minor cleanup in ISACaller on result handling
[openpower-isa.git] / src / openpower / decoder / isa / caller.py
index 5c365befefeba92c456484acb6feee8122b6501a..94ac7c008366d5edc9a7fadd34e8033e135084df 100644 (file)
@@ -37,7 +37,7 @@ from openpower.decoder.power_enums import SVPtype
 from openpower.decoder.helpers import (exts, gtu, ltu, undefined,
                                        ISACallerHelper, ISAFPHelpers)
 from openpower.consts import PIb, MSRb  # big-endian (PowerISA versions)
-from openpower.consts import (SVP64MODE,
+from openpower.consts import (SVP64MODE, SVP64MODEb,
                               SVP64CROffs,
                               )
 from openpower.decoder.power_svp64 import SVP64RM, decode_extra
@@ -66,6 +66,9 @@ special_sprs = {
     'VRSAVE': 256}
 
 
+# rrright.  this is here basically because the compiler pywriter returns
+# results in a specific priority order.  to make sure regs match up they
+# need partial sorting. sigh.
 REG_SORT_ORDER = {
     # TODO (lkcl): adjust other registers that should be in a particular order
     # probably CA, CA32, and CR
@@ -279,33 +282,32 @@ class CRFields:
             _cr = FieldSelectableInt(self.cr, bits)
             self.crl.append(_cr)
 
-# decode SVP64 predicate integer to reg number and invert
-
 
+# decode SVP64 predicate integer to reg number and invert
 def get_predint(gpr, mask):
+    r3 = gpr(3)
     r10 = gpr(10)
     r30 = gpr(30)
     log("get_predint", mask, SVP64PredInt.ALWAYS.value)
     if mask == SVP64PredInt.ALWAYS.value:
         return 0xffff_ffff_ffff_ffff  # 64 bits of 1
     if mask == SVP64PredInt.R3_UNARY.value:
-        return 1 << (gpr(3).value & 0b111111)
+        return 1 << (r3.value & 0b111111)
     if mask == SVP64PredInt.R3.value:
-        return gpr(3).value
+        return r3.value
     if mask == SVP64PredInt.R3_N.value:
-        return ~gpr(3).value
+        return ~r3.value
     if mask == SVP64PredInt.R10.value:
-        return gpr(10).value
+        return r10.value
     if mask == SVP64PredInt.R10_N.value:
-        return ~gpr(10).value
+        return ~r10.value
     if mask == SVP64PredInt.R30.value:
-        return gpr(30).value
+        return r30.value
     if mask == SVP64PredInt.R30_N.value:
-        return ~gpr(30).value
-
-# decode SVP64 predicate CR to reg number and invert status
+        return ~r30.value
 
 
+# decode SVP64 predicate CR to reg number and invert status
 def _get_predcr(mask):
     if mask == SVP64PredCR.LT.value:
         return 0, 1
@@ -324,10 +326,9 @@ def _get_predcr(mask):
     if mask == SVP64PredCR.NS.value:
         return 3, 0
 
+
 # read individual CR fields (0..VL-1), extract the required bit
 # and construct the mask
-
-
 def get_predcr(crl, mask, vl):
     idx, noninv = _get_predcr(mask)
     mask = 0
@@ -536,12 +537,19 @@ class StepLoop:
 
     def __init__(self, svstate):
         self.svstate = svstate
-        self.loopend = False
+        self.new_iterators()
 
