From: Jakub Jelinek Date: Wed, 18 Oct 2023 15:01:26 +0000 (+0200) Subject: cse: Workaround GCC < 5 bug in cse_insn [PR111852] X-Git-Tag: basepoints/gcc-15~5417 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bc4bd69faf986326f6b0fd0400cdd6871577afd1;p=thirdparty%2Fgcc.git cse: Workaround GCC < 5 bug in cse_insn [PR111852] Before the r5-3834 commit for PR63362, GCC 4.8-4.9 refuses to compile cse.cc which contains a variable with rtx_def type, because rtx_def contains a union with poly_uint16 element. poly_int template has defaulted default constructor and a variadic template constructor which could have empty parameter pack. GCC < 5 treated it as non-trivially constructible class and deleted rtunion and rtx_def default constructors. For the cse_insn purposes, all we need is a variable with size and alignment of rtx_def, not necessarily rtx_def itself, which we then memset to 0 and fill in like rtx is normally allocated from heap, so this patch for GCC_VERSION < 5000 uses an unsigned char array of the right size/alignment. 2023-10-18 Jakub Jelinek PR bootstrap/111852 * cse.cc (cse_insn): Add workaround for GCC 4.8-4.9, instead of using rtx_def type for memory_extend_buf, use unsigned char arrayy with size of rtx_def and its alignment. --- diff --git a/gcc/cse.cc b/gcc/cse.cc index c46870059e6c..f9603fdfd437 100644 --- a/gcc/cse.cc +++ b/gcc/cse.cc @@ -4951,8 +4951,15 @@ cse_insn (rtx_insn *insn) && is_a (mode, &int_mode) && (extend_op = load_extend_op (int_mode)) != UNKNOWN) { +#if GCC_VERSION >= 5000 struct rtx_def memory_extend_buf; rtx memory_extend_rtx = &memory_extend_buf; +#else + /* Workaround GCC < 5 bug, fixed in r5-3834 as part of PR63362 + fix. */ + alignas (rtx_def) unsigned char memory_extended_buf[sizeof (rtx_def)]; + rtx memory_extend_rtx = (rtx) &memory_extended_buf[0]; +#endif /* Set what we are trying to extend and the operation it might have been extended with. */