Add -favoid-vect

* Enables vectorisation avoidance

(This commit only adds the flag, not the actual vectorisation avoidance transformation.)

compiler/main/DynFlags.hs

@@ -252,6 +252,7 @@ data DynFlag
    | Opt_DictsCheap
    | Opt_EnableRewriteRules             -- Apply rewrite rules during simplification
    | Opt_Vectorise
+   | Opt_AvoidVect
    | Opt_RegsGraph                      -- do graph coloring register allocation
    | Opt_RegsIterative                  -- do iterative coalescing graph coloring register allocation
    | Opt_PedanticBottoms                -- Be picky about how we treat bottom
@@ -1865,6 +1866,7 @@ fFlags = [
   ( "run-cpsz",                         Opt_RunCPSZ, nop ),
   ( "new-codegen",                      Opt_TryNewCodeGen, nop ),
   ( "vectorise",                        Opt_Vectorise, nop ),
+  ( "avoid-vect",                       Opt_AvoidVect, nop ),
   ( "regs-graph",                       Opt_RegsGraph, nop ),
   ( "regs-iterative",                   Opt_RegsIterative, nop ),
   ( "llvm-tbaa",                        Opt_LlvmTBAA, nop),

docs/users_guide/flags.xml

@@ -1501,6 +1501,20 @@
             <entry><option>-fno-enable-rewrite-rules</option></entry>
           </row>
 
+          <row>
+            <entry><option>-fvectorise</option></entry>
+            <entry>Enable vectorisation of nested data parallelism</entry>
+            <entry>dynamic</entry>
+            <entry><option>-fno-vectorise</option></entry>
+          </row>
+
+          <row>
+            <entry><option>-favoid-vect</option></entry>
+            <entry>Enable vectorisation avoidance (EXPERIMENTAL)</entry>
+            <entry>dynamic</entry>
+            <entry><option>-fno-avoid-vect</option></entry>
+          </row>
+
           <row>
             <entry><option>-fexcess-precision</option></entry>
             <entry>Enable excess intermediate precision</entry>