diff --git a/testsuite/c_test/sanity_test/SANITY0022-cc_param3/cc_param3.c b/testsuite/c_test/sanity_test/SANITY0022-cc_param3/cc_param3.c
new file mode 100644
index 0000000000000000000000000000000000000000..7a8cafb6d7d558665a7af8200b3cf5bf4af48b7e
--- /dev/null
+++ b/testsuite/c_test/sanity_test/SANITY0022-cc_param3/cc_param3.c
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) [2021] Futurewei Technologies, Inc. All rights reverved.
+ *
+ * Licensed under the Mulan Permissive Software License v2.
+ * You can use this software according to the terms and conditions of the MulanPSL - 2.0.
+ * You may obtain a copy of MulanPSL - 2.0 at:
+ *
+ *   https://opensource.org/licenses/MulanPSL-2.0
+ *
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT, MERCHANTABILITY OR
+ * FIT FOR A PARTICULAR PURPOSE.
+ * See the MulanPSL - 2.0 for more details.
+ */
+
+#include <stdlib.h>
+
+typedef struct { int i; long long j; } S1;
+// IntCC: no intreg, entire s passed on stack
+void foo0( int i1, int i2, int i3, int i4, int i5, int i6, int i7, int i8, S1 s )
+{ if (s.j != 2) abort(); }
+
+// IntCC: 1 intreg short, half of s passed on stack, half $a7 reg
+void foo1( int i1, int i2, int i3, int i4, int i5, int i6, int i7, S1 s )
+{ if (s.j != 2) abort(); }
+
+// FpCC: 1 intreg short, move to IntCC: 1 stack
+typedef struct { float i; int j; } S2;
+void foo2( int i1, int i2, int i3, int i4, int i5, int i6, int i7, int i8, S2 s )
+{ if (s.j != 4) abort(); }
+
+// FpCC: 1 fpreg short, move to IntCC: 1 intreg + 1 stack
+void foo3( float i1, float i2, float i3, float i4, float i5, float i6, float i7, float i8, S2 s )
+{ if (s.j != 4) abort(); }
+
+// FpCC: 2 fpregs short, move to IntCC: 2 stacks
+typedef struct { double i; double j; float k; } S4;
+void foo4( float i1, float i2, float i3, float i4, float i5, float i6, float i7, float i8, S4 s )
+{ if (s.j != 6) abort(); }
+
+// IntCC: 1 float on stack, 8 intregs
+typedef struct { float i; int j; } S5;
+void foo5( int i1, int i2, int i3, int i4, int i5, int i6, int i7,
+           float f1, float f2, float f3, float f4, float f5, float f6, float f7, float f8,
+           S5 s )
+{ if (s.i != 7.0f || s.j != 8) abort(); }
+
+// IntCC: 1 int on stack, 8 fpregs
+void foo6( int i1, int i2, int i3, int i4, int i5, int i6, int i7, int i8,
+           float f1, float f2, float f3, float f4, float f5, float f6, float f7,
+           S5 s )
+{ if (s.i != 7.0f || s.j != 8) abort(); }
+
+int main()
+{
+   S1 s1 = { 1, 2 };
+   foo0(1,2,3,4,5,6,7,8, s1);
+// foo1(1,2,3,4,5,6,7, s1);
+
+   S2 s2 = { 3, 4 };
+   foo2(1,2,3,4,5,6,7,8, s2);
+// foo3(0,0,0,0,0,0,0,0, s2);
+
+   S4 s4 = { 5, 6 };
+   foo4(0,0,0,0,0,0,0,0, s4);
+
+   S5 s5 = { 7.0f, 8 };
+// foo5( 1,2,3,4,5,6,7,    10,20,30,40,50,60,70,80, s5 );
+// foo6( 1,2,3,4,5,6,7,8,  10,20,30,40,50,60,70,    s5 );
+
+   return 0;
+}
diff --git a/testsuite/c_test/sanity_test/SANITY0022-cc_param3/test.cfg b/testsuite/c_test/sanity_test/SANITY0022-cc_param3/test.cfg
new file mode 100644
index 0000000000000000000000000000000000000000..54dab4c1323f753876d4abc3bf75a017af66c77a
--- /dev/null
+++ b/testsuite/c_test/sanity_test/SANITY0022-cc_param3/test.cfg
@@ -0,0 +1,3 @@
+clean()
+compile(cc_param3)
+run(cc_param3)
diff --git a/testsuite/c_test/sanity_test/SANITY0023-cc_sret/cc_sret.c b/testsuite/c_test/sanity_test/SANITY0023-cc_sret/cc_sret.c
new file mode 100644
index 0000000000000000000000000000000000000000..3b32e2106e5042e0efe29cfe937b43d1a15111db
--- /dev/null
+++ b/testsuite/c_test/sanity_test/SANITY0023-cc_sret/cc_sret.c
@@ -0,0 +1,186 @@
+/*
+ * Copyright (C) [2021] Futurewei Technologies, Inc. All rights reverved.
