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@@ -34,14 +34,21 @@
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Register allocator introduction.
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-Free Pascal uses a Chaitin style register allocator similair to the one
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-described in the book "Modern compiler implementation in C" by Andrew W. Appel.,
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-published by Cambridge University Press.
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+Free Pascal uses a Chaitin style register allocator. We use a variant similair
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+to the one described in the book "Modern compiler implementation in C" by
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+Andrew W. Appel., published by Cambridge University Press.
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+
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+The register allocator that is described by Appel uses a much improved way
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+of register coalescing, called "iterated register coalescing". Instead
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+of doing coalescing as a prepass to the register allocation, the coalescing
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+is done inside the register allocator. This has the advantage that the
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+register allocator can coalesce very aggresively without introducing spills.
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Reading this book is recommended for a complete understanding. Here is a small
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introduction.
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-The code generator thinks it has an infinite amount of registers. Our processorhas a limited amount of registers. Therefore we must reduce the amount of
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+The code generator thinks it has an infinite amount of registers. Our processor
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+has a limited amount of registers. Therefore we must reduce the amount of
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registers until there are less enough to fit into the processors registers.
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Registers can interfere or not interfere. If two imaginary registers interfere
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@@ -68,6 +75,9 @@ Graph colouring is an NP complete problem. Therefore we use an approximation
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that pushes registers to colour on to a stack. This is done in the "simplify"
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procedure.
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+The register allocator first checks which registers are a candidate for
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+coalescing.
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+
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*******************************************************************************}
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@@ -275,6 +285,11 @@ unit rgobj;
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}
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function getexplicitregisterfpu(list : taasmoutput; r : Toldregister) : tregister;virtual;
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+{$ifdef newra}
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+ procedure allocexplicitregistersint(list:Taasmoutput;r:Tsupregset);
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+ procedure deallocexplicitregistersint(list:Taasmoutput;r:Tsupregset);
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+{$endif}
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+
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{# Deallocate any kind of register }
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procedure ungetregister(list: taasmoutput; r : tregister); virtual;
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@@ -493,7 +508,9 @@ unit rgobj;
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punusedstate = ^tunusedstate;
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tunusedstate = record
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+{$ifndef newra}
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unusedregsint : Tsupregset;
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+{$endif}
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unusedregsaddr : Tsupregset;
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unusedregsfpu : tregisterset;
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unusedregsmm : tregisterset;
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@@ -521,7 +538,12 @@ unit rgobj;
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resetusableregisters;
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lastintreg:=0;
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maxintreg:=first_imreg;
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- cpu_registers:={Acpu_registers}last_supreg-first_supreg+1;
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+ {What madman decided to change the code like this: (??)
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+ cpu_registers:=last_supreg-first_supreg+1;
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+ The amount of registers available for register allocation is
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+ allmost allways smaller than the amount of registers that exists!
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+ Therefore: }
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+ cpu_registers:=Acpu_registers;
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{$ifdef TEMPREGDEBUG}
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fillchar(reg_user,sizeof(reg_user),0);
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fillchar(reg_releaser,sizeof(reg_releaser),0);
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@@ -763,6 +785,52 @@ unit rgobj;
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getexplicitregisterint:=r2;
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end;
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+{$ifdef newra}
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+ procedure Trgobj.allocexplicitregistersint(list:Taasmoutput;r:Tsupregset);
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+
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+ var reg:Tregister;
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+ i:Tsuperregister;
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+
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+ begin
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+ if unusedregsint*r=r then
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+ begin
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+ unusedregsint:=unusedregsint-r;
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+ used_in_proc_int:=used_in_proc_int+r;
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+ for i:=first_supreg to last_supreg do
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+ if i in r then
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+ begin
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+ add_edges_used(i);
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+ reg.enum:=R_INTREGISTER;
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+ reg.number:=i shl 8 or R_SUBWHOLE;
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+ list.concat(Tai_regalloc.alloc(reg));
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+ end;
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+ end
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+ else
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+ internalerror(200305061);
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+ end;
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+
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+ procedure Trgobj.deallocexplicitregistersint(list:Taasmoutput;r:Tsupregset);
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+
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+ var reg:Tregister;
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+ i:Tsuperregister;
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+
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+ begin
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+ if unusedregsint*r=[] then
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+ begin
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+ unusedregsint:=unusedregsint+r;
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+ for i:=last_supreg downto first_supreg do
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+ if i in r then
