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@@ -4789,23 +4789,165 @@ unit aoptx86;
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end;
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+ function IsCmpSubset(cond1, cond2: TAsmCond): Boolean; inline;
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+ begin
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+ Result := condition_in(cond1, cond2) or
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+ { Not strictly subsets due to the actual flags checked, but because we're
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+ comparing integers, E is a subset of AE and GE and their aliases }
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+ ((cond1 in [C_E, C_Z]) and (cond2 in [C_AE, C_NB, C_NC, C_GE, C_NL]));
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+ end;
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+
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+
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function TX86AsmOptimizer.OptPass1Cmp(var p: tai): boolean;
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var
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v: TCGInt;
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- hp1, hp2: tai;
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+ hp1, hp2, p_dist, p_jump, hp1_dist, p_label, hp1_label: tai;
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FirstMatch: Boolean;
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+ JumpLabel, JumpLabel_dist, JumpLabel_far: TAsmLabel;
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begin
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Result:=false;
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+ { All these optimisations need a next instruction }
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+ if not GetNextInstruction(p, hp1) then
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+ Exit;
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+
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+ { Search for:
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+ cmp ###,###
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+ j(c1) @lbl1
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+ ...
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+ @lbl:
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+ cmp ###.### (same comparison as above)
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+ j(c2) @lbl2
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+
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+ If c1 is a subset of c2, change to:
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+ cmp ###,###
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+ j(c2) @lbl2
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+ (@lbl1 may become a dead label as a result)
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+ }
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+
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+ { Also handle cases where there are multiple jumps in a row }
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+ p_jump := hp1;
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+ while Assigned(p_jump) and MatchInstruction(p_jump, A_JCC, []) do
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+ begin
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+ if IsJumpToLabel(taicpu(p_jump)) then
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+ begin
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+ JumpLabel := TAsmLabel(taicpu(p_jump).oper[0]^.ref^.symbol);
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+ p_label := nil;
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+ if Assigned(JumpLabel) then
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+ p_label := getlabelwithsym(JumpLabel);
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+
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+ if Assigned(p_label) and
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+ GetNextInstruction(p_label, p_dist) and
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+ MatchInstruction(p_dist, A_CMP, []) and
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+ MatchOperand(taicpu(p_dist).oper[0]^, taicpu(p).oper[0]^) and
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+ MatchOperand(taicpu(p_dist).oper[1]^, taicpu(p).oper[1]^) and
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+ GetNextInstruction(p_dist, hp1_dist) and
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+ MatchInstruction(hp1_dist, A_JCC, []) then { This doesn't have to be an explicit label }
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+ begin
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+ JumpLabel_dist := TAsmLabel(taicpu(hp1_dist).oper[0]^.ref^.symbol);
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+
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+ if JumpLabel = JumpLabel_dist then
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+ { This is an infinite loop }
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+ Exit;
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+
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+ { Best optimisation when the first condition is a subset (or equal) of the second }
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+ if IsCmpSubset(taicpu(p_jump).condition, taicpu(hp1_dist).condition) then
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+ begin
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+ { Any registers used here will already be allocated }
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+ if Assigned(JumpLabel_dist) then
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+ JumpLabel_dist.IncRefs;
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+
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+ if Assigned(JumpLabel) then
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+ JumpLabel.DecRefs;
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+
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+ DebugMsg(SPeepholeOptimization + 'CMP/Jcc/@Lbl/CMP/Jcc -> CMP/Jcc, redirecting first jump', p_jump);
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+ taicpu(p_jump).condition := taicpu(hp1_dist).condition;
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+ taicpu(p_jump).loadref(0, taicpu(hp1_dist).oper[0]^.ref^);
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+ Result := True;
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+ { Don't exit yet. Since p and p_jump haven't actually been
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+ removed, we can check for more on this iteration }
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+ end
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+ else if IsCmpSubset(taicpu(hp1_dist).condition, inverse_cond(taicpu(p_jump).condition)) and
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+ GetNextInstruction(hp1_dist, hp1_label) and
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+ SkipAligns(hp1_label, hp1_label) and
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+ (hp1_label.typ = ait_label) then
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+ begin
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+ JumpLabel_far := tai_label(hp1_label).labsym;
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+
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+ if (JumpLabel_far = JumpLabel_dist) or (JumpLabel_far = JumpLabel) then
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+ { This is an infinite loop }
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+ Exit;
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+
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+ if Assigned(JumpLabel_far) then
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+ begin
