Fix gcc 4.6 warnings; fixes #5176

Based on a patch from David Terei.

Some parts are a little ugly (e.g. defining things that only ASSERTs
use only when DEBUG is defined), so we might want to tweak things a
little.

I've also turned off -Werror for didn't-inline warnings, as we now
get a few such warnings.

aclocal.m4

@@ -742,7 +742,8 @@ if test -z "$GCC"
 then
   AC_MSG_ERROR([gcc is required])
 fi
-GccLT34=
+GccLT34=NO
+GccLT46=NO
 AC_CACHE_CHECK([version of gcc], [fp_cv_gcc_version],
 [
     fp_cv_gcc_version="`$CC -v 2>&1 | grep 'version ' | sed -e 's/.*version [[^0-9]]*\([[0-9.]]*\).*/\1/g'`"
@@ -752,9 +753,11 @@ AC_CACHE_CHECK([version of gcc], [fp_cv_gcc_version],
     # isn't a very good reason for that, but for now just make configure
     # fail.
     FP_COMPARE_VERSIONS([$fp_cv_gcc_version], [-lt], [3.4], GccLT34=YES)
+    FP_COMPARE_VERSIONS([$fp_cv_gcc_version], [-lt], [4.6], GccLT46=YES)
 ])
 AC_SUBST([GccVersion], [$fp_cv_gcc_version])
 AC_SUBST(GccLT34)
+AC_SUBST(GccLT46)
 ])# FP_GCC_VERSION
 
 dnl Small feature test for perl version. Assumes PerlCmd

mk/config.mk.in

@@ -535,6 +535,7 @@ endif
 WhatGccIsCalled = @WhatGccIsCalled@
 GccVersion      = @GccVersion@
 GccLT34         = @GccLT34@
+GccLT46         = @GccLT46@
 CC              = $(WhatGccIsCalled)
 CC_STAGE0       = @CC_STAGE0@
 CC_STAGE1       = $(CC)

mk/validate-settings.mk

@@ -4,7 +4,16 @@
 WERROR          = -Werror
 
 HADDOCK_DOCS    = YES
+
 SRC_CC_OPTS     += -Wall $(WERROR)
+# Debian doesn't turn -Werror=unused-but-set-variable on by default, so
+# we turn it on explicitly for consistency with other users
+ifeq "$(GccLT46)" "NO"
+SRC_CC_OPTS	    += -Werror=unused-but-set-variable
+endif
+# gcc 4.6 gives 3 warning for giveCapabilityToTask not being inlined
+SRC_CC_OPTS     += -Wno-error=inline
+
 SRC_HC_OPTS     += -Wall $(WERROR) -H64m -O0
 
 # Safe by default

rts/Interpreter.c

@@ -49,13 +49,21 @@
 
 /* Sp points to the lowest live word on the stack. */
 
-#define BCO_NEXT      instrs[bciPtr++]
-#define BCO_NEXT_32   (bciPtr += 2, (((StgWord) instrs[bciPtr-2]) << 16) + ((StgWord) instrs[bciPtr-1]))
-#define BCO_NEXT_64   (bciPtr += 4, (((StgWord) instrs[bciPtr-4]) << 48) + (((StgWord) instrs[bciPtr-3]) << 32) + (((StgWord) instrs[bciPtr-2]) << 16) + ((StgWord) instrs[bciPtr-1]))
+#define BCO_NEXT         instrs[bciPtr++]
+#define BCO_NEXT_32      (bciPtr += 2)
+#define BCO_READ_NEXT_32 (BCO_NEXT_32, (((StgWord) instrs[bciPtr-2]) << 16) \
+                                     + ( (StgWord) instrs[bciPtr-1]))
+#define BCO_NEXT_64      (bciPtr += 4)
+#define BCO_READ_NEXT_64 (BCO_NEXT_64, (((StgWord) instrs[bciPtr-4]) << 48) \
+                                     + (((StgWord) instrs[bciPtr-3]) << 32) \
+                                     + (((StgWord) instrs[bciPtr-2]) << 16) \
+                                     + ( (StgWord) instrs[bciPtr-1]))
 #if WORD_SIZE_IN_BITS == 32
 #define BCO_NEXT_WORD BCO_NEXT_32
+#define BCO_READ_NEXT_WORD BCO_READ_NEXT_32
 #elif WORD_SIZE_IN_BITS == 64
 #define BCO_NEXT_WORD BCO_NEXT_64
+#define BCO_READ_NEXT_WORD BCO_READ_NEXT_64
 #else
 #error Cannot cope with WORD_SIZE_IN_BITS being nether 32 nor 64
 #endif
@@ -776,8 +784,12 @@ run_BCO:
 	register StgWord16* instrs    = (StgWord16*)(bco->instrs->payload);
 	register StgWord*  literals   = (StgWord*)(&bco->literals->payload[0]);
 	register StgPtr*   ptrs       = (StgPtr*)(&bco->ptrs->payload[0]);
+#ifdef DEBUG
 	int bcoSize;
-    bcoSize = BCO_NEXT_WORD;
+    bcoSize = BCO_READ_NEXT_WORD;
+#else
+    BCO_NEXT_WORD;
+#endif
 	IF_DEBUG(interpreter,debugBelch("bcoSize = %d\n", bcoSize));
 
