While looking at the use of cst_and_fits_in_hwi in tree-ssa-loop-ivopts.c, I had difficulty working out what the function actually tests. The final NUNITS check seems redundant, since it asks about the number of HWIs in the _unextended_ constant. We've already checked that the unextended constant has no more than HOST_BITS_PER_WIDE_INT bits, so the length must be 1.
I think this was my fault, sorry. Tested on x86_64-linux-gnu and aarch64-linux-gnu. OK to install? Thanks, Richard gcc/ * tree.c (cst_and_fits_in_hwi): Simplify. Index: gcc/tree.c =================================================================== --- gcc/tree.c +++ gcc/tree.c @@ -1675,13 +1675,8 @@ build_low_bits_mask (tree type, unsigned bits) bool cst_and_fits_in_hwi (const_tree x) { - if (TREE_CODE (x) != INTEGER_CST) - return false; - - if (TYPE_PRECISION (TREE_TYPE (x)) > HOST_BITS_PER_WIDE_INT) - return false; - - return TREE_INT_CST_NUNITS (x) == 1; + return (TREE_CODE (x) == INTEGER_CST + && TYPE_PRECISION (TREE_TYPE (x)) <= HOST_BITS_PER_WIDE_INT); } /* Build a newly constructed VECTOR_CST node of length LEN. */