From 648d30716d0cdb5dec96b2da9ed23328bad7cb9f Mon Sep 17 00:00:00 2001 From: Stefan Schulze Frielinghaus Date: Sun, 15 Oct 2023 11:20:01 +0200 Subject: [PATCH] combine: Fix handling of unsigned constants If a CONST_INT represents an integer of a mode with fewer bits than in HOST_WIDE_INT, then the integer is sign extended. For those two optimizations touched by this patch, the integers of interest have only the most significant bit set w.r.t their mode, therefore, they were sign extended. Thus in order to get the integer of interest, we have to chop off the high bits. gcc/ChangeLog: * combine.cc (simplify_compare_const): Fix handling of unsigned constants. --- gcc/combine.cc | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/gcc/combine.cc b/gcc/combine.cc index 360aa2f25e6a..cb48e7f5b97f 100644 --- a/gcc/combine.cc +++ b/gcc/combine.cc @@ -11923,7 +11923,7 @@ simplify_compare_const (enum rtx_code code, machine_mode mode, /* (unsigned) < 0x80000000 is equivalent to >= 0. */ else if (is_a (mode, &int_mode) && GET_MODE_PRECISION (int_mode) - 1 < HOST_BITS_PER_WIDE_INT - && ((unsigned HOST_WIDE_INT) const_op + && (((unsigned HOST_WIDE_INT) const_op & GET_MODE_MASK (int_mode)) == HOST_WIDE_INT_1U << (GET_MODE_PRECISION (int_mode) - 1))) { const_op = 0; @@ -11962,7 +11962,7 @@ simplify_compare_const (enum rtx_code code, machine_mode mode, /* (unsigned) >= 0x80000000 is equivalent to < 0. */ else if (is_a (mode, &int_mode) && GET_MODE_PRECISION (int_mode) - 1 < HOST_BITS_PER_WIDE_INT - && ((unsigned HOST_WIDE_INT) const_op + && (((unsigned HOST_WIDE_INT) const_op & GET_MODE_MASK (int_mode)) == HOST_WIDE_INT_1U << (GET_MODE_PRECISION (int_mode) - 1))) { const_op = 0; -- 2.47.2