diff --git a/.travis.yml b/.travis.yml
index a9d614d1..e1644a83 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -41,11 +41,14 @@ jobs:
       name: config
       script: cp -r $PWD ../build4 && cd ../build4 && ./ci/regression.sh -config
     - stage: test
-      name: stress
-      script: cp -r $PWD ../build5 && cd ../build5 && ./ci/regression.sh -stress
+      name: stress1
+      script: cp -r $PWD ../build5 && cd ../build5 && ./ci/regression.sh -stress1
+    - stage: test
+      name: stress2
+      script: cp -r $PWD ../build6 && cd ../build6 && ./ci/regression.sh -stress2
     - stage: test
       name: compiler
-      script: cp -r $PWD ../build6 && cd ../build6 && ./ci/test_compiler.sh
+      script: cp -r $PWD ../build7 && cd ../build7 && ./ci/test_compiler.sh
   
 after_success:
   # Gather code coverage
diff --git a/ci/regression.sh b/ci/regression.sh
index 680ae78a..c591070c 100755
--- a/ci/regression.sh
+++ b/ci/regression.sh
@@ -102,7 +102,16 @@ CONFIGS="-DMEM_LATENCY=100 -DMEM_RQ_SIZE=4 -DMEM_STALLS_MODULO=4" ./ci/blackbox.
 echo "configuration tests done!"
 }
 
-stress() 
+stress1() 
+{
+echo "begin stress tests..."
+
+./ci/travis_run.py ./ci/blackbox.sh --driver=rtlsim --cores=1 --app=sgemm --args="-n256"
+
+echo "stress tests done!"
+}
+
+stress2() 
 {
 echo "begin stress tests..."
 
@@ -113,7 +122,7 @@ echo "stress tests done!"
 
 usage()
 {
-    echo "usage: regression [-coverage] [-cluster] [-debug] [-config] [-stress] [-all] [-h|--help]"
+    echo "usage: regression [-coverage] [-cluster] [-debug] [-config] [-stress#n] [-all] [-h|--help]"
 }
 
 while [ "$1" != "" ]; do
@@ -126,13 +135,16 @@ while [ "$1" != "" ]; do
                     ;;
         -config ) config
                 ;;
-        -stress ) stress
+        -stress1 ) stress1
+                ;;
+        -stress2 ) stress2
                 ;;
         -all ) coverage
                cluster
                debug
                config
-               stress
+               stress1
+               stress2
                ;;
         -h | --help ) usage
                       exit
diff --git a/hw/rtl/VX_icache_stage.v b/hw/rtl/VX_icache_stage.v
index 537d759a..1dfaa832 100644
--- a/hw/rtl/VX_icache_stage.v
+++ b/hw/rtl/VX_icache_stage.v
@@ -47,6 +47,8 @@ module VX_icache_stage #(
         .dout({rsp_PC,           rsp_tmask})
     );
 
+    `RUNTIME_ASSERT((!ifetch_req_if.valid || ifetch_req_if.PC >= `STARTUP_ADDR), ("invalid PC=%0h", ifetch_req_if.PC))
+
     // Icache Request
     assign icache_req_if.valid = ifetch_req_if.valid;
     assign icache_req_if.addr  = ifetch_req_if.PC[31:2];