i965/vs: Preserve the type when copy propagating into an instruction.

Consider the following code, which reinterprets a register as a
different type:

mov(8)          g6<1>F          g1.4<0,4,1>.xF
and(8)          g5<1>.xUD       g6<4,4,1>.xUD   0x7fffffffUD

Copy propagation would notice that we can replace the use of g6 with
g1.4 and eliminate the MOV.  Unfortunately, it failed to preserve the UD
type, incorrectly generating:

and(8)          g5<1>.xUD       g6<4,4,1>.xF    0x7fffffffUD

Found while debugging Ian's uncommitted ARB_vertex_program LOG opcode
test with my new Mesa IR -> Vec4 IR translator.

NOTE: This is a candidate for stable release branches.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
index 4d27c53ddf390f8cbdb48bc1991b1eb2f0044f5a..ca757c3c9006b1411a6cebf9dfe858c95d1a7b5a 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
@@ -224,6 +224,7 @@ try_copy_propagation(struct intel_context *intel,
    if (value.equals(&inst->src[arg]))
       return false;
 
+   value.type = inst->src[arg].type;
    inst->src[arg] = value;
    return true;
 }