-    def get_iterators(self):
+    def new_iterators(self):
         self.src_it = self.src_iterator()
         self.dst_it = self.dst_iterator()
-
+        self.loopend = False
+        self.new_srcstep = 0
+        self.new_dststep = 0
+        self.new_ssubstep = 0
+        self.new_dsubstep = 0
+        self.pred_dst_zero = 0
+        self.pred_src_zero = 0
     def src_iterator(self):
         """source-stepping iterator
         """
@@ -550,12 +558,40 @@ class StepLoop:
         # source step
         if pack:
             # pack advances subvl in *outer* loop
-            if end_src:
-                if not end_ssub:
-                    self.svstate.ssubstep += SelectableInt(1, 2)
-                self.svstate.srcstep = SelectableInt(0, 7)  # reset
-            else:
-                self.svstate.srcstep += SelectableInt(1, 7)  # advance srcstep
+            while True:  # outer subvl loop
+                while True:  # inner vl loop
+                    vl = self.svstate.vl
+                    subvl = self.subvl
+                    srcmask = self.srcmask
+                    srcstep = self.svstate.srcstep
+                    pred_src_zero = ((1 << srcstep) & srcmask) != 0
+                    if self.pred_sz or pred_src_zero:
+                        self.pred_src_zero = not pred_src_zero
+                        log("    advance src", srcstep, vl,
+                            self.svstate.ssubstep, subvl)
+                        # yield actual substep/srcstep
+                        yield (self.svstate.ssubstep, srcstep)
+                    # the way yield works these could have been modified.
+                    vl = self.svstate.vl
+                    subvl = self.subvl
+                    srcstep = self.svstate.srcstep
+                    log("    advance src check", srcstep, vl,
+                        self.svstate.ssubstep, subvl, srcstep == vl-1,
+                        self.svstate.ssubstep == subvl)
+                    if srcstep == vl-1:  # end-point
+                        self.svstate.srcstep = SelectableInt(0, 7)  # reset
+                        if self.svstate.ssubstep == subvl:  # end-point
+                            log("    advance pack stop")
+                            return
+                        break # exit inner loop
+                    self.svstate.srcstep += SelectableInt(1, 7)  # advance ss
+                subvl = self.subvl
+                if self.svstate.ssubstep == subvl:  # end-point
+                    self.svstate.ssubstep = SelectableInt(0, 2)  # reset
+                    log("    advance pack stop")
+                    return
+                self.svstate.ssubstep += SelectableInt(1, 2)
+
         else:
             # these cannot be done as for-loops because SVSTATE may change
             # (srcstep/substep may be modified, interrupted, subvl/vl change)
@@ -563,22 +599,26 @@ class StepLoop:
             # "thing" is re-read every single time a yield gives indices
             while True:  # outer vl loop
                 while True:  # inner subvl loop
+                    vl = self.svstate.vl
                     subvl = self.subvl
                     srcmask = self.srcmask
                     srcstep = self.svstate.srcstep
-                    if self.pred_sz or ((1 << srcstep) & srcmask) != 0:
-                        log("    advance src", srcstep, self.svstate.vl,
+                    pred_src_zero = ((1 << srcstep) & srcmask) != 0
+                    if self.pred_sz or pred_src_zero:
+                        self.pred_src_zero = not pred_src_zero
+                        log("    advance src", srcstep, vl,
                             self.svstate.ssubstep, subvl)
                         # yield actual substep/srcstep
                         yield (self.svstate.ssubstep, srcstep)
                     if self.svstate.ssubstep == subvl:  # end-point
                         self.svstate.ssubstep = SelectableInt(0, 2)  # reset
-                        break
+                        break # exit inner loop
                     self.svstate.ssubstep += SelectableInt(1, 2)
                 vl = self.svstate.vl
                 if srcstep == vl-1:  # end-point
                     self.svstate.srcstep = SelectableInt(0, 7)  # reset
-                    break  # trigger StopIteration
+                    self.loopend = True
+                    return
                 self.svstate.srcstep += SelectableInt(1, 7)  # advance srcstep
 
