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cmd/internal/obj/riscv: avoid obj.Prog rewriting for immediate splitting
Rather than rewriting the obj.Prog for a immediate instructions that need splitting, generate the appropriate machine instruction sequence directly. Change-Id: Ie90f0e2a98f97a29281e445c4c3b0c47b793ef4d Reviewed-on: https://go-review.googlesource.com/c/go/+/344453 Trust: Joel Sing <joel@sing.id.au> Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Joel Sing
parent
5c224ec921
commit
2d90df91a8
19
src/cmd/asm/internal/asm/testdata/riscv64.s
vendored
19
src/cmd/asm/internal/asm/testdata/riscv64.s
vendored
@ -10,20 +10,35 @@ start:
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// 2.4: Integer Computational Instructions
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ADDI $2047, X5, X6 // 1383f27f
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ADDI $-2048, X5, X6 // 13830280
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ADDI $2047, X5 // 9382f27f
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ADDI $-2048, X5 // 93820280
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ADDI $2048, X5 // 9382024093820240
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ADDI $-2049, X5 // 938202c09382f2bf
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ADDI $4094, X5 // 9382f27f9382f27f
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ADDI $-4096, X5 // 9382028093820280
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ADDI $4095, X5 // b71f00009b8fffffb382f201
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ADDI $-4097, X5 // b7ffffff9b8fffffb382f201
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ADDI $2047, X5, X6 // 1383f27f
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ADDI $-2048, X5, X6 // 13830280
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ADDI $2048, X5, X6 // 1383024013030340
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ADDI $-2049, X5, X6 // 138302c01303f3bf
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ADDI $4094, X5, X6 // 1383f27f1303f37f
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ADDI $-4096, X5, X6 // 1383028013030380
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ADDI $4095, X5, X6 // b71f00009b8fffff3383f201
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ADDI $-4097, X5, X6 // b7ffffff9b8fffff3383f201
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SLTI $55, X5, X7 // 93a37203
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SLTIU $55, X5, X7 // 93b37203
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ANDI $1, X5, X6 // 13f31200
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ANDI $1, X5 // 93f21200
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ANDI $2048, X5 // b71f00009b8f0f80b3f2f201
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ORI $1, X5, X6 // 13e31200
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ORI $1, X5 // 93e21200
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ORI $2048, X5 // b71f00009b8f0f80b3e2f201
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XORI $1, X5, X6 // 13c31200
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XORI $1, X5 // 93c21200
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XORI $2048, X5 // b71f00009b8f0f80b3c2f201
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SLLI $1, X5, X6 // 13931200
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SLLI $1, X5 // 93921200
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@ -693,76 +693,6 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
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}
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}
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// Split immediates larger than 12-bits.
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for p := cursym.Func().Text; p != nil; p = p.Link {
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switch p.As {
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// <opi> $imm, REG, TO
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case AADDI, AANDI, AORI, AXORI:
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// LUI $high, TMP
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// ADDI $low, TMP, TMP
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// <op> TMP, REG, TO
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q := *p
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low, high, err := Split32BitImmediate(p.From.Offset)
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if err != nil {
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ctxt.Diag("%v: constant %d too large", p, p.From.Offset, err)
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}
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if high == 0 {
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break // no need to split
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}
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// Split into two additions if possible.
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imm := q.From.Offset
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const minInt12, maxInt12 = -(1 << 11), (1 << 11) - 1
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if q.As == AADDI && 2*minInt12 <= imm && imm <= 2*maxInt12 {
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imm0, imm1 := imm/2, imm-imm/2
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// ADDI $(imm/2), REG, TO
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p.Spadj = 0 // needed if TO is SP
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p.As = AADDI
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p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: imm0}
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p.Reg = q.Reg
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p.To = q.To
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p = obj.Appendp(p, newprog)
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// ADDI $(imm-imm/2), TO, TO
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p.Spadj = q.Spadj
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p.As = AADDI
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p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: imm1}
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p.Reg = q.To.Reg
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p.To = q.To
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break
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}
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p.As = ALUI
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p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: high}
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p.Reg = 0
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p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
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p.Spadj = 0 // needed if TO is SP
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p = obj.Appendp(p, newprog)
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p.As = AADDIW
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p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: low}
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p.Reg = REG_TMP
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p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
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p = obj.Appendp(p, newprog)
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switch q.As {
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case AADDI:
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p.As = AADD
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case AANDI:
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p.As = AAND
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case AORI:
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p.As = AOR
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case AXORI:
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p.As = AXOR
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default:
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ctxt.Diag("unsupported instruction %v for splitting", q)
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}
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p.Spadj = q.Spadj
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p.To = q.To
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p.Reg = q.Reg
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p.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
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}
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}
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// Compute instruction addresses. Once we do that, we need to check for
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// overextended jumps and branches. Within each iteration, Pc differences
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// are always lower bounds (since the program gets monotonically longer,
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@ -1960,6 +1890,51 @@ func instructionsForProg(p *obj.Prog) []*instruction {
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ins.funct7 = 2
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ins.rs1, ins.rs2 = uint32(p.From.Reg), REG_ZERO
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case AADDI, AANDI, AORI, AXORI:
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// <opi> $imm, REG, TO
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low, high, err := Split32BitImmediate(ins.imm)
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if err != nil {
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p.Ctxt.Diag("%v: constant %d too large", p, ins.imm, err)
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return nil
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}
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if high == 0 {
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break
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}
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// Split into two additions if possible.
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if ins.as == AADDI && ins.imm >= -(1<<12) && ins.imm < 1<<12-1 {
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imm0 := ins.imm / 2
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imm1 := ins.imm - imm0
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// ADDI $(imm/2), REG, TO
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// ADDI $(imm-imm/2), TO, TO
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ins.imm = imm0
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insADDI := &instruction{as: AADDI, rd: ins.rd, rs1: ins.rd, imm: imm1}
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inss = append(inss, insADDI)
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break
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}
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// LUI $high, TMP
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// ADDI $low, TMP, TMP
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// <op> TMP, REG, TO
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insLUI := &instruction{as: ALUI, rd: REG_TMP, imm: high}
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insADDIW := &instruction{as: AADDIW, rd: REG_TMP, rs1: REG_TMP, imm: low}
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switch ins.as {
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case AADDI:
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ins.as = AADD
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case AANDI:
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ins.as = AAND
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case AORI:
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ins.as = AOR
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case AXORI:
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ins.as = AXOR
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default:
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p.Ctxt.Diag("unsupported instruction %v for splitting", p)
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return nil
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}
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ins.rs2 = REG_TMP
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inss = []*instruction{insLUI, insADDIW, ins}
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case ASCW, ASCD, AAMOSWAPW, AAMOSWAPD, AAMOADDW, AAMOADDD, AAMOANDW, AAMOANDD, AAMOORW, AAMOORD,
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AAMOXORW, AAMOXORD, AAMOMINW, AAMOMIND, AAMOMINUW, AAMOMINUD, AAMOMAXW, AAMOMAXD, AAMOMAXUW, AAMOMAXUD:
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// Set aq to use acquire access ordering, which matches Go's memory requirements.
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