From 3ecec50f0c530760653a73194fa3651b16647ef9 Mon Sep 17 00:00:00 2001 From: joachimschmidt557 Date: Sun, 23 Oct 2022 16:53:44 +0200 Subject: [PATCH] stage2 AArch64: implement basic switch statements --- src/arch/aarch64/CodeGen.zig | 226 +++++++++++++++++++++++++++++------ test/behavior/switch.zig | 25 ---- 2 files changed, 190 insertions(+), 61 deletions(-) diff --git a/src/arch/aarch64/CodeGen.zig b/src/arch/aarch64/CodeGen.zig index f9d8858ef8..13fd5bcd09 100644 --- a/src/arch/aarch64/CodeGen.zig +++ b/src/arch/aarch64/CodeGen.zig @@ -91,7 +91,7 @@ register_manager: RegisterManager = .{}, /// Maps offset to what is stored there. stack: std.AutoHashMapUnmanaged(u32, StackAllocation) = .{}, /// Tracks the current instruction allocated to the compare flags -condition_flags_inst: ?Air.Inst.Index = null, +compare_flags_inst: ?Air.Inst.Index = null, /// Offset from the stack base, representing the end of the stack frame. max_end_stack: u32 = 0, @@ -154,7 +154,7 @@ const MCValue = union(enum) { /// The value resides in the N, Z, C, V flags. The value is 1 (if /// the type is u1) or true (if the type in bool) iff the /// specified condition is true. - condition_flags: Condition, + compare_flags: Condition, /// The value is a function argument passed via the stack. stack_argument_offset: u32, }; @@ -201,6 +201,29 @@ const BigTomb = struct { log.debug("%{d} => {}", .{ bt.inst, result }); const branch = &bt.function.branch_stack.items[bt.function.branch_stack.items.len - 1]; branch.inst_table.putAssumeCapacityNoClobber(bt.inst, result); + + switch (result) { + .register => |reg| { + // In some cases (such as bitcast), an operand + // may be the same MCValue as the result. If + // that operand died and was a register, it + // was freed by processDeath. We have to + // "re-allocate" the register. + if (bt.function.register_manager.isRegFree(reg)) { + bt.function.register_manager.getRegAssumeFree(reg, bt.inst); + } + }, + .register_with_overflow => |rwo| { + if (bt.function.register_manager.isRegFree(rwo.reg)) { + bt.function.register_manager.getRegAssumeFree(rwo.reg, bt.inst); + } + bt.function.compare_flags_inst = bt.inst; + }, + .compare_flags => |_| { + bt.function.compare_flags_inst = bt.inst; + }, + else => {}, + } } bt.function.finishAirBookkeeping(); } @@ -764,10 +787,10 @@ fn processDeath(self: *Self, inst: Air.Inst.Index) void { }, .register_with_overflow => |rwo| { self.register_manager.freeReg(rwo.reg); - self.condition_flags_inst = null; + self.compare_flags_inst = null; }, - .condition_flags => { - self.condition_flags_inst = null; + .compare_flags => { + self.compare_flags_inst = null; }, else => {}, // TODO process stack allocation death } @@ -808,6 +831,15 @@ fn finishAir(self: *Self, inst: Air.Inst.Index, result: MCValue, operands: [Live self.register_manager.getRegAssumeFree(reg, inst); } }, + .register_with_overflow => |rwo| { + if (self.register_manager.isRegFree(rwo.reg)) { + self.register_manager.getRegAssumeFree(rwo.reg, inst); + } + self.compare_flags_inst = inst; + }, + .compare_flags => |_| { + self.compare_flags_inst = inst; + }, else => {}, } } @@ -931,11 +963,11 @@ pub fn spillInstruction(self: *Self, reg: Register, inst: Air.Inst.Index) !void /// Save the current instruction stored in the compare flags if /// occupied fn spillCompareFlagsIfOccupied(self: *Self) !void { - if (self.condition_flags_inst) |inst_to_save| { + if (self.compare_flags_inst) |inst_to_save| { const ty = self.air.typeOfIndex(inst_to_save); const mcv = self.getResolvedInstValue(inst_to_save); const new_mcv = switch (mcv) { - .condition_flags => try self.allocRegOrMem(ty, true, inst_to_save), + .compare_flags => try self.allocRegOrMem(ty, true, inst_to_save), .register_with_overflow => try self.allocRegOrMem(ty, false, inst_to_save), else => unreachable, // mcv doesn't occupy the compare flags }; @@ -946,7 +978,7 @@ fn spillCompareFlagsIfOccupied(self: *Self) !void { const branch = &self.branch_stack.items[self.branch_stack.items.len - 1]; try