RISC-V: Add new option -mrelax/-mno-relax.

gas/
	* config/tc-riscv.c (options): Add OPTION_RELAX and
	OPTION_NO_RELAX.
	(md_longopts): New option -mrelax and -mno-relax.
	(md_parse_option): Handle -mrelax and -mno-relax.
	* doc/c-riscv.texi: Document for -mrelax and -mno-relax.
	* testsuite/gas/riscv/no-relax-reloc.d: New.
	* testsuite/gas/riscv/no-relax-reloc.s: New.
	* testsuite/gas/riscv/relax-reloc.d: New.
	* testsuite/gas/riscv/relax-reloc.s: New.

gas/ChangeLog

@@ -1,3 +1,15 @@
+2018-04-20  Kito Cheng  <kito.cheng@gmail.com>
+
+	* config/tc-riscv.c (options): Add OPTION_RELAX and
+	OPTION_NO_RELAX.
+	(md_longopts): New option -mrelax and -mno-relax.
+	(md_parse_option): Handle -mrelax and -mno-relax.
+	* doc/c-riscv.texi: Document for -mrelax and -mno-relax.
+	* testsuite/gas/riscv/no-relax-reloc.d: New.
+	* testsuite/gas/riscv/no-relax-reloc.s: New.
+	* testsuite/gas/riscv/relax-reloc.d: New.
+	* testsuite/gas/riscv/relax-reloc.s: New.
+
 2018-04-20  Nick Clifton  <nickc@redhat.com>
 
 	* po/es.po: Updated Spanish translation.

gas/config/tc-riscv.c

@@ -2136,6 +2136,8 @@ enum options
   OPTION_PIC,
   OPTION_NO_PIC,
   OPTION_MABI,
+  OPTION_RELAX,
+  OPTION_NO_RELAX,
   OPTION_END_OF_ENUM
 };
 
@@ -2146,6 +2148,8 @@ struct option md_longopts[] =
   {"fpic", no_argument, NULL, OPTION_PIC},
   {"fno-pic", no_argument, NULL, OPTION_NO_PIC},
   {"mabi", required_argument, NULL, OPTION_MABI},
+  {"mrelax", no_argument, NULL, OPTION_RELAX},
+  {"mno-relax", no_argument, NULL, OPTION_NO_RELAX},
 
   {NULL, no_argument, NULL, 0}
 };
@@ -2205,6 +2209,14 @@ md_parse_option (int c, const char *arg)
 	return 0;
       break;
 
+    case OPTION_RELAX:
+      riscv_opts.relax = TRUE;
+      break;
+
+    case OPTION_NO_RELAX:
+      riscv_opts.relax = FALSE;
+      break;
+
     default:
       return 0;
     }
@@ -2921,6 +2933,8 @@ RISC-V options:\n\
   -fno-pic       don't generate position-independent code (default)\n\
   -march=ISA     set the RISC-V architecture\n\
   -mabi=ABI      set the RISC-V ABI\n\
+  -mrelax        enable relax (default)\n\
+  -mno-relax     disable relax\n\
 "));
 }
 

gas/doc/c-riscv.texi

@@ -48,6 +48,15 @@ by "f", "d", or "q" to indicate single-precision, double-precision, or
 quad-precision floating-point calling convention, or none to indicate
 the soft-float calling convention.
 
+@cindex @samp{-mrelax} option, RISC-V
+@item -mrelax
+Take advantage of linker relaxations to reduce the number of instructions
+required to materialize symbol addresses. (default)
+
+@cindex @samp{-mno-relax} option, RISC-V
+@item -mno-relax
+Don't do linker relaxations.
+
 @end table
 @c man end
 

gas/testsuite/gas/riscv/no-relax-reloc.d

@@ -0,0 +1,12 @@
+#as: -mno-relax
+#objdump: -r
+
+.*:[ 	]+file format .*
+
+RELOCATION RECORDS FOR .*
+.*
+0+0 R_RISCV_HI20.*
+0+4 R_RISCV_LO12_I.*
+0+8 R_RISCV_PCREL_HI20.*
+0+c R_RISCV_PCREL_LO12_I.*
+0+10 R_RISCV_CALL.*

gas/testsuite/gas/riscv/no-relax-reloc.s

@@ -0,0 +1,8 @@
+target:
+	lui	a5,%hi(target)
+	lw	a5,%lo(target)(a5)
+
+        .LA0: auipc     a5,%pcrel_hi(bar)
+        lw      a0,%pcrel_lo(.LA0)(a5)
+
+	call target

gas/testsuite/gas/riscv/relax-reloc.d

@@ -0,0 +1,17 @@
+#as:
+#objdump: -r
+
+.*:[ 	]+file format .*
+
+RELOCATION RECORDS FOR .*
+.*
+0+0 R_RISCV_HI20.*
+0+0 R_RISCV_RELAX.*
+0+4 R_RISCV_LO12_I.*
+0+4 R_RISCV_RELAX.*
+0+8 R_RISCV_PCREL_HI20.*
+0+8 R_RISCV_RELAX.*
+0+c R_RISCV_PCREL_LO12_I.*
+0+c R_RISCV_RELAX.*
+0+10 R_RISCV_CALL.*
+0+10 R_RISCV_RELAX.*

gas/testsuite/gas/riscv/relax-reloc.s

@@ -0,0 +1,8 @@
+target:
+	lui	a5,%hi(target)
+	lw	a5,%lo(target)(a5)
+
+        .LA0: auipc     a5,%pcrel_hi(bar)
+        lw      a0,%pcrel_lo(.LA0)(a5)
+
+	call target