| // Inferno utils/8l/pass.c |
| // http://code.google.com/p/inferno-os/source/browse/utils/8l/pass.c |
| // |
| // Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved. |
| // Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net) |
| // Portions Copyright © 1997-1999 Vita Nuova Limited |
| // Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com) |
| // Portions Copyright © 2004,2006 Bruce Ellis |
| // Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net) |
| // Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others |
| // Portions Copyright © 2009 The Go Authors. All rights reserved. |
| // |
| // Permission is hereby granted, free of charge, to any person obtaining a copy |
| // of this software and associated documentation files (the "Software"), to deal |
| // in the Software without restriction, including without limitation the rights |
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| // copies of the Software, and to permit persons to whom the Software is |
| // furnished to do so, subject to the following conditions: |
| // |
| // The above copyright notice and this permission notice shall be included in |
| // all copies or substantial portions of the Software. |
| // |
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| // THE SOFTWARE. |
| |
| package i386 |
| |
| import ( |
| "cmd/internal/obj" |
| "encoding/binary" |
| "fmt" |
| "log" |
| "math" |
| ) |
| |
| func canuselocaltls(ctxt *obj.Link) bool { |
| switch ctxt.Headtype { |
| case obj.Hlinux, |
| obj.Hnacl, |
| obj.Hplan9, |
| obj.Hwindows: |
| return false |
| } |
| |
| return true |
| } |
| |
| func progedit(ctxt *obj.Link, p *obj.Prog) { |
| var literal string |
| var s *obj.LSym |
| var q *obj.Prog |
| |
| // See obj6.c for discussion of TLS. |
| if canuselocaltls(ctxt) { |
| // Reduce TLS initial exec model to TLS local exec model. |
| // Sequences like |
| // MOVL TLS, BX |
| // ... off(BX)(TLS*1) ... |
| // become |
| // NOP |
| // ... off(TLS) ... |
| if p.As == AMOVL && p.From.Type == obj.TYPE_REG && p.From.Reg == REG_TLS && p.To.Type == obj.TYPE_REG && REG_AX <= p.To.Reg && p.To.Reg <= REG_DI { |
| p.As = obj.ANOP |
| p.From.Type = obj.TYPE_NONE |
| p.To.Type = obj.TYPE_NONE |
| } |
| |
| if p.From.Type == obj.TYPE_MEM && p.From.Index == REG_TLS && REG_AX <= p.From.Reg && p.From.Reg <= REG_DI { |
| p.From.Type = obj.TYPE_MEM |
| p.From.Reg = REG_TLS |
| p.From.Scale = 0 |
| p.From.Index = REG_NONE |
| } |
| |
| if p.To.Type == obj.TYPE_MEM && p.To.Index == REG_TLS && REG_AX <= p.To.Reg && p.To.Reg <= REG_DI { |
| p.To.Type = obj.TYPE_MEM |
| p.To.Reg = REG_TLS |
| p.To.Scale = 0 |
| p.To.Index = REG_NONE |
| } |
| } else { |
| // As a courtesy to the C compilers, rewrite TLS local exec load as TLS initial exec load. |
| // The instruction |
| // MOVL off(TLS), BX |
| // becomes the sequence |
| // MOVL TLS, BX |
| // MOVL off(BX)(TLS*1), BX |
| // This allows the C compilers to emit references to m and g using the direct off(TLS) form. |
| if p.As == AMOVL && p.From.Type == obj.TYPE_MEM && p.From.Reg == REG_TLS && p.To.Type == obj.TYPE_REG && REG_AX <= p.To.Reg && p.To.Reg <= REG_DI { |