branch.inst_table.put(self.gpa, inst_to_save, new_mcv); - self.condition_flags_inst = null; + self.compare_flags_inst = null; // TODO consolidate with register manager and spillInstruction // this call should really belong in the register manager! @@ -1155,7 +1187,7 @@ fn airNot(self: *Self, inst: Air.Inst.Index) !void { switch (operand) { .dead => unreachable, .unreach => unreachable, - .condition_flags => |cond| break :result MCValue{ .condition_flags = cond.negate() }, + .compare_flags => |cond| break :result MCValue{ .compare_flags = cond.negate() }, else => { switch (operand_ty.zigTypeTag()) { .Bool => { @@ -1564,9 +1596,9 @@ fn allocRegs( // If the previous MCValue occupied some space we track, we // need to make sure it is marked as free now. switch (mcv) { - .condition_flags => { - assert(self.condition_flags_inst.? == inst); - self.condition_flags_inst = null; + .compare_flags => { + assert(self.compare_flags_inst.? == inst); + self.compare_flags_inst = null; }, .register => |prev_reg| { assert(!self.register_manager.isRegFree(prev_reg)); @@ -2363,7 +2395,7 @@ fn airOverflow(self: *Self, inst: Air.Inst.Index) !void { const stack_offset = try self.allocMem(tuple_size, tuple_align, inst); try self.spillCompareFlagsIfOccupied(); - self.condition_flags_inst = null; + self.compare_flags_inst = null; const base_tag: Air.Inst.Tag = switch (tag) { .add_with_overflow => .add, @@ -2395,7 +2427,7 @@ fn airOverflow(self: *Self, inst: Air.Inst.Index) !void { }); try self.genSetStack(lhs_ty, stack_offset, .{ .register = truncated_reg }); - try self.genSetStack(Type.initTag(.u1), stack_offset - overflow_bit_offset, .{ .condition_flags = .ne }); + try self.genSetStack(Type.initTag(.u1), stack_offset - overflow_bit_offset, .{ .compare_flags = .ne }); break :result MCValue{ .stack_offset = stack_offset }; }, @@ -2430,7 +2462,7 @@ fn airOverflow(self: *Self, inst: Air.Inst.Index) !void { }; try self.spillCompareFlagsIfOccupied(); - self.condition_flags_inst = inst; + self.compare_flags_inst = inst; const dest = blk: { if (rhs_immediate_ok) { @@ -2539,7 +2571,7 @@ fn airMulWithOverflow(self: *Self, inst: Air.Inst.Index) !void { } try self.genSetStack(lhs_ty, stack_offset, .{ .register = truncated_reg }); - try self.genSetStack(Type.initTag(.u1), stack_offset - overflow_bit_offset, .{ .condition_flags = .ne }); + try self.genSetStack(Type.initTag(.u1), stack_offset - overflow_bit_offset, .{ .compare_flags = .ne }); break :result MCValue{ .stack_offset = stack_offset }; } else if (int_info.bits <= 64) { @@ -2679,7 +2711,7 @@ fn airMulWithOverflow(self: *Self, inst: Air.Inst.Index) !void { try self.truncRegister(dest_reg, truncated_reg, int_info.signedness, int_info.bits); try self.genSetStack(lhs_ty, stack_offset, .{ .register = truncated_reg }); - try self.genSetStack(Type.initTag(.u1), stack_offset - overflow_bit_offset, .{ .condition_flags = .ne }); + try self.genSetStack(Type.initTag(.u1), stack_offset - overflow_bit_offset, .{ .compare_flags = .ne }); break :result MCValue{ .stack_offset = stack_offset }; } else return self.fail("TODO implement mul_with_overflow for integers > u64/i64", .{}); @@ -2811,7 +2843,7 @@ fn airShlWithOverflow(self: *Self, inst: Air.Inst.Index) !void { }); try self.genSetStack(lhs_ty, stack_offset, .{ .register = dest_reg }); - try self.genSetStack(Type.initTag(.u1), stack_offset - overflow_bit_offset, .{ .condition_flags = .ne }); + try self.genSetStack(Type.initTag(.u1), stack_offset - overflow_bit_offset, .{ .compare_flags = .ne }); break :result MCValue{ .stack_offset = stack_offset }; } else { @@ -3262,7 +3294,7 @@ fn load(self: *Self, dst_mcv: MCValue, ptr: MCValue, ptr_ty: Type) InnerError!vo .undef => unreachable, .unreach => unreachable, .dead => unreachable, - .condition_flags, + .compare_flags, .register_with_overflow, => unreachable, // cannot hold an address .immediate => |imm| try self.setRegOrMem(elem_ty, dst_mcv, .