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x86_64: implicit definition of RAX after syscall

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This commit is contained in:
David Gonzalez Martin 2023-11-10 11:02:17 -06:00
parent 5dceac7720
commit 9dc5f795b2
1 changed files with 33 additions and 18 deletions
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41
src/backend/x86_64.zig
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@ -45,10 +45,10 @@ pub const Logger = enum {
// .register_allocation_problematic_hint,
// .register_allocation_assignment,
// .register_allocation_reload,
// .register_allocation_function_before,
// .register_allocation_new_instruction,
// .register_allocation_new_instruction_function_before,
// .register_allocation_instruction_avoid_copy,
.register_allocation_function_before,
.register_allocation_new_instruction,
.register_allocation_new_instruction_function_before,
.register_allocation_instruction_avoid_copy,
.register_allocation_function_after,
// .register_allocation_operand_list_verification,
.encoding,
@ -2258,10 +2258,6 @@ pub const MIR = struct {
try instruction_selection.instruction_cache.append(mir.allocator, argument_copy);
}
// TODO: handle syscall return value
const syscall = try mir.buildInstruction(instruction_selection, .syscall, &.{});
try instruction_selection.instruction_cache.append(mir.allocator, syscall);
const produce_syscall_return_value = switch (instruction_i == ir_block.instructions.items.len - 2) {
true => blk: {
const last_block_instruction = mir.ir.instructions.get(ir_block.instructions.items[ir_block.instructions.items.len - 1]);
@ -2274,20 +2270,28 @@ pub const MIR = struct {
false => true,
};
if (produce_syscall_return_value) {
const physical_return_register = Register{
.index = .{
.physical = .rax,
},
};
const physical_return_operand = Operand{
const syscall = try mir.buildInstruction(instruction_selection, .syscall, if (produce_syscall_return_value) &.{
Operand{
.id = .gp64,
.u = .{
.register = physical_return_register,
},
.flags = .{ .type = .def },
};
.flags = .{
.type = .def,
.implicit = true,
},
},
} else &.{});
try instruction_selection.instruction_cache.append(mir.allocator, syscall);
if (produce_syscall_return_value) {
const virtual_return_register = try instruction_selection.getRegisterForValue(mir, ir_instruction_index);
const virtual_return_operand = Operand{
.id = .gp64,
@ -2299,7 +2303,13 @@ pub const MIR = struct {
const syscall_result_copy = try mir.buildInstruction(instruction_selection, .copy, &.{
virtual_return_operand,
physical_return_operand,
Operand{
.id = .gp64,
.u = .{
.register = physical_return_register,
},
.flags = .{},
},
});
try instruction_selection.instruction_cache.append(mir.allocator, syscall_result_copy);
}
@ -3167,6 +3177,10 @@ pub const MIR = struct {
switch (instruction.id) {
.mov32rm => {},
.mov32r0 => {},
.mov32ri => {},
.mov64rm => {},
.lea64r => {},
.mov32ri64 => {},
.copy => {
const operand_index = instruction.operands.items[1];
const operand = mir.operands.get(operand_index);
@ -4149,6 +4163,7 @@ pub const MIR = struct {
} else {
switch (instruction) {
.ret => {},
.syscall => {},
else => unreachable,
}
}