| q = obj.Appendp(ctxt, p) |
| q.As = p.As |
| q.From.Type = obj.TYPE_MEM |
| q.From.Reg = p.To.Reg |
| q.From.Index = REG_TLS |
| q.From.Scale = 2 // TODO: use 1 |
| q.To = p.To |
| p.From.Type = obj.TYPE_REG |
| p.From.Reg = REG_TLS |
| p.From.Index = REG_NONE |
| p.From.Offset = 0 |
| } |
| } |
| |
| // TODO: Remove. |
| if ctxt.Headtype == obj.Hplan9 { |
| if p.From.Scale == 1 && p.From.Index == REG_TLS { |
| p.From.Scale = 2 |
| } |
| if p.To.Scale == 1 && p.To.Index == REG_TLS { |
| p.To.Scale = 2 |
| } |
| } |
| |
| // Rewrite CALL/JMP/RET to symbol as TYPE_BRANCH. |
| switch p.As { |
| case obj.ACALL, |
| obj.AJMP, |
| obj.ARET: |
| if p.To.Type == obj.TYPE_MEM && (p.To.Name == obj.NAME_EXTERN || p.To.Name == obj.NAME_STATIC) && p.To.Sym != nil { |
| p.To.Type = obj.TYPE_BRANCH |
| } |
| } |
| |
| // Rewrite float constants to values stored in memory. |
| switch p.As { |
| // Convert AMOVSS $(0), Xx to AXORPS Xx, Xx |
| case AMOVSS: |
| if p.From.Type == obj.TYPE_FCONST { |
| if p.From.U.Dval == 0 { |
| if p.To.Type == obj.TYPE_REG && REG_X0 <= p.To.Reg && p.To.Reg <= REG_X7 { |
| p.As = AXORPS |
| p.From = p.To |
| break |
| } |
| } |
| } |
| fallthrough |
| |
| // fallthrough |
| |
| case AFMOVF, |
| AFADDF, |
| AFSUBF, |
| AFSUBRF, |
| AFMULF, |
| AFDIVF, |
| AFDIVRF, |
| AFCOMF, |
| AFCOMFP, |
| AADDSS, |
| ASUBSS, |
| AMULSS, |
| ADIVSS, |
| ACOMISS, |
| AUCOMISS: |
| if p.From.Type == obj.TYPE_FCONST { |
| var i32 uint32 |
| var f32 float32 |
| f32 = float32(p.From.U.Dval) |
| i32 = math.Float32bits(f32) |
| literal = fmt.Sprintf("$f32.%08x", i32) |
| s = obj.Linklookup(ctxt, literal, 0) |
| if s.Type == 0 { |
| s.Type = obj.SRODATA |
| obj.Adduint32(ctxt, s, i32) |
| s.Reachable = 0 |
| } |
| |
| p.From.Type = obj.TYPE_MEM |
| p.From.Name = obj.NAME_EXTERN |
| p.From.Sym = s |
| p.From.Offset = 0 |
| } |
| |
| // Convert AMOVSD $(0), Xx to AXORPS Xx, Xx |
| case AMOVSD: |
| if p.From.Type == obj.TYPE_FCONST { |
| if p.From.U.Dval == 0 { |
| if p.To.Type == obj.TYPE_REG && REG_X0 <= p.To.Reg && p.To.Reg <= REG_X7 { |
| p.As = AXORPS |
| p.From = p.To |
| break |
| } |
| } |
| } |
| fallthrough |
| |
| // fallthrough |
| |
| case AFMOVD, |
| AFADDD, |
| AFSUBD, |
| AFSUBRD, |
| AFMULD, |
| AFDIVD, |
| AFDIVRD, |
| AFCOMD, |
| AFCOMDP, |
| AADDSD, |
| ASUBSD, |
| AMULSD, |
| ADIVSD, |
| ACOMISD, |
| AUCOMISD: |
| if p.From.Type == obj.TYPE_FCONST { |
| var i64 uint64 |
| i64 = math.Float64bits(p.From.U.Dval) |
| literal = fmt.Sprintf("$f64.%016x", i64) |
| s = obj.Linklookup(ctxt, literal, 0) |
| if s.Type == 0 { |
| s.Type = obj.SRODATA |
| obj.Adduint64(ctxt, s, i64) |
| s.Reachable = 0 |
| } |
| |
| p.From.Type = obj.TYPE_MEM |
| p.From.Name = obj.NAME_EXTERN |
| p.From.Sym = s |
| p.From.Offset = 0 |
| } |
| } |
| } |
| |
| func preprocess(ctxt *obj.Link, cursym *obj.LSym) { |
| var p *obj.Prog |
| var q *obj.Prog |
| var p1 *obj.Prog |
| var p2 *obj.Prog |
| var autoffset int32 |
| var deltasp int32 |
| var a int |
| |
| if ctxt.Symmorestack[0] == nil { |
