From 414e1d2f597f454329ac21d7c4bda7c623e672de Mon Sep 17 00:00:00 2001 From: Erik Schnetter Date: Thu, 23 Jan 2020 10:04:24 -0500 Subject: [PATCH] jl_special_vector_alignment: Remove work-around for old LLVM version (<=3.8) LLVM <= 3.8 segfaults when LLVM SIMD vectors are not powers of 2 (or a sum of 2 different powers of 2). This LLVM bug was corrected in 2017 (see ). This change removes this work-around, finally allowing arbitrary SIMD vector lengths in Julia. This changes Julia's ABI for SIMD types. All SIMD types are now represented as SIMD vectors in LLVM. The work-around represented some SIMD types as LLVM arrays instead to avoid the LLVM segfault. I don't think that SIMD vector lengths that are not a power of 2 were in widespread use, if at all. --- src/datatype.c | 12 ------------ 1 file changed, 12 deletions(-) diff --git a/src/datatype.c b/src/datatype.c index 57f2111127bfaa..3f511ae8d9723a 100644 --- a/src/datatype.c +++ b/src/datatype.c @@ -191,18 +191,6 @@ unsigned jl_special_vector_alignment(size_t nfields, jl_value_t *t) { if (!jl_is_vecelement_type(t)) return 0; - // LLVM 3.7 and 3.8 either crash or generate wrong code for many - // SIMD vector sizes N. It seems the rule is that N can have at - // most 2 non-zero bits. (This is true at least for N<=100.) See - // also . - size_t mask = nfields; - // See e.g. - // for an - // explanation of this bit-counting algorithm. - mask &= mask-1; // clear least-significant 1 if present - mask &= mask-1; // clear another 1 - if (mask) - return 0; // nfields has more than two 1s assert(jl_datatype_nfields(t)==1); jl_value_t *ty = jl_field_type((jl_datatype_t*)t, 0); if (!jl_is_primitivetype(ty))