     def dst_iterator(self):
@@ -589,7 +629,37 @@ class StepLoop:
         # dest step
         if unpack:
             # pack advances subvl in *outer* loop
-            pass  # TODO
+            while True:  # outer subvl loop
+                while True:  # inner vl loop
+                    vl = self.svstate.vl
+                    subvl = self.subvl
+                    dstmask = self.dstmask
+                    dststep = self.svstate.dststep
+                    pred_dst_zero = ((1 << dststep) & dstmask) != 0
+                    if self.pred_dz or pred_dst_zero:
+                        self.pred_dst_zero = not pred_dst_zero
+                        log("    advance dst", dststep, vl,
+                            self.svstate.dsubstep, subvl)
+                        # yield actual substep/dststep
+                        yield (self.svstate.dsubstep, dststep)
+                    # the way yield works these could have been modified.
+                    vl = self.svstate.vl
+                    dststep = self.svstate.dststep
+                    log("    advance dst check", dststep, vl,
+                        self.svstate.ssubstep, subvl)
+                    if dststep == vl-1:  # end-point
+                        self.svstate.dststep = SelectableInt(0, 7)  # reset
+                        if self.svstate.dsubstep == subvl:  # end-point
+                            log("    advance unpack stop")
+                            return
+                        break
+                    self.svstate.dststep += SelectableInt(1, 7)  # advance ds
+                subvl = self.subvl
+                if self.svstate.dsubstep == subvl:  # end-point
+                    self.svstate.dsubstep = SelectableInt(0, 2)  # reset
+                    log("    advance unpack stop")
+                    return
+                self.svstate.dsubstep += SelectableInt(1, 2)
         else:
             # these cannot be done as for-loops because SVSTATE may change
             # (dststep/substep may be modified, interrupted, subvl/vl change)
@@ -600,7 +670,9 @@ class StepLoop:
                     subvl = self.subvl
                     dstmask = self.dstmask
                     dststep = self.svstate.dststep
-                    if self.pred_dz or ((1 << dststep) & dstmask) != 0:
+                    pred_dst_zero = ((1 << dststep) & dstmask) != 0
+                    if self.pred_dz or pred_dst_zero:
+                        self.pred_dst_zero = not pred_dst_zero
                         log("    advance dst", dststep, self.svstate.vl,
                             self.svstate.dsubstep, subvl)
                         # yield actual substep/dststep
@@ -609,10 +681,11 @@ class StepLoop:
                         self.svstate.dsubstep = SelectableInt(0, 2)  # reset
                         break
                     self.svstate.dsubstep += SelectableInt(1, 2)
+                subvl = self.subvl
                 vl = self.svstate.vl
                 if dststep == vl-1:  # end-point
                     self.svstate.dststep = SelectableInt(0, 7)  # reset
-                    break  # trigger StopIteration
+                    return
                 self.svstate.dststep += SelectableInt(1, 7)  # advance dststep
 
     def src_iterate(self):
@@ -630,28 +703,51 @@ class StepLoop:
             "sub", end_ssub)
         # first source step
         srcstep = self.svstate.srcstep
+        srcmask = self.srcmask
         if pack:
             # pack advances subvl in *outer* loop
-            if end_src:
-                if end_ssub:
-                    self.loopend = True
+            while True:
+                assert srcstep <= vl-1
+                end_src = srcstep == vl-1
+                if end_src:
+                    if end_ssub:
+                        self.loopend = True
+                    else:
+                        self.svstate.ssubstep += SelectableInt(1, 2)
+                    srcstep = 0  # reset
+                    break
                 else:
-                    self.svstate.ssubstep += SelectableInt(1, 2)
-                self.svstate.srcstep = SelectableInt(0, 7)  # reset
-            else:
-                self.svstate.srcstep += SelectableInt(1, 7)  # advance srcstep
+                    srcstep += 1  # advance srcstep
+                    if not self.srcstep_skip:
+                        break
+                    if ((1 << srcstep) & srcmask) != 0:
+                        break
+                    else:
+                        log("      sskip", bin(srcmask), bin(1 << srcstep))
         else:
             # advance subvl in *inner* loop
             if end_ssub:
-                if end_src:  # end-point
-                    self.loopend = True
-                else:
-                    self.svstate.srcstep += SelectableInt(1, 7)
+                while True:
+                    assert srcstep <= vl-1
+                    end_src = srcstep == vl-1
+                    if end_src:  # end-point
+                        self.loopend = True
+                        srcstep = 0
+                        break
+                    else:
+                        srcstep += 1
+                    if not self.srcstep_skip:
+                        break
+                    if ((1 << srcstep) & srcmask) != 0:
+                        break
+                    else:
+                        log("      sskip", bin(srcmask), bin(1 << srcstep))
                 self.svstate.ssubstep = SelectableInt(0, 2)  # reset
             else:
                 # advance ssubstep
                 self.svstate.ssubstep += SelectableInt(1, 2)
 
+        self.svstate.srcstep = SelectableInt(srcstep, 7)
         log("    advance src", self.svstate.srcstep, self.svstate.ssubstep,
                                self.loopend)
 
