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* patch by J. Gareth Moreton to fix faulty conditional jump logic, resolves #38985

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git-svn-id: trunk@49576 -
This commit is contained in:
florian 2021-07-03 21:05:27 +00:00
parent b463d511bf
commit 94a15faa7f
3 changed files with 36 additions and 38 deletions
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34
compiler/aoptobj.pas
View File

@ -2002,10 +2002,7 @@ Unit AoptObj;
{$ifdef cpudelayslot}
RemoveDelaySlot(p);
{$endif cpudelayslot}
UpdateUsedRegs(tai(p.Next));
AsmL.Remove(p);
p.Free;
p := hp1;
RemoveCurrentP(p, hp1);
Result := True;
Exit;
@ -2043,8 +2040,7 @@ Unit AoptObj;
{$ifdef cpudelayslot}
RemoveDelaySlot(hp1);
{$endif cpudelayslot}
asml.remove(hp1);
hp1.free;
RemoveInstruction(hp1);
stoploop := False;
@ -2081,7 +2077,7 @@ Unit AoptObj;
else
begin
{ Do not try to optimize if the test generating the condition
is the same instruction, like 'bne $v0,$zero,.Lj3' for MIPS }
is the same instruction, like 'bne $v0,$zero,.Lj3' for MIPS }
if (taicpu(p).ops>1) or (taicpu(hp1).ops>1) then
exit;
@ -2089,7 +2085,8 @@ Unit AoptObj;
jmp<cond1> @Lbl1
jmp<cond2> @Lbl2
Remove 2nd jump if conditions are equal or cond2 is fully covered by cond1
Remove 2nd jump if conditions are equal or cond2 is a subset of cond1
(as if the first jump didn't branch, then neither will the 2nd)
}
if condition_in(taicpu(hp1).condition, taicpu(p).condition) then
@ -2098,9 +2095,10 @@ Unit AoptObj;
NCJLabel.decrefs;
GetNextInstruction(hp1, hp2);
AsmL.Remove(hp1);
hp1.Free;
{$ifdef cpudelayslot}
RemoveDelaySlot(hp1);
{$endif cpudelayslot}
RemoveInstruction(hp1);
hp1 := hp2;
@ -2114,9 +2112,9 @@ Unit AoptObj;
jmp<cond1> @Lbl1
jmp<cond2> @Lbl2
And inv(cond2) is a subset of cond1 (e.g. je followed by jne, or jae followed by jbe) )
And inv(cond1) is a subset of cond2 (e.g. je followed by jne, or jae followed by jbe) )
}
if condition_in(inverse_cond(taicpu(hp1).condition), taicpu(p).condition) then
if condition_in(inverse_cond(taicpu(p).condition), taicpu(hp1).condition) then
begin
GetNextInstruction(hp1, hp2);
@ -2124,16 +2122,16 @@ Unit AoptObj;
the first jump completely }
if FindLabel(CJLabel, hp2) then
begin
{ However, to be absolutely correct, cond2 must be changed to inv(cond1) }
taicpu(hp1).condition := inverse_cond(taicpu(p).condition);
DebugMsg(SPeepholeOptimization+'jmp<cond> before jmp<inv_cond> - removed first jump',p);
CJLabel.decrefs;
{$ifdef cpudelayslot}
RemoveDelaySlot(p);
{$endif cpudelayslot}
UpdateUsedRegs(tai(p.Next));
AsmL.Remove(p);
p.Free;
p := hp1;
RemoveCurrentP(p, hp1);
Result := True;
Exit;
@ -2146,7 +2144,7 @@ Unit AoptObj;
improve this particular optimisation to work on AVR,
please do. [Kit] }
begin
{ Since cond1 is a subset of inv(cond2), jmp<cond2> will always branch if
{ Since inv(cond1) is a subset of cond2, jmp<cond2> will always branch if
jmp<cond1> does not, so change jmp<cond2> to an unconditional jump. }
DebugMsg(SPeepholeOptimization+'jmp<cond> before jmp<inv_cond> - made second jump unconditional',p);

