예제 #1
0
파일: obj5.go 프로젝트: klueska/go-akaros
func progedit(ctxt *obj.Link, p *obj.Prog) {
	p.From.Class = 0
	p.To.Class = 0

	// Rewrite B/BL to symbol as TYPE_BRANCH.
	switch p.As {
	case AB,
		ABL,
		obj.ADUFFZERO,
		obj.ADUFFCOPY:
		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
		}
	}

	// Replace TLS register fetches on older ARM procesors.
	switch p.As {
	// Treat MRC 15, 0, <reg>, C13, C0, 3 specially.
	case AMRC:
		if p.To.Offset&0xffff0fff == 0xee1d0f70 {
			// Because the instruction might be rewriten to a BL which returns in R0
			// the register must be zero.
			if p.To.Offset&0xf000 != 0 {
				ctxt.Diag("%v: TLS MRC instruction must write to R0 as it might get translated into a BL instruction", p.Line())
			}

			if ctxt.Goarm < 7 {
				// Replace it with BL runtime.read_tls_fallback(SB) for ARM CPUs that lack the tls extension.
				if progedit_tlsfallback == nil {
					progedit_tlsfallback = obj.Linklookup(ctxt, "runtime.read_tls_fallback", 0)
				}

				// MOVW	LR, R11
				p.As = AMOVW

				p.From.Type = obj.TYPE_REG
				p.From.Reg = REGLINK
				p.To.Type = obj.TYPE_REG
				p.To.Reg = REGTMP

				// BL	runtime.read_tls_fallback(SB)
				p = obj.Appendp(ctxt, p)

				p.As = ABL
				p.To.Type = obj.TYPE_BRANCH
				p.To.Sym = progedit_tlsfallback
				p.To.Offset = 0

				// MOVW	R11, LR
				p = obj.Appendp(ctxt, p)

				p.As = AMOVW
				p.From.Type = obj.TYPE_REG
				p.From.Reg = REGTMP
				p.To.Type = obj.TYPE_REG
				p.To.Reg = REGLINK
				break
			}
		}

		// Otherwise, MRC/MCR instructions need no further treatment.
		p.As = AWORD
	}

	// Rewrite float constants to values stored in memory.
	switch p.As {
	case AMOVF:
		if p.From.Type == obj.TYPE_FCONST && chipfloat5(ctxt, p.From.U.Dval) < 0 && (chipzero5(ctxt, p.From.U.Dval) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
			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.Sym = s
			p.From.Name = obj.NAME_EXTERN
			p.From.Offset = 0
		}

	case AMOVD:
		if p.From.Type == obj.TYPE_FCONST && chipfloat5(ctxt, p.From.U.Dval) < 0 && (chipzero5(ctxt, p.From.U.Dval) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
			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.Sym = s
			p.From.Name = obj.NAME_EXTERN
			p.From.Offset = 0
		}
	}

	if ctxt.Flag_shared != 0 {
		// Shared libraries use R_ARM_TLS_IE32 instead of
		// R_ARM_TLS_LE32, replacing the link time constant TLS offset in
		// runtime.tlsg with an address to a GOT entry containing the
		// offset. Rewrite $runtime.tlsg(SB) to runtime.tlsg(SB) to
		// compensate.
		if ctxt.Tlsg == nil {
			ctxt.Tlsg = obj.Linklookup(ctxt, "runtime.tlsg", 0)
		}

		if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN && p.From.Sym == ctxt.Tlsg {
			p.From.Type = obj.TYPE_MEM
		}
		if p.To.Type == obj.TYPE_ADDR && p.To.Name == obj.NAME_EXTERN && p.To.Sym == ctxt.Tlsg {
			p.To.Type = obj.TYPE_MEM
		}
	}
}
예제 #2
0
파일: obj6.go 프로젝트: klueska/go-akaros
func progedit(ctxt *obj.Link, p *obj.Prog) {
	// Maintain information about code generation mode.
	if ctxt.Mode == 0 {
		ctxt.Mode = ctxt.Arch.Regsize * 8
	}
	p.Mode = int8(ctxt.Mode)

	switch p.As {
	case AMODE:
		if p.From.Type == obj.TYPE_CONST || (p.From.Type == obj.TYPE_MEM && p.From.Reg == REG_NONE) {
			switch int(p.From.Offset) {
			case 16, 32, 64:
				ctxt.Mode = int(p.From.Offset)
			}
		}
		obj.Nopout(p)
	}

