[binutils-gdb] PR 34029: bpf: add %dR/%sR register format specifiers

[Jose E. Marchesi]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=350f9e8adbf2a30912162437bebb4f4b7579f689

commit 350f9e8adbf2a30912162437bebb4f4b7579f689
Author: Vineet Gupta <vineet.gupta@linux.dev>
Date:   Tue Mar 31 13:42:11 2026 -0700

    PR 34029: bpf: add %dR/%sR register format specifiers
    
    These accept either r or w prefix registers during assembly
    (pseudoc dialect), while disassembling canonically as r registers.
    
    This eliminates the need for duplicate opcode table entries for
    instructions that accept both w and r register forms.
    
    Signed-off-by: Vineet Gupta <vineet.gupta@linux.dev>

Diff:
---
 gas/config/tc-bpf.c  | 16 ++++++++++++----
 include/opcode/bpf.h |  4 +++-
 opcodes/bpf-dis.c    |  6 ++++--
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/gas/config/tc-bpf.c b/gas/config/tc-bpf.c
index ecb6c5a7053..8d48b128fb9 100644
--- a/gas/config/tc-bpf.c
+++ b/gas/config/tc-bpf.c
@@ -1525,12 +1525,16 @@ md_assemble (char *str ATTRIBUTE_UNUSED)
                   p += 2;
                 }
               else if (strncmp (p, "%dr", 3) == 0
-                       || strncmp (p, "%dw", 3) == 0)
+                       || strncmp (p, "%dw", 3) == 0
+                       || strncmp (p, "%dR", 3) == 0)
                 {
                   char rw = *(p + 2);
                   uint8_t regno;
-                  char *news = parse_bpf_register (s, rw, &regno);
+                  char *news = parse_bpf_register (s, rw == 'R' ? 'r' : rw,
+                                                   &regno);
 
+                  if (rw == 'R' && news == NULL)
+                    news = parse_bpf_register (s, 'w', &regno);
                   if (news == NULL || (insn.has_dst && regno != insn.dst))
                     {
                       if (news != NULL)
@@ -1546,12 +1550,16 @@ md_assemble (char *str ATTRIBUTE_UNUSED)
                   p += 3;
                 }
               else if (strncmp (p, "%sr", 3) == 0
-                       || strncmp (p, "%sw", 3) == 0)
+                       || strncmp (p, "%sw", 3) == 0
+                       || strncmp (p, "%sR", 3) == 0)
                 {
                   char rw = *(p + 2);
                   uint8_t regno;
-                  char *news = parse_bpf_register (s, rw, &regno);
+                  char *news = parse_bpf_register (s, rw == 'R' ? 'r' : rw,
+                                                   &regno);
 
+                  if (rw == 'R' && news == NULL)
+                    news = parse_bpf_register (s, 'w', &regno);
                   if (news == NULL || (insn.has_src && regno != insn.src))
                     {
                       if (news != NULL)
diff --git a/include/opcode/bpf.h b/include/opcode/bpf.h
index e4ccd430f0c..e17ca2fdd2c 100644
--- a/include/opcode/bpf.h
+++ b/include/opcode/bpf.h
@@ -252,8 +252,10 @@ struct bpf_opcode
      %% - literal %.
      %dr - destination 64-bit register.
      %dw - destination 32-bit register.
+     %dR - destination register, either r or w prefix accepted.
      %sr - source 64-bit register.
      %sw - source 32-bit register.
+     %sR - source register, either r or w prefix accepted.
      %d32 - 32-bit signed displacement (in 64-bit words minus one.)
      %d16 - 16-bit signed displacement (in 64-bit words minus one.)
      %o16 - 16-bit signed offset (in bytes.)
@@ -268,7 +270,7 @@ struct bpf_opcode
      denote something like `[%r3 + 10]', please use a template like `[
      %sr %o16]' instead of `[ %sr + %o16 ]'.
      
-     If %dr, %dw, %sr or %sw are found multiple times in a template,
+     If %dr, %dw, %dR, %sr, %sw or %sR are found multiple times in a template,
      they refer to the same register, i.e. `%rd = le64 %rd' denotes
      `r2 = le64 r2', but not `r2 = le64 r1'.
 
diff --git a/opcodes/bpf-dis.c b/opcodes/bpf-dis.c
index de8d417dcd3..07aacb621a3 100644
--- a/opcodes/bpf-dis.c
+++ b/opcodes/bpf-dis.c
@@ -215,13 +215,15 @@ print_insn_bpf (bfd_vma pc, disassemble_info *info)
                   p += 2;
                 }
               else if (strncmp (p, "%dr", 3) == 0
-                       || strncmp (p, "%dw", 3) == 0)
+                       || strncmp (p, "%dw", 3) == 0
+                       || strncmp (p, "%dR", 3) == 0)
                 {
                   print_register (info, p, bpf_extract_dst (word, endian));
                   p += 3;
                 }
               else if (strncmp (p, "%sr", 3) == 0
-                       || strncmp (p, "%sw", 3) == 0)
+                       || strncmp (p, "%sw", 3) == 0
+                       || strncmp (p, "%sR", 3) == 0)
                 {
                   print_register (info, p, bpf_extract_src (word, endian));
                   p += 3;