 #ifdef INTERP_STATS

rts/Linker.c

@@ -1190,11 +1190,15 @@ initLinker( void )
     compileResult = regcomp(&re_invalid,
            "(([^ \t()])+\\.so([^ \t:()])*):([ \t])*(invalid ELF header|file too short)",
            REG_EXTENDED);
-    ASSERT( compileResult == 0 );
+    if (compileResult != 0) {
+        barf("Compiling re_invalid failed");
+    }
     compileResult = regcomp(&re_realso,
            "(GROUP|INPUT) *\\( *(([^ )])+)",
            REG_EXTENDED);
-    ASSERT( compileResult == 0 );
+    if (compileResult != 0) {
+        barf("Compiling re_realso failed");
+    }
 #   endif
 
 #if !defined(ALWAYS_PIC) && defined(x86_64_HOST_ARCH)
@@ -4124,10 +4128,14 @@ do_Elf_Rel_relocations ( ObjectCode* oc, char* ehdrC,
 
       Elf_Addr  P  = ((Elf_Addr)targ) + offset;
       Elf_Word* pP = (Elf_Word*)P;
+#if defined(i386_HOST_ARCH) || defined(DEBUG)
       Elf_Addr  A  = *pP;
+#endif
       Elf_Addr  S;
       void*     S_tmp;
+#ifdef i386_HOST_ARCH
       Elf_Addr  value;
+#endif
       StgStablePtr stablePtr;
       StgPtr stableVal;
 
@@ -4171,7 +4179,9 @@ do_Elf_Rel_relocations ( ObjectCode* oc, char* ehdrC,
                              (void*)P, (void*)S, (void*)A ));
       checkProddableBlock ( oc, pP );
 
+#ifdef i386_HOST_ARCH
       value = S + A;
+#endif
 
       switch (ELF_R_TYPE(info)) {
 #        ifdef i386_HOST_ARCH

rts/ProfHeap.c

@@ -839,7 +839,7 @@ heapCensusChain( Census *census, bdescr *bd )
     nat size;
     counter *ctr;
     nat real_size;
-    rtsBool prim;
+    PROFILING_ONLY( rtsBool prim );
 
     for (; bd != NULL; bd = bd->link) {
 
@@ -854,7 +854,7 @@ heapCensusChain( Census *census, bdescr *bd )
 	p = bd->start;
 	while (p < bd->free) {
 	    info = get_itbl((StgClosure *)p);
-	    prim = rtsFalse;
+	    PROFILING_ONLY( prim = rtsFalse );
 	    
 	    switch (info->type) {
 
@@ -904,7 +904,7 @@ heapCensusChain( Census *census, bdescr *bd )
 		break;
 
 	    case BCO:
-		prim = rtsTrue;
+		PROFILING_ONLY ( prim = rtsTrue );
 		size = bco_sizeW((StgBCO *)p);
 		break;
 
@@ -915,7 +915,7 @@ heapCensusChain( Census *census, bdescr *bd )
 	    case MUT_PRIM:
 	    case MUT_VAR_CLEAN:
 	    case MUT_VAR_DIRTY:
-		prim = rtsTrue;
+		PROFILING_ONLY ( prim = rtsTrue );
 		size = sizeW_fromITBL(info);
 		break;
 
@@ -932,7 +932,7 @@ heapCensusChain( Census *census, bdescr *bd )
 		break;
 		
 	    case ARR_WORDS:
-		prim = rtsTrue;
+		PROFILING_ONLY ( prim = rtsTrue );
 		size = arr_words_sizeW((StgArrWords*)p);
 		break;
 		
