[gem5-dev] Change in gem5/gem5[develop]: arch-power: Refactor load-store instructions

[Sandipan Das (Gerrit) via gem5-dev]

Sandipan Das has uploaded this change for review. (  
https://gem5-review.googlesource.com/c/public/gem5/+/40892 )

Change subject: arch-power: Refactor load-store instructions
......................................................................

arch-power: Refactor load-store instructions

This changes the base classes for load-store instructions
and introduces two new classes for DS form instructions
which use a shifted signed immediate field as the offset
from the base address and for X form instructions which
use registers for both the offset and the base address.
The formats have also been updated to make use of the new
base classes.

Change-Id: Ib5d1bb5d7747813e0e5b1e3075489f1a3aa72660
Signed-off-by: Sandipan Das <sandi...@linux.ibm.com>
---
M src/arch/power/insts/mem.hh
M src/arch/power/isa/decoder.isa
M src/arch/power/isa/formats/mem.isa
3 files changed, 48 insertions(+), 8 deletions(-)



diff --git a/src/arch/power/insts/mem.hh b/src/arch/power/insts/mem.hh
index de9b46c..d14f1e6 100644
--- a/src/arch/power/insts/mem.hh
+++ b/src/arch/power/insts/mem.hh
@@ -75,6 +75,38 @@
             Addr pc, const Loader::SymbolTable *symtab) const override;
 };

+/**
+ * Class for memory operations with shifted displacement.
+ */
+class MemDispShiftOp : public MemOp
+{
+  protected:
+
+    int16_t disp;
+
+    /// Constructor
+    MemDispShiftOp(const char *mnem, MachInst _machInst, OpClass __opClass)
+      : MemOp(mnem, _machInst, __opClass),
+        disp(sext<14>(machInst.ds))
+    {
+    }
+};
+
+
+/**
+ * Class for memory operations with register indexed addressing.
+ */
+class MemIndexOp : public MemOp
+{
+  protected:
+
+    /// Constructor
+    MemIndexOp(const char *mnem, MachInst _machInst, OpClass __opClass)
+      : MemOp(mnem, _machInst, __opClass)
+    {
+    }
+};
+
 } // namespace PowerISA

 #endif //__ARCH_POWER_INSTS_MEM_HH__
diff --git a/src/arch/power/isa/decoder.isa b/src/arch/power/isa/decoder.isa
index 4005da8..b9fc811 100644
--- a/src/arch/power/isa/decoder.isa
+++ b/src/arch/power/isa/decoder.isa
@@ -132,10 +132,8 @@
     }

     58: decode DS_XO {
-        format LoadDispOp {
-            2: lwa({{ Rt = Mem_sw; }},
-                   {{ EA = Ra + (disp & 0xfffffffc); }},
-                   {{ EA = disp & 0xfffffffc; }});
+        format LoadDispShiftOp {
+            2: lwa({{ Rt = Mem_sw; }});
         }
     }

diff --git a/src/arch/power/isa/formats/mem.isa  
b/src/arch/power/isa/formats/mem.isa
index c7be2b1..1f62571 100644
--- a/src/arch/power/isa/formats/mem.isa
+++ b/src/arch/power/isa/formats/mem.isa
@@ -240,7 +240,7 @@
                        mem_flags = [], inst_flags = []) {{
     (header_output, decoder_output, decode_block, exec_output) = \
         GenMemOp(name, Name, memacc_code, ea_code, ea_code_ra0,
-                 'MemOp', 'Load', mem_flags, inst_flags)
+                 'MemIndexOp', 'Load', mem_flags, inst_flags)
 }};


@@ -249,7 +249,7 @@
                         mem_flags = [], inst_flags = []) {{
     (header_output, decoder_output, decode_block, exec_output) = \
         GenMemOp(name, Name, memacc_code, ea_code, ea_code_ra0,
-                 'MemOp', 'Store', mem_flags, inst_flags)
+                 'MemIndexOp', 'Store', mem_flags, inst_flags)
 }};


@@ -262,7 +262,7 @@
     # Generate the class
     (header_output, decoder_output, decode_block, exec_output) = \
         LoadStoreBase(name, Name, ea_code, memacc_code, mem_flags,  
inst_flags,
-                      base_class = 'MemOp',
+                      base_class = 'MemIndexOp',
                       exec_template_base = 'Load')
 }};

@@ -276,7 +276,7 @@
     # Generate the class
     (header_output, decoder_output, decode_block, exec_output) = \
         LoadStoreBase(name, Name, ea_code, memacc_code, mem_flags,  
inst_flags,
-                      base_class = 'MemOp',
+                      base_class = 'MemIndexOp',
                       exec_template_base = 'Store')
 }};

@@ -299,6 +299,16 @@
 }};


+def format LoadDispShiftOp(memacc_code,
+                           ea_code = {{ EA = Ra + (disp << 2); }},
+                           ea_code_ra0 = {{ EA = (disp << 2); }},
+                           mem_flags = [], inst_flags = []) {{
+    (header_output, decoder_output, decode_block, exec_output) = \
+        GenMemOp(name, Name, memacc_code, ea_code, ea_code_ra0,
+                 'MemDispShiftOp', 'Load', mem_flags, inst_flags)
+}};
+
+
 def format LoadDispUpdateOp(memacc_code, ea_code = {{ EA = Ra + disp; }},
                             mem_flags = [], inst_flags = []) {{


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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: Ib5d1bb5d7747813e0e5b1e3075489f1a3aa72660
Gerrit-Change-Number: 40892
Gerrit-PatchSet: 1
Gerrit-Owner: Sandipan Das <sandi...@linux.ibm.com>
Gerrit-MessageType: newchange
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