From 1cde5d85bec20877bed063fc0046b9885231a0ae Mon Sep 17 00:00:00 2001 From: Andrew MacLeod Date: Fri, 9 Oct 2020 10:46:50 +0200 Subject: [PATCH] Fix for PR97317. gcc/ChangeLog: PR tree-optimization/97317 * range-op.cc (operator_cast::op1_range): Handle casts where the precision of the RHS is only 1 greater than the precision of the LHS. gcc/testsuite/ChangeLog: * gcc.dg/pr97317.c: New test. --- gcc/range-op.cc | 25 ++++++++++++++++++------- gcc/testsuite/gcc.dg/pr97317.c | 11 +++++++++++ 2 files changed, 29 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/pr97317.c diff --git a/gcc/range-op.cc b/gcc/range-op.cc index 22bc23c1bbf..d1a11b34894 100644 --- a/gcc/range-op.cc +++ b/gcc/range-op.cc @@ -1849,14 +1849,25 @@ operator_cast::op1_range (irange &r, tree type, type, converted_lhs, lim_range); - // And union this with the entire outer types negative range. - int_range_max neg (type, - wi::min_value (TYPE_PRECISION (type), - SIGNED), - lim - 1); - neg.union_ (lhs_neg); + // lhs_neg now has all the negative versions of the LHS. + // Now union in all the values from SIGNED MIN (0x80000) to + // lim-1 in order to fill in all the ranges with the upper + // bits set. + + // PR 97317. If the lhs has only 1 bit less precision than the rhs, + // we don't need to create a range from min to lim-1 + // calculate neg range traps trying to create [lim, lim - 1]. + wide_int min_val = wi::min_value (TYPE_PRECISION (type), SIGNED); + if (lim != min_val) + { + int_range_max neg (type, + wi::min_value (TYPE_PRECISION (type), + SIGNED), + lim - 1); + lhs_neg.union_ (neg); + } // And finally, munge the signed and unsigned portions. - r.union_ (neg); + r.union_ (lhs_neg); } // And intersect with any known value passed in the extra operand. r.intersect (op2); diff --git a/gcc/testsuite/gcc.dg/pr97317.c b/gcc/testsuite/gcc.dg/pr97317.c new file mode 100644 index 00000000000..f07327ac9a2 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr97317.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +struct a { + unsigned c : 17; +}; +struct a b; +int d(void) { + short e = b.c; + return e ? 0 : b.c; +} -- 2.30.2