Hi,

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 above 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) is downhill from there.

Tested on x86-64/Linux and x86-64/Windows, OK for mainline and 11 branch?


2021-05-05  Eric Botcazou  <ebotcazou@adacore.com>

	PR rtl-optimization/100411
	* cfgcleanup.c (try_crossjump_to_edge): Also skip end of prologue
	and beginning of function markers.

-- 
Eric Botcazou