Mesa (master): nir/copy_prop_vars: Ignore volatile accesses

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Module: Mesa
Branch: master
Commit: 75063fbac522bcbc2e009c292d666e5aadc2d1f1
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=75063fbac522bcbc2e009c292d666e5aadc2d1f1

Author: Connor Abbott <cwabbott0 at gmail.com>
Date:   Wed Jun  5 10:23:00 2019 +0200

nir/copy_prop_vars: Ignore volatile accesses

The spec explicitly says that volatile writes can't be removed and
volatile reads do not guarantee that the same value will still be around
after the read, as if there were a barrier after each read/write. Just
ignore them.

Reviewed-by: Timothy Arceri <tarceri at itsqueeze.com>

---

 src/compiler/nir/nir_opt_copy_prop_vars.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/compiler/nir/nir_opt_copy_prop_vars.c b/src/compiler/nir/nir_opt_copy_prop_vars.c
index 0fd96b7bee8..a1c8ffabf7a 100644
--- a/src/compiler/nir/nir_opt_copy_prop_vars.c
+++ b/src/compiler/nir/nir_opt_copy_prop_vars.c
@@ -812,6 +812,9 @@ copy_prop_vars_block(struct copy_prop_var_state *state,
       case nir_intrinsic_load_deref: {
          if (debug) dump_instr(instr);
 
+         if (nir_intrinsic_access(intrin) & ACCESS_VOLATILE)
+            break;
+
          nir_deref_instr *src = nir_src_as_deref(intrin->src[0]);
 
          /* Direct array_derefs of vectors operate on the vectors (the parent
@@ -892,6 +895,9 @@ copy_prop_vars_block(struct copy_prop_var_state *state,
       case nir_intrinsic_store_deref: {
          if (debug) dump_instr(instr);
 
+         if (nir_intrinsic_access(intrin) & ACCESS_VOLATILE)
+            break;
+
          nir_deref_instr *dst = nir_src_as_deref(intrin->src[0]);
          assert(glsl_type_is_vector_or_scalar(dst->type));
 
@@ -936,6 +942,10 @@ copy_prop_vars_block(struct copy_prop_var_state *state,
       case nir_intrinsic_copy_deref: {
          if (debug) dump_instr(instr);
 
+         if ((nir_intrinsic_src_access(intrin) & ACCESS_VOLATILE) ||
+             (nir_intrinsic_dst_access(intrin) & ACCESS_VOLATILE))
+            break;
+
          nir_deref_instr *dst = nir_src_as_deref(intrin->src[0]);
          nir_deref_instr *src = nir_src_as_deref(intrin->src[1]);
 
@@ -1005,6 +1015,9 @@ copy_prop_vars_block(struct copy_prop_var_state *state,
       case nir_intrinsic_deref_atomic_comp_swap:
          if (debug) dump_instr(instr);
 
+         if (nir_intrinsic_access(intrin) & ACCESS_VOLATILE)
+            break;
+
          nir_deref_instr *dst = nir_src_as_deref(intrin->src[0]);
          unsigned num_components = glsl_get_vector_elements(dst->type);
          unsigned full_mask = (1 << num_components) - 1;