paweld/fpc
1
0
Fork 0
mirror of https://gitlab.com/freepascal.org/fpc/source.git synced 2025-08-18 13:49:12 +02:00
Code Issues Packages Projects Releases Wiki Activity

* Fixed bug in "JccMovJmpMov2CMovCMov" optimisation where it didn't track registers in references getting changed

Browse Source
This commit is contained in:
J. Gareth "Curious Kit" Moreton 2023-04-30 04:34:05 +01:00 committed by J. Gareth "Kit" Moreton
parent 144ee6d51d
commit e40996cd2c
1 changed files with 71 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

77
compiler/x86/aoptx86.pas
View File

@ -128,7 +128,7 @@ unit aoptx86;
{ Returns true if the given MOV instruction can be safely converted to CMOV } { Returns true if the given MOV instruction can be safely converted to CMOV }
class function CanBeCMOV(p, cond_p: tai) : boolean; static; class function CanBeCMOV(p, cond_p: tai; var RefModified: Boolean) : boolean; static;
{ Like UpdateUsedRegs, but ignores deallocations } { Like UpdateUsedRegs, but ignores deallocations }
class procedure UpdateIntRegsNoDealloc(var AUsedRegs: TAllUsedRegs; p: Tai); static; class procedure UpdateIntRegsNoDealloc(var AUsedRegs: TAllUsedRegs; p: Tai); static;
@ -11613,7 +11613,7 @@ unit aoptx86;
end; end;
class function TX86AsmOptimizer.CanBeCMOV(p, cond_p: tai) : boolean; class function TX86AsmOptimizer.CanBeCMOV(p, cond_p: tai; var RefModified: Boolean) : boolean;
begin begin
Result := assigned(p) and Result := assigned(p) and
MatchInstruction(p,A_MOV,[S_W,S_L,S_Q]) and MatchInstruction(p,A_MOV,[S_W,S_L,S_Q]) and
@ -11630,6 +11630,8 @@ unit aoptx86;
( (
IsRefSafe(taicpu(p).oper[0]^.ref) or IsRefSafe(taicpu(p).oper[0]^.ref) or
( (
{ Don't use the reference in the condition if one of its registers got modified by a previous MOV }
not RefModified and
{ If the reference also appears in the condition, then we know it's safe, otherwise { If the reference also appears in the condition, then we know it's safe, otherwise
any kind of access violation would have occurred already } any kind of access violation would have occurred already }
Assigned(cond_p) and Assigned(cond_p) and
@ -11699,6 +11701,7 @@ unit aoptx86;
carryadd_opcode : TAsmOp; carryadd_opcode : TAsmOp;
symbol: TAsmSymbol; symbol: TAsmSymbol;
increg, tmpreg: TRegister; increg, tmpreg: TRegister;
RefModified: Boolean;
{$ifndef i8086} {$ifndef i8086}
{ Code and variables specific to CMOV optimisations } { Code and variables specific to CMOV optimisations }
hp3,hp4,hp5, hp3,hp4,hp5,
@ -12241,6 +12244,7 @@ unit aoptx86;
FillChar(ConstRegs[0], MAX_CMOV_REGISTERS * SizeOf(TRegister), 0); FillChar(ConstRegs[0], MAX_CMOV_REGISTERS * SizeOf(TRegister), 0);
FillChar(ConstVals[0], MAX_CMOV_REGISTERS * SizeOf(TCGInt), 0); FillChar(ConstVals[0], MAX_CMOV_REGISTERS * SizeOf(TCGInt), 0);
RefModified := False;
while assigned(hp1) and while assigned(hp1) and
{ Stop on the label we found } { Stop on the label we found }
(hp1 <> hp_lblxxx) do (hp1 <> hp_lblxxx) do
@ -12249,8 +12253,38 @@ unit aoptx86;
ait_instruction: ait_instruction:
if MatchInstruction(hp1, A_MOV, [S_W, S_L{$ifdef x86_64}, S_Q{$endif x86_64}]) then if MatchInstruction(hp1, A_MOV, [S_W, S_L{$ifdef x86_64}, S_Q{$endif x86_64}]) then
