arch: Remove plumbing for operand predication.

The operand predication mechanism has been replaced by mapping
predicate-false register reads/writes to InvalidRegClass.

Change-Id: I57e7aadb7a0d682c225f6a5fe673cba8ddf1c4f8
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/49749
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/src/arch/arm/isa/operands.isa b/src/arch/arm/isa/operands.isa
index a7ce94f..f0a4c62 100644
--- a/src/arch/arm/isa/operands.isa
+++ b/src/arch/arm/isa/operands.isa
@@ -109,12 +109,12 @@
 
     class IntReg(IntRegNPC):
         @overrideInOperand
-        def makeRead(self, predRead, op_idx):
+        def makeRead(self, op_idx):
             '''Maybe PC read'''
             return f'{self.base_name} = ({self.reg_spec} == PCReg) ? ' \
                    f'readPC(xc) : xc->getRegOperand(this, {op_idx});\n'
         @overrideInOperand
-        def makeWrite(self, predWrite, op_idx):
+        def makeWrite(self, op_idx):
             '''Maybe PC write'''
             return f'''
             if ({self.reg_spec} == PCReg)
@@ -131,7 +131,7 @@
 
     class IntRegAPC(IntReg):
         @overrideInOperand
-        def makeRead(self, predRead, op_idx):
+        def makeRead(self, op_idx):
             '''Maybe aligned PC read'''
             return f'{self.base_name} = ({self.reg_spec} == PCReg) ? ' \
                    f'(roundDown(readPC(xc), 4)) : ' \
@@ -139,7 +139,7 @@
 
     class IntRegIWPC(IntReg):
         @overrideInOperand
-        def makeWrite(self, predWrite, op_idx):
+        def makeWrite(self, op_idx):
             '''Maybe interworking PC write'''
             return f'''
             if ({self.reg_spec} == PCReg)
@@ -152,7 +152,7 @@
 
     class IntRegAIWPC(IntReg):
         @overrideInOperand
-        def makeWrite(self, predWrite, op_idx):
+        def makeWrite(self, op_idx):
             '''Maybe aligned interworking PC write'''
             return f'''
             if ({self.reg_spec} == PCReg) {"{"}
@@ -173,12 +173,12 @@
             return f'gem5::ArmISA::couldBeZero({self.reg_spec}) ? RegId() : ' \
                    f'RegId({self.reg_class}, {self.reg_spec})'
         @overrideInOperand
-        def makeRead(self, predRead, op_idx):
+        def makeRead(self, op_idx):
             '''aarch64 read'''
             return f'{self.base_name} = ' \
                    f'(xc->getRegOperand(this, {op_idx})) & mask(intWidth);\n'
         @overrideInOperand
-        def makeWrite(self, predWrite, op_idx):
+        def makeWrite(self, op_idx):
             '''aarch64 write'''
             return f'''
             xc->setRegOperand(this, {op_idx}, {self.base_name} &
@@ -191,13 +191,13 @@
 
     class IntRegX64(IntReg64):
         @overrideInOperand
-        def makeRead(self, predRead, op_idx):
+        def makeRead(self, op_idx):
             '''Maybe masked to 32 bit read'''
             return f'{self.base_name} = ' \
                    f'(xc->getRegOperand(this, {op_idx}) & ' \
                     'mask(aarch64 ? 64 : 32));\n'
         @overrideInOperand
-        def makeWrite(self, predWrite, op_idx):
+        def makeWrite(self, op_idx):
             '''Maybe masked to 32 bit write'''
             return f'''
             xc->setRegOperand(this, {op_idx}, {self.base_name} &
@@ -208,12 +208,12 @@
 
     class IntRegW64(IntReg64):
         @overrideInOperand
-        def makeRead(self, predRead, op_idx):
+        def makeRead(self, op_idx):
             '''Masked to 32 bit read'''
             return f'{self.base_name} = ' \
                    f'(xc->getRegOperand(this, {op_idx})) & mask(32);\n'
         @overrideInOperand
-        def makeWrite(self, predWrite, op_idx):
+        def makeWrite(self, op_idx):
             '''Masked to 32 bit write'''
             return f'''
             xc->setRegOperand(this, {op_idx}, {self.base_name} & mask(32));
@@ -235,11 +235,11 @@
 
     class CntrlNsBankedReg(CntrlReg):
         @overrideInOperand
-        def makeRead(self, predRead, op_idx):
+        def makeRead(self, op_idx):
             return f'{self.base_name} = ' \
                    f'xc->readMiscReg(snsBankedIndex(op1, xc->tcBase()));\n'
         @overrideInOperand
-        def makeWrite(self, predWrite, op_idx):
+        def makeWrite(self, op_idx):
             return f'''
             xc->setMiscReg(snsBankedIndex(dest, xc->tcBase()),
                            {self.base_name});
diff --git a/src/arch/isa_parser/isa_parser.py b/src/arch/isa_parser/isa_parser.py
index 6a81fbe..d33bcc4 100755
--- a/src/arch/isa_parser/isa_parser.py
+++ b/src/arch/isa_parser/isa_parser.py
@@ -127,17 +127,6 @@
             if operands.readPC or operands.setPC:
                 myDict['op_decl'] += pcstate_decl
 
