From 116c861af6c13f6d3d0d0d91b6dc4e0c1eb88550 Mon Sep 17 00:00:00 2001
From: "J. Gareth \"Curious Kit\" Moreton" <gareth@moreton-family.com>
Date: Mon, 27 Dec 2021 16:18:13 +0000
Subject: [PATCH] MOV/CMP optimisation is now in both Pass 1 and Pass 2 to
catch more eventualities
---
compiler/x86/aoptx86.pas | 123 +++++++++++++++++++++++----------------
1 file changed, 74 insertions(+), 49 deletions(-)
diff --git a/compiler/x86/aoptx86.pas b/compiler/x86/aoptx86.pas
index 39967d8103..85a3791c66 100644
--- a/compiler/x86/aoptx86.pas
+++ b/compiler/x86/aoptx86.pas
@@ -137,6 +137,7 @@ unit aoptx86;
procedure RemoveLastDeallocForFuncRes(p : tai);
function DoSubAddOpt(var p : tai) : Boolean;
+ function DoMovCmpMemOpt(var p : tai; const hp1: tai; UpdateTmpUsedRegs: Boolean) : Boolean;
function PrePeepholeOptSxx(var p : tai) : boolean;
function PrePeepholeOptIMUL(var p : tai) : boolean;
@@ -3878,50 +3879,10 @@ unit aoptx86;
Exit;
end;
- if MatchOpType(taicpu(p),top_ref,top_reg) and
- { The x86 assemblers have difficulty comparing values against absolute addresses }
- (taicpu(p).oper[0]^.ref^.refaddr in [addr_no, addr_pic, addr_pic_no_got]) and
- (taicpu(hp1).oper[0]^.typ <> top_ref) and
- MatchOperand(taicpu(hp1).oper[1]^, taicpu(p).oper[1]^.reg) and
- (
- (
- (taicpu(hp1).opcode = A_TEST)
- ) or (
- (taicpu(hp1).opcode = A_CMP) and
- { A sanity check more than anything }
- not MatchOperand(taicpu(hp1).oper[0]^, taicpu(p).oper[1]^.reg)
- )
- ) then
+ if DoMovCmpMemOpt(p, hp1, True) then
begin
- { change
- mov mem, %reg
- cmp/test x, %reg / test %reg,%reg
- (reg deallocated)
-
- to
-
- cmp/test x, mem / cmp 0, mem
- }
- TransferUsedRegs(TmpUsedRegs);
- UpdateUsedRegs(TmpUsedRegs, tai(p.Next));
- if not RegUsedAfterInstruction(taicpu(p).oper[1]^.reg, hp1, TmpUsedRegs) then
- begin
- { Convert test %reg,%reg or test $-1,%reg to cmp $0,mem }
- if (taicpu(hp1).opcode = A_TEST) and
- (
- MatchOperand(taicpu(hp1).oper[0]^, taicpu(p).oper[1]^.reg) or
- MatchOperand(taicpu(hp1).oper[0]^, -1)
- ) then
- begin
- taicpu(hp1).opcode := A_CMP;
- taicpu(hp1).loadconst(0, 0);
- end;
- taicpu(hp1).loadref(1, taicpu(p).oper[0]^.ref^);
- DebugMsg(SPeepholeOptimization + 'MOV/CMP -> CMP (memory check)', p);
- RemoveCurrentP(p, hp1);
- Result := True;
- Exit;
- end;
+ Result := True;
+ Exit;
end;
end;
@@ -5226,6 +5187,59 @@ unit aoptx86;
end;
+ function TX86AsmOptimizer.DoMovCmpMemOpt(var p : tai; const hp1: tai; UpdateTmpUsedRegs: Boolean) : Boolean;
+ begin
+ Result := False;
+ if UpdateTmpUsedRegs then
+ TransferUsedRegs(TmpUsedRegs);
+
+ if MatchOpType(taicpu(p),top_ref,top_reg) and
+ { The x86 assemblers have difficulty comparing values against absolute addresses }
+ (taicpu(p).oper[0]^.ref^.refaddr <> addr_full) and
+ (taicpu(hp1).oper[0]^.typ <> top_ref) and
+ MatchOperand(taicpu(hp1).oper[1]^, taicpu(p).oper[1]^.reg) and
+ (
+ (
+ (taicpu(hp1).opcode = A_TEST)
+ ) or (
+ (taicpu(hp1).opcode = A_CMP) and
+ { A sanity check more than anything }
+ not MatchOperand(taicpu(hp1).oper[0]^, taicpu(p).oper[1]^.reg)
+ )
+ ) then
+ begin
