Two example patches: enable powerpc64 builds of devel/powerpc64-gcc and lang/gcc8 via system-clang ( avoiding clang's reserving vec_step )

[I experiment with using modern compilers on
powerpc64, here buildworld buildkernel was
via devel/powerpc64-xtoolchain-gcc but included
building clang and having clang as cc. clang's
problems are tied to aspects of buildworld
buildkernel but is otherwise usable.]

When clang is built with support for altivec
for powerpc* (powerpc64 here) and such it
reserves a name not from the C/C++ language
standards: vec_step .

system-clang has enough enabled for powerpc64
to have reserved vec_step.

If devel/llvm* ever enable enough powerpc64
support they would reserve vec_step too. (I've
not checked if this is already happening.)

Unfortunately, various devel/*gcc and lang/gcc*
use that name in gcc/tree-vect-loop.c and so on
powerpc64 those various *gcc* fail to build.

The below just avoids the extra reserved word
by renaming each non-comment vec_step in
gcc/tree-vect-loop.c to vec_step_renamed . This
has allowed me to build the example *gcc* 's in
poudriere-devel on powerpc64 (head -r339076
based).

One could imagine sed'ing or otherwise processing
gcc/tree-vect-loop.c instead of having patch files.
In the examples the original gcc/tree-vect-loop.c
files are not the same: one patch for all *gcc*
would not work.

# svnlite status /usr/ports/devel/powerpc64-gcc/files/ | more
?       /usr/ports/devel/powerpc64-gcc/files/patch-gcc_tree-vect-loop.c

# svnlite status /usr/ports/lang/gcc8/files/ | more
?       /usr/ports/lang/gcc8/files/patch-gcc_tree-vect-loop.c

# more /usr/ports/devel/powerpc64-gcc/files/patch-gcc_tree-vect-loop.c
--- gcc/tree-vect-loop.c.orig   2017-03-28 15:35:56 UTC
+++ gcc/tree-vect-loop.c
@@ -3832,7 +3832,7 @@ get_initial_def_for_induction (gimple *iv_phi)
   edge pe = loop_preheader_edge (loop);
   struct loop *iv_loop;
   basic_block new_bb;
-  tree new_vec, vec_init, vec_step, t;
+  tree new_vec, vec_init, vec_step_renamed, t;
   tree new_name;
   gimple *new_stmt;
   gphi *induction_phi;
@@ -3986,7 +3986,7 @@ get_initial_def_for_induction (gimple *iv_phi)
   stepvectype = get_vectype_for_scalar_type (TREE_TYPE (new_name));
   gcc_assert (stepvectype);
   new_vec = build_vector_from_val (stepvectype, t);
-  vec_step = vect_init_vector (iv_phi, new_vec, stepvectype, NULL);
+  vec_step_renamed = vect_init_vector (iv_phi, new_vec, stepvectype, NULL);
 
 
   /* Create the following def-use cycle:
@@ -4008,7 +4008,7 @@ get_initial_def_for_induction (gimple *iv_phi)
   induc_def = PHI_RESULT (induction_phi);
 
   /* Create the iv update inside the loop  */
-  new_stmt = gimple_build_assign (vec_dest, PLUS_EXPR, induc_def, vec_step);
+  new_stmt = gimple_build_assign (vec_dest, PLUS_EXPR, induc_def, vec_step_renamed);
   vec_def = make_ssa_name (vec_dest, new_stmt);
   gimple_assign_set_lhs (new_stmt, vec_def);
   gsi_insert_before (&si, new_stmt, GSI_SAME_STMT);
@@ -4049,7 +4049,7 @@ get_initial_def_for_induction (gimple *iv_phi)
       gcc_assert (CONSTANT_CLASS_P (new_name)
                  || TREE_CODE (new_name) == SSA_NAME);
       new_vec = build_vector_from_val (stepvectype, t);
-      vec_step = vect_init_vector (iv_phi, new_vec, stepvectype, NULL);
+      vec_step_renamed = vect_init_vector (iv_phi, new_vec, stepvectype, NULL);
 
       vec_def = induc_def;
       prev_stmt_vinfo = vinfo_for_stmt (induction_phi);
@@ -4057,7 +4057,7 @@ get_initial_def_for_induction (gimple *iv_phi)
        {
          /* vec_i = vec_prev + vec_step  */
          new_stmt = gimple_build_assign (vec_dest, PLUS_EXPR,
-                                         vec_def, vec_step);
+                                         vec_def, vec_step_renamed);
          vec_def = make_ssa_name (vec_dest, new_stmt);
          gimple_assign_set_lhs (new_stmt, vec_def);
  
@@ -6324,13 +6324,13 @@ vectorizable_reduction (gimple *stmt, gimple_stmt_iter
 
          /* Create a vector of the step value.  */
          tree step = build_int_cst (cr_index_scalar_type, nunits_out);
-         tree vec_step = build_vector_from_val (cr_index_vector_type, step);
+         tree vec_step_renamed = build_vector_from_val (cr_index_vector_type, step);
 
          /* Create an induction variable.  */
          gimple_stmt_iterator incr_gsi;
          bool insert_after;
          standard_iv_increment_position (loop, &incr_gsi, &insert_after);
-         create_iv (series_vect, vec_step, NULL_TREE, loop, &incr_gsi,
+         create_iv (series_vect, vec_step_renamed, NULL_TREE, loop, &incr_gsi,
                     insert_after, &indx_before_incr, &indx_after_incr);
 