+ *
+ * Licensed under the Mulan Permissive Software License v2.
+ * You can use this software according to the terms and conditions of the MulanPSL - 2.0.
+ * You may obtain a copy of MulanPSL - 2.0 at:
+ *
+ *   https://opensource.org/licenses/MulanPSL-2.0
+ *
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT, MERCHANTABILITY OR
+ * FIT FOR A PARTICULAR PURPOSE.
+ * See the MulanPSL - 2.0 for more details.
+ */
+
+//
+// Test calling convention of struct return type
+#include <stdlib.h>
+typedef struct { int x; int y; } s1;
+typedef struct { long long x; long long y; } s2;
+typedef struct { long long x; long long y; int z; } s3;
+typedef struct { float x; float y; } f1;
+typedef struct { double x; double y; } f2;
+typedef struct { float x; char y; char z; short w; } m1;
+typedef struct { int x[4]; } a1;
+typedef struct { double x[4]; } a2;
+typedef struct { float x[2]; } f3;
+typedef struct { float x[3]; } f4;
+typedef struct { int x; float y; } m2;
+typedef struct { double x; long long y; } m3;
+
+s1 foo1(int i){ s1 x = {1,2}; return x; }             // 1 intreg return
+s2 foo2(int i){ s2 x = {3,4}; return x; }             // 2 intregs return
+s3 foo3(int i){ s3 x = {5,6,7}; return x; }           // hidden 1st arg, >16by
+f1 foo4(int i){ f1 x = {8,9}; return x; }             // 2 fpregs return
+f2 foo5(int i){ f2 x = {10,11}; return x; }           // 2 fpregs return
+m1 foo6(int i){ m1 x = {12,13,14,15}; return x; }     // 1 intregs return
+a1 foo7(int i){ a1 x = {16,17,18,19}; return x; }     // 2 intregs return
+a2 foo8(int i){ a2 x = {20,21,22,23}; return x; }     // hidden 1st arg, >16by
+f3 foo9(int i){ f3 x = {24,25}; return x; }           // 2 fpregs return
+f4 foo10(int i){ f4 x = {26,27,28}; return x; }       // 2 intregs return
+m2 foo11(int i){ m2 x = {29,30.0}; return x; }        // 1 intreg 1 fpreg
+m3 foo12(int i){ m3 x = {31.0,32}; return x; }        // 1 fpreg 1 intreg
+
+typedef struct { int a[2]; } sz8;  // 8 byte struct
+typedef struct { int a[4]; } sz16;  // 16 byte struct
+typedef struct { int a[8]; } sz32;  // 32 byte struct
+
+sz8 call8()
+{
+   s1 x;
+   s2 y;
+   s3 e;
+   f1 z;
+   f2 w;
+   f3 v;
+   f4 u;
+   m1 m;
+   m2 n;
+   m3 o;
+   a1 a;
+   a2 b;
+
+   x = foo1( 0 );
+   if (x.y != 2) abort();
+   y = foo2( 0 );
+   if (y.y != 4) abort();
+   e = foo3( 0 );
+   if (e.z != 7) abort();
+   z = foo4( 0 );
+   if (z.y != 9) abort();
+   w = foo5( 0 );
+   if (w.y != 11) abort();
+   m = foo6( 0 );
+   if (m.w != 15) abort();
+   a = foo7( 0 );
+   if (a.x[3] != 19) abort();