@@ -664,32 +760,57 @@ class StepLoop:
         unpack = self.svstate.unpack
         dsubstep = self.svstate.dsubstep
         end_dsub = dsubstep == subvl
-        end_dst = self.svstate.dststep == vl-1
+        dststep = self.svstate.dststep
+        end_dst = dststep == vl-1
+        dstmask = self.dstmask
         log("    pack/unpack/subvl", pack, unpack, subvl,
             "end", end_dst,
             "sub", end_dsub)
         # now dest step
         if unpack:
             # unpack advances subvl in *outer* loop
-            if end_dst:
-                if end_dsub:
-                    self.loopend = True
+            while True:
+                assert dststep <= vl-1
+                end_dst = dststep == vl-1
+                if end_dst:
+                    if end_dsub:
+                        self.loopend = True
+                    else:
+                        self.svstate.dsubstep += SelectableInt(1, 2)
+                    dststep = 0  # reset
+                    break
                 else:
-                    self.svstate.dsubstep += SelectableInt(1, 2)
-                self.svstate.dststep = SelectableInt(0, 7)  # reset
-            else:
-                self.svstate.dststep += SelectableInt(1, 7)  # advance dststep
+                    dststep += 1  # advance dststep
+                    if not self.dststep_skip:
+                        break
+                    if ((1 << dststep) & dstmask) != 0:
+                        break
+                    else:
+                        log("      dskip", bin(dstmask), bin(1 << dststep))
         else:
             # advance subvl in *inner* loop
             if end_dsub:
-                if end_dst:  # end-point
-                    self.loopend = True
-                else:
-                    self.svstate.dststep += SelectableInt(1, 7)
+                while True:
+                    assert dststep <= vl-1
+                    end_dst = dststep == vl-1
+                    if end_dst:  # end-point
+                        self.loopend = True
+                        dststep = 0
+                        break
+                    else:
+                        dststep += 1
+                    if not self.dststep_skip:
+                        break
+                    if ((1 << dststep) & dstmask) != 0:
+                        break
+                    else:
+                        log("      dskip", bin(dstmask), bin(1 << dststep))
                 self.svstate.dsubstep = SelectableInt(0, 2)  # reset
             else:
                 # advance ssubstep
                 self.svstate.dsubstep += SelectableInt(1, 2)
+
+        self.svstate.dststep = SelectableInt(dststep, 7)
         log("    advance dst", self.svstate.dststep, self.svstate.dsubstep,
                                self.loopend)
 
@@ -714,6 +835,8 @@ class StepLoop:
         TODO when Pack/Unpack is set, substep becomes the *outer* loop
         """
         self.subvl = yield self.dec2.rm_dec.rm_in.subvl
+        if self.loopend: # huhn??
+            return
         self.src_iterate()
         self.dst_iterate()
 
@@ -805,6 +928,7 @@ class StepLoop:
         it is purely for skipping masked-out bits
         """
 
+        self.subvl = yield self.dec2.rm_dec.rm_in.subvl
         yield from self.read_src_mask()
         yield from self.read_dst_mask()
 
@@ -819,6 +943,9 @@ class StepLoop:
         vl = self.svstate.vl
         # srcstep-skipping opportunity identified
         if self.srcstep_skip:
+            # cannot do this with sv.bc - XXX TODO
+            if srcmask == 0:
+                self.loopend = True
             while (((1 << srcstep) & srcmask) == 0) and (srcstep != vl):
                 log("      sskip", bin(1 << srcstep))
                 srcstep += 1
@@ -839,6 +966,9 @@ class StepLoop:
         pred_dst_zero = self.pred_dz
         vl = self.svstate.vl
         if self.dststep_skip:
+            # cannot do this with sv.bc - XXX TODO
+            if dstmask == 0:
+                self.loopend = True
             while (((1 << dststep) & dstmask) == 0) and (dststep != vl):
                 log("      dskip", bin(1 << dststep))
                 dststep += 1
@@ -922,10 +1052,7 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         # set up 4 dummy SVSHAPEs if they aren't already set up
         for i in range(4):
             sname = 'SVSHAPE%d' % i
-            if sname not in self.spr:
-                val = 0
-            else:
-                val = self.spr[sname].value
+            val = self.spr.get(sname, 0)
             # make sure it's an SVSHAPE
             self.spr[sname] = SVSHAPE(val, self.gpr)
         self.last_op_svshape = False
@@ -1097,13 +1224,15 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         if self.is_svp64_mode and insn_name.startswith("sv.bc"):
             # blegh grab bits manually
             mode = yield self.dec2.rm_dec.rm_in.mode
-            bc_vlset = (mode & SVP64MODE.BC_VLSET) != 0
-            bc_vli = (mode & SVP64MODE.BC_VLI) != 0
-            bc_snz = (mode & SVP64MODE.BC_SNZ) != 0
+            mode = SelectableInt(mode, 5) # convert to SelectableInt before test
+            bc_vlset = mode[SVP64MODEb.BC_VLSET] != 0
+            bc_vli = mode[SVP64MODEb.BC_VLI] != 0
+            bc_snz = mode[SVP64MODEb.BC_SNZ] != 0
             bc_vsb = yield self.dec2.rm_dec.bc_vsb
             bc_lru = yield self.dec2.rm_dec.bc_lru
             bc_gate = yield self.dec2.rm_dec.bc_gate
             sz = yield self.dec2.rm_dec.pred_sz
+            self.namespace['mode'] = SelectableInt(mode, 5)
             self.namespace['ALL'] = SelectableInt(bc_gate, 1)
             self.namespace['VSb'] = SelectableInt(bc_vsb, 1)
             self.namespace['LRu'] = SelectableInt(bc_lru, 1)
@@ -1112,7 +1241,7 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
             self.namespace['sz'] = SelectableInt(sz, 1)
             self.namespace['SNZ'] = SelectableInt(bc_snz, 1)
 
