From 4c334e0e4ff05d3a7ca9ebb832428c446cd0ae8d Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 9 Jun 2022 17:42:31 +0200 Subject: c++: Fix up ICE on __builtin_shufflevector constexpr evaluation [PR105871] As the following testcase shows, BIT_FIELD_REF result doesn't have to have just integral type, it can also have vector type. And in that case cxx_eval_bit_field_ref just ICEs on it because it is unprepared for that case, creates the initial value with build_int_cst (sure, that one could be easily replaced with build_zero_cst) and then expects it can through shifts, ands and ors come up with the final value, but that doesn't work for vectors. We already call fold_ternary if whole is a VECTOR_CST, this patch does the same if the result doesn't have integral type. And, there is no guarantee fold_ternary will succeed and the callers certainly don't expect NULL being returned, so it also diagnoses those as non-constant and returns original t in that case. 2022-06-09 Jakub Jelinek PR c++/105871 * constexpr.cc (cxx_eval_bit_field_ref): For BIT_FIELD_REF with non-integral result type use fold_ternary too like for BIT_FIELD_REFs from VECTOR_CST. If fold_ternary returns NULL, diagnose non-constant expression, set *non_constant_p and return t, instead of returning NULL. * g++.dg/pr105871.C: New test. --- gcc/cp/constexpr.cc | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'gcc/cp/constexpr.cc') diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index 6842388..fd7f8c0 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -4198,9 +4198,16 @@ cxx_eval_bit_field_ref (const constexpr_ctx *ctx, tree t, if (*non_constant_p) return t; - if (TREE_CODE (whole) == VECTOR_CST) - return fold_ternary (BIT_FIELD_REF, TREE_TYPE (t), whole, - TREE_OPERAND (t, 1), TREE_OPERAND (t, 2)); + if (TREE_CODE (whole) == VECTOR_CST || !INTEGRAL_TYPE_P (TREE_TYPE (t))) + { + if (tree r = fold_ternary (BIT_FIELD_REF, TREE_TYPE (t), whole, + TREE_OPERAND (t, 1), TREE_OPERAND (t, 2))) + return r; + if (!ctx->quiet) + error ("%qE is not a constant expression", orig_whole); + *non_constant_p = true; + return t; + } start = TREE_OPERAND (t, 2); istart = tree_to_shwi (start); -- cgit v1.1