-            # In case there are predicated register reads and write, declare
-            # the variables for register indicies. It is being assumed that
-            # all the operands in the OperandList are also in the
-            # SubOperandList and in the same order. Otherwise, it is
-            # expected that predication would not be used for the operands.
-            if operands.predRead:
-                myDict['op_decl'] += 'uint8_t _sourceIndex = 0;\n'
-            if operands.predWrite:
-                myDict['op_decl'] += \
-                    '[[maybe_unused]] uint8_t _destIndex = 0;\n'
-
             is_src = lambda op: op.is_src
             is_dest = lambda op: op.is_dest
 
diff --git a/src/arch/isa_parser/operand_list.py b/src/arch/isa_parser/operand_list.py
index c26fdf3..3438777 100755
--- a/src/arch/isa_parser/operand_list.py
+++ b/src/arch/isa_parser/operand_list.py
@@ -122,15 +122,10 @@
 
         self.memOperand = mem[0] if mem else None
 
-        # Flags to keep track if one or more operands are to be read/written
-        # conditionally.
-        self.predRead = any(i.hasReadPred() for i in self.items)
-        self.predWrite = any(i.hasWritePred() for i in self.items)
-
         # now make a final pass to finalize op_desc fields that may depend
         # on the register enumeration
         for op_desc in self.items:
-            op_desc.finalize(self.predRead, self.predWrite)
+            op_desc.finalize()
 
     def __len__(self):
         return len(self.items)
@@ -235,8 +230,3 @@
         self.pcPart = None
         if part: self.pcPart = True
         if whole: self.pcPart = False
-
-        # Flags to keep track if one or more operands are to be read/written
-        # conditionally.
-        self.predRead = any(i.hasReadPred() for i in self.items)
-        self.predWrite = any(i.hasWritePred() for i in self.items)
diff --git a/src/arch/isa_parser/operand_types.py b/src/arch/isa_parser/operand_types.py
index 897235a..4de7121 100755
--- a/src/arch/isa_parser/operand_types.py
+++ b/src/arch/isa_parser/operand_types.py
@@ -45,7 +45,7 @@
 
 class OperandDesc(object):
     def __init__(self, base_cls, dflt_ext, reg_spec, flags=None,
-            sort_pri=None, read_predicate=None, write_predicate=None):
+            sort_pri=None):
 
         from .isa_parser import makeList
 
@@ -96,8 +96,6 @@
             'reg_spec': reg_spec,
             'flags': flags,
             'sort_pri': sort_pri,
-            'read_predicate': read_predicate,
-            'write_predicate': write_predicate,
         })
         self.attrs = attrs
 
@@ -143,35 +141,29 @@
     # Finalize additional fields (primarily code fields).  This step
     # is done separately since some of these fields may depend on the
     # register index enumeration that hasn't been performed yet at the
-    # time of __init__(). The register index enumeration is affected
-    # by predicated register reads/writes. Hence, we forward the flags
-    # that indicate whether or not predication is in use.
-    def finalize(self, pred_read, pred_write):
+    # time of __init__().
+    def finalize(self):
         self.flags = self.getFlags()
-        self.constructor = self.makeConstructor(pred_read, pred_write)
+        self.constructor = self.makeConstructor()
         self.op_decl = self.makeDecl()
 
         if self.is_src:
-            if pred_read:
-                op_idx = '_sourceIndex++'
-            elif hasattr(self, 'src_reg_idx'):
+            if hasattr(self, 'src_reg_idx'):
                 op_idx = str(self.src_reg_idx)
             else:
                 op_idx = None
-            self.op_rd = self.makeRead(pred_read, op_idx)
+            self.op_rd = self.makeRead(op_idx)
             self.op_src_decl = self.makeDecl()
         else:
             self.op_rd = ''
             self.op_src_decl = ''
 
         if self.is_dest:
-            if pred_read:
-                op_idx = '_destIndex++'
-            elif hasattr(self, 'dest_reg_idx'):
+            if hasattr(self, 'dest_reg_idx'):
                 op_idx = str(self.dest_reg_idx)
             else:
                 op_idx = None
-            self.op_wb = self.makeWrite(pred_write, op_idx)
+            self.op_wb = self.makeWrite(op_idx)
             self.op_dest_decl = self.makeDecl()
         else:
             self.op_wb = ''
@@ -189,12 +181,6 @@
     def isPCPart(self):
         return self.isPCState() and self.reg_spec
 