-    def handle_carry_(self, inputs, outputs, already_done):
+    def handle_carry_(self, inputs, output, ca, ca32):
         inv_a = yield self.dec2.e.do.invert_in
         if inv_a:
             inputs[0] = ~inputs[0]
@@ -1121,12 +1250,6 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         if imm_ok:
             imm = yield self.dec2.e.do.imm_data.data
             inputs.append(SelectableInt(imm, 64))
-        assert len(outputs) >= 1
-        log("outputs", repr(outputs))
-        if isinstance(outputs, list) or isinstance(outputs, tuple):
-            output = outputs[0]
-        else:
-            output = outputs
         gts = []
         for x in inputs:
             log("gt input", x, output)
@@ -1135,10 +1258,9 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         log(gts)
         cy = 1 if any(gts) else 0
         log("CA", cy, gts)
-        if not (1 & already_done):
+        if ca is None: # already written
             self.spr['XER'][XER_bits['CA']] = cy
 
-        log("inputs", already_done, inputs)
         # 32 bit carry
         # ARGH... different for OP_ADD... *sigh*...
         op = yield self.dec2.e.do.insn_type
@@ -1161,10 +1283,10 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
                 gts.append(gt)
             cy32 = 1 if any(gts) else 0
             log("CA32", cy32, gts)
-        if not (2 & already_done):
+        if ca32 is None: # already written
             self.spr['XER'][XER_bits['CA32']] = cy32
 
-    def handle_overflow(self, inputs, outputs, div_overflow):
+    def handle_overflow(self, inputs, output, div_overflow):
         if hasattr(self.dec2.e.do, "invert_in"):
             inv_a = yield self.dec2.e.do.invert_in
             if inv_a:
@@ -1174,8 +1296,7 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         if imm_ok:
             imm = yield self.dec2.e.do.imm_data.data
             inputs.append(SelectableInt(imm, 64))
-        assert len(outputs) >= 1
-        log("handle_overflow", inputs, outputs, div_overflow)
+        log("handle_overflow", inputs, output, div_overflow)
         if len(inputs) < 2 and div_overflow is None:
             return
 
@@ -1185,8 +1306,6 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
             ov, ov32 = div_overflow, div_overflow
         # arithmetic overflow can be done by analysing the input and output
         elif len(inputs) >= 2:
-            output = outputs[0]
-
             # OV (64-bit)
             input_sgn = [exts(x.value, x.bits) < 0 for x in inputs]
             output_sgn = exts(output.value, output.bits) < 0
@@ -1207,8 +1326,7 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         self.spr['XER'][XER_bits['SO']] = new_so
         log("    set overflow", ov, ov32, so, new_so)
 