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+ { In this situation, if the first jump branches, the second one will never,
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+ branch so change the destination label to after the second jump }
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+
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+ DebugMsg(SPeepholeOptimization + 'CMP/Jcc/@Lbl/CMP/Jcc/@Lbl -> CMP/Jcc, redirecting first jump to 2nd label', p_jump);
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+
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+ if Assigned(JumpLabel) then
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+ JumpLabel.DecRefs;
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+
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+ JumpLabel_far.IncRefs;
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+
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+ taicpu(p_jump).oper[0]^.ref^.symbol := JumpLabel_far;
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+
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+ Result := True;
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+ { Don't exit yet. Since p and p_jump haven't actually been
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+ removed, we can check for more on this iteration }
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+ Continue;
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+ end;
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+ end;
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+
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+ end;
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+ end;
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+ { Search for:
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+ cmp ###,###
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+ j(c1) @lbl1
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+ cmp ###,### (same as first)
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+
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+ Remove second cmp
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+ }
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+
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+ if GetNextInstruction(p_jump, hp2) and
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+ (
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+ (
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+ MatchInstruction(hp2, A_CMP, []) and
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+ (
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+ (
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+ MatchOpType(taicpu(p), top_const, top_reg) and
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+ (taicpu(hp2).oper[0]^.val = taicpu(p).oper[0]^.val) and
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+ SuperRegistersEqual(taicpu(p).oper[1]^.reg, taicpu(hp2).oper[1]^.reg)
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+ ) or (
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+ MatchOperand(taicpu(hp2).oper[0]^, taicpu(p).oper[0]^) and
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+ MatchOperand(taicpu(hp2).oper[1]^, taicpu(p).oper[1]^)
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+ )
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+ )
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+ ) or (
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+ { Also match cmp $0,%reg; jcc @lbl; test %reg,%reg }
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+ MatchOperand(taicpu(p).oper[0]^, 0) and
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+ (taicpu(p).oper[1]^.typ = top_reg) and
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+ MatchInstruction(hp2, A_TEST, []) and
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+ MatchOpType(taicpu(hp2), top_reg, top_reg) and
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+ (taicpu(hp2).oper[0]^.reg = taicpu(hp2).oper[1]^.reg) and
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+ SuperRegistersEqual(taicpu(p).oper[1]^.reg, taicpu(hp2).oper[1]^.reg)
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+ )
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+ ) then
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+ begin
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+ DebugMsg(SPeepholeOptimization + 'CMP/Jcc/CMP; removed superfluous CMP', hp2);
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+ RemoveInstruction(hp2);
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+ Result := True;
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+ { Continue the while loop in case "Jcc/CMP" follows the second CMP that was just removed }
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+ end;
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+
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+ GetNextInstruction(p_jump, p_jump);
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+ end;
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+
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if taicpu(p).oper[0]^.typ = top_const then
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begin
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- { Though GetNextInstruction can be factored out, it is an expensive
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- call, so delay calling it until we have first checked cheaper
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- conditions that are independent of it. }
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if (taicpu(p).oper[0]^.val = 0) and
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(taicpu(p).oper[1]^.typ = top_reg) and
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- GetNextInstruction(p, hp1) and
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MatchInstruction(hp1,A_Jcc,A_SETcc,[]) then
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begin
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hp2 := p;
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@@ -4908,7 +5050,6 @@ unit aoptx86;
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Exit;
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end
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else if (taicpu(p).oper[0]^.val = 1) and
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- GetNextInstruction(p, hp1) and
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MatchInstruction(hp1,A_Jcc,A_SETcc,[]) and
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(taicpu(hp1).condition in [C_L, C_NGE]) then
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begin
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@@ -4955,7 +5096,6 @@ unit aoptx86;
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end;
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if (taicpu(p).oper[0]^.val=v) and
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- GetNextInstruction(p, hp1) and
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MatchInstruction(hp1,A_Jcc,A_SETcc,[]) and
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(Taicpu(hp1).condition in [C_E,C_NE]) then
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begin
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@@ -4980,7 +5120,6 @@ unit aoptx86;
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end;
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if (taicpu(p).oper[1]^.typ = top_reg) and
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- GetNextInstruction(p, hp1) and
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MatchInstruction(hp1,A_MOV,[]) and
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not RegInInstruction(taicpu(p).oper[1]^.reg, hp1) and
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(
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florian