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Fix PR rtl-optimization/100411

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This is the bootstrap failure of GCC 11 on MinGW64 configured with --enable-
tune=nocona.  The bottom line is that SEH does not support CFI for epilogues
but the x86 back-end nevertheless attaches it to instructions, so we have to
filter it out and this is done by detecting the end of the prologue by means
of the NOTE_INSN_PROLOGUE_END note.

But the compiler manages to generate a second epilogue before this note in
the RTL stream and this fools the aforementioned logic.  The root cause is
cross-jumping, which inserts a jump before the end of the prologue, in fact
just before the note; the rest (CFG cleanup, BB reordering, etc) is downhill
from there.

gcc/
	PR rtl-optimization/100411
	* cfgcleanup.c (try_crossjump_to_edge): Also skip end of prologue
	and beginning of function markers.
This commit is contained in:
Eric Botcazou 2021-05-05 16:50:55 +02:00
parent 14cf6aab85
commit dfd2c92f3f
1 changed files with 5 additions and 1 deletions
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6
gcc/cfgcleanup.c
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@ -2145,7 +2145,11 @@ try_crossjump_to_edge (int mode, edge e1, edge e2,
if (NOTE_INSN_BASIC_BLOCK_P (newpos1))
newpos1 = NEXT_INSN (newpos1);
while (DEBUG_INSN_P (newpos1))
/* Skip also prologue and function markers. */
while (DEBUG_INSN_P (newpos1)
|| (NOTE_P (newpos1)
&& (NOTE_KIND (newpos1) == NOTE_INSN_PROLOGUE_END
|| NOTE_KIND (newpos1) == NOTE_INSN_FUNCTION_BEG)))
newpos1 = NEXT_INSN (newpos1);
redirect_from = split_block (src1, PREV_INSN (newpos1))->src;