PCMPGTB/PCMPGTW/PCMPGTD—Compare Packed Signed Integers for Greater Than

Notes: 1. See note in Section 2.4, “Instruction Exception Specification” in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 2A and Section 22.25.3, “Exception Conditions of Legacy SIMD Instructions Operating on MMX Registers” in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 3A.

Instruction Operand Encoding

Description

Performs an SIMD signed compare for the greater value of the packed byte, word, or doubleword integers in the destination operand (first operand) and the source operand (second operand). If a data element in the destination operand is greater than the corresponding date element in the source operand, the corresponding data element in the destination operand is set to all 1s; otherwise, it is set to all 0s.

The PCMPGTB instruction compares the corresponding signed byte integers in the destination and source operands; the PCMPGTW instruction compares the corresponding signed word integers in the destination and source

operands; and the PCMPGTD instruction compares the corresponding signed doubleword integers in the destination and source operands. In 64-bit mode, using a REX prefix in the form of REX.R permits this instruction to access additional registers (XMM8-XMM15).

Legacy SSE instructions: The source operand can be an MMX technology register or a 64-bit memory location. The destination operand can be an MMX technology register. 128-bit Legacy SSE version: The second source operand can be an XMM register or a 128-bit memory location. The first source operand and destination operand are XMM registers. Bits (VLMAX-1:128) of the corresponding YMM destination register remain unchanged. VEX.128 encoded version: The second source operand can be an XMM register or a 128-bit memory location. The first source operand and destination operand are XMM registers. Bits (VLMAX-1:128) of the corresponding YMM register are zeroed. VEX.256 encoded version: The first source operand is a YMM register. The second source operand is a YMM register or a 256-bit memory location. The destination operand is a YMM register.

Note: VEX.L must be 0, otherwise the instruction will #UD.

Operation

PCMPGTB (with 64-bit operands)
  IF DEST[7:0] > SRC[7:0]
     THEN DEST[7:0) ← FFH;
     ELSE DEST[7:0] ← 0; FI;
  (* Continue comparison of 2nd through 7th bytes in DEST and SRC *)
  IF DEST[63:56] > SRC[63:56]
     THEN DEST[63:56] ← FFH;
     ELSE DEST[63:56] ← 0; FI;
PCMPGTB (with 128-bit operands)
  IF DEST[7:0] > SRC[7:0]
     THEN DEST[7:0) ← FFH;
     ELSE DEST[7:0] ← 0; FI;
  (* Continue comparison of 2nd through 15th bytes in DEST and SRC *)
  IF DEST[127:120] > SRC[127:120]
     THEN DEST[127:120] ← FFH;
     ELSE DEST[127:120] ← 0; FI;
VPCMPGTB (VEX.128 encoded version)
DEST[127:0] ←COMPARE_BYTES_GREATER(SRC1,SRC2)
DEST[VLMAX-1:128] ← 0
VPCMPGTB (VEX.256 encoded version)
DEST[127:0] ←COMPARE_BYTES_GREATER(SRC1[127:0],SRC2[127:0])
DEST[255:128] ←COMPARE_BYTES_GREATER(SRC1[255:128],SRC2[255:128])
PCMPGTW (with 64-bit operands)
  IF DEST[15:0] > SRC[15:0]
     THEN DEST[15:0] ← FFFFH;
     ELSE DEST[15:0] ← 0; FI;
  (* Continue comparison of 2nd and 3rd words in DEST and SRC *)
  IF DEST[63:48] > SRC[63:48]
     THEN DEST[63:48] ← FFFFH;
     ELSE DEST[63:48] ← 0; FI;
PCMPGTW (with 128-bit operands)
  IF DEST[15:0] > SRC[15:0]
     THEN DEST[15:0] ← FFFFH;
     ELSE DEST[15:0] ← 0; FI;
  (* Continue comparison of 2nd through 7th words in DEST and SRC *)
  IF DEST[63:48] > SRC[127:112]
     THEN DEST[127:112] ← FFFFH;
     ELSE DEST[127:112] ← 0; FI;
VPCMPGTW (VEX.128 encoded version)
DEST[127:0] ←COMPARE_WORDS_GREATER(SRC1,SRC2)
DEST[VLMAX-1:128] ← 0
VPCMPGTW (VEX.256 encoded version)
DEST[127:0] ←COMPARE_WORDS_GREATER(SRC1[127:0],SRC2[127:0])
DEST[255:128] ←COMPARE_WORDS_GREATER(SRC1[255:128],SRC2[255:128])
PCMPGTD (with 64-bit operands)
  IF DEST[31:0] > SRC[31:0]
     THEN DEST[31:0] ← FFFFFFFFH;
     ELSE DEST[31:0] ← 0; FI;
  IF DEST[63:32] > SRC[63:32]
     THEN DEST[63:32] ← FFFFFFFFH;
     ELSE DEST[63:32] ← 0; FI;
PCMPGTD (with 128-bit operands)
  IF DEST[31:0] > SRC[31:0]
     THEN DEST[31:0] ← FFFFFFFFH;
     ELSE DEST[31:0] ← 0; FI;
  (* Continue comparison of 2nd and 3rd doublewords in DEST and SRC *)
  IF DEST[127:96] > SRC[127:96]
     THEN DEST[127:96] ← FFFFFFFFH;
     ELSE DEST[127:96] ← 0; FI;
VPCMPGTD (VEX.128 encoded version)
DEST[127:0] ←COMPARE_DWORDS_GREATER(SRC1,SRC2)
DEST[VLMAX-1:128] ← 0
VPCMPGTD (VEX.256 encoded version)
DEST[127:0] ←COMPARE_DWORDS_GREATER(SRC1[127:0],SRC2[127:0])
DEST[255:128] ←COMPARE_DWORDS_GREATER(SRC1[255:128],SRC2[255:128])

Intel C/C++ Compiler Intrinsic Equivalents

Flags Affected

None.

Numeric Exceptions

None.

Other Exceptions

See Exceptions Type 4; additionally