r600g/sb: fix issues cause by GLSL switching to loops for switch

Since 73dd50acf6d244979c2a657906aa56d3ac60d550
glsl: implement switch flow control using a loop

The SB backend was falling over in an assert or crashing.

Tracked this down to the loops having no repeats, but requiring
a working break, initial code just called the loop handler for
all non-if statements, but this caused a regression in
tests/shaders/dead-code-break-interaction.shader_test.
So I had to add further code to detect if all the departure
nodes are empty and avoid generating an empty loop for that case.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=86089
Cc: "10.4" <mesa-stable@lists.freedesktop.org>
Reviewed-By: Glenn Kennard <glenn.kennard@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/src/gallium/drivers/r600/sb/sb_bc_finalize.cpp b/src/gallium/drivers/r600/sb/sb_bc_finalize.cpp
index f0849ca6b6b9a882ea4da80c4320ca0d39921cb1..0fa0910ba172eb41bd14f69656e6ebf315b732a8 100644 (file)
--- a/src/gallium/drivers/r600/sb/sb_bc_finalize.cpp
+++ b/src/gallium/drivers/r600/sb/sb_bc_finalize.cpp
@@ -46,15 +46,22 @@ int bc_finalizer::run() {
        for (regions_vec::reverse_iterator I = rv.rbegin(), E = rv.rend(); I != E;
                        ++I) {
                region_node *r = *I;
-
+               bool is_if = false;
                assert(r);
 
-               bool loop = r->is_loop();
+               assert(r->first);
+               if (r->first->is_container()) {
+                       container_node *repdep1 = static_cast<container_node*>(r->first);
+                       assert(repdep1->is_depart() || repdep1->is_repeat());
+                       if_node *n_if = static_cast<if_node*>(repdep1->first);
+                       if (n_if && n_if->is_if())
+                               is_if = true;
+               }
 
-               if (loop)
-                       finalize_loop(r);
-               else
+               if (is_if)
                        finalize_if(r);
+               else
+                       finalize_loop(r);
 
                r->expand();
        }
@@ -112,16 +119,33 @@ void bc_finalizer::finalize_loop(region_node* r) {
 
        cf_node *loop_start = sh.create_cf(CF_OP_LOOP_START_DX10);
        cf_node *loop_end = sh.create_cf(CF_OP_LOOP_END);
+       bool has_instr = false;
+
+       if (!r->is_loop()) {
+               for (depart_vec::iterator I = r->departs.begin(), E = r->departs.end();
+                    I != E; ++I) {
+                       depart_node *dep = *I;
+                       if (!dep->empty()) {
+                               has_instr = true;
+                               break;
+                       }
+               }
+       } else
+               has_instr = true;
 
-       loop_start->jump_after(loop_end);
-       loop_end->jump_after(loop_start);
+       if (has_instr) {
+               loop_start->jump_after(loop_end);
+               loop_end->jump_after(loop_start);
+       }
 
        for (depart_vec::iterator I = r->departs.begin(), E = r->departs.end();
                        I != E; ++I) {
                depart_node *dep = *I;
-               cf_node *loop_break = sh.create_cf(CF_OP_LOOP_BREAK);
-               loop_break->jump(loop_end);
-               dep->push_back(loop_break);
+               if (has_instr) {
+                       cf_node *loop_break = sh.create_cf(CF_OP_LOOP_BREAK);
+                       loop_break->jump(loop_end);
+                       dep->push_back(loop_break);
+               }
                dep->expand();
        }
 
@@ -137,8 +161,10 @@ void bc_finalizer::finalize_loop(region_node* r) {
                rep->expand();
        }
 
-       r->push_front(loop_start);
-       r->push_back(loop_end);
+       if (has_instr) {
+               r->push_front(loop_start);
+               r->push_back(loop_end);
+       }
 }
 
 void bc_finalizer::finalize_if(region_node* r) {