Mesa (staging/19.1): nir/lower_non_uniform: safely iterate over blocks

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Module: Mesa
Branch: staging/19.1
Commit: 4c7dfaba9c49e2a37e0019833e356908422084c8
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=4c7dfaba9c49e2a37e0019833e356908422084c8

Author: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Date:   Tue May 28 08:52:50 2019 +0100

nir/lower_non_uniform: safely iterate over blocks

This fixes a problem where the same instruction gets replaced twice.
This was happening when the replaced instruction would be at the end
of a block.

Replacement of :

   if ssa_8 {
                ....
      intrinsic bindless_image_store (ssa_44, ssa_16, ssa_0, ssa_15) (5, 0, 34836, 32) /* image_dim=Buf */ /* image_array=false */ /* format=34836 */ /* access=32 */
   }

Would be :

   if ssa_8 {
      loop {
         vec1 32 ssa_47 = intrinsic read_first_invocation (ssa_44) ()
         vec1 1 ssa_48 = ieq ssa_47, ssa_44
         if ssa_48 {
            loop {
               vec1 32 ssa_49 = intrinsic read_first_invocation (ssa_44) ()
               vec1 1 ssa_50 = ieq ssa_49, ssa_44
               if ssa_50 {
                  intrinsic bindless_image_store (ssa_44, ssa_16, ssa_0, ssa_15) (5, 0, 34836, 32) /* image_dim=Buf */ /* image_array=false */ /* format=34836 */ /* access=32 */
                  break
               } else {
        ....
   }

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Fixes: 3bd545764151 ("nir: Add a lowering pass for non-uniform resource access")
Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
(cherry picked from commit 366811bedb67ae7d31a02ea9b1f9fa942fb93602)

---

 src/compiler/nir/nir_lower_non_uniform_access.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/nir/nir_lower_non_uniform_access.c b/src/compiler/nir/nir_lower_non_uniform_access.c
index 6367f5670e8..0ab32100ef2 100644
--- a/src/compiler/nir/nir_lower_non_uniform_access.c
+++ b/src/compiler/nir/nir_lower_non_uniform_access.c
@@ -129,7 +129,7 @@ nir_lower_non_uniform_access_impl(nir_function_impl *impl,
    nir_builder b;
    nir_builder_init(&b, impl);
 
-   nir_foreach_block(block, impl) {
+   nir_foreach_block_safe(block, impl) {
       nir_foreach_instr_safe(instr, block) {
          switch (instr->type) {
          case nir_instr_type_tex: {