-    def handle_comparison(self, outputs, cr_idx=0, overflow=None, no_so=False):
-        out = outputs[0]
+    def handle_comparison(self, out, cr_idx=0, overflow=None, no_so=False):
         assert isinstance(out, SelectableInt), \
             "out zero not a SelectableInt %s" % repr(outputs)
         log("handle_comparison", out.bits, hex(out.value))
@@ -1303,18 +1421,14 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         """execute one instruction
         """
         # get the disassembly code for this instruction
-        if self.is_svp64_mode:
-            if not self.disassembly:
-                code = yield from self.get_assembly_name()
-            else:
-                code = self.disassembly[self._pc+4]
-            log("    svp64 sim-execute", hex(self._pc), code)
+        if not self.disassembly:
+            code = yield from self.get_assembly_name()
         else:
-            if not self.disassembly:
-                code = yield from self.get_assembly_name()
-            else:
-                code = self.disassembly[self._pc]
-            log("sim-execute", hex(self._pc), code)
+            offs, dbg = 0, ""
+            if self.is_svp64_mode:
+               offs, dbg = 4, "svp64 "
+            code = self.disassembly[self._pc+offs]
+            log("    %s sim-execute" % dbg, hex(self._pc), code)
         opname = code.split(' ')[0]
         try:
             yield from self.call(opname)         # execute the instruction
@@ -1418,6 +1532,10 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
                 asmop = 'mtcrf'
         return asmop
 
+    def reset_remaps(self):
+        self.remap_loopends = [0] * 4
+        self.remap_idxs = [0, 1, 2, 3]
+
     def get_remap_indices(self):
         """WARNING, this function stores remap_idxs and remap_loopends
         in the class for later use.  this to avoid problems with yield
@@ -1425,6 +1543,7 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         # go through all iterators in lock-step, advance to next remap_idx
         srcstep, dststep, ssubstep, dsubstep = self.get_src_dststeps()
         # get four SVSHAPEs. here we are hard-coding
+        self.reset_remaps()
         SVSHAPE0 = self.spr['SVSHAPE0']
         SVSHAPE1 = self.spr['SVSHAPE1']
         SVSHAPE2 = self.spr['SVSHAPE2']
@@ -1436,8 +1555,6 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
                   (SVSHAPE3, SVSHAPE3.get_iterator()),
                   ]
 
-        self.remap_loopends = [0] * 4
-        self.remap_idxs = [0, 1, 2, 3]
         dbg = []
         for i, (shape, remap) in enumerate(remaps):
             # zero is "disabled"
@@ -1521,7 +1638,8 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
                        'svshape', 'svshape2',
                        'grev', 'ternlogi', 'bmask', 'cprop',
                        'absdu', 'absds', 'absdacs', 'absdacu', 'avgadd',
-                       'fmvis', 'fishmv', 'pcdec'
+                       'fmvis', 'fishmv', 'pcdec', "maddedu", "divmod2du",
+                       "dsld", "dsrd",
                        ]:
             illegal = False
             ins_name = dotstrp
@@ -1573,6 +1691,7 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         log("sv rm", sv_rm, dest_cr, src_cr, src_byname, dest_byname)
 
         # see if srcstep/dststep need skipping over masked-out predicate bits
+        self.reset_remaps()
         if (self.is_svp64_mode or ins_name in ['setvl', 'svremap', 'svstate']):
             yield from self.svstate_pre_inc()
         if self.is_svp64_mode:
@@ -1655,14 +1774,17 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         # the ALL/ANY mode we can early-exit
         if self.is_svp64_mode and ins_name.startswith("sv.bc"):
             no_in_vec = yield self.dec2.no_in_vec  # BI is scalar
-            # XXX TODO - pack/unpack here
             end_loop = no_in_vec or srcstep == vl-1 or dststep == vl-1
             self.namespace['end_loop'] = SelectableInt(end_loop, 1)
 
         # execute actual instruction here (finally)
         log("inputs", inputs)
         results = info.func(self, *inputs)
-        log("results", results)
+        output_names = create_args(info.write_regs)
+        outs = {}
+        for out, n in zip(results or [], output_names):
+            outs[n] = out
+        log("results", outs)
 
         # "inject" decorator takes namespace from function locals: we need to
         # overwrite NIA being overwritten (sigh)
@@ -1683,34 +1805,18 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
             self.last_st_addr, self.last_ld_addr)
 
         # detect if CA/CA32 already in outputs (sra*, basically)
-        already_done = 0
-        output_names = []
-        if info.write_regs:
-            output_names = create_args(info.write_regs)
-            for name in output_names:
-                if name == 'CA':
-                    already_done |= 1
-                if name == 'CA32':
-                    already_done |= 2
-
-        log("carry already done?", bin(already_done), output_names)
+        ca = outs.get("CA")
+        ca32 = outs.get("CA32 ")
+
+        log("carry already done?", ca, ca32, output_names)
         carry_en = yield self.dec2.e.do.output_carry
         if carry_en:
-            yield from self.handle_carry_(inputs, results, already_done)
+            yield from self.handle_carry_(inputs, results[0], ca, ca32)
 
