Native ARM64 Implementation Using Assembler by superflexible · Pull Request #295 · remobjects/pascalscript

superflexible · 2026-03-25T12:29:59Z

Native ARM64 Implementation Using Assembler
Tested on Linux / ARM64 and macOS / M1

Native ARM64 Implementation Using Assembler Tested on Linux / ARM64 and macOS / M1

martijnlaan · 2026-03-25T13:06:25Z

Source/arm64.inc

@@ -0,0 +1,375 @@
+{$IFDEF CPUARM64}
+  {$IFDEF MSWINDOWS}
+    {$L arm64win.obj}


This file does not actually exist

Hello,
yes, it's for Windows but it will never be used. This should be removed. Thanks fo your comments! I will try to amend the pull request accordingly.

martijnlaan · 2026-03-25T13:07:12Z

Source/arm64.inc

@@ -0,0 +1,375 @@
+{$IFDEF CPUARM64}


I think you're supposed to add a new CPU type next to CPU32/CPU64 to eDefines.inc instead of directly checking CPUARM64 and CPUAARCH64? Not entirely sure though.

martijnlaan · 2026-03-25T13:08:22Z

Source/arm64.inc

+    {$L arm64win.obj}
+  {$ELSE}
+    {$IFDEF MACOS}
+      {$L arm64sysv-macos.o}


There should be instructions on how to recreate to the .o files, because accepting binaries from a PR seems rather unsafe.

Yes, I will add comments. The assembler commands are simple. I will also check if inline asm is possible instead. I know that Delphi doesn't allow it for ARM64 but FPC might.

It's correct that Delphi doesn't allow inline assembler from ARM64, but it also doesn't allow $L for ARM64.

https://docwiki.embarcadero.com/RADStudio/Florence/en/ARM64EC has this example of the syntax they do allow from ARM64 (but not for x86/x64):

function zlibVersion: MarshaledAString; cdecl; external object 'zutil.o';

Yes that's correct. My pull request is only for FPC, which allows it.

martijnlaan · 2026-03-25T13:09:04Z

Source/arm64sysv.S

+.type arm64call, %function
+arm64call:
+#endif
+    stp x29, x30, [sp, #-64]!


Perhaps there could be some comments describing the various steps?

Also, does it handle exceptions?

martijnlaan · 2026-03-25T13:09:25Z

Source/uPSRuntime.pas

  s := '';
 end;

+function AlwaysAsVariable(aType: TPSTypeRec): Boolean;


Accidental move?

This had to be moved before the {$ifdef empty_methods_handler} section, otherwise it won't compile if empty_methods_handler is defined because two functions are missing. The upstream version only compiles for Intel CPUs.

martijnlaan · 2026-03-25T13:10:06Z

Source/uPSRuntime.pas

    {$define empty_methods_handler}
  {$ifend}
+{$else}
+  {$if defined(cpuarm)}


Is cpuarm correct here? That's not ARM64, right. If it's correct and indeed not really ARM64 related then this should be a separate PR.

On ARM64, CPUARM is also defined. So this covers both ARM32 and ARM64.

martijnlaan · 2026-03-25T13:11:22Z

Source/PascalScript.inc

 {$INCLUDE eDefines.inc}

-{$IFDEF FPC}{$H+}{$ENDIF}
+{$IFDEF FPC}{$MODE DELPHI}{$H+}{$ENDIF}


This change and the one to PascalScriptPFC.inc would stop me from merging the PR since I'm not familiar with FCP. Also the changes don't really seem to be related to ARM64? So they should be a separate PR.

I had to do this to get it to compile at all, but maybe I can separate it out.

Copilot

Pull request overview

This PR adds an ARM64 (AArch64) native assembler-based call stub and wires it into the Pascal Script runtime so external/native calls can be invoked on Linux ARM64 and macOS ARM64.

Changes:

Add ARM64 invocation implementation (arm64.inc) and route ARM64 builds to include it from uPSRuntime.pas.
Add ARM64 SysV assembly entrypoint (arm64sysv.S) plus prebuilt Linux/macOS object files for linking.
Adjust FPC include/mode handling in PascalScript.inc / PascalScriptFPC.inc to avoid mode/InvokeCall compilation issues.

Reviewed changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
Source/uPSRuntime.pas	Adds ARM64 include paths and adjusts empty method handler conditional compilation.
Source/arm64.inc	New ARM64 InnerfuseCall implementation and external `arm64call` declaration/linking.
Source/arm64sysv.S	New SysV ARM64 assembly implementation of `arm64call` entrypoint.
Source/arm64sysv-linux.o	Prebuilt Linux ARM64 object for the assembly entrypoint.
Source/arm64sysv-macos.o	Prebuilt macOS ARM64 object for the assembly entrypoint.
Source/PascalScript.inc	Sets FPC mode to Delphi earlier to avoid include-time mode switching issues.
Source/PascalScriptFPC.inc	Disables mode switch and USEINVOKECALL define in this include to avoid FPC compilation errors.

