From 456fdaf0cea4bd195eacc9796fedb71b62290cfe Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Thu, 22 Jul 2010 21:05:13 +0000
Subject: 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



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109149 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/X86CodeEmitter.cpp | 99 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 98 insertions(+), 1 deletion(-)

(limited to 'lib/Target/X86/X86CodeEmitter.cpp')

diff --git a/lib/Target/X86/X86CodeEmitter.cpp b/lib/Target/X86/X86CodeEmitter.cpp
index 9757205147..077004cb49 100644
--- a/lib/Target/X86/X86CodeEmitter.cpp
+++ b/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);
   }
 
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