@@ -940,12 +940,12 @@ heapCensusChain( Census *census, bdescr *bd )
 	    case MUT_ARR_PTRS_DIRTY:
 	    case MUT_ARR_PTRS_FROZEN:
 	    case MUT_ARR_PTRS_FROZEN0:
-		prim = rtsTrue;
+		PROFILING_ONLY ( prim = rtsTrue );
 		size = mut_arr_ptrs_sizeW((StgMutArrPtrs *)p);
 		break;
 		
 	    case TSO:
-		prim = rtsTrue;
+		PROFILING_ONLY ( prim = rtsTrue );
 #ifdef PROFILING
 		if (RtsFlags.ProfFlags.includeTSOs) {
                     size = sizeofW(StgTSO);
@@ -961,7 +961,7 @@ heapCensusChain( Census *census, bdescr *bd )
 #endif
 
             case STACK:
-		prim = rtsTrue;
+		PROFILING_ONLY ( prim = rtsTrue );
 #ifdef PROFILING
 		if (RtsFlags.ProfFlags.includeTSOs) {
                     size = stack_sizeW((StgStack*)p);
@@ -977,7 +977,7 @@ heapCensusChain( Census *census, bdescr *bd )
 #endif
 
             case TREC_CHUNK:
-		prim = rtsTrue;
+		PROFILING_ONLY ( prim = rtsTrue );
 		size = sizeofW(StgTRecChunk);
 		break;
 

rts/Profiling.h

@@ -12,6 +12,13 @@
 #include <stdio.h>
 
 #include "BeginPrivate.h"
+#include "Rts.h"
+
+#ifdef PROFILING
+#define PROFILING_ONLY(s) s
+#else
+#define PROFILING_ONLY(s) doNothing()
+#endif
 
 void initProfiling1 (void);
 void initProfiling2 (void);

rts/STM.c

@@ -1089,7 +1089,7 @@ static void disconnect_invariant(Capability *cap,
   FOR_EACH_ENTRY(last_execution, e, {
     StgTVar *s = e -> tvar;
     StgTVarWatchQueue *q = s -> first_watch_queue_entry;
-    StgBool found = FALSE;
+    DEBUG_ONLY( StgBool found = FALSE );
     TRACE("  looking for trec on tvar=%p", s);
     for (q = s -> first_watch_queue_entry; 
 	 q != END_STM_WATCH_QUEUE; 
@@ -1110,7 +1110,7 @@ static void disconnect_invariant(Capability *cap,
 	}
 	TRACE("  found it in watch queue entry %p", q);
 	free_stg_tvar_watch_queue(cap, q);
-	found = TRUE;
+	DEBUG_ONLY( found = TRUE );
 	break;
       }
     }

rts/Schedule.c

@@ -715,7 +715,9 @@ schedulePushWork(Capability *cap USED_IF_THREADS,
 
     if (n_free_caps > 0) {
 	StgTSO *prev, *t, *next;
+#ifdef SPARK_PUSHING
 	rtsBool pushed_to_all;
+#endif
 
 	debugTrace(DEBUG_sched, 
 		   "cap %d: %s and %d free capabilities, sharing...", 
@@ -725,7 +727,9 @@ schedulePushWork(Capability *cap USED_IF_THREADS,
 		   n_free_caps);
 
 	i = 0;
+#ifdef SPARK_PUSHING
 	pushed_to_all = rtsFalse;
+#endif
 
 	if (cap->run_queue_hd != END_TSO_QUEUE) {
 	    prev = cap->run_queue_hd;
@@ -740,7 +744,9 @@ schedulePushWork(Capability *cap USED_IF_THREADS,
                     setTSOPrev(cap, t, prev);
 		    prev = t;
 		} else if (i == n_free_caps) {
+#ifdef SPARK_PUSHING
 		    pushed_to_all = rtsTrue;
+#endif
 		    i = 0;
 		    // keep one for us
 		    setTSOLink(cap, prev, t);
@@ -1892,7 +1898,7 @@ Capability *
 scheduleWaitThread (StgTSO* tso, /*[out]*/HaskellObj* ret, Capability *cap)
 {
     Task *task;
-    StgThreadID id;
+    DEBUG_ONLY( StgThreadID id );
 
     // We already created/initialised the Task
     task = cap->running_task;
@@ -1908,7 +1914,7 @@ scheduleWaitThread (StgTSO* tso, /*[out]*/HaskellObj* ret, Capability *cap)
 
     appendToRunQueue(cap,tso);
 
