Commit `a7a508fcd9`

Cody Tapscott <topolarity@tapscott.me>

2022-02-27 09:19:02

stage2 sema: Implement comptime result for comparison of uint to comptime value

This adds a comptime result when comparing a comptime value to an unsigned integer. For example: ( 0 <= (unsigned runtime value)) => true (-1 < (unsigned runtime value)) => true ((unsigned runtime value) < -15) => false

master

1 parent b529484

Changed files (2)

src

Sema.zig

test

behavior

eval.zig

@@ -17036,30 +17036,41 @@ fn cmpNumeric(
     if (try sema.resolveMaybeUndefVal(block, lhs_src, lhs)) |lhs_val| {
         if (lhs_val.isUndef())
             return sema.addConstUndef(Type.bool);
-        const is_unsigned = if (lhs_is_float) x: {
+        if (!rhs_is_signed) {
+            switch (lhs_val.orderAgainstZero()) {
+                .gt => {},
+                .eq => switch (op) { // LHS = 0, RHS is unsigned
+                    .lte => return Air.Inst.Ref.bool_true,
+                    .gt => return Air.Inst.Ref.bool_false,
+                    else => {},
+                },
+                .lt => switch (op) { // LHS < 0, RHS is unsigned
+                    .neq, .lt, .lte => return Air.Inst.Ref.bool_true,
+                    .eq, .gt, .gte => return Air.Inst.Ref.bool_false,
+                },
+            }
+        }
+        if (lhs_is_float) {
             var bigint_space: Value.BigIntSpace = undefined;
             var bigint = try lhs_val.toBigInt(&bigint_space).toManaged(sema.gpa);
             defer bigint.deinit();
-            const zcmp = lhs_val.orderAgainstZero();
             if (lhs_val.floatHasFraction()) {
                 switch (op) {
                     .eq => return Air.Inst.Ref.bool_false,
                     .neq => return Air.Inst.Ref.bool_true,
                     else => {},
                 }
-                if (zcmp == .lt) {
+                if (lhs_is_signed) {
                     try bigint.addScalar(bigint.toConst(), -1);
                 } else {
                     try bigint.addScalar(bigint.toConst(), 1);
                 }
             }
             lhs_bits = bigint.toConst().bitCountTwosComp();
-            break :x (zcmp != .lt);
-        } else x: {
+        } else {
             lhs_bits = lhs_val.intBitCountTwosComp(target);
-            break :x (lhs_val.orderAgainstZero() != .lt);
-        };
-        lhs_bits += @boolToInt(is_unsigned and dest_int_is_signed);
+        }
+        lhs_bits += @boolToInt(!lhs_is_signed and dest_int_is_signed);
     } else if (lhs_is_float) {
         dest_float_type = lhs_ty;
     } else {
@@ -17071,30 +17082,41 @@ fn cmpNumeric(
     if (try sema.resolveMaybeUndefVal(block, rhs_src, rhs)) |rhs_val| {
         if (rhs_val.isUndef())
             return sema.addConstUndef(Type.bool);
-        const is_unsigned = if (rhs_is_float) x: {
+        if (!lhs_is_signed) {
+            switch (rhs_val.orderAgainstZero()) {
+                .gt => {},
+                .eq => switch (op) { // RHS = 0, LHS is unsigned
+                    .gte => return Air.Inst.Ref.bool_true,
+                    .lt => return Air.Inst.Ref.bool_false,
+                    else => {},
+                },
+                .lt => switch (op) { // RHS < 0, LHS is unsigned
+                    .neq, .gt, .gte => return Air.Inst.Ref.bool_true,
+                    .eq, .lt, .lte => return Air.Inst.Ref.bool_false,
+                },
+            }
+        }
+        if (rhs_is_float) {
             var bigint_space: Value.BigIntSpace = undefined;
             var bigint = try rhs_val.toBigInt(&bigint_space).toManaged(sema.gpa);
             defer bigint.deinit();
-            const zcmp = rhs_val.orderAgainstZero();
             if (rhs_val.floatHasFraction()) {
                 switch (op) {
                     .eq => return Air.Inst.Ref.bool_false,
                     .neq => return Air.Inst.Ref.bool_true,
                     else => {},
                 }
-                if (zcmp == .lt) {
+                if (rhs_is_signed) {
                     try bigint.addScalar(bigint.toConst(), -1);
                 } else {
                     try bigint.addScalar(bigint.toConst(), 1);
                 }
             }
             rhs_bits = bigint.toConst().bitCountTwosComp();
-            break :x (zcmp != .lt);
-        } else x: {
+        } else {
             rhs_bits = rhs_val.intBitCountTwosComp(target);
-            break :x (rhs_val.orderAgainstZero() != .lt);
-        };
-        rhs_bits += @boolToInt(is_unsigned and dest_int_is_signed);
+        }
+        rhs_bits += @boolToInt(!rhs_is_signed and dest_int_is_signed);
     } else if (rhs_is_float) {
         dest_float_type = rhs_ty;
     } else {

@@ -559,8 +559,6 @@ fn modifySomeBytes(bytes: []u8) void {
 }
 
 test "comparisons 0 <= uint and 0 > uint should be comptime" {
-    if (builtin.zig_backend != .stage1) return error.SkipZigTest; // TODO
-
     testCompTimeUIntComparisons(1234);
 }
 fn testCompTimeUIntComparisons(x: u32) void {

Commit a7a508fcd9

Commit `a7a508fcd9`