diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index ac67885..2e9a3df 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -596,6 +596,10 @@ Wold-style-definition
 C ObjC Var(warn_old_style_definition) Warning
 Warn if an old-style parameter definition is used
 
+Wopenmp-simd
+C C++ Var(warn_openmp_simd) Warning LangEnabledBy(C C++,Wall)
+Warn if a simd directive is overridden by the vectorizer cost model
+
 Woverlength-strings
 C ObjC C++ ObjC++ Var(warn_overlength_strings) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic)
 Warn if a string is longer than the maximum portable length specified by the standard
diff --git a/gcc/common.opt b/gcc/common.opt
index a7af636..a7f4f2f 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2300,10 +2300,17 @@ fvect-cost-model=
 Common Joined RejectNegative Enum(vect_cost_model) Var(flag_vect_cost_model) Init(VECT_COST_MODEL_DEFAULT)
 Specifies the cost model for vectorization
  
+fsimd-cost-model=
+Common Joined RejectNegative Enum(vect_cost_model) Var(flag_simd_cost_model) Init(VECT_COST_MODEL_UNLIMITED)
+Specifies the vectorization cost model for code marked with a simd directive
+
 Enum
 Name(vect_cost_model) Type(enum vect_cost_model) UnknownError(unknown vectorizer cost model %qs)
 
 EnumValue
+Enum(vect_cost_model) String(default) Value(VECT_COST_MODEL_DEFAULT)
+
+EnumValue

Don't add "default", it should be the default ;)  (so yes, please change
the default to VECT_COST_MODEL_DEFAULT)

 Enum(vect_cost_model) String(unlimited) Value(VECT_COST_MODEL_UNLIMITED)
 
 EnumValue
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 501d080..5c8f08f 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -256,7 +256,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wlogical-op -Wlong-long @gol
 -Wmain -Wmaybe-uninitialized -Wmissing-braces  -Wmissing-field-initializers @gol
 -Wmissing-include-dirs @gol
--Wno-multichar  -Wnonnull  -Wno-overflow @gol
+-Wno-multichar  -Wnonnull  -Wno-overflow -Wopenmp-simd @gol
 -Woverlength-strings  -Wpacked  -Wpacked-bitfield-compat  -Wpadded @gol
 -Wparentheses  -Wpedantic-ms-format -Wno-pedantic-ms-format @gol
 -Wpointer-arith  -Wno-pointer-to-int-cast @gol
@@ -3321,6 +3321,7 @@ Options} and @ref{Objective-C and Objective-C++ Dialect Options}.
 -Wmaybe-uninitialized @gol
 -Wmissing-braces @r{(only for C/ObjC)} @gol
 -Wnonnull  @gol
+-Wopenmp-simd @gol
 -Wparentheses  @gol
 -Wpointer-sign  @gol
 -Wreorder   @gol
@@ -4815,6 +4816,12 @@ attribute.
 @opindex Woverflow
 Do not warn about compile-time overflow in constant expressions.
 
+@item -Wopenmp-simd
+@opindex Wopenm-simd
+Warn if the vectorizer cost model overrides the OpenMP or the Cilk Plus
+simd directive set by user.  The @option{-fsimd-cost-model=unlimited} can
+be used to relax the cost model.
+
 @item -Woverride-init @r{(C and Objective-C only)}
 @opindex Woverride-init
 @opindex Wno-override-init
@@ -8071,6 +8078,15 @@ is equal to the @code{dynamic} model.
 The default cost model depends on other optimization flags and is
 either @code{dynamic} or @code{cheap}.
 
+@item -fsimd-cost-model=@var{model}
+@opindex fsimd-cost-model
+Alter the cost model used for vectorization of loops marked with the OpenMP
+or Cilk Plus simd directive.  The @var{model} argument should be one of
+@code{unlimited}, @code{dynamic}, @code{cheap} or @code{default}.  The
+@code{default} model means to reuse model defined by @option{fvect-cost-model}.
+All other values of @var{model} have the same meaning as described in
+@option{fvect-cost-model}.
+
 @item -ftree-vrp
 @opindex ftree-vrp
 Perform Value Range Propagation on trees.  This is similar to the
diff --git a/gcc/fortran/lang.opt b/gcc/fortran/lang.opt
index 5e09cbd..0d328c8 100644
--- a/gcc/fortran/lang.opt
+++ b/gcc/fortran/lang.opt
@@ -257,6 +257,10 @@ Wintrinsics-std
 Fortran Warning
 Warn on intrinsics not part of the selected standard
 