| ctxt.Symmorestack[0] = obj.Linklookup(ctxt, "runtime.morestack", 0) |
| ctxt.Symmorestack[1] = obj.Linklookup(ctxt, "runtime.morestack_noctxt", 0) |
| } |
| |
| if ctxt.Headtype == obj.Hplan9 && ctxt.Plan9privates == nil { |
| ctxt.Plan9privates = obj.Linklookup(ctxt, "_privates", 0) |
| } |
| |
| ctxt.Cursym = cursym |
| |
| if cursym.Text == nil || cursym.Text.Link == nil { |
| return |
| } |
| |
| p = cursym.Text |
| autoffset = int32(p.To.Offset) |
| if autoffset < 0 { |
| autoffset = 0 |
| } |
| |
| cursym.Locals = autoffset |
| cursym.Args = p.To.U.Argsize |
| |
| q = nil |
| |
| if p.From3.Offset&obj.NOSPLIT == 0 || (p.From3.Offset&obj.WRAPPER != 0) { |
| p = obj.Appendp(ctxt, p) |
| p = load_g_cx(ctxt, p) // load g into CX |
| } |
| |
| if cursym.Text.From3.Offset&obj.NOSPLIT == 0 { |
| p = stacksplit(ctxt, p, autoffset, cursym.Text.From3.Offset&obj.NEEDCTXT == 0, &q) // emit split check |
| } |
| |
| if autoffset != 0 { |
| p = obj.Appendp(ctxt, p) |
| p.As = AADJSP |
| p.From.Type = obj.TYPE_CONST |
| p.From.Offset = int64(autoffset) |
| p.Spadj = autoffset |
| } else { |
| // zero-byte stack adjustment. |
| // Insert a fake non-zero adjustment so that stkcheck can |
| // recognize the end of the stack-splitting prolog. |
| p = obj.Appendp(ctxt, p) |
| |
| p.As = obj.ANOP |
| p.Spadj = int32(-ctxt.Arch.Ptrsize) |
| p = obj.Appendp(ctxt, p) |
| p.As = obj.ANOP |
| p.Spadj = int32(ctxt.Arch.Ptrsize) |
| } |
| |
| if q != nil { |
| q.Pcond = p |
| } |
| deltasp = autoffset |
| |
| if cursym.Text.From3.Offset&obj.WRAPPER != 0 { |
| // if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame |
| // |
| // MOVL g_panic(CX), BX |
| // TESTL BX, BX |
| // JEQ end |
| // LEAL (autoffset+4)(SP), DI |
| // CMPL panic_argp(BX), DI |
| // JNE end |
| // MOVL SP, panic_argp(BX) |
| // end: |
| // NOP |
| // |
| // The NOP is needed to give the jumps somewhere to land. |
| // It is a liblink NOP, not an x86 NOP: it encodes to 0 instruction bytes. |
| |
| p = obj.Appendp(ctxt, p) |
| |
| p.As = AMOVL |
| p.From.Type = obj.TYPE_MEM |
| p.From.Reg = REG_CX |
| p.From.Offset = 4 * int64(ctxt.Arch.Ptrsize) // G.panic |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_BX |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = ATESTL |
| p.From.Type = obj.TYPE_REG |
| p.From.Reg = REG_BX |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_BX |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = AJEQ |
| p.To.Type = obj.TYPE_BRANCH |
| p1 = p |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = ALEAL |
| p.From.Type = obj.TYPE_MEM |
| p.From.Reg = REG_SP |
| p.From.Offset = int64(autoffset) + 4 |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_DI |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = ACMPL |
| p.From.Type = obj.TYPE_MEM |
| p.From.Reg = REG_BX |
| p.From.Offset = 0 // Panic.argp |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_DI |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = AJNE |
| p.To.Type = obj.TYPE_BRANCH |
| p2 = p |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = AMOVL |
