internal/bytealg: add power9 version of bytes index

This adds a power9 version of the bytes.Index function
for little endian.

Here is the improvement on power9 for some of the Index
benchmarks:

Index/10           -0.14%
Index/32           -3.19%
Index/4K          -12.66%
Index/4M          -13.34%
Index/64M         -13.17%
Count/10           -0.59%
Count/32           -2.88%
Count/4K          -12.63%
Count/4M          -13.35%
Count/64M         -13.17%
IndexHard1        -23.03%
IndexHard2        -13.01%
IndexHard3        -22.12%
IndexHard4         +0.16%
CountHard1        -23.02%
CountHard2        -13.01%
CountHard3        -22.12%
IndexPeriodic/IndexPeriodic2  -22.85%
IndexPeriodic/IndexPeriodic4  -23.15%

Change-Id: Id72353e2771eba2efbb1544d5f0be65f8a9f0433
Reviewed-on: https://go-review.googlesource.com/c/go/+/311380
Run-TryBot: Carlos Eduardo Seo <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Carlos Eduardo Seo <[email protected]>
Trust: Lynn Boger <[email protected]>

Author: laboger

src/internal/bytealg/bytealg.go

@@ -17,6 +17,8 @@ const (
 	offsetX86HasPOPCNT = unsafe.Offsetof(cpu.X86.HasPOPCNT)
 
 	offsetS390xHasVX = unsafe.Offsetof(cpu.S390X.HasVX)
+
+	offsetPPC64HasPOWER9 = unsafe.Offsetof(cpu.PPC64.IsPOWER9)
 )
 
 // MaxLen is the maximum length of the string to be searched for (argument b) in Index.

src/internal/bytealg/index_ppc64x.go

@@ -8,8 +8,12 @@
 
 package bytealg
 
+import "internal/cpu"
+
 const MaxBruteForce = 16
 
+var SupportsPower9 = cpu.PPC64.IsPOWER9
+
 func init() {
 	MaxLen = 32
 }

src/internal/bytealg/index_ppc64x.s

@@ -51,15 +51,33 @@ TEXT ·Index(SB), NOSPLIT|NOFRAME, $0-56
 	MOVD b_base+24(FP), R5 // R5 = separator pointer
 	MOVD b_len+32(FP), R6  // R6 = separator length
 	MOVD $ret+48(FP), R14  // R14 = &ret
-	BR   indexbody<>(SB)
+
+#ifdef GOARCH_ppc64le
+	MOVBZ internal∕cpu·PPC64+const_offsetPPC64HasPOWER9(SB), R7
+	CMP   R7, $1
+	BNE   power8
+	BR    indexbodyp9<>(SB)
+
+#endif
+power8:
+	BR indexbody<>(SB)
 
 TEXT ·IndexString(SB), NOSPLIT|NOFRAME, $0-40
 	MOVD a_base+0(FP), R3  // R3 = string
 	MOVD a_len+8(FP), R4   // R4 = length
 	MOVD b_base+16(FP), R5 // R5 = separator pointer
 	MOVD b_len+24(FP), R6  // R6 = separator length
 	MOVD $ret+32(FP), R14  // R14 = &ret
-	BR   indexbody<>(SB)
+
+#ifdef GOARCH_ppc64le
+	MOVBZ internal∕cpu·PPC64+const_offsetPPC64HasPOWER9(SB), R7
+	CMP   R7, $1
+	BNE   power8
+	BR    indexbody<>(SB)
+
+#endif
+power8:
+	BR indexbody<>(SB)
 
