[Mesa-dev] [PATCH] i965/vs: Preserve the type when copy propagating into an instruction.

Eric Anholt eric at anholt.net
Thu Oct 25 08:58:07 PDT 2012

Kenneth Graunke <kenneth at whitecape.org> writes:

> 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.

Reviewed-by: Eric Anholt <eric at anholt.net>
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