[binutils-gdb] RISC-V: Don't emit 2-byte NOPs if the C extension is disabled

[Palmer Dabbelt <palmer at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=2c3f27ed0d6a91bc0812bb2fc6965fd03a413fee

commit 2c3f27ed0d6a91bc0812bb2fc6965fd03a413fee
Author: Palmer Dabbelt <palmer@dabbelt.com>
Date:   Fri Oct 6 12:06:45 2017 -0700

    RISC-V: Don't emit 2-byte NOPs if the C extension is disabled
    
    Systems without the C extension mandate 4-byte alignment for
    instructions, so there is no reason to allow for 2-byte alignment.  This
    change avoids emitting lots of unimplemented instructions into object
    files on non-C targets, which users keep reporting as a bug.  While this
    isn't actually a bug (as none of the offsets in object files are
    relevant until RISC-V), it is ugly.
    
    gas/ChangeLog
    
    2017-10-23  Palmer Dabbelt  <palmer@dabbelt.com>
    
            * config/tc-riscv.c (riscv_frag_align_code): Align code by 4
            bytes on non-RVC systems.

Diff:
---
 gas/ChangeLog         | 5 +++++
 gas/config/tc-riscv.c | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/gas/ChangeLog b/gas/ChangeLog
index f095421..bb1aa01 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,8 @@
+2017-10-23  Palmer Dabbelt  <palmer@dabbelt.com>
+
+        * config/tc-riscv.c (riscv_frag_align_code): Align code by 4
+        bytes on non-RVC systems.
+
 2017-10-23  Maciej W. Rozycki  <macro@imgtec.com>
 
 	* config/tc-mips.c (mips_elf_final_processing): Don't set
diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
index 189e40d..f4276c9 100644
--- a/gas/config/tc-riscv.c
+++ b/gas/config/tc-riscv.c
@@ -2277,7 +2277,7 @@ bfd_boolean
 riscv_frag_align_code (int n)
 {
   bfd_vma bytes = (bfd_vma) 1 << n;
-  bfd_vma worst_case_bytes = bytes - 2;
+  bfd_vma worst_case_bytes = bytes - (riscv_opts.rvc ? 2 : 4);
   char *nops = frag_more (worst_case_bytes);
   expressionS ex;