 	// s: string we are searching
 	// sep: string to search for
@@ -420,3 +438,330 @@ found:
 	SUB  R3, R7    // Return byte where found
 	MOVD R7, (R14)
 	RET
+
+TEXT indexbodyp9<>(SB), NOSPLIT|NOFRAME, $0
+	CMP      R6, R4                // Compare lengths
+	BGT      notfound              // If sep len is > string, notfound
+	ADD      R4, R3, LASTBYTE      // find last byte addr
+	SUB      R6, LASTBYTE, LASTSTR // LAST=&s[len(s)-len(sep)] (last valid start index)
+	CMP      R6, $0                // Check sep len
+	BEQ      notfound              // sep len 0 -- not found
+	MOVD     R3, R7                // Copy of string addr
+	MOVD     $16, R16              // Index value 16
+	MOVD     $17, R17              // Index value 17
+	MOVD     $18, R18              // Index value 18
+	MOVD     $1, R19               // Index value 1
+	VSPLTISB $0xFF, ONES           // splat all 1s
+
+	CMP    R6, $16, CR4        // CR4 for len(sep) >= 16
+	VOR    ONES, ONES, SEPMASK // Set up full SEPMASK
+	BGE    CR4, loadge16       // Load for len(sep) >= 16
+	SUB    R6, R16, R9         // 16-len of sep
+	SLD    $3, R9              // Set up for VSLO
+	MTVSRD R9, V9_             // Set up for VSLO
+	VSLDOI $8, V9, V9, V9      // Set up for VSLO
+	VSLO   ONES, V9, SEPMASK   // Mask for separator len(sep) < 16
+
+loadge16:
+	ANDCC $15, R5, R9 // Find byte offset of sep
+	ADD   R9, R6, R10 // Add sep len
+	CMP   R10, $16    // Check if sep len+offset > 16
+	BGE   sepcross16  // Sep crosses 16 byte boundary
+
+	RLDICR  $0, R5, $59, R8 // Adjust addr to 16 byte container
+	LXVB16X (R8)(R0), V0_   // Load 16 bytes @R8 into V0
+	SLD     $3, R9          // Set up shift count for VSLO
+	MTVSRD  R9, V8_         // Set up shift count for VSLO
+	VSLDOI  $8, V8, V8, V8
+	VSLO    V0, V8, V0      // Shift by start byte
+
+	VAND V0, SEPMASK, V0 // Mask separator (< 16)
+	BR   index2plus
+
+sepcross16:
+	LXVB16X (R5)(R0), V0_ // Load 16 bytes @R5 into V0
+
+	VAND V0, SEPMASK, V0 // mask out separator
+	BLE  CR4, index2to16
+	BR   index17plus     // Handle sep > 16
+
+index2plus:
+	CMP      R6, $2       // Check length of sep
+	BNE      index3plus   // If not 2, check for 3
+	ADD      $16, R7, R9  // Check if next 16 bytes past last
+	CMP      R9, LASTBYTE // compare with last
+	BGE      index2to16   // 2 <= len(string) <= 16
+	MOVD     $0xff00, R21 // Mask for later
+	MTVSRD   R21, V25     // Move to Vreg
+	VSPLTH   $3, V25, V31 // Splat mask
+	VSPLTH   $0, V0, V1   // Splat 1st 2 bytes of sep
+	VSPLTISB $0, V10      // Clear V10
+
+	// First case: 2 byte separator
+	// V1: 2 byte separator splatted
+	// V2: 16 bytes at addr
+	// V4: 16 bytes at addr+1
+	// Compare 2 byte separator at start
+	// and at start+1. Use VSEL to combine
+	// those results to find the first
+	// matching start byte, returning
+	// that value when found. Loop as
+	// long as len(string) > 16
+index2loop2:
+	LXVB16X (R7)(R19), V3_ // Load 16 bytes @R7+1 into V3
+
+index2loop:
+	LXVB16X  (R7)(R0), V2_   // Load 16 bytes @R7 into V2
+	VCMPEQUH V1, V2, V5      // Search for sep
+	VCMPEQUH V1, V3, V6      // Search for sep offset by 1
+	VSEL     V6, V5, V31, V7 // merge even and odd indices