+   b = foo8( 0 );
+   if (b.x[3] != 23) abort();
+   v = foo9( 0 );
+   if (v.x[1] != 25) abort();
+   u = foo10( 0 );
+   if (u.x[2] != 28) abort();
+   n = foo11( 0 );
+   if (n.x != 29 || n.y != 30.0) abort();
+   o = foo12( 0 );
+   if (o.x != 31.0 || o.y != 32) abort();
+
+   sz8 x8 = { 1, 2};
+   return x8;
+}
+
+sz16 call16()
+{
+   s1 x;
+   s2 y;
+   s3 e;
+   f1 z;
+   f2 w;
+   f3 v;
+   f4 u;
+   m1 m;
+   m2 n;
+   m3 o;
+   a1 a;
+   a2 b;
+
+   x = foo1( 0 );
+   if (x.y != 2) abort();
+   y = foo2( 0 );
+   if (y.y != 4) abort();
+   e = foo3( 0 );
+   if (e.z != 7) abort();
+   z = foo4( 0 );
+   if (z.y != 9) abort();
+   w = foo5( 0 );
+   if (w.y != 11) abort();
+   m = foo6( 0 );
+   if (m.w != 15) abort();
+   a = foo7( 0 );
+   if (a.x[3] != 19) abort();
+   b = foo8( 0 );
+   if (b.x[3] != 23) abort();
+   v = foo9( 0 );
+   if (v.x[1] != 25) abort();
+   u = foo10( 0 );
+   if (u.x[2] != 28) abort();
+   n = foo11( 0 );
+   if (n.x != 29 || n.y != 30.0) abort();
+   o = foo12( 0 );
+   if (o.x != 31.0 || o.y != 32) abort();
+
+   sz16 x16 = { 1, 2, 3, 4};
+   return x16;
+}
+
+sz32 call32()
+{
+   s1 x;
+   s2 y;
+   s3 e;
+   f1 z;
+   f2 w;
+   f3 v;
+   f4 u;
+   m1 m;
+   m2 n;
+   m3 o;
+   a1 a;
+   a2 b;
+
+   x = foo1( 0 );
+   if (x.y != 2) abort();
+   y = foo2( 0 );
+   if (y.y != 4) abort();
+   e = foo3( 0 );
+   if (e.z != 7) abort();
+   z = foo4( 0 );
+   if (z.y != 9) abort();
+   w = foo5( 0 );
+   if (w.y != 11) abort();
+   m = foo6( 0 );
+   if (m.w != 15) abort();
+   a = foo7( 0 );
+   if (a.x[3] != 19) abort();
+   b = foo8( 0 );
+   if (b.x[3] != 23) abort();
+   v = foo9( 0 );
+   if (v.x[1] != 25) abort();
+   u = foo10( 0 );
+   if (u.x[2] != 28) abort();
+   n = foo11( 0 );
+   if (n.x != 29 || n.y != 30.0) abort();
+   o = foo12( 0 );
+   if (o.x != 31.0 || o.y != 32) abort();
+
+   sz32 x32 = { 1, 2, 3, 4, 5, 6, 7, 8};
+   return x32;
+}
+
+int main()
+{
+  call8();
+  call16();
+  call32();
+}
diff --git a/testsuite/c_test/sanity_test/SANITY0023-cc_sret/test.cfg b/testsuite/c_test/sanity_test/SANITY0023-cc_sret/test.cfg
new file mode 100644
index 0000000000000000000000000000000000000000..242d895516ed5d2efc519c010d89e56150f84324
--- /dev/null
+++ b/testsuite/c_test/sanity_test/SANITY0023-cc_sret/test.cfg
@@ -0,0 +1,3 @@
+clean()
+compile(cc_sret)
+run(cc_sret)
diff --git a/testsuite/c_test/sanity_test/SANITY0024-vararg1/test.cfg b/testsuite/c_test/sanity_test/SANITY0024-vararg1/test.cfg
new file mode 100644
index 0000000000000000000000000000000000000000..bdc023f1b3184f30663b6f3164f39ac47b6622e0
