Hi! profiledbootstrap with --disable-poststage-build-with-cxx and -fexceptions currently fails on x86_64-linux. The problem is that no EDGE_FAKE edge is added from noreturn fatal_error call to the exit block, eventhough fatal_error calls exit. The problem is that we have several places which add EDGE_FAKE edges. One is add_noreturn_fake_exit_edges, which adds EDGE_FAKE to bbs with zero successor (not this case, because after the call there is EDGE_EH (to a ={v} {CLOBBER} bb, which is why this is a regression)). And another one is gimple_flow_call_edges_add, but that one skips all ECF_NORETURN calls, based on the assumption (apparently wrong) that all noreturn calls have zero successor edges. And the third place that adds EDGE_FAKE edges is branch_prob itself, but it does so only for abnormal edges.
I think this bug can be fixed in any of the 3 places, the following patch changes the second one. Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2012-01-04 Jakub Jelinek <ja...@redhat.com> PR bootstrap/51648 * tree-cfg.c (need_fake_edge_p): Return true also for noreturn calls that have any non-fake successor edges. --- gcc/tree-cfg.c.jj 2011-12-27 11:39:49.000000000 +0100 +++ gcc/tree-cfg.c 2012-01-04 22:30:22.072838130 +0100 @@ -6882,9 +6882,20 @@ need_fake_edge_p (gimple t) && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_FORK)) return false; - if (is_gimple_call (t) - && !(call_flags & ECF_NORETURN)) - return true; + if (is_gimple_call (t)) + { + edge_iterator ei; + edge e; + basic_block bb; + + if (!(call_flags & ECF_NORETURN)) + return true; + + bb = gimple_bb (t); + FOR_EACH_EDGE (e, ei, bb->succs) + if ((e->flags & EDGE_FAKE) == 0) + return true; + } if (gimple_code (t) == GIMPLE_ASM && (gimple_asm_volatile_p (t) || gimple_asm_input_p (t))) @@ -6895,9 +6906,10 @@ need_fake_edge_p (gimple t) /* Add fake edges to the function exit for any non constant and non - noreturn calls, volatile inline assembly in the bitmap of blocks - specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return - the number of blocks that were split. + noreturn calls (or noreturn calls with EH/abnormal edges), + volatile inline assembly in the bitmap of blocks specified by BLOCKS + or to the whole CFG if BLOCKS is zero. Return the number of blocks + that were split. The goal is to expose cases in which entering a basic block does not imply that all subsequent instructions must be executed. */ Jakub