+ { change
+ mov mem, %reg
+ cmp/test x, %reg / test %reg,%reg
+ (reg deallocated)
+
+ to
+
+ cmp/test x, mem / cmp 0, mem
+ }
+ UpdateUsedRegs(TmpUsedRegs, tai(p.Next));
+ if not RegUsedAfterInstruction(taicpu(p).oper[1]^.reg, hp1, TmpUsedRegs) then
+ begin
+ { Convert test %reg,%reg or test $-1,%reg to cmp $0,mem }
+ if (taicpu(hp1).opcode = A_TEST) and
+ (
+ MatchOperand(taicpu(hp1).oper[0]^, taicpu(p).oper[1]^.reg) or
+ MatchOperand(taicpu(hp1).oper[0]^, -1)
+ ) then
+ begin
+ taicpu(hp1).opcode := A_CMP;
+ taicpu(hp1).loadconst(0, 0);
+ end;
+ taicpu(hp1).loadref(1, taicpu(p).oper[0]^.ref^);
+ DebugMsg(SPeepholeOptimization + 'MOV/CMP -> CMP (memory check)', p);
+ RemoveCurrentP(p, hp1);
+ Result := True;
+ Exit;
+ end;
+ end;
+ end;
+
+
function TX86AsmOptimizer.OptPass1Sub(var p : tai) : boolean;
var
hp1, hp2: tai;
@@ -6113,6 +6127,7 @@ unit aoptx86;
end;
end;
+
{ Search for:
cmp ###,###
j(c1) @lbl1
@@ -6120,16 +6135,16 @@ unit aoptx86;
Remove second cmp
}
-
if GetNextInstruction(p_jump, hp2) and
(
(
- MatchInstruction(hp2, A_CMP, []) and
+ MatchInstruction(hp2, A_CMP, [taicpu(p).opsize]) and
(
(
MatchOpType(taicpu(p), top_const, top_reg) and
+ MatchOpType(taicpu(hp2), top_const, top_reg) and
(taicpu(hp2).oper[0]^.val = taicpu(p).oper[0]^.val) and
- SuperRegistersEqual(taicpu(p).oper[1]^.reg, taicpu(hp2).oper[1]^.reg)
+ Reg1WriteOverwritesReg2Entirely(taicpu(hp2).oper[1]^.reg, taicpu(p).oper[1]^.reg)
) or (
MatchOperand(taicpu(hp2).oper[0]^, taicpu(p).oper[0]^) and
MatchOperand(taicpu(hp2).oper[1]^, taicpu(p).oper[1]^)
@@ -6142,7 +6157,7 @@ unit aoptx86;
MatchInstruction(hp2, A_TEST, []) and
MatchOpType(taicpu(hp2), top_reg, top_reg) and
(taicpu(hp2).oper[0]^.reg = taicpu(hp2).oper[1]^.reg) and
- SuperRegistersEqual(taicpu(p).oper[1]^.reg, taicpu(hp2).oper[1]^.reg)
+ Reg1WriteOverwritesReg2Entirely(taicpu(hp2).oper[1]^.reg, taicpu(p).oper[1]^.reg)
)
) then
begin
@@ -6175,6 +6190,10 @@ unit aoptx86;
a conditional branch.
}
if not (cs_opt_size in current_settings.optimizerswitches) and
+ (
+ (hp1 = p_jump) or
+ GetNextInstruction(p, hp1)
+ ) and
MatchInstruction(hp1, A_Jcc, []) and
IsJumpToLabel(taicpu(hp1)) and
(taicpu(hp1).condition in [C_E, C_Z]) and
@@ -6182,7 +6201,7 @@ unit aoptx86;
MatchInstruction(hp2, A_CMP, A_TEST, [taicpu(p).opsize]) and
MatchOperand(taicpu(p).oper[1]^, taicpu(hp2).oper[1]^) and
{ The first operand of CMP instructions can only be a register or
- operand anyway, so no need to check }
+ immediate anyway, so no need to check }
GetNextInstruction(hp2, p_label) and
(p_label.typ = ait_label) and
(tai_label(p_label).labsym.getrefs = 1) and
@@ -7516,7 +7535,13 @@ unit aoptx86;
if not GetNextInstruction(p, hp1) then
Exit;
- if MatchInstruction(hp1, A_JMP, [S_NO]) then
+ if MatchInstruction(hp1, A_CMP, A_TEST, [taicpu(p).opsize])
+ and DoMovCmpMemOpt(p, hp1, True) then
+ begin
+ Result := True;
+ Exit;
+ end
+ else if MatchInstruction(hp1, A_JMP, [S_NO]) then
begin
{ Sometimes the MOVs that OptPass2JMP produces can be improved
further, but we can't just put this jump optimisation in pass 1