authorgravatar for kubkon@jakubkonka.comJakub Konka <kubkon@jakubkonka.com> 2020-12-09 07:56:49+01:00
committergravatar for kubkon@jakubkonka.comJakub Konka <kubkon@jakubkonka.com> 2020-12-09 17:20:58+01:00
logeca0727417833b6c60cb2b30ba492ef816f4a4bc
tree1c6c89a45ae3c7fdd64e2568bfdae970a6848dff
parent21dae538caa5eac71b52be5da59d3a18c05b3a89

stage2+aarch64: use stp and ldp to navigate MachO jump table

1 files changed, 29 insertions(+), 26 deletions(-)

src/codegen.zig+29-26
......@@ -2730,13 +2730,10 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
27302730 // For MachO, the binary, with the exception of object files, has to be a PIE.
27312731 // Therefore we cannot load an absolute address.
27322732 // Instead, we need to make use of PC-relative addressing.
2733 // TODO This needs to be optimised in the stack usage (perhaps use a shadow stack
2734 // like described here:
2735 // https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/using-the-stack-in-aarch64-implementing-push-and-pop)
2736 // TODO As far as branching is concerned, instead of saving the return address
2737 // in a register, I'm thinking here of immitating x86_64, and having the address
2738 // passed on the stack.
27392733 if (reg.id() == 0) { // x0 is special-cased
2734 // TODO This needs to be optimised in the stack usage (perhaps use a shadow stack
2735 // like described here:
2736 // https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/using-the-stack-in-aarch64-implementing-push-and-pop)
27402737 // str x28, [sp, #-16]
27412738 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.str(.x28, Register.sp, .{
27422739 .offset = Instruction.Offset.imm_pre_index(-16),
......@@ -2755,21 +2752,25 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
27552752 // b [label]
27562753 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.b(0).toU32());
27572754 // mov r, x0
2758 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.orr(reg, .x0, Instruction.RegisterShift.none()).toU32());
2755 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.orr(
2756 reg,
2757 .x0,
2758 Instruction.RegisterShift.none(),
2759 ).toU32());
27592760 // ldr x28, [sp], #16
27602761 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.ldr(.x28, .{
27612762 .rn = Register.sp,
27622763 .offset = Instruction.Offset.imm_post_index(16),
27632764 }).toU32());
27642765 } else {
2765 // str x28, [sp, #-16]
2766 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.str(.x28, Register.sp, .{
2767 .offset = Instruction.Offset.imm_pre_index(-16),
2768 }).toU32());
2769 // str x0, [sp, #-16]
2770 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.str(.x0, Register.sp, .{
2771 .offset = Instruction.Offset.imm_pre_index(-16),
2772 }).toU32());
2766 // stp x0, x28, [sp, #-16]
2767 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.stp(
2768 .x0,
2769 .x28,
2770 Register.sp,
2771 -2,
2772 .SignedOffset,
2773 ).toU32());
27732774 // adr x28, #8
27742775 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.adr(.x28, 8).toU32());
27752776 if (self.bin_file.cast(link.File.MachO)) |macho_file| {
......@@ -2784,17 +2785,19 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
27842785 // b [label]
27852786 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.b(0).toU32());
27862787 // mov r, x0
2787 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.orr(reg, .x0, Instruction.RegisterShift.none()).toU32());
2788 // ldr x0, [sp], #16
2789 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.ldr(.x0, .{
2790 .rn = Register.sp,
2791 .offset = Instruction.Offset.imm_post_index(16),
2792 }).toU32());
2793 // ldr x28, [sp], #16
2794 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.ldr(.x28, .{
2795 .rn = Register.sp,
2796 .offset = Instruction.Offset.imm_post_index(16),
2797 }).toU32());
2788 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.orr(
2789 reg,
2790 .x0,
2791 Instruction.RegisterShift.none(),
2792 ).toU32());
2793 // ldp x0, x28, [sp, #16]
2794 mem.writeIntLittle(u32, try self.code.addManyAsArray(4), Instruction.ldp(
2795 .x0,
2796 .x28,
2797 Register.sp,
2798 2,
2799 .SignedOffset,
2800 ).toU32());
27982801 }
27992802 } else {
28002803 // The value is in memory at a hard-coded address.