X86: Precompute the default and alternate address and operand size and the stack size.

5 files changed, 69 insertions, 64 deletions

diff --git a/src/arch/x86/miscregfile.cc b/src/arch/x86/miscregfile.cc
index f7c804fd0..317cdadc5 100644
--- a/src/arch/x86/miscregfile.cc
+++ b/src/arch/x86/miscregfile.cc
@@ -97,7 +97,7 @@ using namespace std;
 class Checkpoint;
 
 void MiscRegFile::updateHandyM5Reg(Efer efer, CR0 cr0,
-        SegAttr csAttr, RFLAGS rflags)
+        SegAttr csAttr, SegAttr ssAttr, RFLAGS rflags)
 {
     HandyM5Reg m5reg;
     if (efer.lma) {
@@ -120,6 +120,37 @@ void MiscRegFile::updateHandyM5Reg(Efer efer, CR0 cr0,
     m5reg.cpl = csAttr.dpl;
     m5reg.paging = cr0.pg;
     m5reg.prot = cr0.pe;
+
+    // Compute the default and alternate operand size.
+    if (m5reg.submode == SixtyFourBitMode || csAttr.defaultSize) {
+        m5reg.defOp = 2;
+        m5reg.altOp = 1;
+    } else {
+        m5reg.defOp = 1;
+        m5reg.altOp = 2;
+    }
+
+    // Compute the default and alternate address size.
+    if (m5reg.submode == SixtyFourBitMode) {
+        m5reg.defAddr = 3;
+        m5reg.altAddr = 2;
+    } else if (csAttr.defaultSize) {
+        m5reg.defAddr = 2;
+        m5reg.altAddr = 1;
+    } else {
+        m5reg.defAddr = 1;
+        m5reg.altAddr = 2;
+    }
+
+    // Compute the stack size
+    if (m5reg.submode == SixtyFourBitMode) {
+        m5reg.stack = 3;
+    } else if (ssAttr.defaultSize) {
+        m5reg.stack = 2;
+    } else {
+        m5reg.stack = 1;
+    }
+
     regVal[MISCREG_M5_REG] = m5reg;
 }
 
@@ -199,6 +230,7 @@ void MiscRegFile::setReg(MiscRegIndex miscReg,
             updateHandyM5Reg(regVal[MISCREG_EFER],
                              newCR0,
                              regVal[MISCREG_CS_ATTR],
+                             regVal[MISCREG_SS_ATTR],
                              regVal[MISCREG_RFLAGS]);
         }
         break;
@@ -239,9 +271,17 @@ void MiscRegFile::setReg(MiscRegIndex miscReg,
             updateHandyM5Reg(regVal[MISCREG_EFER],
                              regVal[MISCREG_CR0],
                              newCSAttr,
+                             regVal[MISCREG_SS_ATTR],
                              regVal[MISCREG_RFLAGS]);
         }
         break;
+      case MISCREG_SS_ATTR:
+        updateHandyM5Reg(regVal[MISCREG_EFER],
+                         regVal[MISCREG_CR0],
+                         regVal[MISCREG_CS_ATTR],
+                         val,
+                         regVal[MISCREG_RFLAGS]);
+        break;
       // These segments always actually use their bases, or in other words
       // their effective bases must stay equal to their actual bases.
       case MISCREG_FS_BASE:
@@ -346,6 +386,7 @@ void MiscRegFile::setReg(MiscRegIndex miscReg,
         updateHandyM5Reg(regVal[MISCREG_EFER],
                          regVal[MISCREG_CR0],
                          regVal[MISCREG_CS_ATTR],
+                         regVal[MISCREG_SS_ATTR],
                          regVal[MISCREG_RFLAGS]);
         return;
       default:
diff --git a/src/arch/x86/miscregfile.hh b/src/arch/x86/miscregfile.hh
index 0488dbba7..babc65b44 100644
--- a/src/arch/x86/miscregfile.hh
+++ b/src/arch/x86/miscregfile.hh
@@ -108,7 +108,7 @@ namespace X86ISA
       protected:
         MiscReg regVal[NumMiscRegs];
         void updateHandyM5Reg(Efer efer, CR0 cr0,
-                SegAttr csAttr, RFLAGS rflags);
+                SegAttr csAttr, SegAttr ssAttr, RFLAGS rflags);
 
       public:
         void clear();
diff --git a/src/arch/x86/miscregs.hh b/src/arch/x86/miscregs.hh
index 7d46a87b9..088dbeace 100644
--- a/src/arch/x86/miscregs.hh
+++ b/src/arch/x86/miscregs.hh
@@ -520,6 +520,11 @@ namespace X86ISA
         Bitfield<5, 4> cpl;
         Bitfield<6> paging;
         Bitfield<7> prot;
+        Bitfield<9, 8> defOp;
+        Bitfield<11, 10> altOp;
+        Bitfield<13, 12> defAddr;
+        Bitfield<15, 14> altAddr;
+        Bitfield<17, 16> stack;
     EndBitUnion(HandyM5Reg)
 
