Changeset 345 for soft/giet_vm/giet_libs/barrier.c

Timestamp:

Jun 25, 2014, 2:19:37 PM (10 years ago)

Author:

cfuguet

Message:

giet_vm optimizations:

• Several modifications in GIET_VM in order to support compilation with GCC optimizations (-O2) activated.

• Adding missing volatile in some global variables.

• Using ioread and iowrite utility functions in peripheral drivers which prevent GCC to remove writes or reads in hardware memory mapped registers.

• Code refactoring of stdio printf functions. Now, shr_printf and tty_printf function reuse the same function body. The only difference is that shr_printf wraps printf function call with TTY get lock and release lock.

File:

• soft/giet_vm/giet_libs/barrier.c (modified) (3 diffs)

soft/giet_vm/giet_libs/barrier.c

@@ -20 +20 @@
                    unsigned int    value ) 
 {
-    barrier->init  = value;
-    barrier->count = value;
+    barrier->init  = (volatile unsigned int)value;
+    barrier->count = (volatile unsigned int)value;
+    asm volatile ("sync" ::: "memory");
 }
 
@@ -31 +32 @@
 void barrier_wait( giet_barrier_t* barrier ) 
 {
-    unsigned int * pcount  = (unsigned int *) &barrier->count;
-    unsigned int maxcount = barrier->init;
-    unsigned int count;
+    volatile unsigned int * pcount = (unsigned int *) &barrier->count;
+    volatile unsigned int maxcount = barrier->init;
+    volatile unsigned int count;
 
     // parallel decrement barrier counter using atomic instructions LL/SC
     // - input : pointer on the barrier counter
     // - output : counter value
-    asm volatile ("_barrier_decrement:    \n"
-            "ll   %0, 0(%1)               \n"
-            "addi $3, %0,     -1          \n"
-            "sc   $3, 0(%1)               \n"
-            "beqz $3, _barrier_decrement  \n"
-            : "=&r"(count)
+    asm volatile (
+            "_barrier_decrement:                \n"
+            "ll     %0,   0(%1)                 \n"
+            "addi   $3,   %0,     -1            \n"
+            "sc     $3,   0(%1)                 \n"
+            "beqz   $3,   _barrier_decrement    \n"
+            : "+r"(count)
             : "r"(pcount)
-            : "$2", "$3");
+            : "$3", "memory");
 
     // the last task re-initializes the barrier counter to the max value,
@@ -57 +59 @@
     else {
         // other tasks busy-wait
-        while (*pcount != maxcount) asm volatile ("nop");
+        while (*pcount != maxcount);
     }
+
+    asm volatile ("sync" ::: "memory");
 }