1 files changed, 47 insertions, 1 deletions
diff --git a/src/arch/wasm/CodeGen.zig b/src/arch/wasm/CodeGen.zig
index 9cb61ca4ee..cd1aa286e1 100644
--- a/src/arch/wasm/CodeGen.zig
+++ b/src/arch/wasm/CodeGen.zig
@@ -1316,6 +1316,8 @@ fn genInst(self: *Self, inst: Air.Inst.Index) !WValue {
         .shl_with_overflow => self.airBinOpOverflow(inst, .shl),
         .mul_with_overflow => self.airBinOpOverflow(inst, .mul),
 
+        .clz => self.airClz(inst),
+
         .cmp_eq => self.airCmp(inst, .eq),
         .cmp_gte => self.airCmp(inst, .gte),
         .cmp_gt => self.airCmp(inst, .gt),
@@ -1438,7 +1440,6 @@ fn genInst(self: *Self, inst: Air.Inst.Index) !WValue {
         .shl_sat,
         .ret_addr,
         .frame_addr,
-        .clz,
         .ctz,
         .byte_swap,
         .bit_reverse,
@@ -3932,3 +3933,48 @@ fn airMulAdd(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     const mul_result = try self.binOp(lhs, rhs, ty, .mul);
     return self.binOp(mul_result, addend, ty, .add);
 }
+
+fn airClz(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
+    if (self.liveness.isUnused(inst)) return WValue{ .none = {} };
+    const ty_op = self.air.instructions.items(.data)[inst].ty_op;
+    const ty = self.air.typeOf(ty_op.operand);
+    const result_ty = self.air.typeOfIndex(inst);
+    if (ty.zigTypeTag() == .Vector) {
+        return self.fail("TODO: `@clz` for vectors", .{});
+    }
+
+    const operand = try self.resolveInst(ty_op.operand);
+    const int_info = ty.intInfo(self.target);
+    const wasm_bits = toWasmBits(int_info.bits) orelse {
+        return self.fail("TODO: `@clz` for integers with bitsize '{d}'", .{int_info.bits});
+    };
+
+    try self.emitWValue(operand);
+    switch (wasm_bits) {
+        32 => {
+            try self.addTag(.i32_clz);
+
+            if (wasm_bits != int_info.bits) {
+                const tmp = try self.allocLocal(ty);
+                try self.addLabel(.local_set, tmp.local);
+                const val: i32 = -@intCast(i32, wasm_bits - int_info.bits);
+                return self.wrapBinOp(tmp, .{ .imm32 = @bitCast(u32, val) }, ty, .add);
+            }
+        },
+        64 => {
+            try self.addTag(.i64_clz);
+
+            if (wasm_bits != int_info.bits) {
+                const tmp = try self.allocLocal(ty);
+                try self.addLabel(.local_set, tmp.local);
+                const val: i64 = -@intCast(i64, wasm_bits - int_info.bits);
+                return self.wrapBinOp(tmp, .{ .imm64 = @bitCast(u64, val) }, ty, .add);
+            }
+        },
+        else => unreachable,
+    }
+
+    const result = try self.allocLocal(result_ty);
+    try self.addLabel(.local_set, result.local);
+    return result;
+}