{ .memory = imm }), @@ -3274,7 +3306,7 @@ fn load(self: *Self, dst_mcv: MCValue, ptr: MCValue, ptr_ty: Type) InnerError!vo switch (dst_mcv) { .dead => unreachable, .undef => unreachable, - .condition_flags => unreachable, + .compare_flags => unreachable, .register => |dst_reg| { try self.genLdrRegister(dst_reg, addr_reg, elem_ty); }, @@ -3483,7 +3515,7 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type .undef => unreachable, .unreach => unreachable, .dead => unreachable, - .condition_flags, + .compare_flags, .register_with_overflow, => unreachable, // cannot hold an address .immediate => |imm| { @@ -3638,7 +3670,7 @@ fn airStructFieldVal(self: *Self, inst: Air.Inst.Index) !void { 0 => MCValue{ .register = rwo.reg }, // get overflow bit: return C or V flag - 1 => MCValue{ .condition_flags = rwo.flag }, + 1 => MCValue{ .compare_flags = rwo.flag }, else => unreachable, }; @@ -4092,8 +4124,8 @@ fn cmp( } return switch (int_info.signedness) { - .signed => MCValue{ .condition_flags = Condition.fromCompareOperatorSigned(op) }, - .unsigned => MCValue{ .condition_flags = Condition.fromCompareOperatorUnsigned(op) }, + .signed => MCValue{ .compare_flags = Condition.fromCompareOperatorSigned(op) }, + .unsigned => MCValue{ .compare_flags = Condition.fromCompareOperatorUnsigned(op) }, }; } else { return self.fail("TODO AArch64 cmp for ints > 64 bits", .{}); @@ -4151,7 +4183,7 @@ fn airDbgVar(self: *Self, inst: Air.Inst.Index) !void { fn condBr(self: *Self, condition: MCValue) !Mir.Inst.Index { switch (condition) { - .condition_flags => |cond| return try self.addInst(.{ + .compare_flags => |cond| return try self.addInst(.{ .tag = .b_cond, .data = .{ .inst_cond = .{ @@ -4207,7 +4239,7 @@ fn airCondBr(self: *Self, inst: Air.Inst.Index) !void { var parent_stack = try self.stack.clone(self.gpa); defer parent_stack.deinit(self.gpa); const parent_registers = self.register_manager.registers; - const parent_condition_flags_inst = self.condition_flags_inst; + const parent_compare_flags_inst = self.compare_flags_inst; try self.branch_stack.append(.{}); errdefer { @@ -4226,7 +4258,7 @@ fn airCondBr(self: *Self, inst: Air.Inst.Index) !void { defer saved_then_branch.deinit(self.gpa); self.register_manager.registers = parent_registers; - self.condition_flags_inst = parent_condition_flags_inst; + self.compare_flags_inst = parent_compare_flags_inst; self.stack.deinit(self.gpa); self.stack = parent_stack; @@ -4354,9 +4386,9 @@ fn isErr(self: *Self, ty: Type, operand: MCValue) !MCValue { fn isNonErr(self: *Self, ty: Type, operand: MCValue) !MCValue { const is_err_result = try self.isErr(ty, operand); switch (is_err_result) { - .condition_flags => |cond| { + .compare_flags => |cond| { assert(cond == .hi); - return MCValue{ .condition_flags = cond.negate() }; + return MCValue{ .compare_flags = cond.negate() }; }, .immediate => |imm| { assert(imm == 0); @@ -4519,10 +4551,132 @@ fn airBlock(self: *Self, inst: Air.Inst.Index) !void { fn airSwitch(self: *Self, inst: Air.Inst.Index) !void { const pl_op = self.air.instructions.items(.data)[inst].pl_op; - const condition = pl_op.operand; - _ = condition; + const condition_ty = self.air.typeOf(pl_op.operand); + const switch_br = self.air.extraData(Air.SwitchBr, pl_op.payload); + const liveness = try self.liveness.getSwitchBr( + self.gpa, + inst, + switch_br.data.cases_len + 1, + ); + defer self.gpa.free(liveness.deaths); - return self.fail("TODO airSwitch for {}", .{self.target.cpu.arch}); + var extra_index: usize = switch_br.end; + var case_i: u32 = 0; + while (case_i < switch_br.data.cases_len) : (case_i += 1) { + const case = self.air.extraData(Air.SwitchBr.Case, extra_index); + const items = @ptrCast([]const Air.Inst.Ref, self.air.extra[case.end..][0..case.data.items_len]); + assert(items.len > 0); + const case_body = self.air.extra[case.end + items.len ..][0..case.data.body_len]; + extra_index = case.end + items.len + case_body.len; + + // For every item, we compare it to condition and branch into + // the prong if they are equal. After we compared to all + // items, we branch into the next prong (or if no other prongs + // exist out of the switch statement). + // + // cmp condition, item1 + // beq prong + // cmp condition, item2 + // beq prong + // cmp condition, item3 + // beq prong + // b out + // prong: ... + // ... + // out: ... + const branch_into_prong_relocs = try self.gpa.alloc(u32, items.len); + defer self.gpa.free(branch_into_prong_relocs); + + for (items) |item, idx| { + const cmp_result = try self.cmp(.