-    def hasReadPred(self):
-        return self.read_predicate != None
-
-    def hasWritePred(self):
-        return self.write_predicate != None
-
     def getFlags(self):
         # note the empty slice '[:]' gives us a copy of self.flags[0]
         # instead of a reference to it
@@ -214,27 +200,21 @@
     def isReg(self):
         return 1
 
-    def makeConstructor(self, pred_read, pred_write):
+    def makeConstructor(self):
         c_src = ''
         c_dest = ''
 
         if self.is_src:
             c_src = self.src_reg_constructor % self.srcRegId()
-            if self.hasReadPred():
-                c_src = '\n\tif (%s) {%s\n\t}' % \
-                        (self.read_predicate, c_src)
 
         if self.is_dest:
             c_dest = self.dst_reg_constructor % self.destRegId()
             c_dest += f'\n\t_numTypedDestRegs[{self.reg_class}]++;'
-            if self.hasWritePred():
-                c_dest = '\n\tif (%s) {%s\n\t}' % \
-                         (self.write_predicate, c_dest)
 
         return c_src + c_dest
 
 class RegValOperand(RegOperand):
-    def makeRead(self, pred_read, op_idx):
+    def makeRead(self, op_idx):
         reg_val = f'xc->getRegOperand(this, {op_idx})'
 
         if self.ctype == 'float':
@@ -242,12 +222,9 @@
         elif self.ctype == 'double':
             reg_val = f'bitsToFloat64({reg_val})'
 
-        if pred_read and self.hasReadPred():
-            reg_val = f'({self.read_predicate}) ? {reg_val} : 0'
-
         return f'{self.base_name} = {reg_val};\n'
 
-    def makeWrite(self, pred_write, op_idx):
+    def makeWrite(self, op_idx):
         reg_val = self.base_name
 
         if self.ctype == 'float':
@@ -255,13 +232,7 @@
         elif self.ctype == 'double':
             reg_val = f'floatToBits64({reg_val})'
 
-        if pred_write and self.hasWritePred():
-            wcond = f'if ({self.write_predicate})'
-        else:
-            wcond = ''
-
         return f'''
-        {wcond}
         {{
             RegVal final_val = {reg_val};
             xc->setRegOperand(this, {op_idx}, final_val);
@@ -331,7 +302,7 @@
                   (ctype, elem_name, self.base_name, elem_spec)
         return c_read
 
-    def makeReadW(self, pred_write, op_idx):
+    def makeReadW(self, op_idx):
         c_readw = f'\t\tauto &tmp_d{op_idx} = \n' \
                   f'\t\t    *({self.parser.namespace}::VecRegContainer *)\n' \
                   f'\t\t    xc->getWritableRegOperand(this, {op_idx});\n'
@@ -361,7 +332,7 @@
                   (elem_name, name, elem_spec)
         return c_read
 
-    def makeRead(self, pred_read, op_idx):
+    def makeRead(self, op_idx):
         name = self.base_name
         if self.is_dest and self.is_src:
             name += '_merger'
@@ -383,18 +354,18 @@
                     c_read += self.makeReadElem(elem, name)
         return c_read
 
-    def makeWrite(self, pred_write, op_idx):
+    def makeWrite(self, op_idx):
         return f'''
         if (traceData) {{
             traceData->setData(tmp_d{op_idx});
         }}
         '''
 
-    def finalize(self, pred_read, pred_write):
-        super().finalize(pred_read, pred_write)
+    def finalize(self):
+        super().finalize()
         if self.is_dest:
             op_idx = str(self.dest_reg_idx)
-            self.op_rd = self.makeReadW(pred_write, op_idx) + self.op_rd
+            self.op_rd = self.makeReadW(op_idx) + self.op_rd
 
 class VecRegOperandDesc(RegOperandDesc):
     def __init__(self, *args, **kwargs):
@@ -406,7 +377,7 @@
     def makeDecl(self):
         return ''
 
-    def makeRead(self, pred_read, op_idx):
+    def makeRead(self, op_idx):
         c_read =  f'\t\t{self.parser.namespace}::VecPredRegContainer ' \
                   f'\t\t        tmp_s{op_idx}; ' \
                   f'xc->getRegOperand(this, {op_idx}, &tmp_s{op_idx});\n'
@@ -416,7 +387,7 @@
                       f'{self.parser.operandTypeMap[self.ext]}>();\n'
         return c_read
 
