Shrink the size of PhyLocation

Summary:
It's currently an `int` and a `size_t`.  With padding that sums to 16 bytes.
There's no need to use a `size_t` to represent the bit size of the location, it
maxes out at 128.  Use a `uint32_t` which drops the struct's size down to 8
bytes.  This also drops the size of Operand from 48 to 40 bytes.

Reviewed By: martindemello

Differential Revision: D81930040

fbshipit-source-id: 3facb4560b4ae02960707db8c4abb0faaeb51447

Author: alexmalyshev

cinderx/Jit/codegen/x86_64.cpp

@@ -2,30 +2,9 @@
 
 #include "cinderx/Jit/codegen/x86_64.h"
 
-#include <utility>
-
 namespace jit::codegen {
 
-std::ostream& operator<<(std::ostream& os, const PhyLocation& loc) {
-  return os << loc.toString();
-}
-
-std::string PhyLocation::toString() const {
-  if (is_memory()) {
-    return fmt::format("[RBP({})]", loc);
-  } else if (bitSize == 32) {
-    return std::string{name32(static_cast<RegId>(loc))};
-  } else if (bitSize == 16) {
-    return std::string{name16(static_cast<RegId>(loc))};
-  } else if (bitSize == 8) {
-    return std::string{name8(static_cast<RegId>(loc))};
-  }
-  return std::string{name(static_cast<RegId>(loc))};
-}
-
-// Parse the string given in name to the physical location.  Currently only
-// parsing physical register names is supported.
-PhyLocation PhyLocation::parse(const std::string& name) {
+PhyLocation PhyLocation::parse(std::string_view name) {
 #define FIND_GP_REG(V64, V32, V16, V8)  \
   if (name == #V64) {                   \
     return PhyLocation{RegId::V64, 64}; \
@@ -52,4 +31,21 @@ PhyLocation PhyLocation::parse(const std::string& name) {
   JIT_ABORT("Unrecognized register {}", name);
 }
 
+std::string PhyLocation::toString() const {
+  if (is_memory()) {
+    return fmt::format("[RBP({})]", loc);
+  } else if (bitSize == 32) {
+    return std::string{name32(static_cast<RegId>(loc))};
+  } else if (bitSize == 16) {
+    return std::string{name16(static_cast<RegId>(loc))};
+  } else if (bitSize == 8) {
+    return std::string{name8(static_cast<RegId>(loc))};
+  }
+  return std::string{name(static_cast<RegId>(loc))};
+}
+
+std::ostream& operator<<(std::ostream& os, const PhyLocation& loc) {
+  return os << loc.toString();
+}
+
 } // namespace jit::codegen

cinderx/Jit/codegen/x86_64.h

@@ -131,6 +131,14 @@ struct PhyLocation {
   FOREACH_XMM(DEFINE_REG)
 #undef DEFINE_REG
 
+  // Parse a register name and return the corresponding physical register.
+  // Return REG_INVALID if the name is not a valid register name.  Does not
+  // support parsing stack slots.
+  static PhyLocation parse(std::string_view name);
+
+  int32_t loc{REG_INVALID};
+  uint32_t bitSize{64};
+
   PhyLocation() = default;
 
   /* implicit */ constexpr PhyLocation(RegId reg, size_t size = 64)
@@ -140,7 +148,7 @@ struct PhyLocation {
       : PhyLocation{static_cast<int>(reg), static_cast<size_t>(size)} {}
 
   /* implicit */ constexpr PhyLocation(int loc, size_t size = 64)
-      : loc{loc}, bitSize{size} {}
+      : loc{loc}, bitSize{static_cast<uint32_t>(size)} {}
 
   /* implicit */ constexpr PhyLocation(int loc, int size)
       : PhyLocation{loc, static_cast<size_t>(size)} {}
@@ -161,9 +169,6 @@ struct PhyLocation {
     return is_register() && loc >= XMM_REG_BASE;
   }
 
-  int loc{REG_INVALID};
-  size_t bitSize{64};
-
   std::string toString() const;
 
   // Comparisons are based only on the register ID.
@@ -175,22 +180,9 @@ struct PhyLocation {
     return loc == rhs.loc;
   }
 
-  bool operator==(int rhs) const {
-    return loc == rhs;
-  }
-
   bool operator!=(const PhyLocation& rhs) const {
     return loc != rhs.loc;
   }
-
-  bool operator!=(int rhs) const {
-    return loc != rhs;
-  }
-
-  // Parses the register name in string and returns the corresponding
-  // physical register.
-  // Returns REG_INVALID if name is not a valid register name.
-  static PhyLocation parse(const std::string& name);
 };
 
 // Define global definitions like `RAX` and `XMM0`.