Commit 638f93ebdceb860974aae54b6f8c2c9f52157305 | zig

author	Jacob G-W <jacoblevgw@gmail.com> 2021-01-03 15:45:22-05:00
committer	Andrew Kelley <andrew@ziglang.org> 2021-01-04 12:42:52-07:00
log	638f93ebdceb860974aae54b6f8c2c9f52157305
tree	9197ddee7f48b05a2f77ac6f46018ab0299c26ae
parent	aa0906e9aaaf36bc928b5502bdb34e7a0409b2c0

stage2: implementation of `@setEvalBranchQuota`:

`@setEvalBranchQuota` can be called before the comptime/inline call
stack is created.

For example:

```zig
@setEvalBranchQuota(100);
comptime {
    while (true) {}
}
```

Here we need to set the branch_quota before the comptime block creates a
scope for the branch_count.

5 files changed, 76 insertions(+), 5 deletions(-)

src
test
- stage2
  - cbe.zig

src/Module.zig+21-4

...	...	@@ -765,6 +765,8 @@ pub const Scope = struct {
765	765	label: ?Label = null,
766	766	inlining: ?*Inlining,
767	767	is_comptime: bool,
	768	/// Shared to sub-blocks.
	769	branch_quota: *u32,
768	770
769	771	pub const InstTable = std.AutoHashMap(zir.Inst, Inst);
770	772
...	...	@@ -792,8 +794,7 @@ pub const Scope = struct {
792	794
793	795	pub const Shared = struct {
794	796	caller: ?*Fn,
795		branch_count: u64,
796		branch_quota: u64,
	797	branch_count: u32,
797	798	};
798	799	};
799	800
...	...	@@ -1104,6 +1105,8 @@ fn astGenAndAnalyzeDecl(self: Module, decl: Decl) !bool {
1104	1105	var inst_table = Scope.Block.InstTable.init(self.gpa);
1105	1106	defer inst_table.deinit();
1106	1107
	1108	var branch_quota: u32 = 1000;
	1109
1107	1110	var block_scope: Scope.Block = .{
1108	1111	.parent = null,
1109	1112	.inst_table = &inst_table,
...	...	@@ -1113,6 +1116,7 @@ fn astGenAndAnalyzeDecl(self: Module, decl: Decl) !bool {
1113	1116	.arena = &decl_arena.allocator,
1114	1117	.inlining = null,
1115	1118	.is_comptime = false,
	1119	.branch_quota = &branch_quota,
1116	1120	};
1117	1121	defer block_scope.instructions.deinit(self.gpa);
1118	1122
...	...	@@ -1297,6 +1301,8 @@ fn astGenAndAnalyzeDecl(self: Module, decl: Decl) !bool {
1297	1301	var decl_inst_table = Scope.Block.InstTable.init(self.gpa);
1298	1302	defer decl_inst_table.deinit();
1299	1303
	1304	var branch_quota: u32 = 1000;
	1305
1300	1306	var block_scope: Scope.Block = .{
1301	1307	.parent = null,
1302	1308	.inst_table = &decl_inst_table,
...	...	@@ -1306,6 +1312,7 @@ fn astGenAndAnalyzeDecl(self: Module, decl: Decl) !bool {
1306	1312	.arena = &decl_arena.allocator,
1307	1313	.inlining = null,
1308	1314	.is_comptime = true,
	1315	.branch_quota = &branch_quota,
1309	1316	};
1310	1317	defer block_scope.instructions.deinit(self.gpa);
1311	1318
...	...	@@ -1367,6 +1374,7 @@ fn astGenAndAnalyzeDecl(self: Module, decl: Decl) !bool {
1367	1374	var var_inst_table = Scope.Block.InstTable.init(self.gpa);
1368	1375	defer var_inst_table.deinit();
1369	1376
	1377	var branch_quota_vi: u32 = 1000;
1370	1378	var inner_block: Scope.Block = .{
1371	1379	.parent = null,
1372	1380	.inst_table = &var_inst_table,
...	...	@@ -1376,6 +1384,7 @@ fn astGenAndAnalyzeDecl(self: Module, decl: Decl) !bool {
1376	1384	.arena = &gen_scope_arena.allocator,
1377	1385	.inlining = null,
1378	1386	.is_comptime = true,
	1387	.branch_quota = &branch_quota_vi,
1379	1388	};
1380	1389	defer inner_block.instructions.deinit(self.gpa);
1381	1390	try zir_sema.analyzeBody(self, &inner_block, .{
...	...	@@ -1494,6 +1503,8 @@ fn astGenAndAnalyzeDecl(self: Module, decl: Decl) !bool {
1494	1503	var inst_table = Scope.Block.InstTable.init(self.gpa);
1495	1504	defer inst_table.deinit();
1496	1505
	1506	var branch_quota: u32 = 1000;
	1507
1497	1508	var block_scope: Scope.Block = .{
1498	1509	.parent = null,
1499	1510	.inst_table = &inst_table,
...	...	@@ -1503,6 +1514,7 @@ fn astGenAndAnalyzeDecl(self: Module, decl: Decl) !bool {
1503	1514	.arena = &analysis_arena.allocator,
1504	1515	.inlining = null,
1505	1516	.is_comptime = true,
	1517	.branch_quota = &branch_quota,
1506	1518	};
1507	1519	defer block_scope.instructions.deinit(self.gpa);
1508	1520
...	...	@@ -1875,6 +1887,8 @@ pub fn analyzeFnBody(self: Module, decl: Decl, func: *Fn) !void {
1875	1887	defer decl.typed_value.most_recent.arena.?.* = arena.state;
1876	1888	var inst_table = Scope.Block.InstTable.init(self.gpa);
1877	1889	defer inst_table.deinit();
	1890	var branch_quota: u32 = 1000;
	1891
1878	1892	var inner_block: Scope.Block = .{
1879	1893	.parent = null,
1880	1894	.inst_table = &inst_table,
...	...	@@ -1884,6 +1898,7 @@ pub fn analyzeFnBody(self: Module, decl: Decl, func: *Fn) !void {
1884	1898	.arena = &arena.allocator,
1885	1899	.inlining = null,
1886	1900	.is_comptime = false,
	1901	.branch_quota = &branch_quota,
1887	1902	};
1888	1903	defer inner_block.instructions.deinit(self.gpa);
1889	1904
...	...	@@ -3466,7 +3481,9 @@ pub fn addSafetyCheck(mod: Module, parent_block: Scope.Block, ok: *Inst, panic
3466	3481	.arena = parent_block.arena,
3467	3482	.inlining = parent_block.inlining,
3468	3483	.is_comptime = parent_block.is_comptime,
	3484	.branch_quota = parent_block.branch_quota,
3469	3485	};
	3486
3470	3487	defer fail_block.instructions.deinit(mod.gpa);
3471	3488
3472	3489	_ = try mod.safetyPanic(&fail_block, ok.src, panic_id);
...	...	@@ -3532,10 +3549,10 @@ pub fn identifierTokenString(mod: Module, scope: Scope, token: ast.TokenIndex)
3532	3549	pub fn emitBackwardBranch(mod: Module, block: Scope.Block, src: usize) !void {
3533	3550	const shared = block.inlining.?.shared;
3534	3551	shared.branch_count += 1;
3535		if (shared.branch_count > shared.branch_quota) {
	3552	if (shared.branch_count > block.branch_quota.*) {
3536	3553	// TODO show the "called from here" stack
3537	3554	return mod.fail(&block.base, src, "evaluation exceeded {d} backwards branches", .{
3538		shared.branch_quota,
	3555	block.branch_quota.*,
3539	3556	});
3540	3557	}
3541	3558	}

