This patch rewrites the way simplify_subreg handles constants. It uses similar native_encode/native_decode routines to the tree-level handling of VIEW_CONVERT_EXPR, meaning that we can move between rtx constants and the target memory image of them. The main point of this patch is to support subregs of constant-length vectors for VLA vectors, beyond the very simple cases that were already handled. Many of the new tests failed before the patch for variable- length vectors. The boolean side is tested more by the upcoming SVE ACLE work. 2019-09-19 Richard Sandiford <richard.sandiford@arm.com> gcc/ * defaults.h (TARGET_UNIT): New macro. (target_unit): New type. * rtl.h (native_encode_rtx, native_decode_rtx) (native_decode_vector_rtx, subreg_size_lsb): Declare. (subreg_lsb_1): Turn into an inline wrapper around subreg_size_lsb. * rtlanal.c (subreg_lsb_1): Delete. (subreg_size_lsb): New function. * simplify-rtx.c: Include rtx-vector-builder.h (simplify_immed_subreg): Delete. (native_encode_rtx, native_decode_vector_rtx, native_decode_rtx) (simplify_const_vector_byte_offset, simplify_const_vector_subreg): New functions. (simplify_subreg): Use them. (test_vector_subregs_modes, test_vector_subregs_repeating) (test_vector_subregs_fore_back, test_vector_subregs_stepped) (test_vector_subregs): New functions. (test_vector_ops): Call test_vector_subregs for integer vector modes with at least 2 elements. From-SVN: r275959