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Hi, The PR is logged against Darwin, and (as Jakub points out in the PR thread) indeed Darwin is missing a nonlocal_goto_receiver to restore the PIC reg in code that uses it (most of the patch). However, there is a second issue, and (if I've understood things correctly) this affects GOT targets too - thus there is a single non-darwin-specific hunk for which I need approval for X86 as a whole. consider (x86 -fPIC -m32) == int g42 = 42; int foo (void) <=== doesn't use EBX, so doesn't save it. { __label__ x; int z; int bar (int *zz) <== does use EBX, and saves it { *zz = g42; goto x; <== however, EBX is not restored here. } bar(&z); x: return z; } == ... this all works OK when the caller of foo and foo are in one object (and thus share the same GOT) .. however, suppose we build the code above as a shared lib and call it from a pie executable (or another so). Now, when the caller (with a different GOT value from the lib) calls foo() - EBX gets trashed (probably *boom*). The solution proposed here (for this aspect) is that, if a function contains a nonlocal label, then the PICbase register should be preserved. This is the only non-darwin-specific hunk in the patch. [For the Darwin case, it is always necessary to preserve and restore the PIC base, since a different base is used in each function]. The remainder of the patch is darwin-specific, to provide restoration of the pic register at non-local-goto-recievers. == I have verified that the patch works as expected on x86_64-linux (@m32), i686-darwin9 and x86_64-darwin12 (@m32) - and that, otherwise, there are no test changes (Ada and Java tested on Darwin, but not on Linux). (Other Darwin folks {thanks!} have tested this across a wider range of Darwin versions) == OK for trunk? OK open branches? (since this is a wrong code bug) thanks, Iain gcc/ PR target/51784 * config/i386/i386.c (output_set_got, DARWIN): Adjust to emit a second label for nonlocal goto receivers. Don't output pic base labels unless we're producing PIC; mark that action unreachable(). (ix86_save_reg): If the function contains a nonlocal label, save the PIC base reg. * config/darwin-protos.h (machopic_should_output_picbase_label): New. * gcc/config/darwin.c (emitted_pic_label_num): New GTY. (update_pic_label_number_if_needed): New. (machopic_output_function_base_name): Adjust for nonlocal receiver case. (machopic_should_output_picbase_label): New. * config/i386/i386.md (enum unspecv): UNSPECV_NLGR: New. (nonlocal_goto_receiver): New insn and split.
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