arch, cpu: Factor out the ExecContext into a proper base class

We currently generate and compile one version of the ISA code per CPU
model. This is obviously wasting a lot of resources at compile
time. This changeset factors out the interface into a separate
ExecContext class, which also serves as documentation for the
interface between CPUs and the ISA code. While doing so, this
changeset also fixes up interface inconsistencies between the
different CPU models.

The main argument for using one set of ISA code per CPU model has
always been performance as this avoid indirect branches in the
generated code. However, this argument does not hold water. Booting
Linux on a simulated ARM system running in atomic mode
(opt/10.linux-boot/realview-simple-atomic) is actually 2% faster
(compiled using clang 3.4) after applying this patch. Additionally,
compilation time is decreased by 35%.

1 files changed, 1 insertions, 63 deletions

diff --git a/src/cpu/SConscript b/src/cpu/SConscript
index 1ea92114a..5d9a48716 100644
--- a/src/cpu/SConscript
+++ b/src/cpu/SConscript
@@ -35,71 +35,8 @@ if env['TARGET_ISA'] == 'null':
     Source('intr_control_noisa.cc')
     Return()
 
-#################################################################
-#
-# Generate StaticInst execute() method signatures.
-#
-# There must be one signature for each CPU model compiled in.
-# Since the set of compiled-in models is flexible, we generate a
-# header containing the appropriate set of signatures on the fly.
-#
-#################################################################
-
-# Template for execute() signature.
-exec_sig_template = '''
-virtual Fault execute(%(type)s *xc, Trace::InstRecord *traceData) const = 0;
-virtual Fault eaComp(%(type)s *xc, Trace::InstRecord *traceData) const
-{ panic("eaComp not defined!"); M5_DUMMY_RETURN };
-virtual Fault initiateAcc(%(type)s *xc, Trace::InstRecord *traceData) const
-{ panic("initiateAcc not defined!"); M5_DUMMY_RETURN };
-virtual Fault completeAcc(Packet *pkt, %(type)s *xc,
-                          Trace::InstRecord *traceData) const
-{ panic("completeAcc not defined!"); M5_DUMMY_RETURN };
-'''
-
-mem_ini_sig_template = '''
-virtual Fault eaComp(%(type)s *xc, Trace::InstRecord *traceData) const
-{ panic("eaComp not defined!"); M5_DUMMY_RETURN };
-virtual Fault initiateAcc(%s *xc, Trace::InstRecord *traceData) const { panic("Not defined!"); M5_DUMMY_RETURN };
-'''
-
-mem_comp_sig_template = '''
-virtual Fault completeAcc(uint8_t *data, %s *xc, Trace::InstRecord *traceData) const { panic("Not defined!"); return NoFault; M5_DUMMY_RETURN };
-'''
-
-# Generate a temporary CPU list, including the CheckerCPU if
-# it's enabled.  This isn't used for anything else other than StaticInst
-# headers.
-temp_cpu_list = env['CPU_MODELS'][:]
-temp_cpu_list.append('CheckerCPU')
 SimObject('CheckerCPU.py')
 
-# Generate header.
-def gen_cpu_exec_signatures(target, source, env):
-    f = open(str(target[0]), 'w')
-    print >> f, '''
-#ifndef __CPU_STATIC_INST_EXEC_SIGS_HH__
-#define __CPU_STATIC_INST_EXEC_SIGS_HH__
-'''
-    for cpu in temp_cpu_list:
-        xc_type = CpuModel.dict[cpu].strings['CPU_exec_context']
-        print >> f, exec_sig_template % { 'type' : xc_type }
-    print >> f, '''
-#endif  // __CPU_STATIC_INST_EXEC_SIGS_HH__
-'''
-
-# Generate string that gets printed when header is rebuilt
-def gen_sigs_string(target, source, env):
-    return " [GENERATE] static_inst_exec_sigs.hh: " \
-           + ', '.join(temp_cpu_list)
-
-# Add command to generate header to environment.
-env.Command('static_inst_exec_sigs.hh', (),
-            Action(gen_cpu_exec_signatures, gen_sigs_string,
-                   varlist = temp_cpu_list))
-
-env.Depends('static_inst_exec_sigs.hh', Value(env['CPU_MODELS']))
-
 SimObject('BaseCPU.py')
 SimObject('FuncUnit.py')
 SimObject('ExeTracer.py')
@@ -112,6 +49,7 @@ Source('activity.cc')
 Source('base.cc')
 Source('cpuevent.cc')
 Source('exetrace.cc')
+Source('exec_context.cc')
 Source('func_unit.cc')
 Source('inteltrace.cc')
 Source('intr_control.cc')