Update model (#3304)

Since the GCC update, new instructions are used in CoreMark (mostly clmul).
It decreases the accuracy of the model compared to the CVA6.

This PR updates the performance model to correctly decode and process these instructions.

It also fixes a bug for jump dispatch to functional units.

Note: the current version of the model is still based on the superscalar without ALU forwarding.

Author: cainria

perf-model/isa.py

@@ -385,8 +385,8 @@ def __init__(self, instr):
                 | (((i >> 3) & 3) << 1) \
                 | (((i >> 2) & 1) << 5)
             , 8)
-        if base in CBtype.regimm:
-            if base == 'C.ANDI':
+        else:
+            if (instr.bin >> 10) & 3 == 2:
                 self.shamt = sign_ext(CItype.imm(i), 5)
             else:
                 self.shamt = CItype.imm(i)
@@ -470,7 +470,7 @@ class Instr:
         'C.ADDIW': CItype,
         'C.ADDI4SPN': CIWtype,
         'C.SLLI': CItype,
-        'MISC-ALU': CAtype,
+        'MISC-ALU': lambda instr: CAtype(instr) if (instr.bin >> 10) & 3 == 3 else CBtype(instr),
     }
     iloads = ['C.LW', 'C.LWSP', 'LOAD']
     floads = ['C.FLD', 'C.FLW', 'C.FLDSP', 'C.FLWSP', 'LOAD-FP']
@@ -534,7 +534,10 @@ def is_jump(self):
 
     def is_muldiv(self):
         """Is it a muldiv instruction?"""
-        return self.base() in ['OP', 'OP-32'] and self.fields().funct7 == 1
+        if self.base() not in ['OP', 'OP-32']:
+            return False
+        f = self.fields()
+        return f.funct7 == 1 or (f.funct7 == 5 and f.funct3 in [1, 3])
 
     def offset(self):
         """Get offset from instr (sometimes it is just 'imm' in RISCV spec)"""

perf-model/model.py

@@ -260,7 +260,7 @@ def _index(self, addr):
 # This way we do not have more write-back ports than currently with F
 
 def to_fu(instr):
-    if instr.is_branch() or instr.is_regjump():
+    if instr.is_branch() or instr.is_jump() or instr.is_regjump():
         return Fu.BRANCH
     if instr.is_muldiv():
         return Fu.MUL