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Source/arm64.inc

Copilot · 2026-03-25T19:45:55Z

Source/arm64.inc

+  var _D0: Double;
+  constref Registers: TARM64Registers;
+  Stack: Pointer;
+  Items: NativeInt); external {$IFDEF DARWIN}name '_arm64call'{$ENDIF};


On Apple targets the assembly symbol is exported as _arm64call, but the external declaration only uses name '_arm64call' under {$IFDEF DARWIN}. Delphi defines MACOS (not DARWIN), so Delphi/macOS will likely fail to link. Use a condition that matches Delphi/macOS as well (e.g., DEFINED(DARWIN) or DEFINED(MACOS)).

Suggested change

Items: NativeInt); external {$IFDEF DARWIN}name '_arm64call'{$ENDIF};

Items: NativeInt); external {$IF DEFINED(DARWIN) OR DEFINED(MACOS)}name '_arm64call'{$IFEND};

Copilot · 2026-03-25T19:45:55Z

Source/arm64.inc

+
+procedure arm64call(
+  Address: Pointer;
+  out _X0: IPointer;


arm64call reads the initial value of _X0 to populate x0 (first argument), but the parameter is declared as out. Using an out parameter as input is unsafe/misleading and can allow uninitialized reads if the caller changes. Declare _X0 as var (in/out) to reflect that it is both an input (arg x0) and an output (return x0).

Suggested change

out _X0: IPointer;

var _X0: IPointer;

Copilot · 2026-03-25T19:45:56Z

Source/arm64.inc

+          StoreIntReg(IPointer(Cardinal(FVar^.dta^)));
+        btPChar:
+          if Pointer(fvar^.dta^) = nil then
+            StoreIntReg(IPointer(@EmptyPChar))


EmptyPChar is declared as a PChar, but the code passes @EmptyPChar when a btPChar argument is nil. That passes the address of the pointer variable (PPChar) rather than a pointer to a null-terminated char buffer, which will produce an invalid PChar for callees. Match the existing x86/x64 approach (e.g., define EmptyPchar as an array[0..0] of Char/#0) or pass the pointer value (EmptyPChar) rather than its address.

Suggested change

StoreIntReg(IPointer(@EmptyPChar))

StoreIntReg(IPointer(EmptyPChar))

Copilot · 2026-03-25T19:45:56Z

Source/uPSRuntime.pas

    {$define empty_methods_handler}
  {$ifend}
+{$else}
+  {$if defined(cpuarm)}


For Delphi ARM64 (CPUARM64), empty_methods_handler is not defined, so the CPU64 branch below will try to compile x64 inline assembly in MyAllMethodsHandler, which won’t compile on ARM64. Extend the Delphi-side condition to include CPUARM64 (or add an ARM64 implementation) so ARM64 builds don’t attempt to compile the x64 asm handler.

Suggested change

{$if defined(cpuarm)}

{$if defined(cpuarm) or defined(cpuarm64)}

Copilot · 2026-03-25T19:45:56Z

Source/arm64sysv.S

+    ldp x29, x30, [sp], #64
+    ret
+#ifndef __APPLE__
+.size arm64call, .-arm64call


arm64sysv.S does not emit a .note.GNU-stack section. On Linux/GNU ld this can result in an executable stack marking/warnings for the resulting object. Consider adding a .section .note.GNU-stack,"",@progbits (guarded for non-Apple) to keep stacks non-executable by default.

Suggested change

.size arm64call, .-arm64call

.size arm64call, .-arm64call

.section .note.GNU-stack,"",@progbits

Native ARM64 Implementation Using Assembler

43a0d7c

Native ARM64 Implementation Using Assembler Tested on Linux / ARM64 and macOS / M1

martijnlaan mentioned this pull request Mar 25, 2026

ARM64 support #243

Closed

martijnlaan reviewed Mar 25, 2026

View reviewed changes

martijnlaan requested a review from Copilot March 25, 2026 19:38

Copilot started reviewing on behalf of martijnlaan March 25, 2026 19:39 View session

Copilot AI reviewed Mar 25, 2026

View reviewed changes

	Items: NativeInt); external {$IFDEF DARWIN}name '_arm64call'{$ENDIF};
	Items: NativeInt); external {$IF DEFINED(DARWIN) OR DEFINED(MACOS)}name '_arm64call'{$IFEND};

	StoreIntReg(IPointer(@EmptyPChar))
	StoreIntReg(IPointer(EmptyPChar))

	{$if defined(cpuarm)}
	{$if defined(cpuarm) or defined(cpuarm64)}

	.size arm64call, .-arm64call
	.size arm64call, .-arm64call
	.section .note.GNU-stack,"",@progbits

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superflexible commented Mar 25, 2026

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Pull request overview

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