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llvmpipe: lp_build_gather_elem_vec BE fix for 3x16 load

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Fix loading of a 3x16 vector as a single 48-bit load
on big-endian systems (PPC64, S390).

Roland Scheidegger's commit e827d91756
plus Ray Strode's patch reduce pre-Roland Piglit failures from ~4000 to ~2000.  This patch fixes
three of the four regressions observed by Ray:

- draw-vertices
- draw-vertices-half-float
- draw-vertices-half-float_gles2

One regression remains:
- draw-vertices-2101010

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100613
Cc: "17.2" "17.1" <mesa-stable@lists.freedesktop.org>

Signed-off-by: Ben Crocker <bcrocker@redhat.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
This commit is contained in:
Ben Crocker 2017-08-23 16:32:43 -04:00 • committed by Roland Scheidegger
parent 75cb6e3617
commit 57c8ead0cd
1 changed files with 28 additions and 2 deletions
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30
src/gallium/auxiliary/gallivm/lp_bld_gather.c
View file

@ -234,13 +234,39 @@ lp_build_gather_elem_vec(struct gallivm_state *gallivm,
*/
res = LLVMBuildZExt(gallivm->builder, res, dst_elem_type, "");
if (vector_justify) {
#ifdef PIPE_ARCH_BIG_ENDIAN
if (vector_justify) {
res = LLVMBuildShl(gallivm->builder, res,
LLVMConstInt(dst_elem_type,
dst_type.width - src_width, 0), "");
#endif
}
if (src_width == 48) {
/* Load 3x16 bit vector.
* The sequence of loads on big-endian hardware proceeds as follows.
* 16-bit fields are denoted by X, Y, Z, and 0. In memory, the sequence
* of three fields appears in the order X, Y, Z.
*
* Load 32-bit word: 0.0.X.Y
* Load 16-bit halfword: 0.0.0.Z
* Rotate left: 0.X.Y.0
* Bitwise OR: 0.X.Y.Z
*
* The order in which we need the fields in the result is 0.Z.Y.X,
* the same as on little-endian; permute 16-bit fields accordingly
* within 64-bit register:
*/
LLVMValueRef shuffles[4] = {
lp_build_const_int32(gallivm, 2),
lp_build_const_int32(gallivm, 1),
lp_build_const_int32(gallivm, 0),
lp_build_const_int32(gallivm, 3),
};
res = LLVMBuildBitCast(gallivm->builder, res,
lp_build_vec_type(gallivm, lp_type_uint_vec(16, 4*16)), "");
res = LLVMBuildShuffleVector(gallivm->builder, res, res, LLVMConstVector(shuffles, 4), "");
res = LLVMBuildBitCast(gallivm->builder, res, dst_elem_type, "");
}
#endif
}
}
return res;