On 03.04.2017 02:01, Timothy Arceri wrote:
On 31/03/17 17:30, Nicolai Hähnle wrote:
On 31.03.2017 01:53, Timothy Arceri wrote:
Section 5.7 of the GLSL 4.5 spec says:
"Behavior is undefined if a shader subscripts an array with an
index less than 0 or greater than or equal to the size the array
was declared with."
So we cannot be sure which path the shader will take. Update the
test so that both branches end in the same result.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96684
---
tests/shaders/glsl-array-bounds-01.shader_test | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tests/shaders/glsl-array-bounds-01.shader_test
b/tests/shaders/glsl-array-bounds-01.shader_test
index 2e7c762..a06fef7 100644
--- a/tests/shaders/glsl-array-bounds-01.shader_test
+++ b/tests/shaders/glsl-array-bounds-01.shader_test
@@ -15,21 +15,21 @@ void main()
*/
#version 120
float array[] = float [] (1.0, 2.0, 3.0, 4.0);
void main()
{
int idx = 20;
if (array[idx] == 5.0)
- gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
+ gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);
else
gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);
}
I'm a bit concerned that an optimizer will do tail-merging followed by
eliminating the load. Maybe do something silly like
float tmp = array[idx];
gl_FragColor = vec4(0.0, 1.0 + abs(tmp), 0.0, 1.0);
instead? Then the compiler can't optimize the load away, because the
shader has to work with un-clamped floating point framebuffers.
On second thought, what about NaNs?
Well we are testing undefined behavior, the correct thing might be to
just delete the test?
That's a good point. Though robust buffer access changes this, so that
only the returned value is undefined. So instead of deleting the test,
it should probably be modified / moved to become a test for robust
buffer access.
Cheers,
Nicolai
Cheers,
Nicolai
[test]
clear color 0.0 0.0 0.0 0.0
clear
ortho
draw rect 10 10 10 10
probe rgb 15 15 0.0 1.0 0.0
--
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.
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