-    id = tso->id;
+    DEBUG_ONLY( id = tso->id );
     debugTrace(DEBUG_sched, "new bound thread (%lu)", (unsigned long)id);
 
     cap = schedule(cap,task);

rts/Task.c

@@ -347,8 +347,8 @@ taskDoneGC (Task *task, Ticks cpu_time, Ticks elapsed_time)
 void
 workerTaskStop (Task *task)
 {
-    OSThreadId id;
-    id = osThreadId();
+    DEBUG_ONLY( OSThreadId id );
+    DEBUG_ONLY( id = osThreadId() );
     ASSERT(task->id == id);
     ASSERT(myTask() == task);
 

rts/Trace.h

@@ -194,7 +194,7 @@ void traceOSProcessInfo_ (void);
 #define debugTrace(class, str, ...) /* nothing */
 #define debugTraceCap(class, cap, str, ...) /* nothing */
 #define traceThreadStatus(class, tso) /* nothing */
-#define traceEventStartup_(n_caps) /* nothing */
+INLINE_HEADER void traceEventStartup_ (int n_caps STG_UNUSED) {};
 #define traceCapsetModify_(tag, capset, other) /* nothing */
 #define traceOSProcessInfo_() /* nothing */
 
@@ -243,8 +243,9 @@ void dtraceUserMsgWrapper(Capability *cap, char *msg);
     HASKELLEVENT_REQUEST_PAR_GC(cap)
 #define dtraceCreateSparkThread(cap, spark_tid)         \
     HASKELLEVENT_CREATE_SPARK_THREAD(cap, spark_tid)
-#define dtraceStartup(num_caps)                         \
+INLINE_HEADER void dtraceStartup (int n_caps) {
     HASKELLEVENT_STARTUP(num_caps)
+}
 #define dtraceUserMsg(cap, msg)                         \
     HASKELLEVENT_USER_MSG(cap, msg)
 #define dtraceGcIdle(cap)                               \
@@ -278,7 +279,7 @@ void dtraceUserMsgWrapper(Capability *cap, char *msg);
 #define dtraceRequestSeqGc(cap)                         /* nothing */
 #define dtraceRequestParGc(cap)                         /* nothing */
 #define dtraceCreateSparkThread(cap, spark_tid)         /* nothing */
-#define dtraceStartup(num_caps)                         /* nothing */
+INLINE_HEADER void dtraceStartup (int n_caps STG_UNUSED) {};
 #define dtraceUserMsg(cap, msg)                         /* nothing */
 #define dtraceGcIdle(cap)                               /* nothing */
 #define dtraceGcWork(cap)                               /* nothing */

rts/sm/GC.c

@@ -177,11 +177,15 @@ GarbageCollect (rtsBool force_major_gc,
   bdescr *bd;
   generation *gen;
   lnat live_blocks, live_words, allocated, max_copied, avg_copied;
+#if defined(THREADED_RTS)
   gc_thread *saved_gct;
+#endif
   nat g, n;
 
   // necessary if we stole a callee-saves register for gct:
+#if defined(THREADED_RTS)
   saved_gct = gct;
+#endif
 
 #ifdef PROFILING
   CostCentreStack *prev_CCS;
@@ -956,7 +960,7 @@ any_work (void)
 static void
 scavenge_until_all_done (void)
 {
-    nat r;
+    DEBUG_ONLY( nat r );
 	
 
 loop:
@@ -973,8 +977,13 @@ loop:
     collect_gct_blocks();
 
     // scavenge_loop() only exits when there's no work to do
+
+#ifdef DEBUG
     r = dec_running();
-    
+#else
+    dec_running();
+#endif
+
     traceEventGcIdle(gct->cap);
 
     debugTrace(DEBUG_gc, "%d GC threads still running", r);
@@ -1400,8 +1409,10 @@ mark_root(void *user USED_IF_THREADS, StgClosure **root)
     // so we need to save and restore it here.  NB. only call
     // mark_root() from the main GC thread, otherwise gct will be
     // incorrect.
+#if defined(THREADED_RTS)
     gc_thread *saved_gct;
     saved_gct = gct;
+#endif
     SET_GCT(user);
     
     evacuate(root);

rts/sm/GCUtils.c

@@ -211,8 +211,8 @@ todo_block_full (nat size, gen_workspace *ws)
         // Otherwise, push this block out to the global list.
         else 
         {
-            generation *gen;
-            gen = ws->gen;
+            DEBUG_ONLY( generation *gen );
+            DEBUG_ONLY( gen = ws->gen );
             debugTrace(DEBUG_gc, "push todo block %p (%ld words), step %d, todo_q: %ld", 
                   bd->start, (unsigned long)(bd->free - bd->u.scan),
                   gen->no, dequeElements(ws->todo_q));