--- /dev/null
+++ b/testsuite/c_test/sanity_test/SANITY0024-vararg1/test.cfg
@@ -0,0 +1,3 @@
+clean()
+compile(vararg1)
+run(vararg1)
diff --git a/testsuite/c_test/sanity_test/SANITY0024-vararg1/vararg1.c b/testsuite/c_test/sanity_test/SANITY0024-vararg1/vararg1.c
new file mode 100644
index 0000000000000000000000000000000000000000..9560448c53b86e54a44c359b388cdbf1107e9435
--- /dev/null
+++ b/testsuite/c_test/sanity_test/SANITY0024-vararg1/vararg1.c
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) [2021] Futurewei Technologies, Inc. All rights reverved.
+ *
+ * Licensed under the Mulan Permissive Software License v2.
+ * You can use this software according to the terms and conditions of the MulanPSL - 2.0.
+ * You may obtain a copy of MulanPSL - 2.0 at:
+ *
+ *   https://opensource.org/licenses/MulanPSL-2.0
+ *
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT, MERCHANTABILITY OR
+ * FIT FOR A PARTICULAR PURPOSE.
+ * See the MulanPSL - 2.0 for more details.
+ */
+
+#include "stdarg.h"
+#include "stdlib.h"
+
+int a,b;
+typedef int vfunc_t(int x, int y, ...);
+int foo1( int x, int y, ... )
+{
+   va_list ap;
+
+   va_start(ap, y);
+   a = va_arg(ap, int);
+   b = va_arg(ap, int);
+   return (int)a + b;
+}
+
+typedef struct { int i; long long j; } S;
+int foo2( int a0, int a1, ... )
+{
+   va_list ap;
+
+   va_start(ap, a1);
+   S b = va_arg(ap, S);
+   if (b.i+b.j != 30)
+     abort();
+}
+
+typedef struct { long long x; long long y; int z; } T;
+void foo3( int i1, int i2, int i3, int i4, int i5, int i6, int i7, int i8, T x, ...)
+{
+   va_list ap;
+
+   va_start(ap, x);
+   a = va_arg(ap, int);
+   if (a != 10)    // on the stack
+     abort();
+}
+
+int main()
+{
+    vfunc_t *f = &foo1;
+    int x;
+
+    x = foo1(1,2,3,4);
+    if (x != 7)
+      abort();
+    x = (*f)(1,2,5,6);
+    if (x != 11)
+      abort();
+
+    S s = {10,20};
+    foo2( 1,2, s );
+
+    T y = { 1, 2, 3 };
+
+    foo3(1,2,3,4,5,6,7,8, y,10 );
+}
+
+
diff --git a/testsuite/driver/src/mod/CO2.py b/testsuite/driver/src/mod/CO2.py
index 3f4af06f3154db83a000342c54dc1376cf46e029..36d129027d50b0339c4526799ff2c7376cc4df3c 100644
--- a/testsuite/driver/src/mod/CO2.py
+++ b/testsuite/driver/src/mod/CO2.py
@@ -31,7 +31,7 @@ CO2 = {
             maple="${OUT_ROOT}/aarch64-clang-release/bin/maple",
             run=["mplcg"],
             option={
-                "mplcg": "-O2 --quiet"
+                "mplcg": "-O2 --quiet --no-schedule"
             },
             global_option="",
             infile="${APP}.mpl"