Re: [Mesa-dev] [PATCH 1/3] glsl: don't drop intructions from unreachable terminators continue branch

[Nicolai Hähnle]

On 14.09.2017 06:47, Timothy Arceri wrote:

These instruction will be executed on every iteration of the loop

*instructions

Als, the title of the patch is missing an s ;)

Cheers,
Nicolai

we cannot drop them.
---
  src/compiler/glsl/loop_analysis.h   |  7 +++++++
  src/compiler/glsl/loop_controls.cpp | 15 +++++++++++++++
  src/compiler/glsl/loop_unroll.cpp   |  7 -------
  3 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/compiler/glsl/loop_analysis.h 
b/src/compiler/glsl/loop_analysis.h
index 2894c6359b..0e1bfd8142 100644
--- a/src/compiler/glsl/loop_analysis.h
+++ b/src/compiler/glsl/loop_analysis.h
@@ -27,20 +27,27 @@

#include "ir.h"

  #include "util/hash_table.h"

/**

   * Analyze and classify all variables used in all loops in the instruction 
list
   */
  extern class loop_state *
  analyze_loop_variables(exec_list *instructions);

+static inline bool

+is_break(ir_instruction *ir)
+{
+   return ir != NULL && ir->ir_type == ir_type_loop_jump &&
+      ((ir_loop_jump *) ir)->is_break();
+}
+

/**

   * Fill in loop control fields
   *
   * Based on analysis of loop variables, this function tries to remove
   * redundant sequences in the loop of the form
   *
   *  (if (expression bool ...) (break))
   *
   * For example, if it is provable that one loop exit condition will
diff --git a/src/compiler/glsl/loop_controls.cpp 
b/src/compiler/glsl/loop_controls.cpp
index 895954fc2d..2dff26aec0 100644
--- a/src/compiler/glsl/loop_controls.cpp
+++ b/src/compiler/glsl/loop_controls.cpp
@@ -215,21 +215,36 @@ loop_control_visitor::visit_leave(ir_loop *ir)
      * that are associated with a fixed iteration count, except for the one
      * associated with the limiting terminator--that one needs to stay, since
      * it terminates the loop.  Exception: if the loop still has a normative
      * bound, then that terminates the loop, so we don't even need the limiting
      * terminator.
      */
     foreach_in_list(loop_terminator, t, &ls->terminators) {
        if (t->iterations < 0)
           continue;

+ exec_list *branch_instructions;

        if (t != ls->limiting_terminator) {
+         ir_instruction *ir_if_last = (ir_instruction *)
+           t->ir->then_instructions.get_tail();
+         if (is_break(ir_if_last)) {
+            branch_instructions = &t->ir->else_instructions;
+         } else {
+            branch_instructions = &t->ir->then_instructions;
+            assert(is_break(ir_if_last));
+         }
+
+         exec_list copy_list;
+         copy_list.make_empty();
+         clone_ir_list(ir, &copy_list, branch_instructions);
+
+         t->ir->insert_before(&copy_list);
           t->ir->remove();

assert(ls->num_loop_jumps > 0);

           ls->num_loop_jumps--;

this->progress = true;

        }
     }

return visit_continue;

diff --git a/src/compiler/glsl/loop_unroll.cpp 
b/src/compiler/glsl/loop_unroll.cpp
index dbb3fa2fa5..7f601295a1 100644
--- a/src/compiler/glsl/loop_unroll.cpp
+++ b/src/compiler/glsl/loop_unroll.cpp
@@ -46,27 +46,20 @@ public:
     void splice_post_if_instructions(ir_if *ir_if, exec_list *splice_dest);

loop_state *state; bool progress;

     const struct gl_shader_compiler_options *options;
  };

} /* anonymous namespace */ -static bool

-is_break(ir_instruction *ir)
-{
-   return ir != NULL && ir->ir_type == ir_type_loop_jump
-                    && ((ir_loop_jump *) ir)->is_break();
-}
-
  class loop_unroll_count : public ir_hierarchical_visitor {
  public:
     int nodes;
     bool unsupported_variable_indexing;
     bool array_indexed_by_induction_var_with_exact_iterations;
     /* If there are nested loops, the node count will be inaccurate. */
     bool nested_loop;

loop_unroll_count(exec_list *list, loop_variable_state *ls,

                       const struct gl_shader_compiler_options *options)

--
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/mesa-dev