From 3badbf7f7fa4898c69545fea3c60ea29cf61ae3b Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Thu, 4 Apr 2013 16:30:49 -0700 Subject: [PATCH] i965/vs: When asked to make a dst_reg for a src.xxxx, just write to src.x. We have several places in our pull constant handling where we make a temporary src_reg for an int, and then turn it into a dst. In doing so, we were writing to the dst.xyzw, so we never register coalesced it with a later mov from dst.x to real_dst.x. These extra channels written would be removed if we had channel-wise DCE in the backend, but we don't. Fix it for now by just not writing these extra channels that won't get used. Reviewed-by: Matt Turner --- src/mesa/drivers/dri/i965/brw_vec4.cpp | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp index c58fb444b94..e470ac80ab5 100644 --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp @@ -200,7 +200,14 @@ dst_reg::dst_reg(src_reg reg) this->reg = reg.reg; this->reg_offset = reg.reg_offset; this->type = reg.type; - this->writemask = WRITEMASK_XYZW; + /* How should we do writemasking when converting from a src_reg? It seems + * pretty obvious that for src.xxxx the caller wants to write to src.x, but + * what about for src.wx? Just special-case src.xxxx for now. + */ + if (reg.swizzle == BRW_SWIZZLE_XXXX) + this->writemask = WRITEMASK_X; + else + this->writemask = WRITEMASK_XYZW; this->reladdr = reg.reladdr; this->fixed_hw_reg = reg.fixed_hw_reg; } -- 2.30.2