文件操作 - equal_ppc64x.s
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文件: /usr/share/go-1.23/src/internal/bytealg/equal_ppc64x.s
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// Copyright 2018 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. //go:build ppc64 || ppc64le #include "go_asm.h" #include "textflag.h" // 4K (smallest case) page size offset mask for PPC64. #define PAGE_OFFSET 4095 // Likewise, the BC opcode is hard to read, and no extended // mnemonics are offered for these forms. #define BGELR_CR6 BC 4, CR6LT, (LR) #define BEQLR BC 12, CR0EQ, (LR) // memequal(a, b unsafe.Pointer, size uintptr) bool TEXT runtime·memequal<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-25 // R3 = a // R4 = b // R5 = size BR memeqbody<>(SB) // memequal_varlen(a, b unsafe.Pointer) bool TEXT runtime·memequal_varlen<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-17 // R3 = a // R4 = b CMP R3, R4 BEQ eq MOVD 8(R11), R5 // compiler stores size at offset 8 in the closure BR memeqbody<>(SB) eq: MOVD $1, R3 RET // Do an efficient memequal for ppc64 // R3 = s1 // R4 = s2 // R5 = len // On exit: // R3 = return value TEXT memeqbody<>(SB),NOSPLIT|NOFRAME,$0-0 MOVD R3, R8 // Move s1 into R8 ADD R5, R3, R9 // &s1[len(s1)] ADD R5, R4, R10 // &s2[len(s2)] MOVD $1, R11 CMP R5, $16 // Use GPR checks for check for len <= 16 BLE check0_16 MOVD $0, R3 // Assume no-match in case BGELR CR6 returns CMP R5, $32 // Use overlapping VSX loads for len <= 32 BLE check17_32 // Do a pair of overlapping VSR compares CMP R5, $64 BLE check33_64 // Hybrid check + overlap compare. setup64: SRD $6, R5, R6 // number of 64 byte chunks to compare MOVD R6, CTR MOVD $16, R14 // index for VSX loads and stores MOVD $32, R15 MOVD $48, R16 ANDCC $0x3F, R5, R5 // len%64==0? PCALIGN $16 loop64: LXVD2X (R8+R0), V0 LXVD2X (R4+R0), V1 VCMPEQUBCC V0, V1, V2 // compare, setting CR6 BGELR_CR6 LXVD2X (R8+R14), V0 LXVD2X (R4+R14), V1 VCMPEQUBCC V0, V1, V2 BGELR_CR6 LXVD2X (R8+R15), V0 LXVD2X (R4+R15), V1 VCMPEQUBCC V0, V1, V2 BGELR_CR6 LXVD2X (R8+R16), V0 LXVD2X (R4+R16), V1 VCMPEQUBCC V0, V1, V2 BGELR_CR6 ADD $64,R8 // bump up to next 64 ADD $64,R4 BDNZ loop64 ISEL CR0EQ, R11, R3, R3 // If no tail, return 1, otherwise R3 remains 0. BEQLR // return if no tail. ADD $-64, R9, R8 ADD $-64, R10, R4 LXVD2X (R8+R0), V0 LXVD2X (R4+R0), V1 VCMPEQUBCC V0, V1, V2 BGELR_CR6 LXVD2X (R8+R14), V0 LXVD2X (R4+R14), V1 VCMPEQUBCC V0, V1, V2 BGELR_CR6 LXVD2X (R8+R15), V0 LXVD2X (R4+R15), V1 VCMPEQUBCC V0, V1, V2 BGELR_CR6 LXVD2X (R8+R16), V0 LXVD2X (R4+R16), V1 VCMPEQUBCC V0, V1, V2 ISEL CR6LT, R11, R0, R3 RET check33_64: // Bytes 0-15 LXVD2X (R8+R0), V0 LXVD2X (R4+R0), V1 VCMPEQUBCC V0, V1, V2 BGELR_CR6 ADD $16, R8 ADD $16, R4 // Bytes 16-31 LXVD2X (R8+R0), V0 LXVD2X (R4+R0), V1 VCMPEQUBCC V0, V1, V2 BGELR_CR6 // A little tricky, but point R4,R8 to &sx[len-32], // and reuse check17_32 to check the next 1-31 bytes (with some overlap) ADD $-32, R9, R8 ADD $-32, R10, R4 // Fallthrough check17_32: LXVD2X (R8+R0), V0 LXVD2X (R4+R0), V1 VCMPEQUBCC V0, V1, V2 ISEL CR6LT, R11, R0, R5 // Load sX[len(sX)-16:len(sX)] and compare. ADD $-16, R9 ADD $-16, R10 LXVD2X (R9+R0), V0 LXVD2X (R10+R0), V1 VCMPEQUBCC V0, V1, V2 ISEL CR6LT, R5, R0, R3 RET check0_16: #ifdef GOPPC64_power10 SLD $56, R5, R7 LXVL R8, R7, V0 LXVL R4, R7, V1 VCMPEQUDCC V0, V1, V2 ISEL CR6LT, R11, R0, R3 RET #else CMP R5, $8 BLT check0_7 // Load sX[0:7] and compare. MOVD (R8), R6 MOVD (R4), R7 CMP R6, R7 ISEL CR0EQ, R11, R0, R5 // Load sX[len(sX)-8:len(sX)] and compare. MOVD -8(R9), R6 MOVD -8(R10), R7 CMP R6, R7 ISEL CR0EQ, R5, R0, R3 RET check0_7: CMP R5,$0 MOVD $1, R3 BEQLR // return if len == 0 // Check < 8B loads with a single compare, but select the load address // such that it cannot cross a page boundary. Load a few bytes from the // lower address if that does not cross the lower page. Or, load a few // extra bytes from the higher addresses. And align those values // consistently in register as either address may have differing // alignment requirements. ANDCC $PAGE_OFFSET, R8, R6 // &sX & PAGE_OFFSET ANDCC $PAGE_OFFSET, R4, R9 SUBC R5, $8, R12 // 8-len SLD $3, R12, R14 // (8-len)*8 CMPU R6, R12, CR1 // Enough bytes lower in the page to load lower? CMPU R9, R12, CR0 SUB R12, R8, R6 // compute lower load address SUB R12, R4, R9 ISEL CR1LT, R8, R6, R8 // R8 = R6 < 0 ? R8 (&s1) : R6 (&s1 - (8-len)) ISEL CR0LT, R4, R9, R4 // Similar for s2 MOVD (R8), R15 MOVD (R4), R16 SLD R14, R15, R7 SLD R14, R16, R17 SRD R14, R7, R7 // Clear the upper (8-len) bytes (with 2 shifts) SRD R14, R17, R17 SRD R14, R15, R6 // Clear the lower (8-len) bytes SRD R14, R16, R9 #ifdef GOARCH_ppc64le ISEL CR1LT, R7, R6, R8 // Choose the correct len bytes to compare based on alignment ISEL CR0LT, R17, R9, R4 #else ISEL CR1LT, R6, R7, R8 ISEL CR0LT, R9, R17, R4 #endif CMP R4, R8 ISEL CR0EQ, R11, R0, R3 RET #endif // tail processing if !defined(GOPPC64_power10)
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