Fix to step instruction due to P10 prefix instruction.

In AIX, power 10 instructions like paddi occupy 8 bytes, while the other instructions
4 bytes of space. Due to this when we do a stepi on paddi instruction we get a SIGILL interrupt. Hence, we
need to check during stepi if we are able to step 8 bytes during this instruction execution and is the
breakpoint to this instruction set correctly in both 32- and 64-bit mode.

This patch is a fix to the same.

diff --git a/gdb/rs6000-aix-tdep.c b/gdb/rs6000-aix-tdep.c
index c5446db2c1e66d0ddc466653d45be24c06a0e6e6..b8772bd02bd3bb1aa7717312058ed8f25d40278e 100644 (file)
--- a/gdb/rs6000-aix-tdep.c
+++ b/gdb/rs6000-aix-tdep.c
@@ -1025,7 +1025,11 @@ rs6000_software_single_step (struct regcache *regcache)
   if (!next_pcs.empty ())
     return next_pcs;
   
-  breaks[0] = loc + PPC_INSN_SIZE;
+  /* Here 0xfc000000 is the opcode mask to detect a P10 prefix instruction.  */
+  if ((insn & 0xfc000000) == 1 << 26)
+    breaks[0] = loc + 2 * PPC_INSN_SIZE;
+  else
+    breaks[0] = loc + PPC_INSN_SIZE;
   opcode = insn >> 26;
   breaks[1] = branch_dest (regcache, opcode, insn, loc, breaks[0]);