| p.From.Type = obj.TYPE_REG |
| p.From.Reg = REG_SP |
| p.To.Type = obj.TYPE_MEM |
| p.To.Reg = REG_BX |
| p.To.Offset = 0 // Panic.argp |
| |
| p = obj.Appendp(ctxt, p) |
| |
| p.As = obj.ANOP |
| p1.Pcond = p |
| p2.Pcond = p |
| } |
| |
| if ctxt.Debugzerostack != 0 && autoffset != 0 && cursym.Text.From3.Offset&obj.NOSPLIT == 0 { |
| // 8l -Z means zero the stack frame on entry. |
| // This slows down function calls but can help avoid |
| // false positives in garbage collection. |
| p = obj.Appendp(ctxt, p) |
| |
| p.As = AMOVL |
| p.From.Type = obj.TYPE_REG |
| p.From.Reg = REG_SP |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_DI |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = AMOVL |
| p.From.Type = obj.TYPE_CONST |
| p.From.Offset = int64(autoffset) / 4 |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_CX |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = AMOVL |
| p.From.Type = obj.TYPE_CONST |
| p.From.Offset = 0 |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_AX |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = AREP |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = ASTOSL |
| } |
| |
| for ; p != nil; p = p.Link { |
| a = int(p.From.Name) |
| if a == obj.NAME_AUTO { |
| p.From.Offset += int64(deltasp) |
| } |
| if a == obj.NAME_PARAM { |
| p.From.Offset += int64(deltasp) + 4 |
| } |
| a = int(p.To.Name) |
| if a == obj.NAME_AUTO { |
| p.To.Offset += int64(deltasp) |
| } |
| if a == obj.NAME_PARAM { |
| p.To.Offset += int64(deltasp) + 4 |
| } |
| |
| switch p.As { |
| default: |
| continue |
| |
| case APUSHL, |
| APUSHFL: |
| deltasp += 4 |
| p.Spadj = 4 |
| continue |
| |
| case APUSHW, |
| APUSHFW: |
| deltasp += 2 |
| p.Spadj = 2 |
| continue |
| |
| case APOPL, |
| APOPFL: |
| deltasp -= 4 |
| p.Spadj = -4 |
| continue |
| |
| case APOPW, |
| APOPFW: |
| deltasp -= 2 |
| p.Spadj = -2 |
| continue |
| |
| case obj.ARET: |
| break |
| } |
| |
| if autoffset != deltasp { |
| ctxt.Diag("unbalanced PUSH/POP") |
| } |
| |
| if autoffset != 0 { |
| p.As = AADJSP |
| p.From.Type = obj.TYPE_CONST |
| p.From.Offset = int64(-autoffset) |
| p.Spadj = -autoffset |
| p = obj.Appendp(ctxt, p) |
| p.As = obj.ARET |
| |
| // If there are instructions following |
| // this ARET, they come from a branch |
| // with the same stackframe, so undo |
| // the cleanup. |
| p.Spadj = +autoffset |
| } |
| |
| if p.To.Sym != nil { // retjmp |
| p.As = obj.AJMP |
| } |
| } |
| } |
| |
| // Append code to p to load g into cx. |
| // Overwrites p with the first instruction (no first appendp). |
| // Overwriting p is unusual but it lets use this in both the |
| // prologue (caller must call appendp first) and in the epilogue. |
| // Returns last new instruction. |
| func load_g_cx(ctxt *obj.Link, p *obj.Prog) *obj.Prog { |
| var next *obj.Prog |
| |
| p.As = AMOVL |
| p.From.Type = obj.TYPE_MEM |
| p.From.Reg = REG_TLS |
| p.From.Offset = 0 |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_CX |
| |
| next = p.Link |
| progedit(ctxt, p) |
| for p.Link != next { |
| p = p.Link |
| } |
| |
| if p.From.Index == REG_TLS { |