	// Thread-local storage references use the TLS pseudo-register.
	// As a register, TLS refers to the thread-local storage base, and it
	// can only be loaded into another register:
	//
	//         MOVQ TLS, AX
	//
	// An offset from the thread-local storage base is written off(reg)(TLS*1).
	// Semantically it is off(reg), but the (TLS*1) annotation marks this as
	// indexing from the loaded TLS base. This emits a relocation so that
	// if the linker needs to adjust the offset, it can. For example:
	//
	//         MOVQ TLS, AX
	//         MOVQ 8(AX)(TLS*1), CX // load m into CX
	//
	// On systems that support direct access to the TLS memory, this
	// pair of instructions can be reduced to a direct TLS memory reference:
	//
	//         MOVQ 8(TLS), CX // load m into CX
	//
	// The 2-instruction and 1-instruction forms correspond roughly to
	// ELF TLS initial exec mode and ELF TLS local exec mode, respectively.
	//
	// We applies this rewrite on systems that support the 1-instruction form.
	// The decision is made using only the operating system (and probably
	// the -shared flag, eventually), not the link mode. If some link modes
	// on a particular operating system require the 2-instruction form,
	// then all builds for that operating system will use the 2-instruction
	// form, so that the link mode decision can be delayed to link time.
	//
	// In this way, all supported systems use identical instructions to
	// access TLS, and they are rewritten appropriately first here in
	// liblink and then finally using relocations in the linker.

	if canuselocaltls(ctxt) {
		// Reduce TLS initial exec model to TLS local exec model.
		// Sequences like
		//	MOVQ TLS, BX
		//	... off(BX)(TLS*1) ...
		// become
		//	NOP
		//	... off(TLS) ...
		//
		// TODO(rsc): Remove the Hsolaris special case. It exists only to
		// guarantee we are producing byte-identical binaries as before this code.
		// But it should be unnecessary.
		if (p.As == AMOVQ || 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_R15 && ctxt.Headtype != obj.Hsolaris {
			obj.Nopout(p)
		}
		if p.From.Type == obj.TYPE_MEM && p.From.Index == REG_TLS && REG_AX <= p.From.Reg && p.From.Reg <= REG_R15 {
			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_R15 {
			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
		//	MOVQ off(TLS), BX
		// becomes the sequence
		//	MOVQ TLS, BX
		//	MOVQ 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 == AMOVQ || 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_R15 {
			q := obj.Appendp(ctxt, p)
			q.As = p.As
			q.From = p.From
			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.Hwindows && p.Mode == 64 || 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 0 to $0 in 3rd argment to CMPPS etc.
	// That's what the tables expect.
	switch p.As {
	case ACMPPD, ACMPPS, ACMPSD, ACMPSS:
		if p.To.Type == obj.TYPE_MEM && p.To.Name == obj.NAME_NONE && p.To.Reg == REG_NONE && p.To.Index == REG_NONE && p.To.Sym == nil {
			p.To.Type = obj.TYPE_CONST
		}
	}

	// 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
		}
	}

	if ctxt.Headtype == obj.Hnacl && p.Mode == 64 {
		nacladdr(ctxt, p, &p.From3)
		nacladdr(ctxt, p, &p.From)
		nacladdr(ctxt, p, &p.To)
	}

	// 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_X15 {
					p.As = AXORPS
					p.From = p.To
					break
				}
			}
		}
		fallthrough

	case AFMOVF,
		AFADDF,
		AFSUBF,
		AFSUBRF,
		AFMULF,
		AFDIVF,
		AFDIVRF,
		AFCOMF,
		AFCOMFP,
		AADDSS,
		ASUBSS,
		AMULSS,
		ADIVSS,
		ACOMISS,
		AUCOMISS:
		if p.From.Type == obj.TYPE_FCONST {
			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
		}

	case AMOVSD:
		// Convert AMOVSD $(0), Xx to AXORPS Xx, Xx
		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_X15 {
					p.As = AXORPS
					p.From = p.To
					break
				}
			}
		}
		fallthrough

	case AFMOVD,
		AFADDD,
		AFSUBD,
		AFSUBRD,
		AFMULD,
		AFDIVD,
		AFDIVRD,
		AFCOMD,
		AFCOMDP,
		AADDSD,
		ASUBSD,
		AMULSD,
		ADIVSD,
		ACOMISD,
		AUCOMISD:
		if p.From.Type == obj.TYPE_FCONST {
			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
		}
	}
}