From c7969df1c5d3785c0b409f97e7682a6f0d2637ec Mon Sep 17 00:00:00 2001 From: Jeff Law Date: Mon, 1 Jun 2020 17:14:50 -0400 Subject: [PATCH] Fix 92085-2.c ICE due to having (const_int 0) as the destination of a set. gcc/ * lower-subreg.c (resolve_simple_move): If simplify_gen_subreg_concatn returns (const_int 0) for the destination, then emit nothing. --- gcc/lower-subreg.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/gcc/lower-subreg.c b/gcc/lower-subreg.c index a11e535b5bf..abe7180c686 100644 --- a/gcc/lower-subreg.c +++ b/gcc/lower-subreg.c @@ -1087,12 +1087,21 @@ resolve_simple_move (rtx set, rtx_insn *insn) emit_clobber (dest); for (i = 0; i < words; ++i) - emit_move_insn (simplify_gen_subreg_concatn (word_mode, dest, - dest_mode, - i * UNITS_PER_WORD), - simplify_gen_subreg_concatn (word_mode, src, - orig_mode, - i * UNITS_PER_WORD)); + { + rtx t = simplify_gen_subreg_concatn (word_mode, dest, + dest_mode, + i * UNITS_PER_WORD); + /* simplify_gen_subreg_concatn can return (const_int 0) for + some sub-objects of paradoxical subregs. As a source operand, + that's fine. As a destination it must be avoided. Those are + supposed to be don't care bits, so we can just drop that store + on the floor. */ + if (t != CONST0_RTX (word_mode)) + emit_move_insn (t, + simplify_gen_subreg_concatn (word_mode, src, + orig_mode, + i * UNITS_PER_WORD)); + } } if (real_dest != NULL_RTX) -- 2.30.2