instead of migrating it to the MC instruction encoder, just

rip out the implementation of X86InstrInfo::GetInstSizeInBytes.
The code being ripped out just implemented a copy and hacked up
version of the (old) instruction encoder, and is buggy and 
terrible in other ways.  Since "GetInstSizeInBytes" is really 
only there to support the JIT's "NeedsExactSize" hook (which
noone is using), just rip out the code.  I will rip out the
NeedsExactSize hook next.

This resolves rdar://7617809 - switch X86InstrInfo::GetInstSizeInBytes to use X86MCCodeEmitter

llvm-svn: 109149

1 files changed, 98 insertions, 1 deletions

diff --git a/llvm/lib/Target/X86/X86CodeEmitter.cpp b/llvm/lib/Target/X86/X86CodeEmitter.cpp
index 97572051470..077004cb498 100644
--- a/llvm/lib/Target/X86/X86CodeEmitter.cpp
+++ b/llvm/lib/Target/X86/X86CodeEmitter.cpp
@@ -146,6 +146,103 @@ bool Emitter<CodeEmitter>::runOnMachineFunction(MachineFunction &MF) {
   return false;
 }
 
+/// determineREX - Determine if the MachineInstr has to be encoded with a X86-64
+/// REX prefix which specifies 1) 64-bit instructions, 2) non-default operand
+/// size, and 3) use of X86-64 extended registers.
+static unsigned determineREX(const MachineInstr &MI) {
+  unsigned REX = 0;
+  const TargetInstrDesc &Desc = MI.getDesc();
+  
+  // Pseudo instructions do not need REX prefix byte.
+  if ((Desc.TSFlags & X86II::FormMask) == X86II::Pseudo)
+    return 0;
+  if (Desc.TSFlags & X86II::REX_W)
+    REX |= 1 << 3;
+  
+  unsigned NumOps = Desc.getNumOperands();
+  if (NumOps) {
+    bool isTwoAddr = NumOps > 1 &&
+    Desc.getOperandConstraint(1, TOI::TIED_TO) != -1;
+    
+    // If it accesses SPL, BPL, SIL, or DIL, then it requires a 0x40 REX prefix.
+    unsigned i = isTwoAddr ? 1 : 0;
+    for (unsigned e = NumOps; i != e; ++i) {
+      const MachineOperand& MO = MI.getOperand(i);
+      if (MO.isReg()) {
+        unsigned Reg = MO.getReg();
+        if (X86InstrInfo::isX86_64NonExtLowByteReg(Reg))
+          REX |= 0x40;
+      }
+    }
+    
+    switch (Desc.TSFlags & X86II::FormMask) {
+      case X86II::MRMInitReg:
+        if (X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0)))
+          REX |= (1 << 0) | (1 << 2);
+        break;
+      case X86II::MRMSrcReg: {
+        if (X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0)))
+          REX |= 1 << 2;
+        i = isTwoAddr ? 2 : 1;
+        for (unsigned e = NumOps; i != e; ++i) {
+          const MachineOperand& MO = MI.getOperand(i);
+          if (X86InstrInfo::isX86_64ExtendedReg(MO))
+            REX |= 1 << 0;
+        }
+        break;
+      }
+      case X86II::MRMSrcMem: {
+        if (X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0)))
+          REX |= 1 << 2;
+        unsigned Bit = 0;
+        i = isTwoAddr ? 2 : 1;
+        for (; i != NumOps; ++i) {
+          const MachineOperand& MO = MI.getOperand(i);
+          if (MO.isReg()) {
+            if (X86InstrInfo::isX86_64ExtendedReg(MO))
+              REX |= 1 << Bit;
+            Bit++;
+          }
+        }
+        break;
+      }
+      case X86II::MRM0m: case X86II::MRM1m:
+      case X86II::MRM2m: case X86II::MRM3m:
+      case X86II::MRM4m: case X86II::MRM5m:
+      case X86II::MRM6m: case X86II::MRM7m:
+      case X86II::MRMDestMem: {
+        unsigned e = (isTwoAddr ? X86::AddrNumOperands+1 : X86::AddrNumOperands);
+        i = isTwoAddr ? 1 : 0;
+        if (NumOps > e && X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(e)))
+          REX |= 1 << 2;
+        unsigned Bit = 0;
+        for (; i != e; ++i) {
+          const MachineOperand& MO = MI.getOperand(i);
+          if (MO.isReg()) {
+            if (X86InstrInfo::isX86_64ExtendedReg(MO))
+              REX |= 1 << Bit;
+            Bit++;
+          }
+        }
+        break;
+      }
+      default: {
+        if (X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0)))
+          REX |= 1 << 0;
+        i = isTwoAddr ? 2 : 1;
+        for (unsigned e = NumOps; i != e; ++i) {
+          const MachineOperand& MO = MI.getOperand(i);
+          if (X86InstrInfo::isX86_64ExtendedReg(MO))
+            REX |= 1 << 2;
+        }
+        break;
+      }
+    }
+  }
+  return REX;
+}
+
+
 /// emitPCRelativeBlockAddress - This method keeps track of the information
 /// necessary to resolve the address of this block later and emits a dummy
 /// value.
@@ -569,7 +666,7 @@ void Emitter<CodeEmitter>::emitInstruction(const MachineInstr &MI,
 
   // Handle REX prefix.
   if (Is64BitMode) {
-    if (unsigned REX = X86InstrInfo::determineREX(MI))
+    if (unsigned REX = determineREX(MI))
       MCE.emitByte(0x40 | REX);
   }