| p.From.Scale = 2 |
| } |
| |
| return p |
| } |
| |
| // Append code to p to check for stack split. |
| // Appends to (does not overwrite) p. |
| // Assumes g is in CX. |
| // Returns last new instruction. |
| // On return, *jmpok is the instruction that should jump |
| // to the stack frame allocation if no split is needed. |
| func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32, noctxt bool, jmpok **obj.Prog) *obj.Prog { |
| var q *obj.Prog |
| var q1 *obj.Prog |
| |
| if ctxt.Debugstack != 0 { |
| // 8l -K means check not only for stack |
| // overflow but stack underflow. |
| // On underflow, INT 3 (breakpoint). |
| // Underflow itself is rare but this also |
| // catches out-of-sync stack guard info. |
| p = obj.Appendp(ctxt, p) |
| |
| p.As = ACMPL |
| p.From.Type = obj.TYPE_MEM |
| p.From.Reg = REG_CX |
| p.From.Offset = 4 |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_SP |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = AJCC |
| p.To.Type = obj.TYPE_BRANCH |
| p.To.Offset = 4 |
| q1 = p |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = AINT |
| p.From.Type = obj.TYPE_CONST |
| p.From.Offset = 3 |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = obj.ANOP |
| q1.Pcond = p |
| } |
| |
| q1 = nil |
| |
| if framesize <= obj.StackSmall { |
| // small stack: SP <= stackguard |
| // CMPL SP, stackguard |
| p = obj.Appendp(ctxt, p) |
| |
| p.As = ACMPL |
| p.From.Type = obj.TYPE_REG |
| p.From.Reg = REG_SP |
| p.To.Type = obj.TYPE_MEM |
| p.To.Reg = REG_CX |
| p.To.Offset = 2 * int64(ctxt.Arch.Ptrsize) // G.stackguard0 |
| if ctxt.Cursym.Cfunc != 0 { |
| p.To.Offset = 3 * int64(ctxt.Arch.Ptrsize) // G.stackguard1 |
| } |
| } else if framesize <= obj.StackBig { |
| // large stack: SP-framesize <= stackguard-StackSmall |
| // LEAL -(framesize-StackSmall)(SP), AX |
| // CMPL AX, stackguard |
| p = obj.Appendp(ctxt, p) |
| |
| p.As = ALEAL |
| p.From.Type = obj.TYPE_MEM |
| p.From.Reg = REG_SP |
| p.From.Offset = -(int64(framesize) - obj.StackSmall) |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_AX |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = ACMPL |
| p.From.Type = obj.TYPE_REG |
| p.From.Reg = REG_AX |
| p.To.Type = obj.TYPE_MEM |
| p.To.Reg = REG_CX |
| p.To.Offset = 2 * int64(ctxt.Arch.Ptrsize) // G.stackguard0 |
| if ctxt.Cursym.Cfunc != 0 { |
| p.To.Offset = 3 * int64(ctxt.Arch.Ptrsize) // G.stackguard1 |
| } |
| } else { |
| // Such a large stack we need to protect against wraparound |
| // if SP is close to zero. |
| // SP-stackguard+StackGuard <= framesize + (StackGuard-StackSmall) |
| // The +StackGuard on both sides is required to keep the left side positive: |
| // SP is allowed to be slightly below stackguard. See stack.h. |
| // |
| // Preemption sets stackguard to StackPreempt, a very large value. |
| // That breaks the math above, so we have to check for that explicitly. |
| // MOVL stackguard, CX |
| // CMPL CX, $StackPreempt |
| // JEQ label-of-call-to-morestack |
| // LEAL StackGuard(SP), AX |
| // SUBL stackguard, AX |
| // CMPL AX, $(framesize+(StackGuard-StackSmall)) |
