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cmd/gc: add debugging to liveness analysis

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Even with debugmerge = 1, the debugging output only happens
with the -v command-line flag. This is useful because it gets added
in automatically when debugging things like registerization with -R -v.

Change-Id: I9a5c7f562507b72e8e2fe2686fd07d069721345a
Reviewed-on: https://go-review.googlesource.com/4641
Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Russ Cox 2015-02-10 19:27:49 -05:00
parent bed481d683
commit fa7efa2cb0
1 changed files with 14 additions and 7 deletions
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21
src/cmd/gc/popt.c
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@ -567,7 +567,7 @@ mergetemp(Prog *firstp)
int32 gen;
Graph *g;
enum { Debug = 0 };
enum { debugmerge = 1 };
g = flowstart(firstp, 0);
if(g == nil)
@ -615,7 +615,7 @@ mergetemp(Prog *firstp)
}
}
if(Debug > 1)
if(debugmerge > 1 && debug['v'])
arch.dumpit("before", g->start, 0);
nkill = 0;
@ -632,7 +632,7 @@ mergetemp(Prog *firstp)
p->as = ANOP;
p->to = zprog.to;
v->removed = 1;
if(Debug)
if(debugmerge > 0 && debug['v'])
print("drop write-only %S\n", v->node->sym);
} else
fatal("temp used and not set: %P", p);
@ -656,7 +656,7 @@ mergetemp(Prog *firstp)
p1->from = p->from;
arch.excise(f);
v->removed = 1;
if(Debug)
if(debugmerge > 0 && debug['v'])
print("drop immediate-use %S\n", v->node->sym);
}
nkill++;
@ -696,6 +696,9 @@ mergetemp(Prog *firstp)
nfree = nvar;
for(i=0; i<nvar; i++) {
v = bystart[i];
if(debugmerge > 0 && debug['v'])
print("consider %#N: removed=%d\n", v->node, v->removed);
if(v->removed)
continue;
@ -705,10 +708,14 @@ mergetemp(Prog *firstp)
inuse[--nfree] = v1;
}
if(debugmerge > 0 && debug['v'])
print("consider %#N: removed=%d nfree=%d nvar=%d\n", v->node, v->removed, nfree, nvar);
// Find old temp to reuse if possible.
t = v->node->type;
for(j=nfree; j<nvar; j++) {
v1 = inuse[j];
if(debugmerge > 0 && debug['v'])
print("consider %#N: maybe %#N: type=%T,%T addrtaken=%d,%d\n", v->node, v1->node, t, v1->node->type, v->node->addrtaken, v1->node->addrtaken);
// Require the types to match but also require the addrtaken bits to match.
// If a variable's address is taken, that disables registerization for the individual
// words of the variable (for example, the base,len,cap of a slice).
@ -734,7 +741,7 @@ mergetemp(Prog *firstp)
inuse[j] = v;
}
if(Debug) {
if(debugmerge > 0 && debug['v']) {
print("%S [%d - %d]\n", curfn->nname->sym, nvar, nkill);
for(v=var; v<var+nvar; v++) {
print("var %#N %T %lld-%lld", v->node, v->node->type, v->start, v->end);
@ -744,12 +751,12 @@ mergetemp(Prog *firstp)
print(" dead=1");
if(v->merge)
print(" merge %#N", v->merge->node);
if(v->start == v->end)
if(v->start == v->end && v->def != nil)
print(" %P", v->def->prog);
print("\n");
}
if(Debug > 1)
if(debugmerge > 1 && debug['v'])
arch.dumpit("after", g->start, 0);
}