cmd/5g, cmd/8g: zero ambiguously live values on entry

The code here is being restored after its deletion in CL 14430048.

I restored the copy in cmd/6g in CL 56430043 but neglected the
other two.

This is the reason that enabling precisestack only worked on amd64.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/66170043

diff --git a/src/cmd/5g/ggen.c b/src/cmd/5g/ggen.c
index 18431c2bf94ff3fb028c92114bf715e76edda730..b9930f49e73742aeb288c400b6bc2996bacd3fff 100644 (file)
--- a/src/cmd/5g/ggen.c
+++ b/src/cmd/5g/ggen.c
@@ -9,10 +9,13 @@
 #include "gg.h"
 #include "opt.h"
 
+static Prog* appendpp(Prog*, int, int, int, int32, int, int, int32);
+
 void
 defframe(Prog *ptxt)
 {
        uint32 frame;
+       Prog *p, *p1;
 
        // fill in argument size
        ptxt->to.type = D_CONST2;
@@ -24,6 +27,41 @@ defframe(Prog *ptxt)
        frame = rnd(maxstksize+maxarg, widthptr);
        ptxt->to.offset = frame;
        maxstksize = 0;
+       
+       p = ptxt;
+       if(stkzerosize > 0) {
+               p = appendpp(p, AMOVW, D_CONST, NREG, 0, D_REG, 0, 0);
+               p = appendpp(p, AADD, D_CONST, NREG, 4+frame-stkzerosize, D_REG, 1, 0);
+               p->reg = REGSP; 
+               p = appendpp(p, AADD, D_CONST, NREG, stkzerosize, D_REG, 2, 0); 
+               p->reg = 1;     
+               p1 = p = appendpp(p, AMOVW, D_REG, 0, 0, D_OREG, 1, 4); 
+               p->scond |= C_PBIT;     
+               p = appendpp(p, ACMP, D_REG, 1, 0, D_NONE, 0, 0);       
+               p->reg = 2;     
+               p = appendpp(p, ABNE, D_NONE, NREG, 0, D_BRANCH, NREG, 0);      
+               patch(p, p1);
+       }       
+}
+
+static Prog*   
+appendpp(Prog *p, int as, int ftype, int freg, int32 foffset, int ttype, int treg, int32 toffset)      
+{      
+       Prog *q;        
+               
+       q = mal(sizeof(*q));    
+       clearp(q);      
+       q->as = as;     
+       q->lineno = p->lineno;  
+       q->from.type = ftype;   
+       q->from.reg = freg;     
+       q->from.offset = foffset;       
+       q->to.type = ttype;     
+       q->to.reg = treg;       
+       q->to.offset = toffset; 
+       q->link = p->link;      
+       p->link = q;    
+       return q;       
 }
 
 // Sweep the prog list to mark any used nodes.

diff --git a/src/cmd/8g/ggen.c b/src/cmd/8g/ggen.c
index fe1b63de12cad423aa9357cf34c2e7addc21c1fd..b3e2665ca4e94fa7f87bdd7ecb585b548ee205ba 100644 (file)
--- a/src/cmd/8g/ggen.c
+++ b/src/cmd/8g/ggen.c
@@ -9,10 +9,13 @@
 #include "gg.h"
 #include "opt.h"
 
+static Prog *appendpp(Prog*, int, int, vlong, int, vlong);
+
 void
 defframe(Prog *ptxt)
 {
        uint32 frame;
+       Prog *p;
 
        // fill in argument size
        ptxt->to.offset2 = rnd(curfn->type->argwid, widthptr);
@@ -23,6 +26,35 @@ defframe(Prog *ptxt)
        frame = rnd(maxstksize+maxarg, widthptr);
        ptxt->to.offset = frame;
        maxstksize = 0;
+       
+       // insert code to contain ambiguously live variables
+       // so that garbage collector only sees initialized values
+       // when it looks for pointers.
+       p = ptxt;
+       if(stkzerosize > 0) {
+               p = appendpp(p, AMOVL, D_CONST, 0, D_AX, 0);    
+               p = appendpp(p, AMOVL, D_CONST, stkzerosize/widthptr, D_CX, 0); 
+               p = appendpp(p, ALEAL, D_SP+D_INDIR, frame-stkzerosize, D_DI, 0);       
+               p = appendpp(p, AREP, D_NONE, 0, D_NONE, 0);    
+               appendpp(p, ASTOSL, D_NONE, 0, D_NONE, 0);      
+       }
+}
+
+static Prog*   
+appendpp(Prog *p, int as, int ftype, vlong foffset, int ttype, vlong toffset)  
+{
+       Prog *q;
+       q = mal(sizeof(*q));    
+       clearp(q);      
+       q->as = as;     
+       q->lineno = p->lineno;  
+       q->from.type = ftype;   
+       q->from.offset = foffset;       
+       q->to.type = ttype;     
+       q->to.offset = toffset; 
+       q->link = p->link;      
+       p->link = q;    
+       return q;       
 }
 
 // Sweep the prog list to mark any used nodes.