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-rw-r--r--src/gallium/auxiliary/gallivm/lp_bld_sample_aos.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_sample_aos.c b/src/gallium/auxiliary/gallivm/lp_bld_sample_aos.c
index 641d24b5b6..d3e3b242af 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_sample_aos.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_sample_aos.c
@@ -873,6 +873,26 @@ lp_build_sample_mipmap(struct lp_build_sample_context *bld,
lod_fpart = LLVMBuildTrunc(builder, lod_fpart, h16_bld.elem_type, "");
lod_fpart = lp_build_broadcast_scalar(&h16_bld, lod_fpart);
+#if HAVE_LLVM == 0x208
+ /* This is a work-around for a bug in LLVM 2.8.
+ * Evidently, something goes wrong in the construction of the
+ * lod_fpart short[8] vector. Adding this no-effect shuffle seems
+ * to force the vector to be properly constructed.
+ * Tested with mesa-demos/src/tests/mipmap_limits.c (press t, f).
+ */
+ {
+ LLVMValueRef shuffles[8], shuffle;
+ int i;
+ assert(h16_bld.type.length <= Elements(shuffles));
+ for (i = 0; i < h16_bld.type.length; i++)
+ shuffles[i] = lp_build_const_int32(2 * (i & 1));
+ shuffle = LLVMConstVector(shuffles, h16_bld.type.length);
+ lod_fpart = LLVMBuildShuffleVector(builder,
+ lod_fpart, lod_fpart,
+ shuffle, "");
+ }
+#endif
+
colors0_lo = lp_build_lerp(&h16_bld, lod_fpart,
colors0_lo, colors1_lo);
colors0_hi = lp_build_lerp(&h16_bld, lod_fpart,