src/astgen.zig+15

...	...	@@ -2317,6 +2317,19 @@ fn compileError(mod: Module, scope: Scope, call: *ast.Node.BuiltinCall) InnerE
2317	2317	return addZIRUnOp(mod, scope, src, .compileerror, target);
2318	2318	}
2319	2319
	2320	fn setEvalBranchQuota(mod: Module, scope: Scope, call: ast.Node.BuiltinCall) InnerError!zir.Inst {
	2321	try ensureBuiltinParamCount(mod, scope, call, 1);
	2322	const tree = scope.tree();
	2323	const src = tree.token_locs[call.builtin_token].start;
	2324	const params = call.params();
	2325	const target = try expr(mod, scope, .none, params[0]);
	2326	const u32_type = try addZIRInstConst(mod, scope, src, .{
	2327	.ty = Type.initTag(.type),
	2328	.val = Value.initTag(.u32_type),
	2329	});
	2330	return addZIRUnOp(mod, scope, src, .setevalbranchquota, try rlWrap(mod, scope, .{ .ty = u32_type }, target));
	2331	}
	2332
2320	2333	fn typeOf(mod: Module, scope: Scope, rl: ResultLoc, call: ast.Node.BuiltinCall) InnerError!zir.Inst {
2321	2334	const tree = scope.tree();
2322	2335	const arena = scope.arena();
...	...	@@ -2362,6 +2375,8 @@ fn builtinCall(mod: Module, scope: Scope, rl: ResultLoc, call: *ast.Node.Built
2362	2375	return rlWrap(mod, scope, rl, try import(mod, scope, call));
2363	2376	} else if (mem.eql(u8, builtin_name, "@compileError")) {
2364	2377	return compileError(mod, scope, call);
	2378	} else if (mem.eql(u8, builtin_name, "@setEvalBranchQuota")) {
	2379	return setEvalBranchQuota(mod, scope, call);
2365	2380	} else {
2366	2381	return mod.failTok(scope, call.builtin_token, "invalid builtin function: '{s}'", .{builtin_name});
2367	2382	}

