cpu,arm: Add a method to RegClass-es to print register values.

This further abstracts the properties of registers so they can be
removed from the CPUs.

Change-Id: I2aa1bffe8b095a0301579e60270965c611d6db4e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/49694
Maintainer: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/arm/isa.cc

@@ -80,7 +80,7 @@ class MiscRegClassOps : public RegClassOps
     }
 } miscRegClassOps;
 
-VecElemRegClassOps vecRegElemClassOps(NumVecElemPerVecReg);
+VecElemRegClassOps<ArmISA::VecElem> vecRegElemClassOps(NumVecElemPerVecReg);
 
 ISA::ISA(const Params &p) : BaseISA(p), system(NULL),
     _decoderFlavor(p.decoderFlavor), pmu(p.pmu), impdefAsNop(p.impdef_nop),

src/cpu/reg_class.cc

@@ -39,23 +39,61 @@
  */
 
 #include "cpu/reg_class.hh"
+
+#include <sstream>
+
 #include "base/cprintf.hh"
 
 namespace gem5
 {
 
 std::string
-DefaultRegClassOps::regName(const RegId &id) const
+RegClassOps::regName(const RegId &id) const
 {
     return csprintf("r%d", id.index());
 }
 
 std::string
-VecElemRegClassOps::regName(const RegId &id) const
+RegClassOps::valString(const void *val, size_t size) const
 {
-    RegIndex reg_idx = id.index() / elemsPerVec;
-    RegIndex elem_idx = id.index() % elemsPerVec;
-    return csprintf("v%d[%d]", reg_idx, elem_idx);
+    // If this is just a RegVal, or could be interpreted as one, print it
+    // that way.
+    if (size == sizeof(uint64_t))
+        return csprintf("0x%016x", *(const uint64_t *)val);
+    else if (size == sizeof(uint32_t))
+        return csprintf("0x%08x", *(const uint32_t *)val);
+    else if (size == sizeof(uint16_t))
+        return csprintf("0x%04x", *(const uint16_t *)val);
+    else if (size == sizeof(uint8_t))
+        return csprintf("0x%02x", *(const uint8_t *)val);
+
+    // Otherwise, print it as a sequence of bytes, 4 in a chunk, separated by
+    // spaces, and all surrounded by []s.
+
+    std::stringstream out;
+    ccprintf(out, "[");
+
+    constexpr size_t chunk_size = 4;
+    const uint8_t *bytes = (const uint8_t *)val;
+
+    while (size >= chunk_size) {
+        size -= chunk_size;
+        if (size) {
+            ccprintf(out, "%02x%02x%02x%02x ", bytes[0], bytes[1], bytes[2],
+                    bytes[3]);
+        } else {
+            ccprintf(out, "%02x%02x%02x%02x", bytes[0], bytes[1], bytes[2],
+                    bytes[3]);
+        }
+        bytes += chunk_size;
+    }
+
+    while (size--)
+        ccprintf(out, "%02x", *bytes++);
+
+    ccprintf(out, "]");
+
+    return out.str();
 }
 
 const char *RegId::regClassStrings[] = {

src/cpu/reg_class.hh

@@ -44,6 +44,7 @@
 #include <cstddef>
 #include <string>
 
+#include "base/cprintf.hh"
 #include "base/intmath.hh"
 #include "base/types.hh"
 
@@ -69,26 +70,10 @@ class RegId;
 class RegClassOps
 {
   public:
-    virtual std::string regName(const RegId &id) const = 0;
-};
-
-class DefaultRegClassOps : public RegClassOps
-{
-  public:
-    std::string regName(const RegId &id) const override;
-};
-
-class VecElemRegClassOps : public RegClassOps
-{
-  protected:
-    size_t elemsPerVec;
-
-  public:
-    explicit VecElemRegClassOps(size_t elems_per_vec) :
-        elemsPerVec(elems_per_vec)
-    {}
-
-    std::string regName(const RegId &id) const override;
+    /** Print the name of the register specified in id. */
+    virtual std::string regName(const RegId &id) const;
+    /** Print the value of a register pointed to by val of size size. */
+    virtual std::string valString(const void *val, size_t size) const;
 };
 
 class RegClass
@@ -102,7 +87,7 @@ class RegClass
     // be calculated with a multiply.
     size_t _regShift;
 
-    static inline DefaultRegClassOps defaultOps;
+    static inline RegClassOps defaultOps;
     RegClassOps *_ops = &defaultOps;
 
   public:
@@ -124,6 +109,11 @@ class RegClass
     size_t regShift() const { return _regShift; }
 
     std::string regName(const RegId &id) const { return _ops->regName(id); }
+    std::string
+    valString(const void *val) const
+    {
+        return _ops->valString(val, regBytes());
+    }
 };
 
 /** Register ID: describe an architectural register with its class and index.
@@ -197,6 +187,38 @@ class RegId
     }
 };
 
+template <typename ValueType>
+class TypedRegClassOps : public RegClassOps
+{
+  public:
+    std::string
+    valString(const void *val, size_t size) const override
+    {
+        assert(size == sizeof(ValueType));
+        return csprintf("%s", *(const ValueType *)val);
+    }
+};
+
+template <typename ValueType>
+class VecElemRegClassOps : public TypedRegClassOps<ValueType>
+{
+  protected:
+    size_t elemsPerVec;
+
+  public:
+    explicit VecElemRegClassOps(size_t elems_per_vec) :
+        elemsPerVec(elems_per_vec)
+    {}
+
+    std::string
+    regName(const RegId &id) const override
+    {
+        RegIndex reg_idx = id.index() / elemsPerVec;
+        RegIndex elem_idx = id.index() % elemsPerVec;
+        return csprintf("v%d[%d]", reg_idx, elem_idx);
+    }
+};
+
 /** Physical register ID.
  * Like a register ID but physical. The inheritance is private because the
  * only relationship between this types is functional, and it is done to