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-rw-r--r--src/mesa/drivers/dri/i965/brw_vec4.cpp21
1 files changed, 21 insertions, 0 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index 6d73bb2faec..cc0a76a7eb4 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -2267,7 +2267,28 @@ vec4_visitor::apply_logical_swizzle(struct brw_reg *hw_reg,
*/
assert(brw_is_single_value_swizzle(reg.swizzle));
+ /* To gain access to Z/W components we need to select the second half
+ * of the register and then use a X/Y swizzle to select Z/W respectively.
+ */
unsigned swizzle = BRW_GET_SWZ(reg.swizzle, 0);
+
+ if (swizzle >= 2) {
+ *hw_reg = suboffset(*hw_reg, 2);
+ swizzle -= 2;
+ }
+
+ /* Any 64-bit source with an offset at 16B is intended to address the
+ * second half of a register and needs a vertical stride of 0 so we:
+ *
+ * 1. Don't violate register region restrictions.
+ * 2. Activate the gen7 instruction decompresion bug exploit when
+ * execsize > 4
+ */
+ if (hw_reg->subnr % REG_SIZE == 16) {
+ assert(devinfo->gen == 7);
+ hw_reg->vstride = BRW_VERTICAL_STRIDE_0;
+ }
+
hw_reg->swizzle = BRW_SWIZZLE4(swizzle * 2, swizzle * 2 + 1,
swizzle * 2, swizzle * 2 + 1);
}