[gcc/devel/omp/gcc-14] vect: WORKAROUND vectorizer bug

[Paul-Antoine Arras]

https://gcc.gnu.org/g:3eabba8cc53d92d60ae8d3dc008d0c732c43f84f

commit 3eabba8cc53d92d60ae8d3dc008d0c732c43f84f
Author: Andrew Stubbs <ams@codesourcery.com>
Date:   Fri Oct 21 14:19:31 2022 +0100

    vect: WORKAROUND vectorizer bug
    
    This patch disables vectorization of memory accesses to non-default address
    spaces where the pointer size is different to the usual pointer size.  This
    condition typically occurs in OpenACC programs on amdgcn, where LDS memory is
    used for broadcasting gang-private variables between threads. In particular,
    see libgomp.oacc-c-c++-common/private-variables.c
    
    The problem is that the address space information is dropped from the various
    types in the middle-end and eventually it triggers an ICE trying to do an
    address conversion.  That ICE can be avoided by defining
    POINTERS_EXTEND_UNSIGNED, but that just produces wrong RTL code later on.
    
    A correct solution would ensure that all the vectypes have the correct address
    spaces, but I don't have time for that right now.
    
    gcc/ChangeLog:
    
            * tree-vect-data-refs.cc (vect_analyze_data_refs): Workaround an
            address-space bug.

Diff:
---
 gcc/ChangeLog.omp          |  5 +++++
 gcc/tree-vect-data-refs.cc | 16 +++++++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/gcc/ChangeLog.omp b/gcc/ChangeLog.omp
index c4b70ba1849..7d04b110b3a 100644
--- a/gcc/ChangeLog.omp
+++ b/gcc/ChangeLog.omp
@@ -1,3 +1,8 @@
+2022-10-24  Andrew Stubbs  <ams@codesourcery.com>
+
+	* tree-vect-data-refs.cc (vect_analyze_data_refs): Workaround an
+	address-space bug.
+
 2023-11-19  Tobias Burnus  <tobias@codesourcery.com>
 	    Chung-Lin Tang <cltang@codesourcery.com>
 
diff --git a/gcc/tree-vect-data-refs.cc b/gcc/tree-vect-data-refs.cc
index c531079d3bb..7f2b8f0b928 100644
--- a/gcc/tree-vect-data-refs.cc
+++ b/gcc/tree-vect-data-refs.cc
@@ -4929,7 +4929,21 @@ vect_analyze_data_refs (vec_info *vinfo, poly_uint64 *min_vf, bool *fatal)
       /* Set vectype for STMT.  */
       scalar_type = TREE_TYPE (DR_REF (dr));
       tree vectype = get_vectype_for_scalar_type (vinfo, scalar_type);
-      if (!vectype)
+
+      /* FIXME: If the object is in an address-space in which the pointer size
+	 is different to the default address space then vectorizing here will
+	 lead to an ICE down the road because the address space information
+	 gets lost.  This work-around fixes the problem until we have a proper
+	 solution.  */
+      tree base_object = DR_REF (dr);
+      tree op = (TREE_CODE (base_object) == COMPONENT_REF
+		 || TREE_CODE (base_object) == ARRAY_REF
+		 ? TREE_OPERAND (base_object, 0) : base_object);
+      addr_space_t as = TYPE_ADDR_SPACE (TREE_TYPE (op));
+      bool addr_space_bug = (!ADDR_SPACE_GENERIC_P (as)
+			     && targetm.addr_space.pointer_mode (as) != Pmode);
+
+      if (!vectype || addr_space_bug)
         {
           if (dump_enabled_p ())
             {