arch-power: Rename program counter registers

The Power ISA specification lists the Program Counter (PC) and
the Next Program Counter (NPC) registers as Current Instruction
Address (CIA) and Next Instruction Address (NIA). This applies
the ISA naming convention for these two registers.

Change-Id: I8b9094ab1c809f4dfdb4d7330c17f360adf063e9
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/16603
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/arch/power/isa/decoder.isa

@@ -386,12 +386,12 @@ decode OPCODE default Unknown::unknown() {
 
         // Conditionally branch relative to PC based on CR and CTR.
         format BranchPCRelCondCtr {
-            0: bc({{ NPC = (uint32_t)(PC + disp); }});
+            0: bc({{ NIA = (uint32_t)(CIA + disp); }});
         }
 
         // Conditionally branch to fixed address based on CR and CTR.
         format BranchNonPCRelCondCtr {
-            1: bca({{ NPC = targetAddr; }});
+            1: bca({{ NIA = targetAddr; }});
         }
     }
 
@@ -399,12 +399,12 @@ decode OPCODE default Unknown::unknown() {
 
         // Unconditionally branch relative to PC.
         format BranchPCRel {
-            0: b({{ NPC = (uint32_t)(PC + disp); }});
+            0: b({{ NIA = (uint32_t)(CIA + disp); }});
         }
 
         // Unconditionally branch to fixed address.
         format BranchNonPCRel {
-            1: ba({{ NPC = targetAddr; }});
+            1: ba({{ NIA = targetAddr; }});
         }
     }
 
@@ -412,12 +412,12 @@ decode OPCODE default Unknown::unknown() {
 
         // Conditionally branch to address in LR based on CR and CTR.
         format BranchLrCondCtr {
-           16: bclr({{ NPC = LR & 0xfffffffc; }});
+           16: bclr({{ NIA = LR & 0xfffffffc; }});
         }
 
         // Conditionally branch to address in CTR based on CR.
         format BranchCtrCond {
-           528: bcctr({{ NPC = CTR & 0xfffffffc; }});
+           528: bcctr({{ NIA = CTR & 0xfffffffc; }});
         }
 
         // Condition register manipulation instructions.

src/arch/power/isa/formats/branch.isa

@@ -48,7 +48,7 @@
 let {{
 
 # Simple code to update link register (LR).
-updateLrCode = 'LR = PC + 4;'
+updateLrCode = 'LR = CIA + 4;'
 
 }};
 
@@ -105,7 +105,7 @@ def GetCondCode(br_code):
     cond_code =  'if(condOk(CR)) {\n'
     cond_code += '    ' + br_code + '\n'
     cond_code += '} else {\n'
-    cond_code += '    NPC = NPC;\n'
+    cond_code += '    NIA = NIA;\n'
     cond_code += '}\n'
     return cond_code
 
@@ -119,7 +119,7 @@ def GetCtrCondCode(br_code):
     cond_code += 'if(ctr_ok && cond_ok) {\n'
     cond_code += '    ' + br_code + '\n'
     cond_code += '} else {\n'
-    cond_code += '    NPC = NPC;\n'
+    cond_code += '    NIA = NIA;\n'
     cond_code += '}\n'
     cond_code += 'CTR = ctr;\n'
     return cond_code

src/arch/power/isa/operands.isa

@@ -59,8 +59,8 @@ def operands {{
     'Mem': ('Mem', 'uw', None, ('IsMemRef', 'IsLoad', 'IsStore'), 8),
 
     # Program counter and next
-    'PC': ('PCState', 'uw', 'pc', (None, None, 'IsControl'), 9),
-    'NPC': ('PCState', 'uw', 'npc', (None, None, 'IsControl'), 9),
+    'CIA': ('PCState', 'uw', 'pc', (None, None, 'IsControl'), 9),
+    'NIA': ('PCState', 'uw', 'npc', (None, None, 'IsControl'), 9),
 
     # Control registers
     'CR': ('IntReg', 'uw', 'INTREG_CR', 'IsInteger', 9),