From 6cdcce60ff317b9a3feca930306194f110ed0171 Mon Sep 17 00:00:00 2001 From: Segher Boessenkool Date: Wed, 19 Jul 2017 21:31:26 +0200 Subject: [PATCH] combine: Fix for PR81423 We here have an AND of a SUBREG of an LSHIFTRT. If that SUBREG is paradoxical, the extraction we form is the length of the size of the inner mode, which includes some bits that should not be in the result. Just give up in that case. PR rtl-optimization/81423 * combine.c (make_compound_operation_int): Don't try to optimize the AND of a SUBREG of an LSHIFTRT if that SUBREG is paradoxical. From-SVN: r250365 --- gcc/ChangeLog | 6 ++++++ gcc/combine.c | 15 +++------------ 2 files changed, 9 insertions(+), 12 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 4de6391..96c0e35 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2018-07-19 Segher Boessenkool + + PR rtl-optimization/81423 + * combine.c (make_compound_operation_int): Don't try to optimize + the AND of a SUBREG of an LSHIFTRT if that SUBREG is paradoxical. + 2017-07-19 Segher Boessenkool PR rtl-optimization/81423 diff --git a/gcc/combine.c b/gcc/combine.c index c1eec91..8dc62b5 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -7956,18 +7956,9 @@ make_compound_operation_int (machine_mode mode, rtx *x_ptr, XEXP (inner_x0, 1), i, 1, 0, in_code == COMPARE); - if (new_rtx) - { - /* If we narrowed the mode when dropping the subreg, then - we must zero-extend to keep the semantics of the AND. */ - if (GET_MODE_SIZE (inner_mode) >= GET_MODE_SIZE (mode)) - ; - else if (SCALAR_INT_MODE_P (inner_mode)) - new_rtx = simplify_gen_unary (ZERO_EXTEND, mode, - new_rtx, inner_mode); - else - new_rtx = NULL; - } + /* If we narrowed the mode when dropping the subreg, then we lose. */ + if (GET_MODE_SIZE (inner_mode) < GET_MODE_SIZE (mode)) + new_rtx = NULL; /* If that didn't give anything, see if the AND simplifies on its own. */ -- 2.7.4