nios2: Don't disable relaxation with --gdwarf-N

GCC 11 passes --gdwarf-5 to assembler to enable DWARF5 debug info.  Don't
disable relaxation when --gdwarf-N is specified.  The assembler generated
debug information will treat the sequence of the relaxed instructions as
a single instruction.

	PR gas/27243
	* config/tc-nios2.c (md_begin): Don't disable relaxation with
	--gdwarf-N.
	* testsuite/gas/nios2/relax.d: New file.
	* testsuite/gas/nios2/relax.s: Likewise.

(cherry picked from commit 1f583bc)

Author: hjl-tools

gas/ChangeLog

@@ -1,3 +1,11 @@
+2021-01-26  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR gas/27243
+	* config/tc-nios2.c (md_begin): Don't disable relaxation with
+	--gdwarf-N.
+	* testsuite/gas/nios2/relax.d: New file.
+	* testsuite/gas/nios2/relax.s: Likewise.
+
 2021-01-24  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR gas/27228

gas/config/tc-nios2.c

@@ -3643,10 +3643,6 @@ md_begin (void)
   nios2_as_options.noat = FALSE;
   nios2_as_options.nobreak = FALSE;
 
-  /* Debug information is incompatible with relaxation.  */
-  if (debug_type != DEBUG_UNSPECIFIED)
-    nios2_as_options.relax = relax_none;
-
   /* Initialize the alignment data.  */
   nios2_current_align_seg = now_seg;
   nios2_last_label = NULL;

gas/testsuite/gas/nios2/relax.d

@@ -0,0 +1,25 @@
+#source: relax.s
+#as: --gdwarf-5
+#objdump: -w -WL -dr --prefix-addresses --show-raw-insn
+#name: NIOS2 relax with --gdwarf-5
+
+# Test relaxation with assembler generated debug info.
+.*:     file format elf32-littlenios2
+
+Contents of the .debug_line section:
+
+CU: ./relax.s:
+File +name +Line +number +Starting +address +View +Stmt
+relax.s +2 +0 +x
+relax.s +5 +0x10018 +x
+relax.s +- +0x1001c
+
+Disassembly of section .text:
+0x00000000 21400526 	beq	r4,r5,0x00000018
+0x00000004 0002e03a 	nextpc	at
+0x00000008 085fffc4 	addi	at,at,32767
+0x0000000c 085fffc4 	addi	at,at,32767
+0x00000010 08400484 	addi	at,at,18
+0x00000014 0800683a 	jmp	at
+	...
+0x00010018 f800283a 	ret

gas/testsuite/gas/nios2/relax.s

@@ -0,0 +1,5 @@
+	.text
+	bne	r4, r5, 1f
+	.zero 0x10000
+1:
+	ret