src/zir.zig+4

...	...	@@ -127,6 +127,8 @@ pub const Inst = struct {
127	127	coerce_to_ptr_elem,
128	128	/// Emit an error message and fail compilation.
129	129	compileerror,
	130	/// Changes the maximum number of backwards branches that compile-time code execution can use before giving up and making a compile error.
	131	setevalbranchquota,
130	132	/// Conditional branch. Splits control flow based on a boolean condition value.
131	133	condbr,
132	134	/// Special case, has no textual representation.
...	...	@@ -347,6 +349,7 @@ pub const Inst = struct {
347	349	.anyframe_type,
348	350	.bitnot,
349	351	.import,
	352	.setevalbranchquota,
350	353	=> UnOp,
351	354
352	355	.add,
...	...	@@ -535,6 +538,7 @@ pub const Inst = struct {
535	538	.switch_range,
536	539	.typeof_peer,
537	540	.resolve_inferred_alloc,
	541	.setevalbranchquota,
538	542	=> false,
539	543
540	544	.@"break",

src/zir_sema.zig+21-1

...	...	@@ -81,6 +81,7 @@ pub fn analyzeInst(mod: Module, scope: Scope, old_inst: *zir.Inst) InnerError!
81	81	.mut_slice_type => return analyzeInstSimplePtrType(mod, scope, old_inst.castTag(.mut_slice_type).?, true, .Slice),
82	82	.ptr_type => return analyzeInstPtrType(mod, scope, old_inst.castTag(.ptr_type).?),
83	83	.store => return analyzeInstStore(mod, scope, old_inst.castTag(.store).?),
	84	.setevalbranchquota => return analyzeInstSetEvalBranchQuota(mod, scope, old_inst.castTag(.setevalbranchquota).?),
84	85	.str => return analyzeInstStr(mod, scope, old_inst.castTag(.str).?),
85	86	.int => {
86	87	const big_int = old_inst.castTag(.int).?.positionals.int;
...	...	@@ -486,6 +487,18 @@ fn analyzeInstStoreToInferredPtr(
486	487	return mod.storePtr(scope, inst.base.src, bitcasted_ptr, value);
487	488	}
488	489
	490	fn analyzeInstSetEvalBranchQuota(
	491	mod: *Module,
	492	scope: *Scope,
	493	inst: *zir.Inst.UnOp,
	494	) InnerError!*Inst {
	495	const b = try mod.requireFunctionBlock(scope, inst.base.src);
	496	const quota = @truncate(u32, try resolveInt(mod, scope, inst.positionals.operand, Type.initTag(.u32)));
	497	if (b.branch_quota.* < quota)
	498	b.branch_quota.* = quota;
	499	return mod.constVoid(scope, inst.base.src);
	500	}
	501
489	502	fn analyzeInstStore(mod: Module, scope: Scope, inst: zir.Inst.BinOp) InnerError!Inst {
490	503	const ptr = try resolveInst(mod, scope, inst.positionals.lhs);
491	504	const value = try resolveInst(mod, scope, inst.positionals.rhs);
...	...	@@ -594,6 +607,7 @@ fn analyzeInstLoop(mod: Module, scope: Scope, inst: *zir.Inst.Loop) InnerError
594	607	.arena = parent_block.arena,
595	608	.inlining = parent_block.inlining,
596	609	.is_comptime = parent_block.is_comptime,
	610	.branch_quota = parent_block.branch_quota,
597	611	};
598	612	defer child_block.instructions.deinit(mod.gpa);
599	613
...	...	@@ -619,6 +633,7 @@ fn analyzeInstBlockFlat(mod: Module, scope: Scope, inst: *zir.Inst.Block, is_c
619	633	.label = null,
620	634	.inlining = parent_block.inlining,
621	635	.is_comptime = parent_block.is_comptime or is_comptime,
	636	.branch_quota = parent_block.branch_quota,