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+ begin
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+ reg.enum:=R_INTREGISTER;
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+ reg.number:=i shl 8 or R_SUBWHOLE;
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+ list.concat(Tai_regalloc.dealloc(reg));
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+ end;
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+ end
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+ else
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+ internalerror(200305062);
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+ end;
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+{$endif}
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+
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{ tries to allocate the passed register, if possible }
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function trgobj.getexplicitregisterfpu(list : taasmoutput; r : Toldregister) : tregister;
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@@ -853,9 +921,7 @@ unit rgobj;
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exit;
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if r.enum>lastreg then
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internalerror(200301081);
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- if r.enum in intregs then
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- ungetregisterint(list,r)
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- else if r.enum in fpuregs then
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+ if r.enum in fpuregs then
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ungetregisterfpu(list,r,OS_NO)
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else if r.enum in mmregs then
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ungetregistermm(list,r)
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@@ -1357,7 +1423,9 @@ unit rgobj;
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procedure trgobj.saveUnusedState(var state: pointer);
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begin
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new(punusedstate(state));
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+ {$ifndef newra}
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punusedstate(state)^.unusedregsint := unusedregsint;
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+ {$endif}
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punusedstate(state)^.unusedregsfpu := unusedregsfpu;
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punusedstate(state)^.unusedregsmm := unusedregsmm;
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{$ifndef newra}
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@@ -1370,7 +1438,9 @@ unit rgobj;
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procedure trgobj.restoreUnusedState(var state: pointer);
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begin
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+ {$ifndef newra}
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unusedregsint := punusedstate(state)^.unusedregsint;
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+ {$endif}
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unusedregsfpu := punusedstate(state)^.unusedregsfpu;
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unusedregsmm := punusedstate(state)^.unusedregsmm;
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{$ifndef newra}
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@@ -1643,7 +1713,9 @@ unit rgobj;
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end;
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end;
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n:=Tsuperregister(simplifyworklist[p]);
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- delete(simplifyworklist,p,1);
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+ if length(simplifyworklist)>1 then
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+ simplifyworklist[p]:=simplifyworklist[length(simplifyworklist)];
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+ dec(simplifyworklist[0]);
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{Push it on the selectstack.}
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selectstack:=selectstack+char(n);
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@@ -1671,7 +1743,10 @@ unit rgobj;
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if not(u in [first_supreg..last_supreg]) and not move_related(u) and
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(degree[u]<cpu_registers) then
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begin
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- delete(freezeworklist,pos(char(u),freezeworklist),1);
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+ if length(freezeworklist)>1 then
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+ freezeworklist[pos(char(u),freezeworklist)]:=freezeworklist[length(freezeworklist)];
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+ dec(freezeworklist[0]);
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+{ delete(freezeworklist,pos(char(u),freezeworklist),1);}
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simplifyworklist:=simplifyworklist+char(u);
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end;
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end;
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@@ -1940,6 +2015,7 @@ unit rgobj;
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if a in colourednodes then
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include(adj_colours,colour[a]);
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end;
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+ include(adj_colours,RS_STACK_POINTER_REG);
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{Assume a spill by default...}
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spillednodes:=spillednodes+char(n);
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{Search for a colour not in this list.}
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@@ -2246,9 +2322,8 @@ unit rgobj;
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begin
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if r.enum<=lastreg then
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- internalerror(2003010803);
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+ internalerror(200301083);
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supreg:=r.number shr 8;
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- { takes much time }
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include(unusedregsint,supreg);
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if position=nil then
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list.insert(Tai_regalloc.dealloc(r))
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@@ -2271,9 +2346,10 @@ unit rgobj;
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spill_registers:=false;
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unusedregsint:=[0..255];
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fillchar(degree,sizeof(degree),0);
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+{ exclude(unusedregsint,RS_STACK_POINTER_REG);}
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if current_procinfo.framepointer.number=NR_FRAME_POINTER_REG then
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{Make sure the register allocator won't allocate registers into ebp.}
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- exclude(rg.unusedregsint,RS_FRAME_POINTER_REG);
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+ exclude(unusedregsint,RS_FRAME_POINTER_REG);
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new(spill_temps);
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fillchar(spill_temps^,sizeof(spill_temps^),0);
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regs_to_spill_set:=[];
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@@ -2459,7 +2535,10 @@ end.
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{
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$Log$
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- Revision 1.59 2003-07-06 15:00:47 jonas
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+ Revision 1.60 2003-07-06 15:31:21 daniel
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+ * Fixed register allocator. *Lots* of fixes.
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+
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+ Revision 1.59 2003/07/06 15:00:47 jonas
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* fixed my previous completely broken commit. It's not perfect though,
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registers > last_supreg and < max_intreg may still be "translated"
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daniel