Bug 105438

I can reproduce this issue on Skylake with most mesa versions: 11.0.0-rc1 .. 17.3.6 .. latest git master in firefox, chrome and chromium browsers.

The crash is caused by the unreachable("not reached"); trap in the end of void
nir_visitor::visit(ir_expression *ir) (src/compiler/glsl/glsl_to_nir.cpp, line 1963).


Issue can be fixed by adding empty case for ir_binop_vector_extract:

diff --git a/src/compiler/glsl/glsl_to_nir.cpp b/src/compiler/glsl/glsl_to_nir.cpp
index c4a6d52a5b..24acfa1f8d 100644
--- a/src/compiler/glsl/glsl_to_nir.cpp
+++ b/src/compiler/glsl/glsl_to_nir.cpp
@@ -1952,6 +1952,9 @@ nir_visitor::visit(ir_expression *ir)
    case ir_quadop_vector:
       result = nir_vec(&b, srcs, ir->type->vector_elements);
       break;
+   case ir_binop_vector_extract:
+      /* Prevent the unreachable trap */
+      break;
 
    default:
       unreachable("not reached");


or by adding its handler to special cases:

diff --git a/src/compiler/glsl/glsl_to_nir.cpp b/src/compiler/glsl/glsl_to_nir.cpp
index c4a6d52a5b..d9efdd7170 100644
--- a/src/compiler/glsl/glsl_to_nir.cpp
+++ b/src/compiler/glsl/glsl_to_nir.cpp
@@ -1493,6 +1493,12 @@ nir_visitor::visit(ir_expression *ir)
       return;
    }
 
+   case ir_binop_vector_extract:
+      assert(ir->num_operands == 2);
+      ir->operands[0]->accept(this);
+      ir->operands[1]->accept(this);
+      return;
+
    default:
       break;
    }

I've sent a Piglit test for this, Andriy please send your patch to mesa-dev mailing list.

Hi Tapani. As I can see, fix was sent
https://patchwork.freedesktop.org/patch/214406/
but it is still in "New" state.

Do you mind to test if the following patch also fixes this issue:

https://patchwork.freedesktop.org/patch/221815/

Piglit's glsl-fs-vec4-indexing-8.shader_test is exactly this bug.
See the commit message:
https://cgit.freedesktop.org/piglit/commit/?id=965b55efbdf37985c731d68259012fdc5cef3d09

Nice! Thanks for confirming.

Hello, Felix.
Seems patch-fix was applied.

Could you, please, close the issue?

Ah, i didn't notice that, thanks.
I can confirm this is fixed with newest Mesa release.