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stage2: add lowering to O encoding

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Example includes push/pop register.
This commit is contained in:
Jakub Konka 2021-12-23 09:47:38 +01:00
parent 603f826779
commit b657956c44
1 changed files with 34 additions and 27 deletions
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61
src/arch/x86_64/Emit.zig
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@ -204,16 +204,7 @@ fn mirPushPop(emit: *Emit, tag: Tag, inst: Mir.Inst.Index) InnerError!void {
switch (ops.flags) {
0b00 => {
// PUSH/POP reg
const opc: u8 = switch (tag) {
.push => 0x50,
.pop => 0x58,
else => unreachable,
};
const encoder = try Encoder.init(emit.code, 2);
encoder.rex(.{
.b = ops.reg1.isExtended(),
});
encoder.opcode_withReg(opc, ops.reg1.lowId());
return lowerToOEnc(tag, ops.reg1, emit.code);
},
0b01 => {
// PUSH/POP r/m64
@ -240,22 +231,11 @@ fn mirPushPop(emit: *Emit, tag: Tag, inst: Mir.Inst.Index) InnerError!void {
}
fn mirPushPopRegsFromCalleePreservedRegs(emit: *Emit, tag: Tag, inst: Mir.Inst.Index) InnerError!void {
const callee_preserved_regs = bits.callee_preserved_regs;
// PUSH/POP reg
const opc: u8 = switch (tag) {
.push => 0x50,
.pop => 0x58,
else => unreachable,
};
const regs = emit.mir.instructions.items(.data)[inst].regs_to_push_or_pop;
if (tag == .push) {
for (callee_preserved_regs) |reg, i| {
if ((regs >> @intCast(u5, i)) & 1 == 0) continue;
const encoder = try Encoder.init(emit.code, 2);
encoder.rex(.{
.b = reg.isExtended(),
});
encoder.opcode_withReg(opc, reg.lowId());
try lowerToOEnc(.push, reg, emit.code);
}
} else {
// pop in the reverse direction
@ -263,11 +243,7 @@ fn mirPushPopRegsFromCalleePreservedRegs(emit: *Emit, tag: Tag, inst: Mir.Inst.I
while (i > 0) : (i -= 1) {
const reg = callee_preserved_regs[i - 1];
if ((regs >> @intCast(u5, i - 1)) & 1 == 0) continue;
const encoder = try Encoder.init(emit.code, 2);
encoder.rex(.{
.b = reg.isExtended(),
});
encoder.opcode_withReg(opc, reg.lowId());
try lowerToOEnc(.pop, reg, emit.code);
}
}
}
@ -526,6 +502,9 @@ const Encoding = enum {
/// OP r/m64
m,
/// OP r64
o,
/// OP r/m64, imm32
mi,
@ -557,6 +536,11 @@ inline fn getOpCode(tag: Tag, enc: Encoding) ?u8 {
.pop => 0x8f,
else => null,
},
.o => return switch (tag) {
.push => 0x50,
.pop => 0x58,
else => null,
},
.mi => return switch (tag) {
.adc, .add, .sub, .xor, .@"and", .@"or", .sbb, .cmp => 0x81,
.mov => 0xc7,
@ -662,6 +646,20 @@ const RegisterOrMemory = union(enum) {
}
};
fn lowerToOEnc(tag: Tag, reg: Register, code: *std.ArrayList(u8)) InnerError!void {
if (reg.size() != 16 and reg.size() != 64) return error.EmitFail; // TODO correct for push/pop, but is it universal?
const opc = getOpCode(tag, .o).?;
const encoder = try Encoder.init(code, 3);
if (reg.size() == 16) {
encoder.opcode_1byte(0x66);
}
encoder.rex(.{
.w = false,
.b = reg.isExtended(),
});
encoder.opcode_withReg(opc, reg.lowId());
}
fn lowerToDEnc(tag: Tag, imm: i32, code: *std.ArrayList(u8)) InnerError!void {
const opc = getOpCode(tag, .d).?;
const encoder = try Encoder.init(code, 5);
@ -1727,3 +1725,12 @@ test "lower M encoding" {
try lowerToMEnc(.jmp_near, RegisterOrMemory.mem(null, 0x10), code.buffer());
try expectEqualHexStrings("\xFF\x24\x25\x10\x00\x00\x00", code.emitted(), "jmp qword ptr [ds:0x10]");
}
test "lower O encoding" {
var code = TestEmitCode.init();
defer code.deinit();
try lowerToOEnc(.pop, .r12, code.buffer());
try expectEqualHexStrings("\x41\x5c", code.emitted(), "pop r12");
try lowerToOEnc(.push, .r12w, code.buffer());
try expectEqualHexStrings("\x66\x41\x54", code.emitted(), "push r12w");
}