https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112993
--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Kewen Lin <li...@gcc.gnu.org>: https://gcc.gnu.org/g:33dca0a4c1c421625cedb2d6105ef1c05f6b774e commit r15-2084-g33dca0a4c1c421625cedb2d6105ef1c05f6b774e Author: Kewen Lin <li...@linux.ibm.com> Date: Wed Jul 17 00:14:43 2024 -0500 rs6000: Make all 128 bit scalar FP modes have 128 bit precision [PR112993] On rs6000, there are three 128 bit scalar floating point modes TFmode, IFmode and KFmode. With some historical reasons, we defines them with different mode precisions, that is KFmode 126, TFmode 127 and IFmode 128. But in fact all of them should have the same mode precision 128, this special setting has caused some issues like some unexpected failures mentioned in [1] and also made us have to introduce some workarounds, such as: the workaround in build_common_tree_nodes for KFmode 126, the workaround in range_compatible_p for same mode but different precision issue. This patch is to make these three 128 bit scalar floating point modes TFmode, IFmode and KFmode have 128 bit mode precision, and keep the order same as previous in order to make machine independent parts of the compiler not try to widen IFmode to TFmode. Besides, build_common_tree_nodes adopts the newly added hook mode_for_floating_type so we don't need to worry about unexpected mode for long double type node. In function convert_mode_scalar, with the proposed change, it adopts sext_optab for converting ieee128 format mode to ibm128 format mode while trunc_optab for converting ibm128 format mode to ieee128 format mode. Thus this patch removes useless extend and trunc optab supports, supplements new define_expands expandkftf2 and trunctfkf2 to align with convert_mode_scalar implementation. It also unnames two define_insn_and_split to avoid conflicts and make them more clear. Considering the current implementation that there is no chance to have KF <-> IF conversion (since either of them would be TF already), it adds two dummy define_expands to assert this. [1] https://inbox.sourceware.org/gcc-patches/ 718677e7-614d-7977-312d-05a75e1fd...@linux.ibm.com/ PR target/112993 gcc/ChangeLog: * config/rs6000/rs6000-modes.def (IFmode, KFmode, TFmode): Define with FLOAT_MODE instead of FRACTIONAL_FLOAT_MODE, don't use special precisions any more. (rs6000-modes.h): Remove include. * config/rs6000/rs6000-modes.h: Remove. * config/rs6000/rs6000.h (rs6000-modes.h): Remove include. * config/rs6000/t-rs6000: Remove rs6000-modes.h include. * config/rs6000/rs6000.cc (rs6000_option_override_internal): Replace all uses of FLOAT_PRECISION_TFmode with 128. (rs6000_c_mode_for_floating_type): Likewise. * config/rs6000/rs6000.md (define_expand extendiftf2): Remove. (define_expand extendifkf2): Remove. (define_expand extendtfkf2): Remove. (define_expand trunckftf2): Remove. (define_expand trunctfif2): Remove. (define_expand extendtfif2): Add new assertion. (define_expand expandkftf2): New. (define_expand trunciftf2): Add new assertion. (define_expand trunctfkf2): New. (define_expand truncifkf2): Change with gcc_unreachable. (define_expand expandkfif2): New. (define_insn_and_split extendkftf2): Rename to ... (define_insn_and_split *extendkftf2): ... this. (define_insn_and_split trunctfkf2): Rename to ... (define_insn_and_split *extendtfkf2): ... this.
