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authorPaul Berry <stereotype441@gmail.com>2013-11-22 12:37:22 -0800
committerIan Romanick <ian.d.romanick@intel.com>2013-11-26 21:04:52 -0800
commit444a621e55044f4d44efb98b76cb4ce1bde47da4 (patch)
treeb14ae224a6888276a32b9d359a8bfea691bc46b9 /src/glsl
parent756b4f9a8c657c4ba93a0a082bd77a9c3390c11e (diff)
glsl: Fix lowering of direct assignment in lower_clip_distance.
In commit 065da16 (glsl: Convert lower_clip_distance_visitor to be an ir_rvalue_visitor), we failed to notice that since lower_clip_distance_visitor overrides visit_leave(ir_assignment *), ir_rvalue_visitor::visit_leave(ir_assignment *) wasn't getting called. As a result, clip distance dereferences appearing directly on the right hand side of an assignment (not in a subexpression) weren't getting properly lowered. This caused an ir_dereference_variable node to be left in the IR that referred to the old gl_ClipDistance variable. However, since the lowering pass replaces gl_ClipDistance with gl_ClipDistanceMESA, this turned into a dangling pointer when the IR got reparented. Prior to the introduction of geometry shaders, this bug was unlikely to arise, because (a) reading from gl_ClipDistance[i] in the fragment shader was rare, and (b) when it happened, it was likely that it would either appear in a subexpression, or be hoisted into a subexpression by tree grafting. However, in a geometry shader, we're likely to see a statement like this, which would trigger the bug: gl_ClipDistance[i] = gl_in[j].gl_ClipDistance[i]; This patch causes lower_clip_distance_visitor::visit_leave(ir_assignment *) to call the base class visitor, so that the right hand side of the assignment is properly lowered. Fixes piglit test: - spec/glsl-1.50/execution/geometry/clip-distance-itemized-copy Cc: Ian Romanick <idr@freedesktop.org> Cc: "9.2" <mesa-stable@lists.freedesktop.org> Cc: "10.0" <mesa-stable@lists.freedesktop.org> Reviewed-by: Eric Anholt <eric@anholt.net> Reviewed-by: Ian Romanick <ian.d.romanick@intel.com> (cherry picked from commit 9dfcb05fa649ee7a573eab3d16851ebd4cb96010)
Diffstat (limited to 'src/glsl')
-rw-r--r--src/glsl/lower_clip_distance.cpp5
1 files changed, 5 insertions, 0 deletions
diff --git a/src/glsl/lower_clip_distance.cpp b/src/glsl/lower_clip_distance.cpp
index 682c8fdcd3e..04fa6d4108a 100644
--- a/src/glsl/lower_clip_distance.cpp
+++ b/src/glsl/lower_clip_distance.cpp
@@ -381,6 +381,11 @@ lower_clip_distance_visitor::fix_lhs(ir_assignment *ir)
ir_visitor_status
lower_clip_distance_visitor::visit_leave(ir_assignment *ir)
{
+ /* First invoke the base class visitor. This causes handle_rvalue() to be
+ * called on ir->rhs and ir->condition.
+ */
+ ir_rvalue_visitor::visit_leave(ir);
+
if (this->is_clip_distance_vec8(ir->lhs) ||
this->is_clip_distance_vec8(ir->rhs)) {
/* LHS or RHS of the assignment is the entire 1D gl_ClipDistance array