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perf(runtime): stack buffers for WriteDecimal and Format

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WriteDecimal/WriteDecimalU heap-allocated a 22-byte digit scratch on
every call, the IntToStr family allocated a second per-call scratch on
top, and _StringFormatN allocated and freed a buffer per %d argument in
both of its passes — four allocator round-trips per formatted integer
on one of the hottest runtime paths (every emitted temp name goes
through IntToStr).  All nine sites now use fixed stack arrays; one
shared scratch serves both _StringFormatN passes.

Compiler self-compile: 8.73G -> 8.65G instructions.
This commit is contained in:
Graeme Geldenhuys 2026-06-10 19:47:19 +01:00
parent 3799f1516a
commit 8ce374c0ba
1 changed files with 19 additions and 36 deletions
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55
runtime/src/main/pascal/blaise_str.pas
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@ -500,13 +500,13 @@ var
IsNeg: Boolean;
AbsN: Int64;
Pos: Integer;
Tmp: Pointer;
Tmp: array[0..21] of Byte; { stack scratch — this is the hottest
integer-to-text path; no heap traffic }
TP: PChar;
I, J: Integer;
Digit: Integer;
begin
Tmp := _BlaiseGetMem(22);
TP := PChar(Tmp);
TP := PChar(@Tmp[0]);
IsNeg := N < 0;
if IsNeg then
AbsN := -N
@ -541,7 +541,6 @@ begin
Inc(I);
Dec(J);
end;
_BlaiseFreeMem(Tmp);
Result := I;
end;
@ -551,17 +550,15 @@ end;
function _IntToStr(N: Integer): Pointer;
var
Buf: Pointer;
Buf: array[0..21] of Byte;
BP: PChar;
Written: Integer;
begin
Buf := _BlaiseGetMem(22);
BP := PChar(Buf);
BP := PChar(@Buf[0]);
Written := WriteDecimal(Int64(N), BP);
Result := StrAlloc(Written);
if (Result <> nil) and (Written > 0) then
MemCopy(StrData(Result), Buf, Written);
_BlaiseFreeMem(Buf);
MemCopy(StrData(Result), Pointer(BP), Written);
end;
{ ------------------------------------------------------------------ }
@ -570,17 +567,15 @@ end;
function _Int64ToStr(N: Int64): Pointer;
var
Buf: Pointer;
Buf: array[0..21] of Byte;
BP: PChar;
Written: Integer;
begin
Buf := _BlaiseGetMem(22);
BP := PChar(Buf);
BP := PChar(@Buf[0]);
Written := WriteDecimal(N, BP);
Result := StrAlloc(Written);
if (Result <> nil) and (Written > 0) then
MemCopy(StrData(Result), Buf, Written);
_BlaiseFreeMem(Buf);
MemCopy(StrData(Result), Pointer(BP), Written);
end;
{ Write a UInt64 value (passed as Int64 bit pattern during bootstrap) as
@ -590,13 +585,12 @@ end;
function WriteDecimalU(N: UInt64; Buf: PChar): Integer;
var
Pos: Integer;
Tmp: Pointer;
Tmp: array[0..21] of Byte;
TP: PChar;
I, J: Integer;
Digit: Integer;
begin
Tmp := _BlaiseGetMem(22);
TP := PChar(Tmp);
TP := PChar(@Tmp[0]);
if N = UInt64(0) then
begin
TP[0] := 48; { '0' }
@ -621,23 +615,20 @@ begin
Inc(I);
Dec(J);
end;
_BlaiseFreeMem(Tmp);
Result := I;
end;
function _UInt64ToStr(N: UInt64): Pointer;
var
Buf: Pointer;
Buf: array[0..21] of Byte;
BP: PChar;
Written: Integer;
begin
Buf := _BlaiseGetMem(22);
BP := PChar(Buf);
BP := PChar(@Buf[0]);
Written := WriteDecimalU(N, BP);
Result := StrAlloc(Written);
if (Result <> nil) and (Written > 0) then
MemCopy(StrData(Result), Buf, Written);
_BlaiseFreeMem(Buf);
MemCopy(StrData(Result), Pointer(BP), Written);
end;
{ ------------------------------------------------------------------ }
@ -915,7 +906,7 @@ var
Val: Int64;
AP: Pointer;
TagPtr, ValPtr: ^Int64;
IntBuf: Pointer;
IntBuf: array[0..21] of Byte; { shared stack scratch for %d rendering }
IBP: PChar;
begin
F := StrData(Fmt);
@ -941,11 +932,9 @@ begin
Val := ValPtr^;
if Tag = 0 then
begin
IntBuf := _BlaiseGetMem(22);
IBP := PChar(IntBuf);
IBP := PChar(@IntBuf[0]);
Written := WriteDecimal(Val, IBP);
OutLen := OutLen + Written;
_BlaiseFreeMem(IntBuf);
end
else
begin
@ -972,11 +961,9 @@ begin
end
else
begin
IntBuf := _BlaiseGetMem(22);
IBP := PChar(IntBuf);
IBP := PChar(@IntBuf[0]);
Written := WriteDecimal(Val, IBP);
OutLen := OutLen + Written;
_BlaiseFreeMem(IntBuf);
end;
end;
Inc(ArgIdx);
@ -1023,12 +1010,10 @@ begin
Val := ValPtr^;
if Tag = 0 then
begin
IntBuf := _BlaiseGetMem(22);
IBP := PChar(IntBuf);
IBP := PChar(@IntBuf[0]);
Written := WriteDecimal(Val, IBP);
MemCopy(Dst, IBP, Written);
Dst := Dst + Written;
_BlaiseFreeMem(IntBuf);
end
else
begin
@ -1059,12 +1044,10 @@ begin
end
else
begin
IntBuf := _BlaiseGetMem(22);
IBP := PChar(IntBuf);
IBP := PChar(@IntBuf[0]);
Written := WriteDecimal(Val, IBP);
MemCopy(Dst, IBP, Written);
Dst := Dst + Written;
_BlaiseFreeMem(IntBuf);
end;
end;
Inc(ArgIdx);