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* better cse handling of short boolean evaluated boolean expressions

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git-svn-id: trunk@22369 -
This commit is contained in:
florian 2012-09-10 18:42:50 +00:00
parent e4c0132109
commit a1da9b7710
1 changed files with 44 additions and 16 deletions
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60
compiler/optcse.pas
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@ -47,7 +47,7 @@ unit optcse;
uses
globtype,globals,
cclasses,
cutils,cclasses,
verbose,
nutils,
procinfo,
@ -104,7 +104,36 @@ unit optcse;
result:=collectnodes(n,arg);
end;
function collectnodes(var n:tnode; arg: pointer) : foreachnoderesult;
{ when compiling a tree like
and
/ \
and C
/ \
A B
all expressions of B are available during evaluation of C. However considerung the whole expression,
values of B and C might not be available due to short boolean evaluation.
So recurseintobooleanchain detectes such chained and/or expressions and makes sub-expressions of B
available during the evaluation of C
firstleftend is later used to remove all sub expressions of B and C by storing the expression count
in the cse table after handling A
}
var
firstleftend : longint;
procedure recurseintobooleanchain(t : tnodetype;n : tnode);
begin
if (tbinarynode(n).left.nodetype=t) and is_boolean(tbinarynode(n).left.resultdef) then
recurseintobooleanchain(t,tbinarynode(n).left)
else
foreachnodestatic(pm_postprocess,tbinarynode(n).left,@collectnodes2,arg);
firstleftend:=min(plists(arg)^.nodelist.count,firstleftend);
foreachnodestatic(pm_postprocess,tbinarynode(n).right,@collectnodes2,arg);
end;
var
i,j : longint;
begin
@ -193,22 +222,21 @@ unit optcse;
break;
end;
end;
{ boolean and/or require a special handling: after evaluating the and/or node,
the expressions of the right side might not be available due to short boolean
evaluation, so after handling the right side, mark those expressions
as unavailable }
if (n.nodetype in [orn,andn]) and is_boolean(taddnode(n).left.resultdef) then
begin
foreachnodestatic(pm_postprocess,taddnode(n).left,@collectnodes2,arg);
j:=plists(arg)^.nodelist.count;
foreachnodestatic(pm_postprocess,taddnode(n).right,@collectnodes2,arg);
for i:=j to plists(arg)^.nodelist.count-1 do
DFASetExclude(plists(arg)^.avail,i);
result:=fen_norecurse_false;
end;
end;
end;
{ boolean and/or require a special handling: after evaluating the and/or node,
the expressions of the right side might not be available due to short boolean
evaluation, so after handling the right side, mark those expressions
as unavailable }
if (n.nodetype in [orn,andn]) and is_boolean(taddnode(n).left.resultdef) then
begin
firstleftend:=high(longint);
recurseintobooleanchain(n.nodetype,n);
for i:=firstleftend to plists(arg)^.nodelist.count-1 do
DFASetExclude(plists(arg)^.avail,i);
result:=fen_norecurse_false;
end;
end;
function searchcsedomain(var n: tnode; arg: pointer) : foreachnoderesult;