Using multiply and reciprocal for integer division involves potentially
lossy floating point conversions. This is okay for older GPUs that
represent integers as floating point, but undesirable for GPUs with
native integer division instructions.
TGSI, for example, has UDIV/IDIV instructions for integer division,
so it makes sense to handle this directly. Likewise for i965.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Signed-off-by: Bryan Cain <bryancain3@gmail.com>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
This patch fixes a bug when lowering an integer division:
x/y
to a multiplication by a reciprocal:
int(float(x)*reciprocal(float(y)))
If x was a plain int and y was an ivecN, the lowering pass
incorrectly assigned the type of the product to be float, when in fact
it should be vecN. This caused mesa to abort with an IR validation
error.
Fixes piglit tests {fs,vs}-op-div-int-ivec{2,3,4}.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
MOD_TO_FRACT was designed to lower the GLSL 1.20 mod() function, which
operates on floating point values. However, we also use ir_binop_mod
for GLSL 1.30's % operator, which operates on integers.
For now, make MOD_TO_FRACT only apply to floating-point mod operations.
In the future, we may want to add a lowering pass for integer-based mod.
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
f2i results in an int/ivec; we need i2u to get a uint/uvec.
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
This should save on the overhead of tree-walking and provide a
convenient place to add more instruction lowering in the future.
Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
