stage2: improvements to @setEvalBranchQuota

* extract magic number into a constant * properly use result location casting for the operand * naming convention for ZIR instructions
g-w1 · Jan 4, 2021 · 7e64dc4 · 7e64dc4
1 parent 638f93e
commit 7e64dc4
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Showing 4 changed files with 34 additions and 13 deletions.
diff --git a/src/Module.zig b/src/Module.zig
@@ -23,6 +23,8 @@ const trace = @import("tracy.zig").trace;
 const astgen = @import("astgen.zig");
 const zir_sema = @import("zir_sema.zig");
 
+const default_eval_branch_quota = 1000;
+
 /// General-purpose allocator. Used for both temporary and long-term storage.
 gpa: *Allocator,
 comp: *Compilation,
@@ -1105,7 +1107,7 @@ fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
             var inst_table = Scope.Block.InstTable.init(self.gpa);
             defer inst_table.deinit();
 
-            var branch_quota: u32 = 1000;
+            var branch_quota: u32 = default_eval_branch_quota;
 
             var block_scope: Scope.Block = .{
                 .parent = null,
@@ -1301,7 +1303,7 @@ fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
             var decl_inst_table = Scope.Block.InstTable.init(self.gpa);
             defer decl_inst_table.deinit();
 
-            var branch_quota: u32 = 1000;
+            var branch_quota: u32 = default_eval_branch_quota;
 
             var block_scope: Scope.Block = .{
                 .parent = null,
@@ -1374,7 +1376,7 @@ fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
                 var var_inst_table = Scope.Block.InstTable.init(self.gpa);
                 defer var_inst_table.deinit();
 
-                var branch_quota_vi: u32 = 1000;
+                var branch_quota_vi: u32 = default_eval_branch_quota;
                 var inner_block: Scope.Block = .{
                     .parent = null,
                     .inst_table = &var_inst_table,
@@ -1503,7 +1505,7 @@ fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
             var inst_table = Scope.Block.InstTable.init(self.gpa);
             defer inst_table.deinit();
 
-            var branch_quota: u32 = 1000;
+            var branch_quota: u32 = default_eval_branch_quota;
 
             var block_scope: Scope.Block = .{
                 .parent = null,
@@ -1887,7 +1889,7 @@ pub fn analyzeFnBody(self: *Module, decl: *Decl, func: *Fn) !void {
     defer decl.typed_value.most_recent.arena.?.* = arena.state;
     var inst_table = Scope.Block.InstTable.init(self.gpa);
     defer inst_table.deinit();
-    var branch_quota: u32 = 1000;
+    var branch_quota: u32 = default_eval_branch_quota;
 
     var inner_block: Scope.Block = .{
         .parent = null,

diff --git a/src/astgen.zig b/src/astgen.zig
@@ -2322,12 +2322,12 @@ fn setEvalBranchQuota(mod: *Module, scope: *Scope, call: *ast.Node.BuiltinCall)
     const tree = scope.tree();
     const src = tree.token_locs[call.builtin_token].start;
     const params = call.params();
-    const target = try expr(mod, scope, .none, params[0]);
     const u32_type = try addZIRInstConst(mod, scope, src, .{
         .ty = Type.initTag(.type),
         .val = Value.initTag(.u32_type),
     });
-    return addZIRUnOp(mod, scope, src, .setevalbranchquota, try rlWrap(mod, scope, .{ .ty = u32_type }, target));
+    const quota = try expr(mod, scope, .{ .ty = u32_type }, params[0]);
+    return addZIRUnOp(mod, scope, src, .set_eval_branch_quota, quota);
 }
 
 fn typeOf(mod: *Module, scope: *Scope, rl: ResultLoc, call: *ast.Node.BuiltinCall) InnerError!*zir.Inst {