{ .inst = pl_op.operand }, .{ .inst = item }, condition_ty, .neq); + branch_into_prong_relocs[idx] = try self.condBr(cmp_result); + } + + const branch_away_from_prong_reloc = try self.addInst(.{ + .tag = .b, + .data = .{ .inst = undefined }, // populated later through performReloc + }); + + for (branch_into_prong_relocs) |reloc| { + try self.performReloc(reloc); + } + + // Capture the state of register and stack allocation state so that we can revert to it. + const parent_next_stack_offset = self.next_stack_offset; + const parent_free_registers = self.register_manager.free_registers; + const parent_compare_flags_inst = self.compare_flags_inst; + var parent_stack = try self.stack.clone(self.gpa); + defer parent_stack.deinit(self.gpa); + const parent_registers = self.register_manager.registers; + + try self.branch_stack.append(.{}); + errdefer { + _ = self.branch_stack.pop(); + } + + try self.ensureProcessDeathCapacity(liveness.deaths[case_i].len); + for (liveness.deaths[case_i]) |operand| { + self.processDeath(operand); + } + try self.genBody(case_body); + + // Revert to the previous register and stack allocation state. + var saved_case_branch = self.branch_stack.pop(); + defer saved_case_branch.deinit(self.gpa); + + self.register_manager.registers = parent_registers; + self.compare_flags_inst = parent_compare_flags_inst; + self.stack.deinit(self.gpa); + self.stack = parent_stack; + parent_stack = .{}; + + self.next_stack_offset = parent_next_stack_offset; + self.register_manager.free_registers = parent_free_registers; + + try self.performReloc(branch_away_from_prong_reloc); + } + + if (switch_br.data.else_body_len > 0) { + const else_body = self.air.extra[extra_index..][0..switch_br.data.else_body_len]; + + // Capture the state of register and stack allocation state so that we can revert to it. + const parent_next_stack_offset = self.next_stack_offset; + const parent_free_registers = self.register_manager.free_registers; + const parent_compare_flags_inst = self.compare_flags_inst; + var parent_stack = try self.stack.clone(self.gpa); + defer parent_stack.deinit(self.gpa); + const parent_registers = self.register_manager.registers; + + try self.branch_stack.append(.{}); + errdefer { + _ = self.branch_stack.pop(); + } + + const else_deaths = liveness.deaths.len - 1; + try self.ensureProcessDeathCapacity(liveness.deaths[else_deaths].len); + for (liveness.deaths[else_deaths]) |operand| { + self.processDeath(operand); + } + try self.genBody(else_body); + + // Revert to the previous register and stack allocation state. + var saved_case_branch = self.branch_stack.pop(); + defer saved_case_branch.deinit(self.gpa); + + self.register_manager.registers = parent_registers; + self.compare_flags_inst = parent_compare_flags_inst; + self.stack.deinit(self.gpa); + self.stack = parent_stack; + parent_stack = .{}; + + self.next_stack_offset = parent_next_stack_offset; + self.register_manager.free_registers = parent_free_registers; + + // TODO consolidate returned MCValues between prongs and else branch like we do + // in airCondBr. + } + + return self.finishAir(inst, .unreach, .{ pl_op.operand, .none, .none }); } fn performReloc(self: *Self, inst: Mir.Inst.Index) !void { @@ -4551,7 +4705,7 @@ fn br(self: *Self, block: Air.Inst.Index, operand: Air.Inst.Ref) !void { block_data.mcv = switch (operand_mcv) { .none, .dead, .unreach => unreachable, .register, .stack_offset, .memory => operand_mcv, - .immediate, .stack_argument_offset, .condition_flags => blk: { + .immediate, .stack_argument_offset, .compare_flags => blk: { const new_mcv = try self.allocRegOrMem(self.air.typeOfIndex(block), true, block); try self.setRegOrMem(self.air.typeOfIndex(block), new_mcv, operand_mcv); break :blk new_mcv; @@ -4734,7 +4888,7 @@ fn genSetStack(self: *Self, ty: Type, stack_offset: u32, mcv: MCValue) InnerErro else => return self.fail("TODO implement memset", .