begin begin
if CanBeCMOV(hp1, hp_prev) then if CanBeCMOV(hp1, hp_prev, RefModified) then
Inc(l) begin
Inc(l);
{ MOV instruction will be writing to a register }
if Assigned(hp_prev) and
{ Make sure the sizes match too so we're reading and writing the same number of bytes }
(hp_prev.typ = ait_instruction) and
(taicpu(hp_prev).ops = 2) and
(
(
(taicpu(hp_prev).oper[0]^.typ = top_ref) and
RegInRef(taicpu(hp1).oper[1]^.reg, taicpu(hp_prev).oper[0]^.ref^)
) or
(
(taicpu(hp_prev).oper[1]^.typ = top_ref) and
RegInRef(taicpu(hp1).oper[1]^.reg, taicpu(hp_prev).oper[1]^.ref^)
)
) then
{ It is no longer safe to use the reference in the condition.
this prevents problems such as:
mov (%reg),%reg
mov (%reg),...
When the comparison is cmp (%reg),0 and guarding against a null pointer deallocation
(fixes #40165)
Note: "mov (%reg1),%reg2; mov (%reg2),..." won't be optimised this way since
at least one of (%reg1) and (%reg2) won't be in the condition and is hence unsafe.
}
RefModified := True;
end
else if not (cs_opt_size in current_settings.optimizerswitches) and else if not (cs_opt_size in current_settings.optimizerswitches) and
{ CMOV with constants grows the code size } { CMOV with constants grows the code size }
TryCMOVConst(hp1, hp_prev, hp_stop, c, l) then TryCMOVConst(hp1, hp_prev, hp_stop, c, l) then
@ -12445,6 +12479,7 @@ unit aoptx86;
end; end;
{ Analyse the second batch of MOVs to see if the setup is valid } { Analyse the second batch of MOVs to see if the setup is valid }
RefModified := False;
hp1 := hpmov2; hp1 := hpmov2;
while assigned(hp1) and while assigned(hp1) and
(hp1 <> hp_lblyyy) do (hp1 <> hp_lblyyy) do
@ -12453,8 +12488,38 @@ unit aoptx86;
ait_instruction: ait_instruction:
if MatchInstruction(hp1, A_MOV, [S_W, S_L{$ifdef x86_64}, S_Q{$endif x86_64}]) then if MatchInstruction(hp1, A_MOV, [S_W, S_L{$ifdef x86_64}, S_Q{$endif x86_64}]) then
begin begin
if CanBeCMOV(hp1, hp_prev) then if CanBeCMOV(hp1, hp_prev, RefModified) then
Inc(l) begin
Inc(l);
{ MOV instruction will be writing to a register }
if Assigned(hp_prev) and
{ Make sure the sizes match too so we're reading and writing the same number of bytes }
(hp_prev.typ = ait_instruction) and
(taicpu(hp_prev).ops = 2) and
(
(
(taicpu(hp_prev).oper[0]^.typ = top_ref) and
RegInRef(taicpu(hp1).oper[1]^.reg, taicpu(hp_prev).oper[0]^.ref^)
) or
(
(taicpu(hp_prev).oper[1]^.typ = top_ref) and
RegInRef(taicpu(hp1).oper[1]^.reg, taicpu(hp_prev).oper[1]^.ref^)
)
) then
{ It is no longer safe to use the reference in the condition.
this prevents problems such as:
mov (%reg),%reg
mov (%reg),...
When the comparison is cmp (%reg),0 and guarding against a null pointer deallocation
(fixes #40165)
Note: "mov (%reg1),%reg2; mov (%reg2),..." won't be optimised this way since
at least one of (%reg1) and (%reg2) won't be in the condition and is hence unsafe.
}
RefModified := True;
end
else if not (cs_opt_size in current_settings.optimizerswitches) else if not (cs_opt_size in current_settings.optimizerswitches)
{ CMOV with constants grows the code size } { CMOV with constants grows the code size }
and TryCMOVConst(hp1, hpmov2, hp_lblyyy, c, l) then and TryCMOVConst(hp1, hpmov2, hp_lblyyy, c, l) then