From 630c9a4d54de7c084e146afe82c6e89a9f2cf3d7 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Sat, 5 Dec 2020 18:26:25 +0000 Subject: [PATCH] jump: Also handle jumps wrapped in UNSPEC or UNSPEC_VOLATILE VAX has interlocked branch instructions used for atomic operations and we want to have them wrapped in UNSPEC_VOLATILE so as not to have code carried across. This however breaks with jump optimization and leads to an ICE in the build of libbacktrace like: .../libbacktrace/mmap.c:190:1: internal compiler error: in fixup_reorder_chain, at cfgrtl.c:3934 190 | } | ^ 0x1087d46b fixup_reorder_chain .../gcc/cfgrtl.c:3934 0x1087f29f cfg_layout_finalize() .../gcc/cfgrtl.c:4447 0x1087c74f execute .../gcc/cfgrtl.c:3662 on RTL like: (jump_insn 18 17 150 4 (unspec_volatile [ (set (pc) (if_then_else (eq (zero_extract:SI (mem/v:SI (reg/f:SI 23 [ _2 ]) [-1 S4 A32]) (const_int 1 [0x1]) (const_int 0 [0])) (const_int 1 [0x1])) (label_ref 20) (pc))) (set (zero_extract:SI (mem/v:SI (reg/f:SI 23 [ _2 ]) [-1 S4 A32]) (const_int 1 [0x1]) (const_int 0 [0])) (const_int 1 [0x1])) ] 101) ".../libbacktrace/mmap.c":135:14 158 {jbbssisi} (nil) -> 20) when those branches are enabled with a follow-up change. Also showing with: FAIL: gcc.dg/pr61756.c (internal compiler error) Handle branches wrapped in UNSPEC_VOLATILE then and, for consistency, also in UNSPEC. The presence of UNSPEC_VOLATILE will prevent such branches from being removed as they won't be accepted by `onlyjump_p', we just need to let them through. gcc/ * jump.c (pc_set): Also accept a jump wrapped in UNSPEC or UNSPEC_VOLATILE. (any_uncondjump_p, any_condjump_p): Update comment accordingly. --- gcc/jump.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/gcc/jump.c b/gcc/jump.c index 34a8f209e20..c508467c696 100644 --- a/gcc/jump.c +++ b/gcc/jump.c @@ -850,9 +850,17 @@ pc_set (const rtx_insn *insn) pat = PATTERN (insn); /* The set is allowed to appear either as the insn pattern or - the first set in a PARALLEL. */ - if (GET_CODE (pat) == PARALLEL) - pat = XVECEXP (pat, 0, 0); + the first set in a PARALLEL, UNSPEC or UNSPEC_VOLATILE. */ + switch (GET_CODE (pat)) + { + case PARALLEL: + case UNSPEC: + case UNSPEC_VOLATILE: + pat = XVECEXP (pat, 0, 0); + break; + default: + break; + } if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == PC) return pat; @@ -860,7 +868,9 @@ pc_set (const rtx_insn *insn) } /* Return true when insn is an unconditional direct jump, - possibly bundled inside a PARALLEL. */ + possibly bundled inside a PARALLEL, UNSPEC or UNSPEC_VOLATILE. + The instruction may have various other effects so before removing the jump + you must verify onlyjump_p. */ int any_uncondjump_p (const rtx_insn *insn) @@ -876,9 +886,9 @@ any_uncondjump_p (const rtx_insn *insn) } /* Return true when insn is a conditional jump. This function works for - instructions containing PC sets in PARALLELs. The instruction may have - various other effects so before removing the jump you must verify - onlyjump_p. + instructions containing PC sets in PARALLELs, UNSPECs or UNSPEC_VOLATILEs. + The instruction may have various other effects so before removing the jump + you must verify onlyjump_p. Note that unlike condjump_p it returns false for unconditional jumps. */ -- 2.30.2