github.com/tidwall/go@v0.0.0-20170415222209-6694a6888b7d/src/cmd/compile/internal/ppc64/ggen.go (about)

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package ppc64
     6  
     7  import (
     8  	"cmd/compile/internal/gc"
     9  	"cmd/internal/obj"
    10  	"cmd/internal/obj/ppc64"
    11  )
    12  
    13  func defframe(pp *gc.Progs, fn *gc.Node, sz int64) {
    14  	// fill in argument size, stack size
    15  	pp.Text.To.Type = obj.TYPE_TEXTSIZE
    16  
    17  	pp.Text.To.Val = int32(gc.Rnd(fn.Type.ArgWidth(), int64(gc.Widthptr)))
    18  	frame := uint32(gc.Rnd(sz, int64(gc.Widthreg)))
    19  	pp.Text.To.Offset = int64(frame)
    20  
    21  	// insert code to zero ambiguously live variables
    22  	// so that the garbage collector only sees initialized values
    23  	// when it looks for pointers.
    24  	p := pp.Text
    25  
    26  	hi := int64(0)
    27  	lo := hi
    28  
    29  	// iterate through declarations - they are sorted in decreasing xoffset order.
    30  	for _, n := range fn.Func.Dcl {
    31  		if !n.Name.Needzero() {
    32  			continue
    33  		}
    34  		if n.Class != gc.PAUTO {
    35  			gc.Fatalf("needzero class %d", n.Class)
    36  		}
    37  		if n.Type.Width%int64(gc.Widthptr) != 0 || n.Xoffset%int64(gc.Widthptr) != 0 || n.Type.Width == 0 {
    38  			gc.Fatalf("var %L has size %d offset %d", n, int(n.Type.Width), int(n.Xoffset))
    39  		}
    40  
    41  		if lo != hi && n.Xoffset+n.Type.Width >= lo-int64(2*gc.Widthreg) {
    42  			// merge with range we already have
    43  			lo = n.Xoffset
    44  
    45  			continue
    46  		}
    47  
    48  		// zero old range
    49  		p = zerorange(pp, p, int64(frame), lo, hi)
    50  
    51  		// set new range
    52  		hi = n.Xoffset + n.Type.Width
    53  
    54  		lo = n.Xoffset
    55  	}
    56  
    57  	// zero final range
    58  	zerorange(pp, p, int64(frame), lo, hi)
    59  }
    60  
    61  func zerorange(pp *gc.Progs, p *obj.Prog, frame int64, lo int64, hi int64) *obj.Prog {
    62  	cnt := hi - lo
    63  	if cnt == 0 {
    64  		return p
    65  	}
    66  	if cnt < int64(4*gc.Widthptr) {
    67  		for i := int64(0); i < cnt; i += int64(gc.Widthptr) {
    68  			p = pp.Appendpp(p, ppc64.AMOVD, obj.TYPE_REG, ppc64.REGZERO, 0, obj.TYPE_MEM, ppc64.REGSP, gc.Ctxt.FixedFrameSize()+frame+lo+i)
    69  		}
    70  	} else if cnt <= int64(128*gc.Widthptr) {
    71  		p = pp.Appendpp(p, ppc64.AADD, obj.TYPE_CONST, 0, gc.Ctxt.FixedFrameSize()+frame+lo-8, obj.TYPE_REG, ppc64.REGRT1, 0)
    72  		p.Reg = ppc64.REGSP
    73  		p = pp.Appendpp(p, obj.ADUFFZERO, obj.TYPE_NONE, 0, 0, obj.TYPE_MEM, 0, 0)
    74  		p.To.Name = obj.NAME_EXTERN
    75  		p.To.Sym = gc.Duffzero
    76  		p.To.Offset = 4 * (128 - cnt/int64(gc.Widthptr))
    77  	} else {
    78  		p = pp.Appendpp(p, ppc64.AMOVD, obj.TYPE_CONST, 0, gc.Ctxt.FixedFrameSize()+frame+lo-8, obj.TYPE_REG, ppc64.REGTMP, 0)
    79  		p = pp.Appendpp(p, ppc64.AADD, obj.TYPE_REG, ppc64.REGTMP, 0, obj.TYPE_REG, ppc64.REGRT1, 0)
    80  		p.Reg = ppc64.REGSP
    81  		p = pp.Appendpp(p, ppc64.AMOVD, obj.TYPE_CONST, 0, cnt, obj.TYPE_REG, ppc64.REGTMP, 0)
    82  		p = pp.Appendpp(p, ppc64.AADD, obj.TYPE_REG, ppc64.REGTMP, 0, obj.TYPE_REG, ppc64.REGRT2, 0)
    83  		p.Reg = ppc64.REGRT1
    84  		p = pp.Appendpp(p, ppc64.AMOVDU, obj.TYPE_REG, ppc64.REGZERO, 0, obj.TYPE_MEM, ppc64.REGRT1, int64(gc.Widthptr))
    85  		p1 := p
    86  		p = pp.Appendpp(p, ppc64.ACMP, obj.TYPE_REG, ppc64.REGRT1, 0, obj.TYPE_REG, ppc64.REGRT2, 0)
    87  		p = pp.Appendpp(p, ppc64.ABNE, obj.TYPE_NONE, 0, 0, obj.TYPE_BRANCH, 0, 0)
    88  		gc.Patch(p, p1)
    89  	}
    90  
    91  	return p
    92  }
    93  
    94  func ginsnop(pp *gc.Progs) {
    95  	p := pp.Prog(ppc64.AOR)
    96  	p.From.Type = obj.TYPE_REG
    97  	p.From.Reg = ppc64.REG_R0
    98  	p.To.Type = obj.TYPE_REG
    99  	p.To.Reg = ppc64.REG_R0
   100  }
   101  
   102  func ginsnop2(pp *gc.Progs) {
   103  	// PPC64 is unusual because TWO nops are required
   104  	// (see gc/cgen.go, gc/plive.go -- copy of comment below)
   105  	//
   106  	// On ppc64, when compiling Go into position
   107  	// independent code on ppc64le we insert an
   108  	// instruction to reload the TOC pointer from the
   109  	// stack as well. See the long comment near
   110  	// jmpdefer in runtime/asm_ppc64.s for why.
   111  	// If the MOVD is not needed, insert a hardware NOP
   112  	// so that the same number of instructions are used
   113  	// on ppc64 in both shared and non-shared modes.
   114  
   115  	ginsnop(pp)
   116  	if gc.Ctxt.Flag_shared {
   117  		p := pp.Prog(ppc64.AMOVD)
   118  		p.From.Type = obj.TYPE_MEM
   119  		p.From.Offset = 24
   120  		p.From.Reg = ppc64.REGSP
   121  		p.To.Type = obj.TYPE_REG
   122  		p.To.Reg = ppc64.REG_R2
   123  	} else {
   124  		ginsnop(pp)
   125  	}
   126  }