+	VCLZD    V7, V18         // find index of first match
+	MFVSRD   V18, R25        // get first value
+	CMP      R25, $64        // Found if < 64
+	BLT      foundR25        // Return byte index where found
+
+	MFVSRLD V18, R25        // get second value
+	CMP     R25, $64        // Found if < 64
+	ADD     $64, R25        // Update byte offset
+	BLT     foundR25        // Return value
+	ADD     $16, R7         // R7+=16 Update string pointer
+	ADD     $17, R7, R9     // R9=F7+17 since loop unrolled
+	CMP     R9, LASTBYTE    // Compare addr+17 against last byte
+	BLT     index2loop2     // If < last, continue loop
+	CMP     R7, LASTBYTE    // Compare addr+16 against last byte
+	BLT     index2to16      // If < 16 handle specially
+	LXVB16X (R7)(R0), V3_   // Load 16 bytes @R7 into V3
+	VSLDOI  $1, V3, V10, V3 // Shift left by 1 byte
+	BR      index2loop
+
+index3plus:
+	CMP    R6, $3       // Check if sep == 3
+	BNE    index4plus   // If not check larger
+	ADD    $19, R7, R9  // Find bytes for use in this loop
+	CMP    R9, LASTBYTE // Compare against last byte
+	BGE    index2to16   // Remaining string 2<=len<=16
+	MOVD   $0xff00, R21 // Set up mask for upcoming loop
+	MTVSRD R21, V25     // Move mask to Vreg
+	VSPLTH $3, V25, V31 // Splat mask
+	VSPLTH $0, V0, V1   // Splat 1st two bytes of sep
+	VSPLTB $2, V0, V8   // Splat 3rd byte of sep
+
+	// Loop to process 3 byte separator.
+	// string[0:16] is in V2
+	// string[2:18] is in V3
+	// sep[0:2] splatted in V1
+	// sec[3] splatted in v8
+	// Load vectors at string, string+1
+	// and string+2. Compare string, string+1
+	// against first 2 bytes of separator
+	// splatted, and string+2 against 3rd
+	// byte splatted. Merge the results with
+	// VSEL to find the first byte of a match.
+
+	// Special handling for last 16 bytes if the
+	// string fits in 16 byte multiple.
+index3loop2:
+	MOVD     $2, R21          // Set up index for 2
+	VSPLTISB $0, V10          // Clear V10
+	LXVB16X  (R7)(R21), V3_   // Load 16 bytes @R7+2 into V3
+	VSLDOI   $14, V3, V10, V3 // Left justify next 2 bytes
+
+index3loop:
+	LXVB16X  (R7)(R0), V2_   // Load 16 bytes @R7
+	VSLDOI   $1, V2, V3, V4  // string[1:17]
+	VSLDOI   $2, V2, V3, V9  // string[2:18]
+	VCMPEQUH V1, V2, V5      // compare hw even indices
+	VCMPEQUH V1, V4, V6      // compare hw odd indices
+	VCMPEQUB V8, V9, V10     // compare 3rd to last byte
+	VSEL     V6, V5, V31, V7 // Find 1st matching byte using mask
+	VAND     V7, V10, V7     // AND matched bytes with matched 3rd byte
+	VCLZD    V7, V18         // Find first nonzero indexes
+	MFVSRD   V18, R25        // Move 1st doubleword
+	CMP      R25, $64        // If < 64 found
+	BLT      foundR25        // Return matching index
+
+	MFVSRLD  V18, R25     // Move 2nd doubleword
+	CMP      R25, $64     // If < 64 found
+	ADD      $64, R25     // Update byte index
+	BLT      foundR25     // Return matching index
+	ADD      $16, R7      // R7+=16 string ptr
+	ADD      $19, R7, R9  // Number of string bytes for loop
+	CMP      R9, LASTBYTE // Compare against last byte of string
+	BLT      index3loop2  // If within, continue this loop
+	CMP      R7, LASTSTR  // Compare against last start byte
+	BLT      index2to16   // Process remainder