         # check if one of the regs was named "overflow"
-        overflow = None
-        if info.write_regs:
-            for name, output in zip(output_names, results):
-                if name == 'overflow':
-                    overflow = output
-
+        overflow = outs.get('overflow')
         # and one called CR0
-        cr0 = None
-        if info.write_regs:
-            for name, output in zip(output_names, results):
-                if name == 'CR0':
-                    cr0 = output
+        cr0 = outs.get('CR0')
 
         if not self.is_svp64_mode:  # yeah just no. not in parallel processing
             # detect if overflow was in return result
@@ -1718,7 +1824,7 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
             ov_ok = yield self.dec2.e.do.oe.ok
             log("internal overflow", ins_name, overflow, "en?", ov_en, ov_ok)
             if ov_en & ov_ok:
-                yield from self.handle_overflow(inputs, results, overflow)
+                yield from self.handle_overflow(inputs, results[0], overflow)
 
         # only do SVP64 dest predicated Rc=1 if dest-pred is not enabled
         rc_en = False
@@ -1729,9 +1835,18 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         # XXX TODO: now that CR0 is supported, sort out svstep's pseudocode
         # to write directly to CR0 instead of in ISACaller. hooyahh.
         if rc_en and ins_name not in ['svstep']:
-            yield from self.do_rc_ov(ins_name, results, overflow, cr0)
+            yield from self.do_rc_ov(ins_name, results[0], overflow, cr0)
 
         # check failfirst
+        ffirst_hit = False
+        if self.is_svp64_mode:
+            ffirst_hit = (yield from self.check_ffirst(rc_en, srcstep))
+
+        # any modified return results?
+        yield from self.do_outregs_nia(asmop, ins_name, info, outs,
+                                       carry_en, rc_en, ffirst_hit)
+
+    def check_ffirst(self, rc_en, srcstep):
         rm_mode = yield self.dec2.rm_dec.mode
         ff_inv = yield self.dec2.rm_dec.inv
         cr_bit = yield self.dec2.rm_dec.cr_sel
@@ -1742,60 +1857,54 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         log("        RC1", RC1)
         log("        vli", vli)
         log("     cr_bit", cr_bit)
-        ffirst_hit = False
-        if rc_en and rm_mode == SVP64RMMode.FFIRST.value:
-            regnum, is_vec = yield from get_pdecode_cr_out(self.dec2, "CR0")
-            crtest = self.crl[regnum]
-            ffirst_hit = crtest[cr_bit] != ff_inv
-            log("cr test", regnum, int(crtest), crtest, cr_bit, ff_inv)
-            log("cr test?", ffirst_hit)
-            if ffirst_hit:
-                vli = SelectableInt(int(vli), 7)
-                self.svstate.vl = srcstep + vli
-                yield self.dec2.state.svstate.eq(self.svstate.value)
-                yield Settle()  # let decoder update
-
-        # any modified return results?
-        yield from self.do_outregs_nia(asmop, ins_name, info,
-                                       output_names, results,
-                                       carry_en, rc_en, ffirst_hit)
+        if not rc_en or rm_mode != SVP64RMMode.FFIRST.value:
+            return False
+        regnum, is_vec = yield from get_pdecode_cr_out(self.dec2, "CR0")
+        crtest = self.crl[regnum]
+        ffirst_hit = crtest[cr_bit] != ff_inv
+        log("cr test", regnum, int(crtest), crtest, cr_bit, ff_inv)
+        log("cr test?", ffirst_hit)
+        if not ffirst_hit:
+            return False
+        vli = SelectableInt(int(vli), 7)
+        self.svstate.vl = srcstep + vli
+        yield self.dec2.state.svstate.eq(self.svstate.value)
+        yield Settle()  # let decoder update
+        return True
 
-    def do_rc_ov(self, ins_name, results, overflow, cr0):
+    def do_rc_ov(self, ins_name, result, overflow, cr0):
         if ins_name.startswith("f"):
             rc_reg = "CR1"  # not calculated correctly yet (not FP compares)
         else:
             rc_reg = "CR0"
         regnum, is_vec = yield from get_pdecode_cr_out(self.dec2, rc_reg)
-        cmps = results
         # hang on... for `setvl` actually you want to test SVSTATE.VL
         is_setvl = ins_name == 'setvl'
         if is_setvl:
-            vl = results[0].vl
-            cmps = (SelectableInt(vl, 64), overflow,)
+            result = SelectableInt(result.vl, 64)
         else:
             overflow = None  # do not override overflow except in setvl
 
