Implement support for the bizarre 3DNow! encoding (which is unlike anything

else in X86), and add support for pavgusb.  This is apparently the
only instruction (other than movsx) that is preventing ffmpeg from building
with clang.

If someone else is interested in banging out the rest of the 3DNow! 
instructions, it should be quite easy now.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115466 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 22 insertions, 14 deletions

diff --git a/lib/Target/X86/X86InstrInfo.h b/lib/Target/X86/X86InstrInfo.h
index 2e7e063637..b58984fce6 100644
--- a/lib/Target/X86/X86InstrInfo.h
+++ b/lib/Target/X86/X86InstrInfo.h
@@ -449,28 +449,36 @@ namespace X86II {
     OpcodeMask    = 0xFF << OpcodeShift,
 
     //===------------------------------------------------------------------===//
-    // VEX - The opcode prefix used by AVX instructions
+    /// VEX - The opcode prefix used by AVX instructions
     VEX         = 1U << 0,
 
-    // VEX_W - Has a opcode specific functionality, but is used in the same
-    // way as REX_W is for regular SSE instructions.
+    /// VEX_W - Has a opcode specific functionality, but is used in the same
+    /// way as REX_W is for regular SSE instructions.
     VEX_W       = 1U << 1,
 
-    // VEX_4V - Used to specify an additional AVX/SSE register. Several 2
-    // address instructions in SSE are represented as 3 address ones in AVX
-    // and the additional register is encoded in VEX_VVVV prefix.
+    /// VEX_4V - Used to specify an additional AVX/SSE register. Several 2
+    /// address instructions in SSE are represented as 3 address ones in AVX
+    /// and the additional register is encoded in VEX_VVVV prefix.
     VEX_4V      = 1U << 2,
 
-    // VEX_I8IMM - Specifies that the last register used in a AVX instruction,
-    // must be encoded in the i8 immediate field. This usually happens in
-    // instructions with 4 operands.
+    /// VEX_I8IMM - Specifies that the last register used in a AVX instruction,
+    /// must be encoded in the i8 immediate field. This usually happens in
+    /// instructions with 4 operands.
     VEX_I8IMM   = 1U << 3,
 
-    // VEX_L - Stands for a bit in the VEX opcode prefix meaning the current
-    // instruction uses 256-bit wide registers. This is usually auto detected if
-    // a VR256 register is used, but some AVX instructions also have this field
-    // marked when using a f256 memory references.
-    VEX_L       = 1U << 4
+    /// VEX_L - Stands for a bit in the VEX opcode prefix meaning the current
+    /// instruction uses 256-bit wide registers. This is usually auto detected
+    /// if a VR256 register is used, but some AVX instructions also have this
+    /// field marked when using a f256 memory references.
+    VEX_L       = 1U << 4,
+    
+    /// Has3DNow0F0FOpcode - This flag indicates that the instruction uses the
+    /// wacky 0x0F 0x0F prefix for 3DNow! instructions.  The manual documents
+    /// this as having a 0x0F prefix with a 0x0F opcode, and each instruction
+    /// storing a classifier in the imm8 field.  To simplify our implementation,
+    /// we handle this by storeing the classifier in the opcode field and using
+    /// this flag to indicate that the encoder should do the wacky 3DNow! thing.
+    Has3DNow0F0FOpcode = 1U << 5
   };
   
   // getBaseOpcodeFor - This function returns the "base" X86 opcode for the