https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126447
--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-16 branch has been updated by Jakub Jelinek <[email protected]>: https://gcc.gnu.org/g:d6a1fe04e7cec6b378ecbf6c5b8ee36dd918d5d2 commit r16-9428-gd6a1fe04e7cec6b378ecbf6c5b8ee36dd918d5d2 Author: Jakub Jelinek <[email protected]> Date: Wed Jul 29 10:04:30 2026 +0200 bitintlower: Fix _BitInt SSA_NAME coalescing ICE [PR126447] The following testcases ICE, because the build_bitint_stmt_ssa_conflicts function sets for those ifns muldiv_p to true (similarly to the MULT_EXPR and division/modulo ones) to prevent the lhs from being mapped into the same underlying variable as the input operand(s). Now, if the lhs and at least one of the operands SSA_NAME_OCCURS_IN_ABNORMAL_PHI, we can trigger ICE because we fail to coalesce something that has to be coalesced. For MULT_EXPR etc. we handle this in gimple_lower_bitint, by /* For multiplication and division with (ab) lhs and one or both operands force the operands into new SSA_NAMEs to avoid coalescing failures. */ if (TREE_CODE (rhs1) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs1)) { first_large_huge = 0; tree t = make_ssa_name (TREE_TYPE (rhs1)); g = gimple_build_assign (t, SSA_NAME, rhs1); gsi_insert_before (&gsi, g, GSI_SAME_STMT); gimple_set_location (g, loc); gimple_assign_set_rhs1 (stmt, t); if (rhs1 == rhs2) { gimple_assign_set_rhs2 (stmt, t); rhs2 = t; } update_stmt (stmt); } etc. a few lines above the hunk below. This patch just adds the same thing for the problematic internal fn calls (not handling that way the .MUL_OVERFLOW etc. ifns, because those do return COMPLEX_EXPR of BITINT_TYPE and so the problematic case shouldn't exist there). 2026-07-29 Jakub Jelinek <[email protected]> PR middle-end/126447 * gimple-lower-bitint.cc (gimple_lower_bitint): For ifn calls with large/huge _BitInt (ab) SSA_NAME lhs if they have such (ab) argument too, force it into temporary SSA_NAME for IFN_UBSAN_CHECK_MUL and, if bitint_big_endian, also for IFN_UBSAN_CHECK_{ADD,SUB}. * gcc.dg/ubsan/bitint-5.c: New test. Reviewed-by: Andrea Pinski <[email protected]> (cherry picked from commit cd9428362b6585e77ea2a171ec030894fcfa4d1c)
