[Mesa-dev] [PATCH] i965: Fix hangs with FP KIL instructions pre-gen6.

[Eric Anholt]

We can't support IF statements in 16-wide on these.  To get back to 16-wide
for these shaders, we need to support predicate on discard instructions in the
backend IR, which is something we've sort of got on the list to do anyway.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=55828
---
 src/mesa/drivers/dri/i965/brw_fs_fp.cpp |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_fp.cpp b/src/mesa/drivers/dri/i965/brw_fs_fp.cpp
index c0a8810..636199e 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_fp.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_fp.cpp
@@ -260,6 +260,8 @@ fs_visitor::emit_fragment_program_code()
                                  regoffset(src[0], i), 0.0f);
             inst->conditional_mod = BRW_CONDITIONAL_L;
 
+            if (intel->gen < 6 && c->dispatch_width == 16)
+               fail("Can't support (non-uniform) control flow on 16-wide");
             inst = emit(BRW_OPCODE_IF);
             inst->predicate = BRW_PREDICATE_NORMAL;
             emit(FS_OPCODE_DISCARD);
-- 
1.7.10.4