diff --git a/src/zir.zig b/src/zir.zig
@@ -127,8 +127,9 @@ pub const Inst = struct {
         coerce_to_ptr_elem,
         /// Emit an error message and fail compilation.
         compileerror,
-        /// Changes the maximum number of backwards branches that compile-time code execution can use before giving up and making a compile error.
-        setevalbranchquota,
+        /// Changes the maximum number of backwards branches that compile-time
+        /// code execution can use before giving up and making a compile error.
+        set_eval_branch_quota,
         /// Conditional branch. Splits control flow based on a boolean condition value.
         condbr,
         /// Special case, has no textual representation.
@@ -349,7 +350,7 @@ pub const Inst = struct {
                 .anyframe_type,
                 .bitnot,
                 .import,
-                .setevalbranchquota,
+                .set_eval_branch_quota,
                 => UnOp,
 
                 .add,
@@ -538,7 +539,7 @@ pub const Inst = struct {
                 .switch_range,
                 .typeof_peer,
                 .resolve_inferred_alloc,
-                .setevalbranchquota,
+                .set_eval_branch_quota,
                 => false,
 
                 .@"break",

diff --git a/src/zir_sema.zig b/src/zir_sema.zig
@@ -81,7 +81,7 @@ pub fn analyzeInst(mod: *Module, scope: *Scope, old_inst: *zir.Inst) InnerError!
         .mut_slice_type => return analyzeInstSimplePtrType(mod, scope, old_inst.castTag(.mut_slice_type).?, true, .Slice),
         .ptr_type => return analyzeInstPtrType(mod, scope, old_inst.castTag(.ptr_type).?),
         .store => return analyzeInstStore(mod, scope, old_inst.castTag(.store).?),
-        .setevalbranchquota => return analyzeInstSetEvalBranchQuota(mod, scope, old_inst.castTag(.setevalbranchquota).?),
+        .set_eval_branch_quota => return analyzeInstSetEvalBranchQuota(mod, scope, old_inst.castTag(.set_eval_branch_quota).?),
         .str => return analyzeInstStr(mod, scope, old_inst.castTag(.str).?),
         .int => {
             const big_int = old_inst.castTag(.int).?.positionals.int;
@@ -281,6 +281,24 @@ fn resolveType(mod: *Module, scope: *Scope, old_inst: *zir.Inst) !Type {
     return val.toType(scope.arena());
 }
 
+/// Appropriate to call when the coercion has already been done by result
+/// location semantics. Asserts the value fits in the provided `Int` type.
+/// Only supports `Int` types 64 bits or less.
+fn resolveAlreadyCoercedInt(
+    mod: *Module,
+    scope: *Scope,
+    old_inst: *zir.Inst,
+    comptime Int: type,
+) !Int {
+    comptime assert(@typeInfo(Int).Int.bits <= 64);
+    const new_inst = try resolveInst(mod, scope, old_inst);
+    const val = try mod.resolveConstValue(scope, new_inst);
+    switch (@typeInfo(Int).Int.signedness) {
+        .signed => return @intCast(Int, val.toSignedInt()),
+        .unsigned => return @intCast(Int, val.toUnsignedInt()),
+    }
+}
+
 fn resolveInt(mod: *Module, scope: *Scope, old_inst: *zir.Inst, dest_type: Type) !u64 {
     const new_inst = try resolveInst(mod, scope, old_inst);
     const coerced = try mod.coerce(scope, dest_type, new_inst);
@@ -493,7 +511,7 @@ fn analyzeInstSetEvalBranchQuota(
     inst: *zir.Inst.UnOp,
 ) InnerError!*Inst {
     const b = try mod.requireFunctionBlock(scope, inst.base.src);
-    const quota = @truncate(u32, try resolveInt(mod, scope, inst.positionals.operand, Type.initTag(.u32)));
+    const quota = try resolveAlreadyCoercedInt(mod, scope, inst.positionals.operand, u32);
     if (b.branch_quota.* < quota)
         b.branch_quota.* = quota;
     return mod.constVoid(scope, inst.base.src);