On 01/28/2013 05:06 PM, Frank Henigman wrote:
An assertion in fs_visitor::remove_dead_constants() would fail on
code like this, which accesses a non-existent uniform:
uniform vec u[1];
...
a += u[0] + u[1];
Shader code is checked for that error, but apparently only before
transformations like loop unrolling. So the following code would get
transformed to the same as above and then the assertion would fail:
for (int i = 0; i < 2; ++i) a += u[i];
This patch changes the assertion failure to a compile failure.
The behavior of an out-of-bounds access is undefined, but compilation is
not allowed to fail. I think there are two good solutions:
1. Always generate zero. I believe this is what DX requires, so there
may be apps ported from DX that assume this behavior. This is also what
happens when you access out of bounds of a UBO.
2. Clamp the index to the bounds of the array.
https://bugs.freedesktop.org/show_bug.cgi?id=59429
Also... if you're working on a bug, you should assign it to yourself. I
was planning to start working on this bug tomorrow. :)
Signed-off-by: Frank Henigman <fjhenig...@google.com>
---
src/mesa/drivers/dri/i965/brw_fs.cpp | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 8e57eb0..548f7d6 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -1467,7 +1467,12 @@ fs_visitor::remove_dead_constants()
if (inst->src[i].file != UNIFORM)
continue;
- assert(constant_nr < (int)c->prog_data.nr_params);
+ if (constant_nr >= (int)c->prog_data.nr_params) {
+ ralloc_free(this->params_remap);
+ this->params_remap = NULL;
+ fail("accessed non-existent uniform");
+ return false;
+ }
/* For now, set this to non-negative. We'll give it the
* actual new number in a moment, in order to keep the
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