+Wopenmp-simd
+Fortran
+; Documented in C
+

 Wreal-q-constant
 Fortran Warning
 Warn about real-literal-constants with 'q' exponent-letter
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index 5e3b520..dd0ecc4 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -1096,7 +1096,8 @@ vect_peeling_hash_insert (loop_vec_info loop_vinfo, struct data_reference *dr,
       *new_slot = slot;
     }
 
-  if (!supportable_dr_alignment && unlimited_cost_model ())
+  if (!supportable_dr_alignment
+      && unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
     slot->count += VECT_MAX_COST;
 }
 
@@ -1206,7 +1207,7 @@ vect_peeling_hash_choose_best_peeling (loop_vec_info loop_vinfo,
    res.peel_info.dr = NULL;
    res.body_cost_vec = stmt_vector_for_cost ();
 
-   if (!unlimited_cost_model ())
+   if (!unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
      {
        res.inside_cost = INT_MAX;
        res.outside_cost = INT_MAX;
@@ -1435,7 +1436,7 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
                  vectorization factor.
                  We do this automtically for cost model, since we calculate cost
                  for every peeling option.  */
-              if (unlimited_cost_model ())
+              if (unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
                 possible_npeel_number = vf /nelements;
 
               /* Handle the aligned case. We may decide to align some other
@@ -1443,7 +1444,7 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
               if (DR_MISALIGNMENT (dr) == 0)
                 {
                   npeel_tmp = 0;
-                  if (unlimited_cost_model ())
+                  if (unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
                     possible_npeel_number++;
                 }
 
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index c91c2e1..fc8fa95 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -2703,7 +2703,7 @@ vect_estimate_min_profitable_iters (loop_vec_info loop_vinfo,
   void *target_cost_data = LOOP_VINFO_TARGET_COST_DATA (loop_vinfo);
 
   /* Cost model disabled.  */
-  if (unlimited_cost_model ())
+  if (unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
     {
       dump_printf_loc (MSG_NOTE, vect_location, "cost model disabled.\n");
       *ret_min_profitable_niters = 0;
@@ -2936,6 +2936,10 @@ vect_estimate_min_profitable_iters (loop_vec_info loop_vinfo,
   /* vector version will never be profitable.  */
   else
     {
+      if (warn_openmp_simd && LOOP_VINFO_LOOP (loop_vinfo)->force_vect)

Testing warn_openmp_simd is redundant here, it is taken care
of by warning_at and the OPT_Wopenmp_simd flag you passed

Otherwise the patch looks ok to me and is good for trunk.

Thanks,
Richard.


+	warning_at (vect_location, OPT_Wopenmp_simd, "vectorization "
+		    "did not happen for a simd loop");
+
       if (dump_enabled_p ())
         dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
 			 "cost model: the vector iteration cost = %d "
diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index 680a6d8..2387c0d 100644
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -2176,7 +2176,7 @@ vect_slp_analyze_bb_1 (basic_block bb)
     }
 
   /* Cost model: check if the vectorization is worthwhile.  */
-  if (!unlimited_cost_model ()
+  if (!unlimited_cost_model (NULL)
       && !vect_bb_vectorization_profitable_p (bb_vinfo))
     {
       if (dump_enabled_p ())
diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index 58884f8..8013983 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -910,9 +910,12 @@ known_alignment_for_access_p (struct data_reference *data_ref_info)
 
 /* Return true if the vect cost model is unlimited.  */
 static inline bool
-unlimited_cost_model ()
+unlimited_cost_model (loop_p loop)
 {
-  return flag_vect_cost_model == VECT_COST_MODEL_UNLIMITED;
+  if (loop != NULL && loop->force_vect
+      && flag_simd_cost_model != VECT_COST_MODEL_DEFAULT)
+    return flag_simd_cost_model == VECT_COST_MODEL_UNLIMITED;
+  return (flag_vect_cost_model == VECT_COST_MODEL_UNLIMITED);
 }
 
 /* Source location */
