aarch64_simd_vector_alignment was only giving predicates 16-bit alignment in VLA mode, not VLS mode. I think the problem is latent because we can't yet create an ABI predicate type, but it seemed worth fixing in a standalone patch rather than as part of the main ACLE series.
The ACLE patches have tests for this. Tested on aarch64-linux-gnu (with and without SVE) and aarch64_be-elf. Applied as r274522. Richard 2019-08-15 Richard Sandiford <richard.sandif...@arm.com> gcc/ * config/aarch64/aarch64.c (aarch64_simd_vector_alignment): Return 16 for SVE predicates even if they are fixed-length. Index: gcc/config/aarch64/aarch64.c =================================================================== --- gcc/config/aarch64/aarch64.c 2019-08-15 09:52:24.842110687 +0100 +++ gcc/config/aarch64/aarch64.c 2019-08-15 09:56:41.816215015 +0100 @@ -15915,11 +15915,13 @@ aarch64_simd_attr_length_rglist (machine static HOST_WIDE_INT aarch64_simd_vector_alignment (const_tree type) { + /* ??? Checking the mode isn't ideal, but VECTOR_BOOLEAN_TYPE_P can + be set for non-predicate vectors of booleans. Modes are the most + direct way we have of identifying real SVE predicate types. */ + if (GET_MODE_CLASS (TYPE_MODE (type)) == MODE_VECTOR_BOOL) + return 16; if (TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST) - /* ??? Checking the mode isn't ideal, but VECTOR_BOOLEAN_TYPE_P can - be set for non-predicate vectors of booleans. Modes are the most - direct way we have of identifying real SVE predicate types. */ - return GET_MODE_CLASS (TYPE_MODE (type)) == MODE_VECTOR_BOOL ? 16 : 128; + return 128; return wi::umin (wi::to_wide (TYPE_SIZE (type)), 128).to_uhwi (); }