          /* Next create a new phi node vector (NEW_PHI_TREE) which starts


# more /usr/ports/lang/gcc8/files/patch-gcc_tree-vect-loop.c
--- gcc/tree-vect-loop.c.orig   2018-10-10 22:41:40.295753000 -0700
+++ gcc/tree-vect-loop.c        2018-10-10 22:57:44.698855000 -0700
@@ -4970,13 +4970,13 @@
 
       /* Create a vector of the step value.  */
       tree step = build_int_cst (cr_index_scalar_type, nunits_out);
-      tree vec_step = build_vector_from_val (cr_index_vector_type, step);
+      tree vec_step_renamed = build_vector_from_val (cr_index_vector_type, step);
 
       /* Create an induction variable.  */
       gimple_stmt_iterator incr_gsi;
       bool insert_after;
       standard_iv_increment_position (loop, &incr_gsi, &insert_after);
-      create_iv (series_vect, vec_step, NULL_TREE, loop, &incr_gsi,
+      create_iv (series_vect, vec_step_renamed, NULL_TREE, loop, &incr_gsi,
                 insert_after, &indx_before_incr, &indx_after_incr);
 
       /* Next create a new phi node vector (NEW_PHI_TREE) which starts
@@ -7641,7 +7641,7 @@
   tree vec_def;
   edge pe = loop_preheader_edge (loop);
   basic_block new_bb;
-  tree new_vec, vec_init, vec_step, t;
+  tree new_vec, vec_init, vec_step_renamed, t;
   tree new_name;
   gimple *new_stmt;
   gphi *induction_phi;
@@ -7834,7 +7834,7 @@
        new_name = vect_init_vector (phi, new_name,
                                     TREE_TYPE (step_expr), NULL);
       new_vec = build_vector_from_val (vectype, new_name);
-      vec_step = vect_init_vector (phi, new_vec, vectype, NULL);
+      vec_step_renamed = vect_init_vector (phi, new_vec, vectype, NULL);
 
       /* Now generate the IVs.  */
       unsigned group_size = SLP_TREE_SCALAR_STMTS (slp_node).length ();
@@ -7873,7 +7873,7 @@
 
          /* Create the iv update inside the loop  */
          vec_def = make_ssa_name (vec_dest);
-         new_stmt = gimple_build_assign (vec_def, PLUS_EXPR, induc_def, vec_step);
+         new_stmt = gimple_build_assign (vec_def, PLUS_EXPR, induc_def, vec_step_renamed);
          gsi_insert_before (&si, new_stmt, GSI_SAME_STMT);
          set_vinfo_for_stmt (new_stmt, new_stmt_vec_info (new_stmt, loop_vinfo));
 
@@ -7904,7 +7904,7 @@
            new_name = vect_init_vector (phi, new_name,
                                         TREE_TYPE (step_expr), NULL);
          new_vec = build_vector_from_val (vectype, new_name);
-         vec_step = vect_init_vector (phi, new_vec, vectype, NULL);
+         vec_step_renamed = vect_init_vector (phi, new_vec, vectype, NULL);
          for (; ivn < nvects; ++ivn)
            {
              gimple *iv = SLP_TREE_VEC_STMTS (slp_node)[ivn - nivs];
@@ -7915,7 +7915,7 @@
                def = gimple_assign_lhs (iv);
              new_stmt = gimple_build_assign (make_ssa_name (vectype),
                                              PLUS_EXPR,
-                                             def, vec_step);
+                                             def, vec_step_renamed);
              if (gimple_code (iv) == GIMPLE_PHI)
                gsi_insert_before (&si, new_stmt, GSI_SAME_STMT);
              else
@@ -8041,7 +8041,7 @@
   gcc_assert (CONSTANT_CLASS_P (new_name)
              || TREE_CODE (new_name) == SSA_NAME);
   new_vec = build_vector_from_val (vectype, t);
-  vec_step = vect_init_vector (phi, new_vec, vectype, NULL);
+  vec_step_renamed = vect_init_vector (phi, new_vec, vectype, NULL);
 
 
   /* Create the following def-use cycle:
@@ -8064,7 +8064,7 @@
 
   /* Create the iv update inside the loop  */
   vec_def = make_ssa_name (vec_dest);
-  new_stmt = gimple_build_assign (vec_def, PLUS_EXPR, induc_def, vec_step);
+  new_stmt = gimple_build_assign (vec_def, PLUS_EXPR, induc_def, vec_step_renamed);
   gsi_insert_before (&si, new_stmt, GSI_SAME_STMT);
   set_vinfo_for_stmt (new_stmt, new_stmt_vec_info (new_stmt, loop_vinfo));
 
@@ -8108,7 +8108,7 @@
       gcc_assert (CONSTANT_CLASS_P (new_name)
                  || TREE_CODE (new_name) == SSA_NAME);
       new_vec = build_vector_from_val (vectype, t);
-      vec_step = vect_init_vector (phi, new_vec, vectype, NULL);
+      vec_step_renamed = vect_init_vector (phi, new_vec, vectype, NULL);
 
       vec_def = induc_def;
       prev_stmt_vinfo = vinfo_for_stmt (induction_phi);
@@ -8116,7 +8116,7 @@
        {
          /* vec_i = vec_prev + vec_step  */
          new_stmt = gimple_build_assign (vec_dest, PLUS_EXPR,
-                                         vec_def, vec_step);
+                                         vec_def, vec_step_renamed);
          vec_def = make_ssa_name (vec_dest, new_stmt);
          gimple_assign_set_lhs (new_stmt, vec_def);
  


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)