622	637	};
623	638	defer child_block.instructions.deinit(mod.gpa);
624	639
...	...	@@ -666,6 +681,7 @@ fn analyzeInstBlock(mod: Module, scope: Scope, inst: *zir.Inst.Block, is_compt
666	681	}),
667	682	.inlining = parent_block.inlining,
668	683	.is_comptime = is_comptime or parent_block.is_comptime,
	684	.branch_quota = parent_block.branch_quota,
669	685	};
670	686	const merges = &child_block.label.?.merges;
671	687
...	...	@@ -867,7 +883,6 @@ fn analyzeInstCall(mod: Module, scope: Scope, inst: *zir.Inst.Call) InnerError
867	883	// Otherwise we pass on the shared data from the parent scope.
868	884	var shared_inlining = Scope.Block.Inlining.Shared{
869	885	.branch_count = 0,
870		.branch_quota = 1000,
871	886	.caller = b.func,
872	887	};
873	888	// This one is shared among sub-blocks within the same callee, but not
...	...	@@ -896,7 +911,9 @@ fn analyzeInstCall(mod: Module, scope: Scope, inst: *zir.Inst.Call) InnerError
896	911	.label = null,
897	912	.inlining = &inlining,
898	913	.is_comptime = is_comptime_call,
	914	.branch_quota = b.branch_quota,
899	915	};
	916
900	917	const merges = &child_block.inlining.?.merges;
901	918
902	919	defer child_block.instructions.deinit(mod.gpa);
...	...	@@ -1417,6 +1434,7 @@ fn analyzeInstSwitchBr(mod: Module, scope: Scope, inst: *zir.Inst.SwitchBr) In
1417	1434	.arena = parent_block.arena,
1418	1435	.inlining = parent_block.inlining,
1419	1436	.is_comptime = parent_block.is_comptime,
	1437	.branch_quota = parent_block.branch_quota,
1420	1438	};
1421	1439	defer case_block.instructions.deinit(mod.gpa);
1422	1440
...	...	@@ -1960,6 +1978,7 @@ fn analyzeInstCondBr(mod: Module, scope: Scope, inst: *zir.Inst.CondBr) InnerE
1960	1978	.arena = parent_block.arena,
1961	1979	.inlining = parent_block.inlining,
1962	1980	.is_comptime = parent_block.is_comptime,
	1981	.branch_quota = parent_block.branch_quota,
1963	1982	};
1964	1983	defer true_block.instructions.deinit(mod.gpa);
1965	1984	try analyzeBody(mod, &true_block, inst.positionals.then_body);
...	...	@@ -1973,6 +1992,7 @@ fn analyzeInstCondBr(mod: Module, scope: Scope, inst: *zir.Inst.CondBr) InnerE
1973	1992	.arena = parent_block.arena,
1974	1993	.inlining = parent_block.inlining,
1975	1994	.is_comptime = parent_block.is_comptime,
	1995	.branch_quota = parent_block.branch_quota,
1976	1996	};
1977	1997	defer false_block.instructions.deinit(mod.gpa);
1978	1998	try analyzeBody(mod, &false_block, inst.positionals.else_body);

test/stage2/cbe.zig+15

...	...	@@ -67,7 +67,22 @@ pub fn addCases(ctx: *TestContext) !void {
67	67	\\}
68	68	, "");
69	69	}
	70	{
	71	var case = ctx.exeFromCompiledC("@setEvalBranchQuota", .{});
70	72
	73	case.addCompareOutput(
	74	\\export fn main() i32 {
	75	\\ @setEvalBranchQuota(1001);
	76	\\ const y = rec(1001);
	77	\\ return y - 1;
	78	\\}
	79	\\
	80	\\inline fn rec(n: usize) usize {
	81	\\ if (n <= 1) return n;
	82	\\ return rec(n - 1);
	83	\\}
	84	, "");
	85	}
71	86	ctx.c("empty start function", linux_x64,
72	87	\\export fn _start() noreturn {
73	88	\\ unreachable;