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stage2: x86_64 codegen for movs to/from stack variables

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Andrew Kelley 2020-07-28 19:11:23 -07:00
parent 5ccee4c986
commit cb3e8e323d
1 changed files with 41 additions and 2 deletions
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43
src-self-hosted/codegen.zig
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@ -1271,7 +1271,25 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
return self.fail(src, "TODO implement set stack variable from embedded_in_code", .{});
},
.register => |reg| {
return self.fail(src, "TODO implement set stack variable from register", .{});
try self.code.ensureCapacity(self.code.items.len + 7);
self.rex(.{ .w = reg.size() == 64, .b = reg.isExtended() });
const reg_id: u8 = @truncate(u3, reg.id());
if (stack_offset <= 128) {
// example: 48 89 55 7f mov QWORD PTR [rbp+0x7f],rdx
const RM = @as(u8, 0b01_101_000) | reg_id;
const negative_offset = @intCast(i8, -@intCast(i32, stack_offset));
const twos_comp = @bitCast(u8, negative_offset);
self.code.appendSliceAssumeCapacity(&[_]u8{ 0x89, RM, twos_comp });
} else if (stack_offset <= 2147483648) {
// example: 48 89 95 80 00 00 00 mov QWORD PTR [rbp+0x80],rdx
const RM = @as(u8, 0b10_101_000) | reg_id;
const negative_offset = @intCast(i32, -@intCast(i33, stack_offset));
const twos_comp = @bitCast(u32, negative_offset);
self.code.appendSliceAssumeCapacity(&[_]u8{ 0x89, RM });
mem.writeIntLittle(u32, self.code.addManyAsArrayAssumeCapacity(4), twos_comp);
} else {
return self.fail(src, "stack offset too large", .{});
}
},
.memory => |vaddr| {
return self.fail(src, "TODO implement set stack variable from memory vaddr", .{});
@ -1475,7 +1493,28 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
}
},
.stack_offset => |off| {
return self.fail(src, "TODO implement genSetReg for stack variables", .{});
if (reg.size() != 64) {
return self.fail(src, "TODO decide whether to implement non-64-bit loads", .{});
}
try self.code.ensureCapacity(self.code.items.len + 7);
self.rex(.{ .w = true, .r = reg.isExtended() });
const reg_id: u8 = @truncate(u3, reg.id());
if (off <= 128) {
// Example: 48 8b 4d 7f mov rcx,QWORD PTR [rbp+0x7f]
const RM = @as(u8, 0b01_000_101) | (reg_id << 3);
const negative_offset = @intCast(i8, -@intCast(i32, off));
const twos_comp = @bitCast(u8, negative_offset);
self.code.appendSliceAssumeCapacity(&[_]u8{ 0x8b, RM, twos_comp });
} else if (off <= 2147483648) {
// Example: 48 8b 8d 80 00 00 00 mov rcx,QWORD PTR [rbp+0x80]
const RM = @as(u8, 0b10_000_101) | (reg_id << 3);
const negative_offset = @intCast(i32, -@intCast(i33, off));
const twos_comp = @bitCast(u32, negative_offset);
self.code.appendSliceAssumeCapacity(&[_]u8{ 0x8b, RM });
mem.writeIntLittle(u32, self.code.addManyAsArrayAssumeCapacity(4), twos_comp);
} else {
return self.fail(src, "stack offset too large", .{});
}
},
},
else => return self.fail(src, "TODO implement getSetReg for {}", .{self.target.cpu.arch}),