+	VSPLTISB $0, V3       // Special case for last 16 bytes
+	BR       index3loop   // Continue this loop
+
+	// Loop to process 4 byte separator
+	// string[0:16] in V2
+	// string[3:16] in V3
+	// sep[0:4] splatted in V1
+	// Set up vectors with strings at offsets
+	// 0, 1, 2, 3 and compare against the 4 byte
+	// separator also splatted. Use VSEL with the
+	// compare results to find the first byte where
+	// a separator match is found.
+index4plus:
+	CMP  R6, $4       // Check if 4 byte separator
+	BNE  index5plus   // If not next higher
+	ADD  $20, R7, R9  // Check string size to load
+	CMP  R9, LASTBYTE // Verify string length
+	BGE  index2to16   // If not large enough, process remaining
+	MOVD $2, R15      // Set up index
+
+	// Set up masks for use with VSEL
+	MOVD    $0xff, R21 // Set up mask 0xff000000ff000000...
+	SLD     $24, R21
+	MTVSRWS R21, V29
+
+	VSLDOI  $2, V29, V29, V30 // Mask 0x0000ff000000ff00...
+	MOVD    $0xffff, R21
+	SLD     $16, R21
+	MTVSRWS R21, V31
+
+	VSPLTW $0, V0, V1 // Splat 1st word of separator
+
+index4loop:
+	LXVB16X (R7)(R0), V2_ // Load 16 bytes @R7 into V2
+
+next4:
+	VSPLTISB $0, V10            // Clear
+	MOVD     $3, R9             // Number of bytes beyond 16
+	LXVB16X  (R7)(R9), V3_      // Load 16 bytes @R7 into V2
+	VSLDOI   $13, V3, V10, V3   // Shift left last 3 bytes
+	VSLDOI   $1, V2, V3, V4     // V4=(V2:V3)<<1
+	VSLDOI   $2, V2, V3, V9     // V9=(V2:V3)<<2
+	VSLDOI   $3, V2, V3, V10    // V10=(V2:v3)<<3
+	VCMPEQUW V1, V2, V5         // compare index 0, 4, ... with sep
+	VCMPEQUW V1, V4, V6         // compare index 1, 5, ... with sep
+	VCMPEQUW V1, V9, V11        // compare index 2, 6, ... with sep
+	VCMPEQUW V1, V10, V12       // compare index 3, 7, ... with sep
+	VSEL     V6, V5, V29, V13   // merge index 0, 1, 4, 5, using mask
+	VSEL     V12, V11, V30, V14 // merge index 2, 3, 6, 7, using mask
+	VSEL     V14, V13, V31, V7  // final merge
+	VCLZD    V7, V18            // Find first index for each half
+	MFVSRD   V18, R25           // Isolate value
+	CMP      R25, $64           // If < 64, found
+	BLT      foundR25           // Return found index
+
+	MFVSRLD V18, R25     // Isolate other value
+	CMP     R25, $64     // If < 64, found
+	ADD     $64, R25     // Update index for high doubleword
+	BLT     foundR25     // Return found index
+	ADD     $16, R7      // R7+=16 for next string
+	ADD     $20, R7, R9  // R+20 for all bytes to load
+	CMP     R9, LASTBYTE // Past end? Maybe check for extra?
+	BLT     index4loop   // If not, continue loop
+	CMP     R7, LASTSTR  // Check remainder
+	BLE     index2to16   // Process remainder
+	BR      notfound     // Not found
+
+index5plus:
+	CMP R6, $16     // Check for sep > 16
+	BGT index17plus // Handle large sep
+
+	// Assumption is that the separator is smaller than the string at this point
+index2to16:
+	CMP R7, LASTSTR // Compare last start byte
+	BGT notfound    // last takes len(sep) into account
+
+	ADD $16, R7, R9    // Check for last byte of string
+	CMP R9, LASTBYTE
+	BGT index2to16tail
+
+	// At least 16 bytes of string left
+	// Mask the number of bytes in sep
+index2to16loop:
+	LXVB16X (R7)(R0), V1_ // Load 16 bytes @R7 into V1
+
+compare:
+	VAND       V1, SEPMASK, V2 // Mask out sep size
+	VCMPEQUBCC V0, V2, V3      // Compare masked string
+	BLT        CR6, found      // All equal
+	ADD        $1, R7          // Update ptr to next byte
+	CMP        R7, LASTSTR     // Still less than last start byte
+	BGT        notfound        // Not found
+	ADD        $16, R7, R9     // Verify remaining bytes
+	CMP        R9, LASTBYTE    // At least 16
+	BLT        index2to16loop  // Try again
+
+	// Less than 16 bytes remaining in string
+	// Separator >= 2
+index2to16tail:
+	ADD     R3, R4, R9     // End of string
+	SUB     R7, R9, R9     // Number of bytes left
+	ANDCC   $15, R7, R10   // 16 byte offset
+	ADD     R10, R9, R11   // offset + len
+	CMP     R11, $16       // >= 16?
+	BLE     short          // Does not cross 16 bytes
+	LXVB16X (R7)(R0), V1_  // Load 16 bytes @R7 into V1
+	BR      index2to16next // Continue on
+
+short:
+	RLDICR   $0, R7, $59, R9 // Adjust addr to 16 byte container
+	LXVB16X  (R9)(R0), V1_   // Load 16 bytes @R9 into V1
+	SLD      $3, R10         // Set up shift
+	MTVSRD   R10, V8_        // Set up shift
+	VSLDOI   $8, V8, V8, V8
+	VSLO     V1, V8, V1      // Shift by start byte
+	VSPLTISB $0, V25         // Clear for later use
+
+index2to16next:
+	VAND       V1, SEPMASK, V2 // Just compare size of sep
+	VCMPEQUBCC V0, V2, V3      // Compare sep and partial string
+	BLT        CR6, found      // Found
+	ADD        $1, R7          // Not found, try next partial string
+	CMP        R7, LASTSTR     // Check for end of string
+	BGT        notfound        // If at end, then not found
+	VSLDOI     $1, V1, V25, V1 // Shift string left by 1 byte
+	BR         index2to16next  // Check the next partial string
+
+index17plus:
+	CMP      R6, $32       // Check if 17 < len(sep) <= 32
+	BGT      index33plus
+	SUB      $16, R6, R9   // Extra > 16
+	SLD      $56, R9, R10  // Shift to use in VSLO
+	MTVSRD   R10, V9_      // Set up for VSLO
+	LXVB16X  (R5)(R9), V1_ // Load 16 bytes @R5+R9 into V1
+	VSLO     V1, V9, V1    // Shift left
+	VSPLTISB $0xff, V7     // Splat 1s
+	VSPLTISB $0, V27       // Splat 0
+
+index17to32loop:
+	LXVB16X (R7)(R0), V2_ // Load 16 bytes @R7 into V2
+
+next17:
+	LXVB16X    (R7)(R9), V3_   // Load 16 bytes @R7+R9 into V3
+	VSLO       V3, V9, V3      // Shift left
+	VCMPEQUB   V0, V2, V4      // Compare first 16 bytes
+	VCMPEQUB   V1, V3, V5      // Compare extra over 16 bytes
+	VAND       V4, V5, V6      // Check if both equal
+	VCMPEQUBCC V6, V7, V8      // All equal?
+	BLT        CR6, found      // Yes
+	ADD        $1, R7          // On to next byte
+	CMP        R7, LASTSTR     // Check if last start byte
+	BGT        notfound        // If too high, not found
+	BR         index17to32loop // Continue
+
+notfound:
+	MOVD $-1, R8   // Return -1 if not found
+	MOVD R8, (R14)
+	RET
+
+index33plus:
+	MOVD $0, (R0) // Case not implemented
+	RET           // Crash before return
+
+foundR25:
+	SRD  $3, R25   // Convert from bits to bytes
+	ADD  R25, R7   // Add to current string address
+	SUB  R3, R7    // Subtract from start of string
+	MOVD R7, (R14) // Return byte where found
+	RET
+
+found:
+	SUB  R3, R7    // Return byte where found
+	MOVD R7, (R14)
+	RET
+