disasm: add struct disasm_insn to describe to-be-disassembled instruction

The "record instruction-history" command prints for each instruction in
addition to the instruction's disassembly:

  - the instruction number in the recorded execution trace
  - a '?' before the instruction if it was executed speculatively

To allow the "record instruction-history" command to use GDB's disassembly
infrastructure, we extend gdb_pretty_print_insn to optionally print those
additional fields and export the function.

Add a new struct disasm_insn to add additional fields describing the
to-be-disassembled instruction.  The additional fields are:

  number            an optional instruction number, zero if omitted.
  is_speculative    a predicate saying whether the instruction was
                    executed speculatively.

If non-zero, the instruction number is printed first.  It will also appear
as a new optional field "insn-number" in MI.  The field will be present if
insn_num is non-zero.

If is_speculative is set, speculative execution will be indicated by a "?"
following the new instruction number field.  Unless the PC is omitted, it
will overwrite the first byte of the PC prefix.  It will appear as a new
optional field "is-speculative" in MI.  The field will contain "?" and will
be present if is_speculative is set.

The speculative execution indication is guarded by a new flag
DISASSEMBLY_SPECULATION.

Replace the PC parameter of gdb_pretty_print_insn with a pointer to the above
struct.  GDB's "disassemble" command does not use the new fields.

gdb/
	* disasm.h (DISASSEMBLY_SPECULATION): New.
	(struct disasm_insn): New.
	(gdb_pretty_print_insn): New.
	* disasm.c (gdb_pretty_print_insn): Replace parameter PC with INSN.
	Update users.  Print instruction number and indicate speculative
	execution, if requested.

1 files changed, 23 insertions, 0 deletions

diff --git a/gdb/disasm.h b/gdb/disasm.h
index 7e6f1a2..32b64ff 100644
--- a/gdb/disasm.h
+++ b/gdb/disasm.h
@@ -27,11 +27,34 @@
 #define DISASSEMBLY_FILENAME	(0x1 << 3)
 #define DISASSEMBLY_OMIT_PC	(0x1 << 4)
 #define DISASSEMBLY_SOURCE	(0x1 << 5)
+#define DISASSEMBLY_SPECULATIVE	(0x1 << 6)
 
 struct gdbarch;
 struct ui_out;
 struct ui_file;
 
+/* An instruction to be disassembled.  */
+
+struct disasm_insn
+{
+  /* The address of the memory containing the instruction.  */
+  CORE_ADDR addr;
+
+  /* An optional instruction number.  If non-zero, it is printed first.  */
+  unsigned int number;
+
+  /* True if the instruction was executed speculatively.  */
+  unsigned int is_speculative:1;
+};
+
+/* Prints the instruction INSN into UIOUT and returns the length of the
+   printed instruction in bytes.  */
+
+extern int gdb_pretty_print_insn (struct gdbarch *gdbarch, struct ui_out *uiout,
+				  struct disassemble_info * di,
+				  const struct disasm_insn *insn, int flags,
+				  struct ui_file *stb);
+
 /* Return a filled in disassemble_info object for use by gdb.  */
 
 extern struct disassemble_info gdb_disassemble_info (struct gdbarch *gdbarch,