From 294ca9eca0293146d91768f7a75335fb642b489e Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Sun, 13 Dec 2020 20:46:17 +0000 Subject: [PATCH] VAX: Handle subtracting from self with QMATH DImode add/sub Remove an assertion the failure of which has not been actually observed, but which appears clearly dangerous, for when the QMATH DImode add/sub handler is invoked with the subtrahend and the minuend both the same. Instead handle the operation by emitting a move of constant 0 to the output operand. Adjust the relevant inline comment accordingly. gcc/ * config/vax/vax.c (vax_expand_addsub_di_operands): Handle equal input operands with subtraction. --- gcc/config/vax/vax.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/gcc/config/vax/vax.c b/gcc/config/vax/vax.c index 2274cce6a5b..07c499c78af 100644 --- a/gcc/config/vax/vax.c +++ b/gcc/config/vax/vax.c @@ -2042,12 +2042,14 @@ vax_expand_addsub_di_operands (rtx * operands, enum rtx_code code) } else { - /* If are adding the same value together, that's really a multiply by 2, - and that's just a left shift of 1. */ + /* If we are adding a value to itself, that's really a multiply by 2, + and that's just a left shift by 1. If subtracting, it's just 0. */ if (rtx_equal_p (operands[1], operands[2])) { - gcc_assert (code != MINUS); - emit_insn (gen_ashldi3 (operands[0], operands[1], const1_rtx)); + if (code == PLUS) + emit_insn (gen_ashldi3 (operands[0], operands[1], const1_rtx)); + else + emit_move_insn (operands[0], const0_rtx); return; } -- 2.30.2