gdb/

2010-06-14  Pedro Alves  <pedro@codesourcery.com>

	* NEWS: Mention GDBserver's JIT compilation of tracepoint
	bytecode.

gdb/gdbserver/
2010-06-14  Stan Shebs  <stan@codesourcery.com>
	    Pedro Alves  <pedro@codesourcery.com>

	Bytecode compiler.

	* linux-x86-low.c: Include limits.h.
	(add_insns): New.
	(always_true): New.
	(EMIT_ASM): New.
	(EMIT_ASM32): New.
	(amd64_emit_prologue, amd64_emit_epilogue, amd64_emit_add)
	(amd64_emit_sub, amd64_emit_mul, amd64_emit_lsh)
	(amd64_emit_rsh_signed, amd64_emit_rsh_unsigned, amd64_emit_ext,
	(amd64_emit_log_not, amd64_emit_bit_and, amd64_emit_bit_or)
	(amd64_emit_bit_xor, amd64_emit_bit_not, amd64_emit_equal,
	(amd64_emit_less_signed, amd64_emit_less_unsigned, amd64_emit_ref,
	(amd64_emit_if_goto, amd64_emit_goto, amd64_write_goto_address)
	(amd64_emit_const, amd64_emit_call, amd64_emit_reg)
	(amd64_emit_pop, amd64_emit_stack_flush, amd64_emit_zero_ext)
	(amd64_emit_swap, amd64_emit_stack_adjust, amd64_emit_int_call_1)
	(amd64_emit_void_call_2): New.
	(amd64_emit_ops): New.
	(i386_emit_prologue, i386_emit_epilogue, i386_emit_add)
	(i386_emit_sub,i386_emit_mul, i386_emit_lsh, i386_emit_rsh_signed)
	(i386_emit_rsh_unsigned, i386_emit_ext, i386_emit_log_not)
	(i386_emit_bit_and, i386_emit_bit_or, i386_emit_bit_xor)
	(i386_emit_bit_not, i386_emit_equal, i386_emit_less_signed)
	(i386_emit_less_unsigned, i386_emit_ref, i386_emit_if_goto)
	(i386_emit_goto, i386_write_goto_address, i386_emit_const)
	(i386_emit_call, i386_emit_reg, i386_emit_pop)
	(i386_emit_stack_flush, i386_emit_zero_ext, i386_emit_swap)
	(i386_emit_stack_adjust, i386_emit_int_call_1)
	(i386_emit_void_call_2): New.
	(i386_emit_ops): New.
	(x86_emit_ops): New.
	(the_low_target): Install x86_emit_ops.
	* server.h (struct emit_ops): New.
	(get_raw_reg_func_addr): Declare.
	(current_insn_ptr, emit_error): Declare.
	* tracepoint.c (get_raw_reg, get_trace_state_variable_value)
	(set_trace_state_variable_value): New defines.
	(struct ipa_sym_addresses): New fields addr_get_raw_reg,
	addr_get_trace_state_variable_value and
	addr_set_trace_state_variable_value.
	(symbol_list): New fields for get_raw_reg,
	get_trace_state_variable_value and set_trace_state_variable_value.
	(condfn): New typedef.
	(struct tracepoint): New field `compiled_cond'.
	(do_action_at_tracepoint): Clear compiled_cond.
	(get_trace_state_variable_value, set_trace_state_variable_value):
	Export in the IPA.
	(condition_true_at_tracepoint): If there's a compiled condition,
	run that.
	(current_insn_ptr, emit_error): New globals.
	(struct bytecode_address): New.
	(get_raw_reg_func_addr): New.
	(emit_prologue, emit_epilogue, emit_add, emit_sub, emit_mul)
	(emit_lsh, emit_rsh_signed, emit_rsh_unsigned, emit_ext)
	(emit_log_not, emit_bit_and, emit_bit_or, emit_bit_xor)
	(emit_bit_not, emit_equal, emit_less_signed, emit_less_unsigned)
	(emit_ref, emit_if_goto, emit_goto, write_goto_address, emit_const)
	(emit_reg, emit_pop, emit_stack_flush, emit_zero_ext, emit_swap)
	(emit_stack_adjust, emit_int_call_1, emit_void_call_2): New.
	(compile_tracepoint_condition, compile_bytecodes): New.
	* target.h (emit_ops): Forward declare.
	(struct target_ops): New field emit_ops.
	(target_emit_ops): New.
	* linux-amd64-ipa.c (gdb_agent_get_raw_reg): New.
	* linux-i386-ipa.c (gdb_agent_get_raw_reg): New.
	* linux-low.c (linux_emit_ops): New.
	(linux_target_ops): Install it.
	* linux-low.h (struct linux_target_ops): New field emit_ops.

1 files changed, 8 insertions, 1 deletions

diff --git a/gdb/NEWS b/gdb/NEWS
index 61208b1..af65274 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -36,7 +36,14 @@ qRelocInsn
   - GDBserver now support tracepoints (including fast tracepoints).
     The feature is currently supported by the i386-linux and
     amd64-linux builds.  See the "Tracepoints support in gdbserver"
-    section in the manual for more information.
+    section in the manual for more information.  GDBserver JIT
+    compiles the tracepoint's conditional agent expression bytecode
+    into native code whenever possible for low overhead dynamic
+    tracepoints conditionals.  For such tracepoints, an expression
+    that examines program state is evaluated when the tracepoint is
+    reached, in order to determine whether to capture trace data.  If
+    the condition is simple and false, processing the tracepoint
+    finishes very quickly and no data is gathered.
 
   - GDBserver now supports x86_64 Windows 64-bit debugging.