Change assertions in Stats.c to warnings (and introduce WARN macro)wip/t20899

ASSERT should be used in situations where something very bad will happen
later on if a certain invariant doesn't hold. The idea is that IF we
catch the assertion earlier then it will be easier to work out what's
going on at that point rather than at some indeterminate point in the
future of the program.

The assertions in Stats.c do not obey this philsophy and it is quite
annoying if you are running a debug build (or a ticky compiler) and one
of these assertions fails right at the end of your program, before the
ticky report is printed out so you don't get any profiling information.

Given that nothing terrible happens if these assertions are not true, or
at least the terrible thing will happen in very close proximity to the
assertion failure, these assertions use the new WARN macro which prints
the assertion failure to stdout but does not exit the program.

Of course, it would be better to fix these metrics to not trigger the
assertion in the first place but if they did fail again in the future it
is frustrating to be bamboozled in this manner.

Fixes #20899

3 files changed, 26 insertions, 7 deletions

diff --git a/rts/RtsMessages.c b/rts/RtsMessages.c
index 9ecd831a83..8ece485854 100644
--- a/rts/RtsMessages.c
+++ b/rts/RtsMessages.c
@@ -73,6 +73,12 @@ errorBelch(const char*s, ...)
 }
 
 void
+_warnFail(const char*filename, unsigned int linenum)
+{
+    errorBelch("ASSERTION FAILED: file %s, line %u\n", filename, linenum);
+}
+
+void
 verrorBelch(const char*s, va_list ap)
 {
   (*errorMsgFn)(s,ap);
diff --git a/rts/Stats.c b/rts/Stats.c
index ed6695ad45..7abe2f7417 100644
--- a/rts/Stats.c
+++ b/rts/Stats.c
@@ -1275,7 +1275,7 @@ stat_exitReport (void)
             Time exit_gc_cpu     = stats.gc_cpu_ns - start_exit_gc_cpu;
             Time exit_gc_elapsed = stats.gc_elapsed_ns - start_exit_gc_elapsed;
 
-            ASSERT(exit_gc_elapsed > 0);
+            WARN(exit_gc_elapsed > 0);
 
             sum.exit_cpu_ns     = end_exit_cpu
                                       - start_exit_cpu
@@ -1284,7 +1284,7 @@ stat_exitReport (void)
                                        - start_exit_elapsed
                                        - exit_gc_elapsed;
 
-            ASSERT(sum.exit_elapsed_ns >= 0);
+            WARN(sum.exit_elapsed_ns >= 0);
 
             stats.mutator_cpu_ns     = start_exit_cpu
                                  - end_init_cpu
@@ -1294,7 +1294,7 @@ stat_exitReport (void)
                                  - end_init_elapsed
                                  - (stats.gc_elapsed_ns - exit_gc_elapsed);
 
-            ASSERT(stats.mutator_elapsed_ns >= 0);
+            WARN(stats.mutator_elapsed_ns >= 0);
 
             if (stats.mutator_cpu_ns < 0) { stats.mutator_cpu_ns = 0; }
 
@@ -1302,7 +1302,7 @@ stat_exitReport (void)
             // and subtracting, so the parts should add up to the total exactly.
             // Note that stats->total_ns is captured a tiny bit later than
             // end_exit_elapsed, so we don't use it here.
-            ASSERT(stats.init_elapsed_ns // INIT
+            WARN(stats.init_elapsed_ns // INIT
                    + stats.mutator_elapsed_ns // MUT
                    + stats.gc_elapsed_ns // GC
                    + sum.exit_elapsed_ns // EXIT
@@ -1319,7 +1319,7 @@ stat_exitReport (void)
 
             // This assertion is probably not necessary; make sure the
             // subdivision with PROF also makes sense
-            ASSERT(stats.init_elapsed_ns // INIT
+            WARN(stats.init_elapsed_ns // INIT
                    + stats.mutator_elapsed_ns // MUT
                    + stats.gc_elapsed_ns // GC
                    + sum.exit_elapsed_ns // EXIT
@@ -1401,7 +1401,7 @@ stat_exitReport (void)
                                 - sum.exit_cpu_ns)
                 / TimeToSecondsDbl(stats.cpu_ns);
 
-            ASSERT(sum.productivity_cpu_percent >= 0);
+            WARN(sum.productivity_cpu_percent >= 0);
 
             sum.productivity_elapsed_percent =
                 TimeToSecondsDbl(stats.elapsed_ns
@@ -1410,7 +1410,7 @@ stat_exitReport (void)
                                 - sum.exit_elapsed_ns)
                 / TimeToSecondsDbl(stats.elapsed_ns);
 
-            ASSERT(sum.productivity_elapsed_percent >= 0);
+            WARN(sum.productivity_elapsed_percent >= 0);
 
             for(uint32_t g = 0; g < RtsFlags.GcFlags.generations; ++g) {
                 const generation* gen = &generations[g];
diff --git a/rts/include/Rts.h b/rts/include/Rts.h
index e3471cf333..2399f8ce7f 100644
--- a/rts/include/Rts.h
+++ b/rts/include/Rts.h
@@ -120,12 +120,20 @@ extern "C" {
 void _assertFail(const char *filename, unsigned int linenum)
    GNUC3_ATTRIBUTE(__noreturn__);
 
+void _warnFail(const char *filename, unsigned int linenum);
+
 #define CHECK(predicate)                        \
         if (RTS_LIKELY(predicate))              \
             /*null*/;                           \
         else                                    \
             _assertFail(__FILE__, __LINE__)
 
+#define CHECKWARN(predicate)                        \
+        if (RTS_LIKELY(predicate))              \
+            /*null*/;                           \
+        else                                    \
+            _warnFail(__FILE__, __LINE__)
+
 #define CHECKM(predicate, msg, ...)             \
         if (RTS_LIKELY(predicate))              \
             /*null*/;                           \
@@ -143,11 +151,16 @@ void _assertFail(const char *filename, unsigned int linenum)
     do { CHECK(predicate); } while(0)
 #define ASSERTM(predicate,msg,...)              \
     do { CHECKM(predicate, msg, ##__VA_ARGS__); } while(0)
+#define WARN(predicate) \
+    do { CHECKWARN(predicate); } while(0)
+
 #else
 #define ASSERT(predicate)                       \
     do { (void) sizeof(predicate); } while(0)
 #define ASSERTM(predicate,msg,...)              \
     do { (void) sizeof(predicate); (void) sizeof(msg); } while(0)
+#define WARN(predicate)                       \
+    do { (void) sizeof(predicate); } while(0)
 #endif /* DEBUG */
 
 /*