https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113783
--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:c9bdcb0c3433ce09f5bb713a51a14130858578a2 commit r14-8899-gc9bdcb0c3433ce09f5bb713a51a14130858578a2 Author: Jakub Jelinek <ja...@redhat.com> Date: Fri Feb 9 16:17:08 2024 +0100 lower-bitint: Fix handling of VIEW_CONVERT_EXPRs to minimally supported huge INTEGER_TYPEs [PR113783] On the following testcases memcpy lowering folds the calls to reading and writing of MEM_REFs with huge INTEGER_TYPEs - uint256_t with OImode or uint512_t with XImode. Further optimization turn the load from MEM_REF from the large/huge _BitInt var into VIEW_CONVERT_EXPR from it to the uint256_t/uint512_t. The backend doesn't really support those except for "movoi"/"movxi" insns, so it isn't possible to handle it like casts to supportable INTEGER_TYPEs where we can construct those from individual limbs - there are no OImode/XImode shifts and the like we can use. So, the following patch makes sure for such VCEs that the SSA_NAME operand of the VCE lives in memory and then turns it into a VIEW_CONVERT_EXPR so that we actually load the OImode/XImode integer from memory (i.e. a mov). We need to make sure those aren't merged with other operations in the gimple_lower_bitint hunks. For SSA_NAMEs which have underlying VAR_DECLs that is all we need, those VAR_DECL have ARRAY_TYPEs. For SSA_NAMEs which have underlying PARM_DECLs or RESULT_DECLs those have BITINT_TYPE and I had to tweak expand_expr_real_1 for that so that it doesn't try convert_modes on those when one of the modes is BLKmode - we want to fall through into the adjust_address on the MEM. 2024-02-09 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/113783 * gimple-lower-bitint.cc (bitint_large_huge::lower_stmt): Look through VIEW_CONVERT_EXPR for final cast checks. Handle VIEW_CONVERT_EXPRs from large/huge _BitInt to > MAX_FIXED_MODE_SIZE INTEGER_TYPEs. (gimple_lower_bitint): Don't merge mergeable operations or other casts with VIEW_CONVERT_EXPRs to > MAX_FIXED_MODE_SIZE INTEGER_TYPEs. * expr.cc (expand_expr_real_1): Don't use convert_modes if either mode is BLKmode. * gcc.dg/bitint-88.c: New test.
