[Mesa-dev] [PATCH 06/12] nir/opt_peephole_select: Don't try to remove flow control around indirect loads

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

That flow control may be trying to avoid invalid loads.  On at least
some platforms, those loads can also be expensive.

No shader-db changes on any Intel platform (even with the later patch
"intel/compiler: More peephole select").

NOTE: I've tried to CC everyone whose drive might be affected by this
change.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Cc: Eric Anholt <eric at anholt.net>
Cc: Rob Clark <robdclark at gmail.com>
Cc: Marek Olšák <marek.olsak at amd.com>
---
 src/compiler/nir/nir_opt_peephole_select.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/compiler/nir/nir_opt_peephole_select.c b/src/compiler/nir/nir_opt_peephole_select.c
index 4ca4f80d788..920ced2137c 100644
--- a/src/compiler/nir/nir_opt_peephole_select.c
+++ b/src/compiler/nir/nir_opt_peephole_select.c
@@ -58,7 +58,8 @@
  */
 
 static bool
-block_check_for_allowed_instrs(nir_block *block, unsigned *count, bool alu_ok)
+block_check_for_allowed_instrs(nir_block *block, unsigned *count,
+                               gl_shader_stage stage, bool alu_ok)
 {
    nir_foreach_instr(instr, block) {
       switch (instr->type) {
@@ -70,6 +71,13 @@ block_check_for_allowed_instrs(nir_block *block, unsigned *count, bool alu_ok)
             switch (intrin->variables[0]->var->data.mode) {
             case nir_var_shader_in:
             case nir_var_uniform:
+               /* Don't try to remove flow control around an indirect load
+                * because that flow control may be trying to avoid invalid
+                * loads.
+                */
+               if (nir_deref_has_indirect(stage, intrin->variables[0]))
+                  return false;
+
                break;
 
             default:
@@ -168,8 +176,10 @@ nir_opt_peephole_select_block(nir_block *block, nir_shader *shader,
 
    /* ... and those blocks must only contain "allowed" instructions. */
    unsigned count = 0;
-   if (!block_check_for_allowed_instrs(then_block, &count, limit != 0) ||
-       !block_check_for_allowed_instrs(else_block, &count, limit != 0))
+   if (!block_check_for_allowed_instrs(then_block, &count, shader->info.stage,
+                                       limit != 0) ||
+       !block_check_for_allowed_instrs(else_block, &count, shader->info.stage,
+                                       limit != 0))
       return false;
 
    if (count > limit)
-- 
2.14.4