[Piglit] [PATCH] maxuniformblocksize: fix vs/fsexceed test index

[Brian Paul]

For the exceed test, we create an array in a UBO that's one vector
larger than what's supposed to be supported.

The shader program is allowed to link or not link in this situation.
But if it does link, the behavior of indexing beyond the UBO size
probably isn't well defined.  Instead of testing/probing at a
position that's out of bounds, test/probe the last position inside
the max UBO size.

Plus, clean up the code a bit to make it a little easier to understand.
---
 .../arb_uniform_buffer_object/maxuniformblocksize.c  |   18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/tests/spec/arb_uniform_buffer_object/maxuniformblocksize.c b/tests/spec/arb_uniform_buffer_object/maxuniformblocksize.c
index 07b0bd0..c9cff49 100644
--- a/tests/spec/arb_uniform_buffer_object/maxuniformblocksize.c
+++ b/tests/spec/arb_uniform_buffer_object/maxuniformblocksize.c
@@ -112,6 +112,7 @@ piglit_display(void)
 	bool pass = true;
 	bool may_link_fail;
 	const float green[4] = { 0, 1, 0, 0 };
+	int test_index;
 
 	piglit_require_extension("GL_ARB_uniform_buffer_object");
 
@@ -123,20 +124,24 @@ piglit_display(void)
 	case VS:
 		target = GL_VERTEX_SHADER;
 		may_link_fail = false;
+		test_index = vec4s - 1;
 		break;
 	case VS_EXCEED:
 		target = GL_VERTEX_SHADER;
 		may_link_fail = true;
 		vec4s++;
+		test_index = vec4s - 2;
 		break;
 	case FS:
 		target = GL_FRAGMENT_SHADER;
 		may_link_fail = false;
+		test_index = vec4s - 1;
 		break;
 	case FS_EXCEED:
 		target = GL_FRAGMENT_SHADER;
 		may_link_fail = true;
 		vec4s++;
+		test_index = vec4s - 2;
 		break;
 	default:
 		assert(false);
@@ -189,15 +194,18 @@ piglit_display(void)
 	data = glMapBuffer(GL_UNIFORM_BUFFER, GL_READ_WRITE);
 	memset(data, 0, size);
 
-	data[(vec4s - 1) * 4 + 0] = 0.0;
-	data[(vec4s - 1) * 4 + 1] = 1.0;
-	data[(vec4s - 1) * 4 + 2] = 0.0;
-	data[(vec4s - 1) * 4 + 3] = 0.0;
+	/* The whole uniform buffer will be zeros, except for the
+	 * entry at v[test_index] which will be green.
+	 */
+	data[test_index * 4 + 0] = green[0];
+	data[test_index * 4 + 1] = green[1];
+	data[test_index * 4 + 2] = green[2];
+	data[test_index * 4 + 3] = green[3];
 	glUnmapBuffer(GL_UNIFORM_BUFFER);
 
 	glUseProgram(prog);
 	i_location = glGetUniformLocation(prog, "i");
-	glUniform1i(i_location, vec4s - 1);
+	glUniform1i(i_location, test_index);
 
 	glUniformBlockBinding(prog, 0, 0);
 	glBindBufferBase(GL_UNIFORM_BUFFER, 0, bo);
-- 
1.7.10.4