arb_gpu_shader_int64: test shift-left of shift-right with same count

There is an optimization in Mesa that converts this to a mask operation.
However, the base mask used is 0xffffffff.  This is not correct (but
should still work) for 16-bit and 8-bit values, but it means the high
32-bits of 64-bit values will get chopped off.

Part-of: <https://gitlab.freedesktop.org/mesa/piglit/-/merge_requests/469>

1 files changed, 43 insertions, 0 deletions

diff --git a/tests/spec/arb_gpu_shader_int64/fs-shl-of-shr-int64.shader_test b/tests/spec/arb_gpu_shader_int64/fs-shl-of-shr-int64.shader_test
new file mode 100644
index 000000000..63806d045
--- /dev/null
+++ b/tests/spec/arb_gpu_shader_int64/fs-shl-of-shr-int64.shader_test
@@ -0,0 +1,43 @@
+[require]
+GLSL >= 4.00
+GL_ARB_gpu_shader_int64
+
+[vertex shader passthrough]
+
+[fragment shader]
+#extension GL_ARB_gpu_shader_int64: require
+
+out vec4 piglit_fragcolor;
+
+void main()
+{
+    /* The scale factor and the bias values ensure that every fragment will
+     * generate a value larger than (1 << 32).  It also ensures that at least
+     * some fragments will have some of the low four bits set.
+     */
+    uint64_t a = uint64_t(int(gl_FragCoord.x) + 8179) *
+		 uint64_t(int(gl_FragCoord.y) + 9931) * 1693ul;
+
+    /* This should effectively mask off the low four bits, but leave
+     * the bits about the 32-bit boundary intact.
+     */
+    uint64_t b = (a >> 4) << 4;
+
+    if (b < (1ul << 32))
+	piglit_fragcolor = vec4(1.0, 0.0, 0.0, 1.0);
+    else {
+	/* This tries to avoid a possible optimization of (x & y) & ~y -> 0 */
+	uint64_t c = b & 31ul;
+	if (c != 0ul && c != 16ul)
+	    piglit_fragcolor = vec4(0.0, 0.0, 1.0, 1.0);
+	else
+	    piglit_fragcolor = vec4(0.0, 1.0, 0.0, 1.0);
+    }
+}
+
+[test]
+clear color 0.3 0.3 0.3 0.0
+clear
+
+draw rect -1 -1 2 2
+probe all rgba 0.0 1.0 0.0 1.0