Mesa (master): mesa/glsl: new compiler option EmitNoIndirectSampler

[Tapani Pälli]

Module: Mesa
Branch: master
Commit: e4512e1581cf90f56d13cfa6a809832ef3517283
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=e4512e1581cf90f56d13cfa6a809832ef3517283

Author: Tapani Pälli <tapani.palli at intel.com>
Date:   Tue Jun  9 13:33:39 2015 +0300

mesa/glsl: new compiler option EmitNoIndirectSampler

Patch provides new compiler option for backend to force unroll loops
that have non-constant expression indexing on sampler arrays.

This makes sure that we can never end up with a shader that uses loop
induction variable as sampler array index but does not unroll because
of having too much instructions. This would not work without dynamic
indexing support.

v2: change option name as EmitNoIndirectSampler

Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
Reviewed-by: Francisco Jerez <currojerez at riseup.net>
Cc: "10.5" and "10.6" <mesa-stable at lists.freedesktop.org>

---

 src/glsl/loop_unroll.cpp |   12 ++++++++++++
 src/mesa/main/mtypes.h   |    1 +
 2 files changed, 13 insertions(+)

diff --git a/src/glsl/loop_unroll.cpp b/src/glsl/loop_unroll.cpp
index 635e1dd..7a00fb8 100644
--- a/src/glsl/loop_unroll.cpp
+++ b/src/glsl/loop_unroll.cpp
@@ -100,6 +100,18 @@ public:
 
    virtual ir_visitor_status visit_enter(ir_dereference_array *ir)
    {
+      /* Force unroll in case of dynamic indexing with sampler arrays
+       * when EmitNoIndirectSampler is set.
+       */
+      if (options->EmitNoIndirectSampler) {
+         if ((ir->array->type->is_array() &&
+              ir->array->type->contains_sampler()) &&
+             !ir->array_index->constant_expression_value()) {
+            unsupported_variable_indexing = true;
+            return visit_continue;
+         }
+      }
+
       /* Check for arrays variably-indexed by a loop induction variable.
        * Unrolling the loop may convert that access into constant-indexing.
        *
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index 983b9dc..7b55677 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -2881,6 +2881,7 @@ struct gl_shader_compiler_options
    GLboolean EmitNoIndirectOutput;  /**< No indirect addressing of outputs */
    GLboolean EmitNoIndirectTemp;    /**< No indirect addressing of temps */
    GLboolean EmitNoIndirectUniform; /**< No indirect addressing of constants */
+   GLboolean EmitNoIndirectSampler; /**< No indirect addressing of samplers */
    /*@}*/
 
    GLuint MaxIfDepth;               /**< Maximum nested IF blocks */