{}), } }, - .condition_flags, + .compare_flags, .immediate, .ptr_stack_offset, => { @@ -4894,7 +5048,7 @@ fn genSetReg(self: *Self, ty: Type, reg: Register, mcv: MCValue) InnerError!void } }, }); }, - .condition_flags => |condition| { + .compare_flags => |condition| { _ = try self.addInst(.{ .tag = .cset, .data = .{ .r_cond = .{ @@ -5171,7 +5325,7 @@ fn genSetStackArgument(self: *Self, ty: Type, stack_offset: u32, mcv: MCValue) I try self.genInlineMemcpy(src_reg, dst_reg, len_reg, count_reg, tmp_reg); } }, - .condition_flags, + .compare_flags, .immediate, .ptr_stack_offset, => { diff --git a/test/behavior/switch.zig b/test/behavior/switch.zig index b852974240..165b1a8037 100644 --- a/test/behavior/switch.zig +++ b/test/behavior/switch.zig @@ -5,8 +5,6 @@ const expectError = std.testing.expectError; const expectEqual = std.testing.expectEqual; test "switch with numbers" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - try testSwitchWithNumbers(13); } @@ -20,8 +18,6 @@ fn testSwitchWithNumbers(x: u32) !void { } test "switch with all ranges" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - try expect(testSwitchWithAllRanges(50, 3) == 1); try expect(testSwitchWithAllRanges(101, 0) == 2); try expect(testSwitchWithAllRanges(300, 5) == 3); @@ -53,8 +49,6 @@ test "implicit comptime switch" { } test "switch on enum" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - const fruit = Fruit.Orange; nonConstSwitchOnEnum(fruit); } @@ -72,8 +66,6 @@ fn nonConstSwitchOnEnum(fruit: Fruit) void { } test "switch statement" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - try nonConstSwitch(SwitchStatementFoo.C); } fn nonConstSwitch(foo: SwitchStatementFoo) !void { @@ -89,7 +81,6 @@ const SwitchStatementFoo = enum { A, B, C, D }; test "switch with multiple expressions" { if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO const x = switch (returnsFive()) { 1, 2, 3 => 1, @@ -103,8 +94,6 @@ fn returnsFive() i32 { } test "switch on type" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - try expect(trueIfBoolFalseOtherwise(bool)); try expect(!trueIfBoolFalseOtherwise(i32)); } @@ -117,8 +106,6 @@ fn trueIfBoolFalseOtherwise(comptime T: type) bool { } test "switching on booleans" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - try testSwitchOnBools(); comptime try testSwitchOnBools(); } @@ -170,8 +157,6 @@ test "undefined.u0" { } test "switch with disjoint range" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - var q: u8 = 0; switch (q) { 0...125 => {}, @@ -214,8 +199,6 @@ fn poll() void { } test "switch on global mutable var isn't constant-folded" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - while (state < 2) { poll(); } @@ -273,7 +256,6 @@ fn testSwitchEnumPtrCapture() !void { test "switch handles all cases of number" { if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO try testSwitchHandleAllCases(); comptime try testSwitchHandleAllCases(); @@ -363,8 +345,6 @@ test "anon enum literal used in switch on union enum" { } test "switch all prongs unreachable" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - try testAllProngsUnreachable(); comptime try testAllProngsUnreachable(); } @@ -400,7 +380,6 @@ fn return_a_number() anyerror!i32 { test "switch on integer with else capturing expr" { if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO const S = struct { fn doTheTest() !void { @@ -641,8 +620,6 @@ test "switch capture copies its payload" { } test "capture of integer forwards the switch condition directly" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - const S = struct { fn foo(x: u8) !void { switch (x) { @@ -662,8 +639,6 @@ test "capture of integer forwards the switch condition directly" { } test "enum value without tag name used as switch item" { - if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO - const E = enum(u32) { a = 1, b = 2,