| p = obj.Appendp(ctxt, p) |
| |
| p.As = AMOVL |
| p.From.Type = obj.TYPE_MEM |
| p.From.Reg = REG_CX |
| p.From.Offset = 0 |
| p.From.Offset = 2 * int64(ctxt.Arch.Ptrsize) // G.stackguard0 |
| if ctxt.Cursym.Cfunc != 0 { |
| p.From.Offset = 3 * int64(ctxt.Arch.Ptrsize) // G.stackguard1 |
| } |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_SI |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = ACMPL |
| p.From.Type = obj.TYPE_REG |
| p.From.Reg = REG_SI |
| p.To.Type = obj.TYPE_CONST |
| p.To.Offset = int64(uint32(obj.StackPreempt & (1<<32 - 1))) |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = AJEQ |
| p.To.Type = obj.TYPE_BRANCH |
| q1 = p |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = ALEAL |
| p.From.Type = obj.TYPE_MEM |
| p.From.Reg = REG_SP |
| p.From.Offset = obj.StackGuard |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_AX |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = ASUBL |
| p.From.Type = obj.TYPE_REG |
| p.From.Reg = REG_SI |
| p.From.Offset = 0 |
| p.To.Type = obj.TYPE_REG |
| p.To.Reg = REG_AX |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = ACMPL |
| p.From.Type = obj.TYPE_REG |
| p.From.Reg = REG_AX |
| p.To.Type = obj.TYPE_CONST |
| p.To.Offset = int64(framesize) + (obj.StackGuard - obj.StackSmall) |
| } |
| |
| // common |
| p = obj.Appendp(ctxt, p) |
| |
| p.As = AJHI |
| p.To.Type = obj.TYPE_BRANCH |
| p.To.Offset = 4 |
| q = p |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = obj.ACALL |
| p.To.Type = obj.TYPE_BRANCH |
| if ctxt.Cursym.Cfunc != 0 { |
| p.To.Sym = obj.Linklookup(ctxt, "runtime.morestackc", 0) |
| } else { |
| p.To.Sym = ctxt.Symmorestack[bool2int(noctxt)] |
| } |
| |
| p = obj.Appendp(ctxt, p) |
| p.As = obj.AJMP |
| p.To.Type = obj.TYPE_BRANCH |
| p.Pcond = ctxt.Cursym.Text.Link |
| |
| if q != nil { |
| q.Pcond = p.Link |
| } |
| if q1 != nil { |
| q1.Pcond = q.Link |
| } |
| |
| *jmpok = q |
| return p |
| } |
| |
| func follow(ctxt *obj.Link, s *obj.LSym) { |
| var firstp *obj.Prog |
| var lastp *obj.Prog |
| |
| ctxt.Cursym = s |
| |
| firstp = ctxt.NewProg() |
| lastp = firstp |
| xfol(ctxt, s.Text, &lastp) |
| lastp.Link = nil |
| s.Text = firstp.Link |
| } |
| |
| func nofollow(a int) bool { |
| switch a { |
| case obj.AJMP, |
| obj.ARET, |
| AIRETL, |
| AIRETW, |
| obj.AUNDEF: |
| return true |
| } |
| |
| return false |
| } |
| |
| func pushpop(a int) bool { |
| switch a { |
| case APUSHL, |
| APUSHFL, |
| APUSHW, |
| APUSHFW, |
| APOPL, |
| APOPFL, |
| APOPW, |
| APOPFW: |
| return true |
| } |
| |
| return false |
| } |
| |
| func relinv(a int) int { |
| switch a { |
| case AJEQ: |
| return AJNE |
| case AJNE: |
| return AJEQ |
| case AJLE: |
| return AJGT |
| case AJLS: |
| return AJHI |
| case AJLT: |
| return AJGE |
| case AJMI: |
| return AJPL |
| case AJGE: |
| return AJLT |
| case AJPL: |
| return AJMI |
| case AJGT: |
| return AJLE |
| case AJHI: |
| return AJLS |
| case AJCS: |
| return AJCC |
| case AJCC: |
| return AJCS |
| case AJPS: |
| return AJPC |
| case AJPC: |
| return AJPS |
| case AJOS: |
| return AJOC |