         # if there was not an explicit CR0 in the pseudocode, do implicit Rc=1
         if cr0 is None:
-            self.handle_comparison(cmps, regnum, overflow, no_so=is_setvl)
+            self.handle_comparison(result, regnum, overflow, no_so=is_setvl)
         else:
             # otherwise we just blat CR0 into the required regnum
             log("explicit rc0", cr0)
             self.crl[regnum].eq(cr0)
 
-    def do_outregs_nia(self, asmop, ins_name, info, output_names, results,
+    def do_outregs_nia(self, asmop, ins_name, info, outs,
                        carry_en, rc_en, ffirst_hit):
         # write out any regs for this instruction
-        if info.write_regs:
-            for name, output in zip(output_names, results):
-                yield from self.check_write(info, name, output, carry_en)
+        for name, output in outs.items():
+            yield from self.check_write(info, name, output, carry_en)
 
         if ffirst_hit:
             self.svp64_reset_loop()
             nia_update = True
         else:
             # check advancement of src/dst/sub-steps and if PC needs updating
-            nia_update = (yield from self.check_step_increment(results, rc_en,
+            nia_update = (yield from self.check_step_increment(rc_en,
                                                            asmop, ins_name))
         if nia_update:
             self.update_pc_next()
@@ -1979,7 +2088,7 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         else:
             self.gpr[regnum] = output
 
-    def check_step_increment(self, results, rc_en, asmop, ins_name):
+    def check_step_increment(self, rc_en, asmop, ins_name):
         # check if it is the SVSTATE.src/dest step that needs incrementing
         # this is our Sub-Program-Counter loop from 0 to VL-1
         if not self.allow_next_step_inc:
@@ -2011,8 +2120,7 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
             self.update_nia()
             if not rc_en:
                 return True
-            results = [SelectableInt(0, 64)]
-            self.handle_comparison(results)  # CR0
+            self.handle_comparison(SelectableInt(0, 64))  # CR0
             return True
         if self.allow_next_step_inc == 2:
             log("SVSTATE_NEXT: read")
@@ -2083,19 +2191,23 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
         return (self.new_srcstep, self.new_dststep,
                 self.new_ssubstep, self.new_dsubstep)
 
-    def update_new_svstate_steps(self):
-        # note, do not get the bit-reversed srcstep here!
-        srcstep, dststep = self.new_srcstep, self.new_dststep
-        ssubstep, dsubstep = self.new_ssubstep, self.new_dsubstep
-
-        # update SVSTATE with new srcstep
-        self.svstate.srcstep = srcstep
-        self.svstate.dststep = dststep
-        self.svstate.ssubstep = ssubstep
-        self.svstate.dsubstep = dsubstep
+    def update_svstate_namespace(self, overwrite_svstate=True):
+        if overwrite_svstate:
+            # note, do not get the bit-reversed srcstep here!
+            srcstep, dststep = self.new_srcstep, self.new_dststep
+            ssubstep, dsubstep = self.new_ssubstep, self.new_dsubstep
+
+            # update SVSTATE with new srcstep
+            self.svstate.srcstep = srcstep
+            self.svstate.dststep = dststep
+            self.svstate.ssubstep = ssubstep
+            self.svstate.dsubstep = dsubstep
         self.namespace['SVSTATE'] = self.svstate
         yield self.dec2.state.svstate.eq(self.svstate.value)
         yield Settle()  # let decoder update
+
+    def update_new_svstate_steps(self, overwrite_svstate=True):
+        yield from self.update_svstate_namespace(overwrite_svstate)
         srcstep = self.svstate.srcstep
         dststep = self.svstate.dststep
         ssubstep = self.svstate.ssubstep
@@ -2121,6 +2233,8 @@ class ISACaller(ISACallerHelper, ISAFPHelpers, StepLoop):
 
         # check if end reached (we let srcstep overrun, above)
         # nothing needs doing (TODO zeroing): just do next instruction
+        if self.loopend:
+            return True
         return ((ssubstep == subvl and srcstep == vl) or
                 (dsubstep == subvl and dststep == vl))