diff --git a/src/arch/x86_64/CodeGen.zig b/src/arch/x86_64/CodeGen.zig index fe2b23e126..f4dbd502e7 100644 --- a/src/arch/x86_64/CodeGen.zig +++ b/src/arch/x86_64/CodeGen.zig @@ -5325,8 +5325,10 @@ fn airStructFieldVal(self: *Self, inst: Air.Inst.Index) !void { const index = extra.field_index; const container_ty = self.air.typeOf(operand); + const container_rc = regClassForType(container_ty); const field_ty = container_ty.structFieldType(index); if (!field_ty.hasRuntimeBitsIgnoreComptime()) break :result .none; + const field_rc = regClassForType(field_ty); const src_mcv = try self.resolveInst(operand); const field_off = switch (container_ty.containerLayout()) { @@ -5410,30 +5412,23 @@ fn airStructFieldVal(self: *Self, inst: Air.Inst.Index) !void { if (field_extra_bits > 0) try self.truncateRegister(field_ty, dst_reg); const dst_mcv = MCValue{ .register = dst_reg }; - const dst_rc = regClassForType(field_ty); - if (dst_rc.eql(gp)) break :result dst_mcv; - - const result_reg = try self.register_manager.allocReg(inst, dst_rc); - try self.genSetReg(result_reg, field_ty, dst_mcv); - break :result .{ .register = result_reg }; + break :result if (field_rc.supersetOf(gp)) + dst_mcv + else + try self.copyToRegisterWithInstTracking(inst, field_ty, dst_mcv); }, .register => |reg| { const reg_lock = self.register_manager.lockRegAssumeUnused(reg); defer self.register_manager.unlockReg(reg_lock); - const dst_mcv = if (self.reuseOperand(inst, operand, 0, src_mcv)) - src_mcv + const dst_reg = if (src_mcv.isRegister() and field_rc.supersetOf(container_rc) and + self.reuseOperand(inst, operand, 0, src_mcv)) + src_mcv.getReg().? else - try self.copyToRegisterWithInstTracking( - inst, - Type.usize, - .{ .register = reg.to64() }, - ); - const dst_mcv_lock: ?RegisterLock = switch (dst_mcv) { - .register => |a_reg| self.register_manager.lockReg(a_reg), - else => null, - }; - defer if (dst_mcv_lock) |lock| self.register_manager.unlockReg(lock); + try self.copyToTmpRegister(Type.usize, .{ .register = reg.to64() }); + const dst_mcv = MCValue{ .register = dst_reg }; + const dst_lock = self.register_manager.lockReg(dst_reg); + defer if (dst_lock) |lock| self.register_manager.unlockReg(lock); // Shift by struct_field_offset. try self.genShiftBinOpMir( @@ -5460,7 +5455,11 @@ fn airStructFieldVal(self: *Self, inst: Air.Inst.Index) !void { registerAlias(dst_mcv.register, field_byte_size), ); } - break :result dst_mcv; + + break :result if (field_rc.supersetOf(gp)) + dst_mcv + else + try self.copyToRegisterWithInstTracking(inst, field_ty, dst_mcv); }, .register_overflow => |ro| { switch (index) {