From b8697d0cd06da3375063295fe7161671e0904459 Mon Sep 17 00:00:00 2001 From: Roger Sayle Date: Mon, 13 Jul 2020 09:49:34 +0100 Subject: [PATCH] middle-end: Remove truly_noop_truncation check from convert.c This patch eliminates a check of targetm.truly_noop_truncation from the early middle-end, where the gimple/generic being generated by GCC's front-ends is being inappropriately influenced by the target's TRULY_NOOP_TRUNCATION. The (recent) intention of TRULY_NOOP_TRUNCATION is to indicate that a backend requires explicit truncation instructions rather than using SUBREGs to perform truncations. A long standing (and probably unintentional) side-effect has been that this setting also controls whether the middle-end narrows integer operations at the tree-level. Understandably, GCC and its testsuite assume that GIMPLE and GENERIC behave consistently across platforms, and alas defining TRULY_NOOP_TRUNCATION away from the default triggers several regressions (including gcc.dg/fold-rotate-1.c). 2020-07-13 Roger Sayle gcc/ChangeLog * convert.c (convert_to_integer_1): Narrow integer operations even on targets that require explicit truncation instructions. --- gcc/convert.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/gcc/convert.c b/gcc/convert.c index 42509c518a9..292c5133974 100644 --- a/gcc/convert.c +++ b/gcc/convert.c @@ -836,16 +836,10 @@ convert_to_integer_1 (tree type, tree expr, bool dofold) && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg1, 0)))) break; - if (outprec >= BITS_PER_WORD - || targetm.truly_noop_truncation (outprec, inprec) - || inprec > TYPE_PRECISION (TREE_TYPE (arg0)) - || inprec > TYPE_PRECISION (TREE_TYPE (arg1))) - { - tree tem = do_narrow (loc, ex_form, type, arg0, arg1, - expr, inprec, outprec, dofold); - if (tem) - return tem; - } + tree tem = do_narrow (loc, ex_form, type, arg0, arg1, + expr, inprec, outprec, dofold); + if (tem) + return tem; } break; -- 2.30.2