-    def makeReadW(self, pred_write, op_idx):
+    def makeReadW(self, op_idx):
         c_readw = f'\t\tauto &tmp_d{op_idx} = \n' \
                   f'\t\t    *({self.parser.namespace}::' \
                   f'VecPredRegContainer *)xc->getWritableRegOperand(' \
@@ -427,18 +398,18 @@
                     self.parser.operandTypeMap[self.ext])
         return c_readw
 
-    def makeWrite(self, pred_write, op_idx):
+    def makeWrite(self, op_idx):
         return f'''
         if (traceData) {{
             traceData->setData(tmp_d{op_idx});
         }}
         '''
 
-    def finalize(self, pred_read, pred_write):
-        super().finalize(pred_read, pred_write)
+    def finalize(self):
+        super().finalize()
         if self.is_dest:
             op_idx = str(self.dest_reg_idx)
-            self.op_rd = self.makeReadW(pred_write, op_idx) + self.op_rd
+            self.op_rd = self.makeReadW(op_idx) + self.op_rd
 
 class VecPredRegOperandDesc(RegOperandDesc):
     def __init__(self, *args, **kwargs):
@@ -453,7 +424,7 @@
     def isControlReg(self):
         return 1
 
-    def makeConstructor(self, pred_read, pred_write):
+    def makeConstructor(self):
         c_src = ''
         c_dest = ''
 
@@ -465,7 +436,7 @@
 
         return c_src + c_dest
 
-    def makeRead(self, pred_read, op_idx):
+    def makeRead(self, op_idx):
         bit_select = 0
         if (self.ctype == 'float' or self.ctype == 'double'):
             error('Attempt to read control register as FP')
@@ -473,7 +444,7 @@
         return '%s = xc->readMiscRegOperand(this, %s);\n' % \
             (self.base_name, op_idx)
 
-    def makeWrite(self, pred_write, op_idx):
+    def makeWrite(self, op_idx):
         if (self.ctype == 'float' or self.ctype == 'double'):
             error('Attempt to write control register as FP')
         wb = 'xc->setMiscRegOperand(this, %s, %s);\n' % \
@@ -491,17 +462,17 @@
     def isMem(self):
         return 1
 
-    def makeConstructor(self, pred_read, pred_write):
+    def makeConstructor(self):
         return ''
 
     def makeDecl(self):
         # Declare memory data variable.
         return '%s %s = {};\n' % (self.ctype, self.base_name)
 
-    def makeRead(self, pred_read, op_idx):
+    def makeRead(self, op_idx):
         return ''
 
-    def makeWrite(self, pred_write, op_idx):
+    def makeWrite(self, op_idx):
         return ''
 
 class MemOperandDesc(OperandDesc):
@@ -513,10 +484,10 @@
         super().__init__(parser, *args, **kwargs)
         self.parser = parser
 
-    def makeConstructor(self, pred_read, pred_write):
+    def makeConstructor(self):
         return ''
 
-    def makeRead(self, pred_read, op_idx):
+    def makeRead(self, op_idx):
         if self.reg_spec:
             # A component of the PC state.
             return '%s = __parserAutoPCState.%s();\n' % \
@@ -526,7 +497,7 @@
             return f'{self.base_name} = ' \
                     f'xc->pcState().as<{self.parser.namespace}::PCState>();\n'
 
-    def makeWrite(self, pred_write, op_idx):
+    def makeWrite(self, op_idx):
         if self.reg_spec:
             # A component of the PC state.
             return '__parserAutoPCState.%s(%s);\n' % \
diff --git a/src/arch/x86/isa/operands.isa b/src/arch/x86/isa/operands.isa
index 518d79d..be39b7d 100644
--- a/src/arch/x86/isa/operands.isa
+++ b/src/arch/x86/isa/operands.isa
@@ -65,7 +65,7 @@
 
     class PickedReg(IntReg):
         @overrideInOperand
-        def makeRead(self, predRead, op_idx):
+        def makeRead(self, op_idx):
             return f'{self.base_name} = pick(xc->getRegOperand(' \
                         f'this, {op_idx}), {self.reg_spec}, ' \
                         f'{self.data_size});\n'
@@ -75,7 +75,7 @@
 
     class SignedPickedReg(IntReg):
         @overrideInOperand
-        def makeRead(self, predRead, op_idx):
+        def makeRead(self, op_idx):
             return f'{self.base_name} = signedPick(xc->getRegOperand(' \
                         f'this, {op_idx}), {self.reg_spec}, ' \
                         f'{self.data_size});\n'