Add -Wdisabled-optimization to loop prefetching pass (PR tree-optimization/79803).

2017-03-03  Martin Liska  <mliska@suse.cz>

	PR tree-optimization/79803
	* tree-ssa-loop-prefetch.c (tree_ssa_prefetch_arrays): Remove
	assert.
	(pass_loop_prefetch::execute): Disabled optimization if an
	assumption about L1 cache size is not met.
2017-03-03  Martin Liska  <mliska@suse.cz>

	PR tree-optimization/79803
	* gcc.dg/tree-ssa/pr79803.c: New test.

From-SVN: r245869

gcc/ChangeLog

@@ -1,3 +1,11 @@
+2017-03-03  Martin Liska  <mliska@suse.cz>
+
+	PR tree-optimization/79803
+	* tree-ssa-loop-prefetch.c (tree_ssa_prefetch_arrays): Remove
+	assert.
+	(pass_loop_prefetch::execute): Disabled optimization if an
+	assumption about L1 cache size is not met.
+
 2017-03-03  Martin Liska  <mliska@suse.cz>
 
 	PR rtl-optimization/79574

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2017-03-03  Martin Liska  <mliska@suse.cz>
+
+	PR tree-optimization/79803
+	* gcc.dg/tree-ssa/pr79803.c: New test.
+
 2017-03-03  Martin Liska  <mliska@suse.cz>
 
 	PR rtl-optimization/79574

gcc/testsuite/gcc.dg/tree-ssa/pr79803.c

@@ -0,0 +1,60 @@
+/* { dg-do compile { target { x86_64-*-* } } } */
+/* { dg-options "-march=opteron-sse3 -Ofast --param l1-cache-line-size=3 -Wdisabled-optimization" } */
+/* { dg-require-effective-target indirect_jumps } */
+
+#include <setjmp.h>
+
+extern void abort (void);
+
+jmp_buf buf;
+
+void raise0(void)
+{
+  __builtin_longjmp (buf, 1);
+}
+
+int execute(int cmd) /* { dg-warning "'l1-cache-size' parameter is not a power of two 3" } */
+{
+  int last = 0;
+
+  if (__builtin_setjmp (buf) == 0)
+    while (1)
+      {
+	last = 1;
+	raise0 ();
+      }
+
+  if (last == 0)
+    return 0;
+  else
+    return cmd;
+}
+
+int execute2(int cmd, int cmd2)
+{
+  int last = 0;
+
+  if (__builtin_setjmp (buf) == 0)
+    while (1)
+      {
+	last = 1;
+	raise0 ();
+      }
+
+  if (last == 0)
+    return 0;
+  else
+    return cmd;
+}
+
+
+int main(void)
+{
+  if (execute (1) == 0)
+    abort ();
+
+  if (execute2 (1, 2) == 0)
+    abort ();
+
+  return 0;
+}

gcc/tree-ssa-loop-prefetch.c

@@ -47,6 +47,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "langhooks.h"
 #include "tree-inline.h"
 #include "tree-data-ref.h"
+#include "diagnostic-core.h"
 
 /* This pass inserts prefetch instructions to optimize cache usage during
    accesses to arrays in loops.  It processes loops sequentially and:
@@ -1977,10 +1978,6 @@ tree_ssa_prefetch_arrays (void)
       set_builtin_decl (BUILT_IN_PREFETCH, decl, false);
     }
 
-  /* We assume that size of cache line is a power of two, so verify this
-     here.  */
-  gcc_assert ((PREFETCH_BLOCK & (PREFETCH_BLOCK - 1)) == 0);
-
   FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
     {
       if (dump_file && (dump_flags & TDF_DETAILS))
@@ -2038,6 +2035,21 @@ pass_loop_prefetch::execute (function *fun)
   if (number_of_loops (fun) <= 1)
     return 0;
 
+  bool warned_p = false;
+  if ((PREFETCH_BLOCK & (PREFETCH_BLOCK - 1)) != 0)
+    {
+      static bool warned = false;
+
+      if (!warned)
+	{
+	  warning (OPT_Wdisabled_optimization,
+		   "%<l1-cache-size%> parameter is not a power of two %d",
+		   PREFETCH_BLOCK);
+	  warned = true;
+	}
+      return 0;
+    }
+
   return tree_ssa_prefetch_arrays ();
 }