     /**
diff --git a/src/arch/x86/predecoder.cc b/src/arch/x86/predecoder.cc
index 620ab89ea..5bac8e711 100644
--- a/src/arch/x86/predecoder.cc
+++ b/src/arch/x86/predecoder.cc
@@ -80,9 +80,9 @@ namespace X86ISA
 
         emi.modRM = 0;
         emi.sib = 0;
-        HandyM5Reg m5reg = tc->readMiscRegNoEffect(MISCREG_M5_REG);
-        emi.mode.mode = m5reg.mode;
-        emi.mode.submode = m5reg.submode;
+        m5Reg = tc->readMiscRegNoEffect(MISCREG_M5_REG);
+        emi.mode.mode = m5Reg.mode;
+        emi.mode.submode = m5Reg.submode;
     }
 
     void Predecoder::process()
@@ -216,34 +216,15 @@ namespace X86ISA
             DPRINTF(Predecoder, "Found opcode %#x.\n", nextByte);
             emi.opcode.op = nextByte;
 
-            SegAttr csAttr = tc->readMiscRegNoEffect(MISCREG_CS_ATTR);
-
             //Figure out the effective operand size. This can be overriden to
             //a fixed value at the decoder level.
             int logOpSize;
-            if (emi.mode.submode == SixtyFourBitMode)
-            {
-                if(emi.rex.w)
-                    logOpSize = 3; // 64 bit operand size
-                else if(emi.legacy.op)
-                    logOpSize = 1; // 16 bit operand size
-                else
-                    logOpSize = 2; // 32 bit operand size
-            }
-            else if(csAttr.defaultSize)
-            {
-                if(emi.legacy.op)
-                    logOpSize = 1; // 16 bit operand size
-                else
-                    logOpSize = 2; // 32 bit operand size
-            }
-            else // 16 bit default operand size
-            {
-                if(emi.legacy.op)
-                    logOpSize = 2; // 32 bit operand size
-                else
-                    logOpSize = 1; // 16 bit operand size
-            }
+            if (emi.rex.w)
+                logOpSize = 3; // 64 bit operand size
+            else if (emi.legacy.op)
+                logOpSize = m5Reg.altOp;
+            else
+                logOpSize = m5Reg.defOp;
 
             //Set the actual op size
             emi.opSize = 1 << logOpSize;
@@ -251,41 +232,18 @@ namespace X86ISA
             //Figure out the effective address size. This can be overriden to
             //a fixed value at the decoder level.
             int logAddrSize;
-            if(emi.mode.submode == SixtyFourBitMode)
-            {
-                if(emi.legacy.addr)
-                    logAddrSize = 2; // 32 bit address size
-                else
-                    logAddrSize = 3; // 64 bit address size
-            }
-            else if(csAttr.defaultSize)
-            {
-                if(emi.legacy.addr)
-                    logAddrSize = 1; // 16 bit address size
-                else
-                    logAddrSize = 2; // 32 bit address size
-            }
-            else // 16 bit default operand size
-            {
-                if(emi.legacy.addr)
-                    logAddrSize = 2; // 32 bit address size
-                else
-                    logAddrSize = 1; // 16 bit address size
-            }
-
-            SegAttr ssAttr = tc->readMiscRegNoEffect(MISCREG_SS_ATTR);
-            //Figure out the effective stack width. This can be overriden to
-            //a fixed value at the decoder level.
-            if(emi.mode.submode == SixtyFourBitMode)
-                emi.stackSize = 8; // 64 bit stack width
-            else if(ssAttr.defaultSize)
-                emi.stackSize = 4; // 32 bit stack width
+            if(emi.legacy.addr)
+                logAddrSize = m5Reg.altAddr;
             else
-                emi.stackSize = 2; // 16 bit stack width
+                logAddrSize = m5Reg.defAddr;
 
             //Set the actual address size
             emi.addrSize = 1 << logAddrSize;
 
+            //Figure out the effective stack width. This can be overriden to
+            //a fixed value at the decoder level.
+            emi.stackSize = 1 << m5Reg.stack;
+
             //Figure out how big of an immediate we'll retreive based
             //on the opcode.
             int immType = ImmediateType[emi.opcode.num - 1][nextByte];
@@ -318,9 +276,7 @@ namespace X86ISA
         ModRM modRM;
         modRM = nextByte;
         DPRINTF(Predecoder, "Found modrm byte %#x.\n", nextByte);
-        SegAttr csAttr = tc->readMiscRegNoEffect(MISCREG_CS_ATTR);
-        if (emi.mode.submode != SixtyFourBitMode &&
-                !csAttr.defaultSize) {
+        if (m5Reg.defOp == 1) {
             //figure out 16 bit displacement size
             if ((modRM.mod == 0 && modRM.rm == 6) || modRM.mod == 2)
                 displacementSize = 2;
diff --git a/src/arch/x86/predecoder.hh b/src/arch/x86/predecoder.hh
index a16ce6fb8..4893f1de9 100644
--- a/src/arch/x86/predecoder.hh
+++ b/src/arch/x86/predecoder.hh
@@ -61,6 +61,7 @@
 #include <cassert>
 
 #include "arch/x86/types.hh"
+#include "arch/x86/miscregs.hh"
 #include "base/bitfield.hh"
 #include "base/misc.hh"
 #include "base/trace.hh"
@@ -91,10 +92,11 @@ namespace X86ISA
         int offset;
         //The extended machine instruction being generated
         ExtMachInst emi;
+        HandyM5Reg m5Reg;
 
         inline uint8_t getNextByte()
         {
-            return (fetchChunk >> (offset * 8)) & 0xff;
+            return ((uint8_t *)&fetchChunk)[offset];
         }
 
         void getImmediate(int &collected, uint64_t &current, int size)
@@ -182,6 +184,7 @@ namespace X86ISA
         {
             emi.mode.mode = LongMode;
             emi.mode.submode = SixtyFourBitMode;
+            m5Reg = 0;
         }
 
         void reset()