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From: "rsandifo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/96536] New: -fcf-protection code in i386.md:restore_stack_nonlocal uses invalid compare-and-jump rtl Date: Sat, 08 Aug 2020 10:36:54 +0000 [thread overview] Message-ID: <bug-96536-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96536 Bug ID: 96536 Summary: -fcf-protection code in i386.md:restore_stack_nonlocal uses invalid compare-and-jump rtl Product: gcc Version: 11.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: rsandifo at gcc dot gnu.org Target Milestone: --- Target: x86_64 Noticed while working on an optimisation that the -fcf-protection code in restore_stack_nonlocal uses a branch based on a clobber result: (insn 14 13 15 2 (parallel [ (set (reg:DI 85) (minus:DI (reg:DI 85) (mem:DI (plus:DI (reg/f:DI 82) (const_int 16 [0x10])) [2 S8 A8]))) (clobber (reg:CC 17 flags)) ]) "gcc/testsuite/gcc.target/i386/cet-sjlj-1.c":16:3 -1 (nil)) (jump_insn 15 14 40 2 (set (pc) (if_then_else (eq (reg:CCZ 17 flags) (const_int 0 [0])) (label_ref 28) (pc))) "gcc/testsuite/gcc.target/i386/cet-sjlj-1.c":16:3 -1 (int_list:REG_BR_PROB 536870916 (nil)) -> 28) IMO this is invalid RTL. A clobber: Represents the storing or possible storing of an unpredictable, undescribed value … but this usage requires it to be predictable. I think we need to use the parallel-SET *sub<mode>_2 representation instead.
next reply other threads:[~2020-08-08 10:36 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-08 10:36 rsandifo at gcc dot gnu.org [this message] 2020-08-10 8:43 ` [Bug target/96536] " crazylht at gmail dot com 2020-08-10 9:04 ` ubizjak at gmail dot com 2020-08-10 9:32 ` crazylht at gmail dot com 2020-08-13 21:06 ` ubizjak at gmail dot com 2020-08-14 6:33 ` crazylht at gmail dot com 2020-08-17 14:39 ` ubizjak at gmail dot com 2020-08-18 8:54 ` crazylht at gmail dot com 2020-08-18 15:32 ` cvs-commit at gcc dot gnu.org 2020-08-18 15:36 ` cvs-commit at gcc dot gnu.org 2020-08-18 16:49 ` cvs-commit at gcc dot gnu.org 2020-08-18 17:49 ` cvs-commit at gcc dot gnu.org 2020-08-18 17:50 ` ubizjak at gmail dot com
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