| case AJOC: |
| return AJOS |
| } |
| |
| log.Fatalf("unknown relation: %s", Anames[a]) |
| return 0 |
| } |
| |
| func xfol(ctxt *obj.Link, p *obj.Prog, last **obj.Prog) { |
| var q *obj.Prog |
| var i int |
| var a int |
| |
| loop: |
| if p == nil { |
| return |
| } |
| if p.As == obj.AJMP { |
| q = p.Pcond |
| if q != nil && q.As != obj.ATEXT { |
| /* mark instruction as done and continue layout at target of jump */ |
| p.Mark = 1 |
| |
| p = q |
| if p.Mark == 0 { |
| goto loop |
| } |
| } |
| } |
| |
| if p.Mark != 0 { |
| /* |
| * p goes here, but already used it elsewhere. |
| * copy up to 4 instructions or else branch to other copy. |
| */ |
| i = 0 |
| q = p |
| for ; i < 4; (func() { i++; q = q.Link })() { |
| if q == nil { |
| break |
| } |
| if q == *last { |
| break |
| } |
| a = int(q.As) |
| if a == obj.ANOP { |
| i-- |
| continue |
| } |
| |
| if nofollow(a) || pushpop(a) { |
| break // NOTE(rsc): arm does goto copy |
| } |
| if q.Pcond == nil || q.Pcond.Mark != 0 { |
| continue |
| } |
| if a == obj.ACALL || a == ALOOP { |
| continue |
| } |
| for { |
| if p.As == obj.ANOP { |
| p = p.Link |
| continue |
| } |
| |
| q = obj.Copyp(ctxt, p) |
| p = p.Link |
| q.Mark = 1 |
| (*last).Link = q |
| *last = q |
| if int(q.As) != a || q.Pcond == nil || q.Pcond.Mark != 0 { |
| continue |
| } |
| |
| q.As = int16(relinv(int(q.As))) |
| p = q.Pcond |
| q.Pcond = q.Link |
| q.Link = p |
| xfol(ctxt, q.Link, last) |
| p = q.Link |
| if p.Mark != 0 { |
| return |
| } |
| goto loop |
| /* */ |
| } |
| } |
| q = ctxt.NewProg() |
| q.As = obj.AJMP |
| q.Lineno = p.Lineno |
| q.To.Type = obj.TYPE_BRANCH |
| q.To.Offset = p.Pc |
| q.Pcond = p |
| p = q |
| } |
| |
| /* emit p */ |
| p.Mark = 1 |
| |
| (*last).Link = p |
| *last = p |
| a = int(p.As) |
| |
| /* continue loop with what comes after p */ |
| if nofollow(a) { |
| return |
| } |
| if p.Pcond != nil && a != obj.ACALL { |
| /* |
| * some kind of conditional branch. |
| * recurse to follow one path. |
| * continue loop on the other. |
| */ |
| q = obj.Brchain(ctxt, p.Pcond) |
| if q != nil { |
| p.Pcond = q |
| } |
| q = obj.Brchain(ctxt, p.Link) |
| if q != nil { |
| p.Link = q |
| } |
| if p.From.Type == obj.TYPE_CONST { |
| if p.From.Offset == 1 { |
| /* |
| * expect conditional jump to be taken. |
| * rewrite so that's the fall-through case. |
| */ |
| p.As = int16(relinv(a)) |
| |
| q = p.Link |
| p.Link = p.Pcond |
| p.Pcond = q |
| } |
| } else { |
| q = p.Link |
| if q.Mark != 0 { |
| if a != ALOOP { |
| p.As = int16(relinv(a)) |
| p.Link = p.Pcond |
| p.Pcond = q |
| } |
| } |
| } |
| |
| xfol(ctxt, p.Link, last) |
| if p.Pcond.Mark != 0 { |
| return |
| } |
| p = p.Pcond |
| goto loop |
| } |
| |
| p = p.Link |
| goto loop |
| } |
| |
| var Link386 = obj.LinkArch{ |
| Dconv: Dconv, |
| Rconv: Rconv, |
| ByteOrder: binary.LittleEndian, |
| Pconv: Pconv, |
| Name: "386", |
| Thechar: '8', |
| Endian: obj.LittleEndian, |
| Preprocess: preprocess, |
| Assemble: span8, |
| Follow: follow, |
| Progedit: progedit, |
| Minlc: 1, |
| Ptrsize: 4, |
| Regsize: 4, |
| } |
