stage2-wasm: clz fix

Author: pavelverigo

src/arch/wasm/CodeGen.zig

@@ -6272,11 +6272,21 @@ fn airClz(cg: *CodeGen, inst: Air.Inst.Index) InnerError!void {
 
     switch (wasm_bits) {
         32 => {
-            try cg.emitWValue(operand);
+            if (int_info.signedness == .signed) {
+                const mask = ~@as(u32, 0) >> @intCast(32 - int_info.bits);
+                _ = try cg.binOp(operand, .{ .imm32 = mask }, ty, .@"and");
+            } else {
+                try cg.emitWValue(operand);
+            }
             try cg.addTag(.i32_clz);
         },
         64 => {
-            try cg.emitWValue(operand);
+            if (int_info.signedness == .signed) {
+                const mask = ~@as(u64, 0) >> @intCast(64 - int_info.bits);
+                _ = try cg.binOp(operand, .{ .imm64 = mask }, ty, .@"and");
+            } else {
+                try cg.emitWValue(operand);
+            }
             try cg.addTag(.i64_clz);
             try cg.addTag(.i32_wrap_i64);
         },

test/behavior/math.zig

@@ -65,7 +65,6 @@ test "@clz" {
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
-    if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_x86_64 and builtin.target.ofmt != .elf and builtin.target.ofmt != .macho) return error.SkipZigTest;
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;