[X86] Remove the single AdSize indicator and replace it with separate AdSize16/32/64 flags.

This removes a hardcoded list of instructions in the CodeEmitter. Eventually I intend to remove the predicates on the affected instructions since in any given mode two of them are valid if we supported addr32/addr16 prefixes in the assembler.

llvm-svn: 224809

2 files changed, 19 insertions, 18 deletions

diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86BaseInfo.h b/llvm/lib/Target/X86/MCTargetDesc/X86BaseInfo.h
index 5d6bc5ff7a0..5915d119307 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86BaseInfo.h
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86BaseInfo.h
@@ -328,21 +328,28 @@ namespace X86II {
     OpSizeShift = 7,
     OpSizeMask = 0x3 << OpSizeShift,
 
-    OpSize16 = 1 << OpSizeShift,
-    OpSize32 = 2 << OpSizeShift,
-
-    // AsSize - Set if this instruction requires an operand size prefix (0x67),
-    // which most often indicates that the instruction address 16 bit address
-    // instead of 32 bit address (or 32 bit address in 64 bit mode).
+    OpSizeFixed = 0 << OpSizeShift,
+    OpSize16    = 1 << OpSizeShift,
+    OpSize32    = 2 << OpSizeShift,
+
+    // AsSize - AdSizeX implies this instruction determines its need of 0x67
+    // prefix from a normal ModRM memory operand. The other types indicate that
+    // an operand is encoded with a specific width and a prefix is needed if
+    // it differs from the current mode.
     AdSizeShift = OpSizeShift + 2,
-    AdSize      = 1 << AdSizeShift,
+    AdSizeMask  = 0x3 << AdSizeShift,
+
+    AdSizeX  = 1 << AdSizeShift,
+    AdSize16 = 1 << AdSizeShift,
+    AdSize32 = 2 << AdSizeShift,
+    AdSize64 = 3 << AdSizeShift,
 
     //===------------------------------------------------------------------===//
     // OpPrefix - There are several prefix bytes that are used as opcode
     // extensions. These are 0x66, 0xF3, and 0xF2. If this field is 0 there is
     // no prefix.
     //
-    OpPrefixShift = AdSizeShift + 1,
+    OpPrefixShift = AdSizeShift + 2,
     OpPrefixMask  = 0x7 << OpPrefixShift,
 
     // PS, PD - Prefix code for packed single and double precision vector
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
index 443fac4770a..5d925243dd6 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -1199,16 +1199,10 @@ EncodeInstruction(const MCInst &MI, raw_ostream &OS,
 
   // Emit the address size opcode prefix as needed.
   bool need_address_override;
-  // The AdSize prefix is only for 32-bit and 64-bit modes. Hm, perhaps we
-  // should introduce an AdSize16 bit instead of having seven special cases?
-  if ((!is16BitMode(STI) && TSFlags & X86II::AdSize) ||
-      (is16BitMode(STI) && (MI.getOpcode() == X86::JECXZ_32 ||
-                         MI.getOpcode() == X86::MOV8o8a ||
-                         MI.getOpcode() == X86::MOV16o16a ||
-                         MI.getOpcode() == X86::MOV32o32a ||
-                         MI.getOpcode() == X86::MOV8ao8 ||
-                         MI.getOpcode() == X86::MOV16ao16 ||
-                         MI.getOpcode() == X86::MOV32ao32))) {
+  uint64_t AdSize = TSFlags & X86II::AdSizeMask;
+  if ((is16BitMode(STI) && AdSize == X86II::AdSize32) ||
+      (is32BitMode(STI) && AdSize == X86II::AdSize16) ||
+      (is64BitMode(STI) && AdSize == X86II::AdSize32)) {
     need_address_override = true;
   } else if (MemoryOperand < 0) {
     need_address_override = false;