On Wed, Apr 30, 2025 at 7:40 PM Uros Bizjak <ubiz...@gmail.com> wrote: > > On Tue, Apr 29, 2025 at 12:22 PM H.J. Lu <hjl.to...@gmail.com> wrote: > > > > On Tue, Apr 29, 2025 at 5:30 PM Uros Bizjak <ubiz...@gmail.com> wrote: > > > > > > On Tue, Apr 29, 2025 at 9:56 AM H.J. Lu <hjl.to...@gmail.com> wrote: > > > > > > > > Don't expand UNSPEC_TLS_LD_BASE to a call so that the RTL local copy > > > > propagation pass can eliminate multiple __tls_get_addr calls. > > > > > > __tls_get_addr needs to be called with 16-byte aligned stack, I don't > > > think the compiler will correctly handle required call alignment if > > > you emit the call without emit_libcall_block. > > > > ix86_split_tls_local_dynamic_base_64 generates the same sequence > > as emit_libcall_block. stack alignment is handled by > > > > (define_expand "@tls_local_dynamic_base_64_<mode>" > > [(set (match_operand:P 0 "register_operand") > > (unspec:P > > [(match_operand 1 "constant_call_address_operand") > > (reg:P SP_REG)] > > UNSPEC_TLS_LD_BASE))] > > "TARGET_64BIT" > > "ix86_tls_descriptor_calls_expanded_in_cfun = true;") > > The above is to align the initial %rsp at the beginning of the > function. When PUSH instructions in the function misaling %rsp, there > will be nothing to keep %rsp aligned before the call to > __tls_get_addr. > > We have been bitten by this in the past. >
True: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066 which was fixed by commit 272325bd6abba598a8f125dab36b626acb648b03 Author: Wei Mi <w...@google.com> Date: Thu May 8 16:44:52 2014 +0000 re PR target/58066 (__tls_get_addr is called with misaligned stack on x86-64 ) __tls_get_addr doesn't take an argument and my patch still aligns the stack properly. -- H.J.
