func1
+	.type	_func1, @function
+_func1:
+	.cfi_startproc
+	lla	a1,_func2
+	add	sp,sp,-16
+	.cfi_def_cfa_offset 16
+	.cfi_endproc
+	.size	_func1, .-_func1
diff --git a/gas/testsuite/gas/riscv/riscv.exp b/gas/testsuite/gas/riscv/riscv.exp
index 2ab885a..8a128ac 100644
--- a/gas/testsuite/gas/riscv/riscv.exp
+++ b/gas/testsuite/gas/riscv/riscv.exp
@@ -25,4 +25,5 @@ if [istarget riscv*-*-*] {
     run_dump_test "c-addi4spn-fail"
     run_dump_test "c-addi16sp-fail"
     run_dump_test "satp"
+    run_dump_test "eh-relocs"
 }