| Message ID | 20120202223046.556E9C214D@rong.mtv.corp.google.com |
|---|---|
| State | New |
| Headers | show |
ok for google branches. David On Thu, Feb 2, 2012 at 2:30 PM, Rong Xu <xur@google.com> wrote: > Hi, > > This patch curbs the counter scaling factor that causing counter > overflow in inline transformation. The negavie counter triggers > a later pass assertion. > > Tested: inertnal performance benchmarks. > > -Rong > > 2012-02-02 Rong Xu <xur@google.com> > > * tree-inline.c (copy_cfg_body): Curb the scaling factor to > avoid counter overflow. > > Index: tree-inline.c > =================================================================== > --- tree-inline.c (revision 183768) > +++ tree-inline.c (working copy) > @@ -2198,8 +2198,49 @@ > gcov_type incoming_count = 0; > > if (ENTRY_BLOCK_PTR_FOR_FUNCTION (src_cfun)->count) > - count_scale = (REG_BR_PROB_BASE * (double)count > - / ENTRY_BLOCK_PTR_FOR_FUNCTION (src_cfun)->count); > + { > + struct cgraph_node *node = cgraph_node (callee_fndecl); > + double f_max; > + gcov_type max_count_scale; > + gcov_type callee_max_bb_cnt; > + gcov_type max_value = ((gcov_type) 1 << ((sizeof(gcov_type) * 8) - 1)); > + max_value = ~max_value; > + count_scale = (REG_BR_PROB_BASE * (double)count > + / ENTRY_BLOCK_PTR_FOR_FUNCTION (src_cfun)->count); > + > + /* Reducing the scaling factor when it can cause counter overflow. > + This can happen for comdat functions where the counters are split. > + It's more likely for recursive inlines. */ > + gcc_assert (node); > + callee_max_bb_cnt = node->max_bb_count; > + > + if (callee_max_bb_cnt == 0) > + { > + gcov_type c = ENTRY_BLOCK_PTR_FOR_FUNCTION (src_cfun)->count; > + > + FOR_EACH_BB_FN (bb, src_cfun) > + if (bb->count > node->max_bb_count) > + callee_max_bb_cnt = node->max_bb_count; > + > + if (c > callee_max_bb_cnt) > + callee_max_bb_cnt = c; > + > + node->max_bb_count = callee_max_bb_cnt; > + } > + > + f_max = (double) max_value * REG_BR_PROB_BASE / callee_max_bb_cnt - 1; > + if (f_max > max_value) > + max_count_scale = max_value; > + else > + max_count_scale = f_max; > + > + if (count_scale > max_count_scale) > + { > + if (flag_opt_info >= OPT_INFO_MED) > + warning (0, "Reducing scaling factor to avoid counter overflow."); > + count_scale = max_count_scale; > + } > + } > else > count_scale = REG_BR_PROB_BASE; > > @@ -2221,7 +2262,7 @@ > incoming_frequency += EDGE_FREQUENCY (e); > incoming_count += e->count; > } > - incoming_count = incoming_count * count_scale / REG_BR_PROB_BASE; > + incoming_count = ((double) incoming_count) * count_scale / REG_BR_PROB_BASE; > incoming_frequency > = incoming_frequency * frequency_scale / REG_BR_PROB_BASE; > ENTRY_BLOCK_PTR->count = incoming_count; > > -- > This patch is available for review at http://codereview.appspot.com/5622052
Index: tree-inline.c =================================================================== --- tree-inline.c (revision 183768) +++ tree-inline.c (working copy) @@ -2198,8 +2198,49 @@ gcov_type incoming_count = 0; if (ENTRY_BLOCK_PTR_FOR_FUNCTION (src_cfun)->count) - count_scale = (REG_BR_PROB_BASE * (double)count - / ENTRY_BLOCK_PTR_FOR_FUNCTION (src_cfun)->count); + { + struct cgraph_node *node = cgraph_node (callee_fndecl); + double f_max; + gcov_type max_count_scale; + gcov_type callee_max_bb_cnt; + gcov_type max_value = ((gcov_type) 1 << ((sizeof(gcov_type) * 8) - 1)); + max_value = ~max_value; + count_scale = (REG_BR_PROB_BASE * (double)count + / ENTRY_BLOCK_PTR_FOR_FUNCTION (src_cfun)->count); + + /* Reducing the scaling factor when it can cause counter overflow. + This can happen for comdat functions where the counters are split. + It's more likely for recursive inlines. */ + gcc_assert (node); + callee_max_bb_cnt = node->max_bb_count; + + if (callee_max_bb_cnt == 0) + { + gcov_type c = ENTRY_BLOCK_PTR_FOR_FUNCTION (src_cfun)->count; + + FOR_EACH_BB_FN (bb, src_cfun) + if (bb->count > node->max_bb_count) + callee_max_bb_cnt = node->max_bb_count; + + if (c > callee_max_bb_cnt) + callee_max_bb_cnt = c; + + node->max_bb_count = callee_max_bb_cnt; + } + + f_max = (double) max_value * REG_BR_PROB_BASE / callee_max_bb_cnt - 1; + if (f_max > max_value) + max_count_scale = max_value; + else + max_count_scale = f_max; + + if (count_scale > max_count_scale) + { + if (flag_opt_info >= OPT_INFO_MED) + warning (0, "Reducing scaling factor to avoid counter overflow."); + count_scale = max_count_scale; + } + } else count_scale = REG_BR_PROB_BASE; @@ -2221,7 +2262,7 @@ incoming_frequency += EDGE_FREQUENCY (e); incoming_count += e->count; } - incoming_count = incoming_count * count_scale / REG_BR_PROB_BASE; + incoming_count = ((double) incoming_count) * count_scale / REG_BR_PROB_BASE; incoming_frequency = incoming_frequency * frequency_scale / REG_BR_PROB_BASE; ENTRY_BLOCK_PTR->count = incoming_count;
Hi, This patch curbs the counter scaling factor that causing counter overflow in inline transformation. The negavie counter triggers a later pass assertion. Tested: inertnal performance benchmarks. -Rong 2012-02-02 Rong Xu <xur@google.com> * tree-inline.c (copy_cfg_body): Curb the scaling factor to avoid counter overflow. -- This patch is available for review at http://codereview.appspot.com/5622052