9
compiler/x86/aoptx86.pas
View File

@ -3406,7 +3406,7 @@ unit aoptx86;
if (taicpu(p).oper[0]^.typ = top_reg) and
(taicpu(p).oper[0]^.reg = taicpu(p).oper[1]^.reg) and
MatchInstruction(hp1, A_JCC, []) and
(taicpu(hp1).oper[0]^.typ = top_ref) then
IsJumpToLabel(taicpu(hp1)) then
begin
JumpLabel := TAsmLabel(taicpu(hp1).oper[0]^.ref^.symbol);
p_label := nil;
@ -3422,7 +3422,7 @@ unit aoptx86;
SuperRegistersEqual(taicpu(p_dist).oper[0]^.reg, taicpu(p).oper[0]^.reg) and
SuperRegistersEqual(taicpu(p_dist).oper[1]^.reg, taicpu(p).oper[1]^.reg) and
GetNextInstruction(p_dist, hp1_dist) and
MatchInstruction(hp1_dist, A_JCC, []) then
MatchInstruction(hp1_dist, A_JCC, []) then { This doesn't have to be an explicit label }
begin
JumpLabel_dist := TAsmLabel(taicpu(hp1_dist).oper[0]^.ref^.symbol);
@ -3430,9 +3430,10 @@ unit aoptx86;
{ This is an infinite loop }
Exit;
{ Best optimisation when the second condition is a subset (or equal) to the first }
if condition_in(taicpu(hp1_dist).condition, taicpu(hp1).condition) then
{ Best optimisation when the first condition is a subset (or equal) of the second }
if condition_in(taicpu(hp1).condition, taicpu(hp1_dist).condition) then
begin
{ Any registers used here will already be allocated }
if Assigned(JumpLabel_dist) then
JumpLabel_dist.IncRefs;

31
compiler/x86/cpubase.pas
View File

@ -697,33 +697,32 @@ implementation
if not Result then
case Subset of
C_A, C_NBE:
Result := (c in [C_A, C_AE, C_NB, C_NBE]);
C_AE, C_NB:
Result := (c in [C_AE, C_NB]);
C_B, C_NAE:
Result := (c in [C_A, C_AE, C_NB, C_NC, C_NBE,C_NE, C_NZ]);
C_AE, C_NB, C_NC:
{ C_A / C_NBE: CF = 0 and ZF = 0; not a subset because ZF has to be zero as well
C_AE / C_NB: CF = 0 }
Result := (c in [C_AE, C_NB, C_NC]);
C_B, C_C, C_NAE:
{ C_B / C_NAE: CF = 1
C_BE / C_NA: CF = 1 or ZF = 1 }
Result := (c in [C_B, C_BE, C_C, C_NA, C_NAE]);
C_BE, C_NA:
Result := (c in [C_BE, C_NA]);
C_C:
{ C_B / C_NAE: CF = 1
C_BE / C_NA: CF = 1 or ZF = 1 }
Result := (c in [C_B, C_BE, C_NA, C_NAE]);
C_E, C_Z:
Result := (c in [C_AE, C_BE, C_E, C_NA, C_NB, C_NG, C_NL]);
Result := (c in [C_AE, C_BE, C_E, C_NA, C_NG, C_Z]);
C_G, C_NLE:
Result := (c in [C_G, C_GE, C_NL, C_NLE]);
{ Not-equal can be considered equivalent to less than or greater than }
Result := (c in [C_G, C_GE, C_NE, C_NL, C_NLE,C_NZ]);
C_GE, C_NL:
Result := (c in [C_GE, C_NL]);
C_L, C_NGE:
Result := (c in [C_L, C_LE, C_NG, C_NGE]);
Result := (c in [C_L, C_LE, C_NE, C_NG, C_NGE,C_NZ]);
C_LE, C_NG:
Result := (c in [C_LE, C_NG]);
C_NC:
{ C_A / C_NBE: CF = 0 and ZF = 0; not a subset because ZF has to be zero as well
C_AE / C_NB: CF = 0 }
Result := (c in [C_AE, C_NB]);
C_NE, C_NZ:
Result := (c in [C_NE, C_NZ, C_A, C_B, C_NAE,C_NBE,C_L, C_G, C_NLE,C_NGE]);
{ Note that not equal is NOT a subset of greater/less than because
not equal is less than OR greater than. Same with above and below }
Result := (c in [C_NE, C_NZ]);
C_NP, C_PO:
Result := (c in [C_NP, C_PO]);
C_P, C_PE: