[binutils-gdb] or1k: Fix disassembly for little-endian binaries

[Stafford Horne]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=7a23d8a82634d52878b83582bb50832f85297a41

commit 7a23d8a82634d52878b83582bb50832f85297a41
Author: Stafford Horne <shorne@gmail.com>
Date:   Sun Jun 15 05:15:40 2025 +0100

    or1k: Fix disassembly for little-endian binaries
    
    There are some OpenRISC CPUs that have their binaries stored in
    little-endian format.  Using objdump to disassemble these is
    problematic, as some instructions fail to disassemble, for example:
    
        objdump -D -b binary -EB -m or1k test_be.bin
    
           0:       18 60 07 27     l.movhi r3,0x727
           4:       a8 63 0e 00     l.ori r3,r3,0xe00
           8:       9c 63 ff ff     l.addi r3,r3,-1
           c:       bc 43 00 00     l.sfgtui r3,0
          10:       13 ff ff fe     l.bf 0x8
          14:       44 00 48 00     l.jr r9
    
        objdump -D -b binary -EL -m or1k test_le.bin
    
           0:       27 07 60 18     *unknown*
           4:       00 0e 63 a8     l.ori r3,r3,0xe00
           8:       ff ff 63 9c     *unknown*
           c:       00 00 43 bc     l.sfgtui r3,0
          10:       fe ff ff 13     *unknown*
          14:       00 48 00 44     l.jr r9
    
    It was found that the hash function was using the still little-endian
    buffer to extract the opcode used for the hash lookup.  This didn't work
    as it was pulling the wrong hashcode causing instruction lookup to fail.
    
    Fix the hash function by using the normalized/byte-swapped value instead
    of the buffer.
    
    Signed-off-by: Stafford Horne <shorne@gmail.com>

Diff:
---
 cpu/or1k.opc       | 2 +-
 opcodes/or1k-opc.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/cpu/or1k.opc b/cpu/or1k.opc
index 5d20a1f33a7..748187edcdf 100644
--- a/cpu/or1k.opc
+++ b/cpu/or1k.opc
@@ -38,7 +38,7 @@
 #undef  CGEN_DIS_HASH_SIZE
 #define CGEN_DIS_HASH_SIZE 256
 #undef  CGEN_DIS_HASH
-#define CGEN_DIS_HASH(buffer, value) (((unsigned char *) (buffer))[0] >> 2)
+#define CGEN_DIS_HASH(buffer, value) ((value >> 26) & 0xff)
 
 /* Check applicability of instructions against machines.  */
 #define CGEN_VALIDATE_INSN_SUPPORTED
diff --git a/opcodes/or1k-opc.h b/opcodes/or1k-opc.h
index d3d084b1bec..6eec8006828 100644
--- a/opcodes/or1k-opc.h
+++ b/opcodes/or1k-opc.h
@@ -35,7 +35,7 @@ extern "C" {
 #undef  CGEN_DIS_HASH_SIZE
 #define CGEN_DIS_HASH_SIZE 256
 #undef  CGEN_DIS_HASH
-#define CGEN_DIS_HASH(buffer, value) (((unsigned char *) (buffer))[0] >> 2)
+#define CGEN_DIS_HASH(buffer, value) ((value >> 26) & 0xff)
 
 /* Check applicability of instructions against machines.  */
 #define CGEN_VALIDATE_INSN_SUPPORTED