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codegen rdx set immediate

master
Andrew Kelley 2020-04-23 20:30:20 -04:00
parent 757d13d784
commit 2d35f71fa9
1 changed files with 31 additions and 6 deletions
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37
src-self-hosted/codegen.zig
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@ -249,6 +249,37 @@ const Function = struct {
.embedded_in_code => return self.fail(src, "TODO implement x86_64 genSetReg %rax = embedded_in_code", .{}),
.register => return self.fail(src, "TODO implement x86_64 genSetReg %rax = register", .{}),
},
.rdx => switch (mcv) {
.none, .unreach => unreachable,
.immediate => |x| {
// Setting the edx register zeroes the upper part of rdx, so if the number is small
// enough, that is preferable.
// Best case: zero
// 31 d2 xor edx,edx
if (x == 0) {
return self.code.appendSlice(&[_]u8{ 0x31, 0xd2 });
}
// Next best case: set edx with 4 bytes
// ba 04 03 02 01 mov edx,0x1020304
if (x <= std.math.maxInt(u32)) {
try self.code.resize(self.code.items.len + 5);
self.code.items[self.code.items.len - 5] = 0xba;
const imm_ptr = self.code.items[self.code.items.len - 4 ..][0..4];
mem.writeIntLittle(u32, imm_ptr, @intCast(u32, x));
return;
}
// Worst case: set rdx with 8 bytes
// 48 ba 08 07 06 05 04 03 02 01 movabs rdx,0x0102030405060708
try self.code.resize(self.code.items.len + 10);
self.code.items[self.code.items.len - 10] = 0x48;
self.code.items[self.code.items.len - 9] = 0xba;
const imm_ptr = self.code.items[self.code.items.len - 8 ..][0..8];
mem.writeIntLittle(u64, imm_ptr, x);
return;
},
.embedded_in_code => return self.fail(src, "TODO implement x86_64 genSetReg %rdx = embedded_in_code", .{}),
.register => return self.fail(src, "TODO implement x86_64 genSetReg %rdx = register", .{}),
},
.rdi => switch (mcv) {
.none, .unreach => unreachable,
.immediate => |x| {
@ -305,12 +336,6 @@ const Function = struct {
},
.register => return self.fail(src, "TODO implement x86_64 genSetReg %rsi = register", .{}),
},
.rdx => switch (mcv) {
.none, .unreach => unreachable,
.immediate => return self.fail(src, "TODO implement x86_64 genSetReg %rdx = immediate", .{}),
.embedded_in_code => return self.fail(src, "TODO implement x86_64 genSetReg %rdx = embedded_in_code", .{}),
.register => return self.fail(src, "TODO implement x86_64 genSetReg %rdx = register", .{}),
},
else => return self.fail(src, "TODO implement genSetReg for x86_64 '{}'", .{@tagName(reg)}),
},
else => return self.fail(src, "TODO implement genSetReg for more architectures", .{}),