On 23 May 2014 17:05, Richard Biener <richard.guent...@gmail.com> wrote: > On Fri, May 23, 2014 at 9:23 AM, Zhenqiang Chen > <zhenqiang.c...@linaro.org> wrote: >> Hi, >> >> The patch fixes PR rtl-optimization/61278. Root cause for issue is >> that df_live does not exist at -O1. >> >> Bootstrap and no make check regression on X86-64. >> >> OK for trunk? > > Why do you need to give up? It seems you can simply avoid > marking the block as dirty (though df_get_live_in/out also hands you > back DF_LR_IN/OUT if !df_live). So isn't the df_grow_bb_info the > "real" fix?
The df_get_live_in of the new basic block will be used to analyse later INSNs. If it is not set or incorrect, it will impact on later analysis. df_grow_bb_info is to make sure the live_in data structure is allocated for the new basic block (although I have not found any case fail without it). After bitmap_copy(...), we can use it for later INSNs. > Note that df_get_live_in/out are functions tailored to IRA that > knows that they handle both df_live and df_lr dependent on > optimization level. Is shrink-wrapping supposed to work with > both problems as well? Yes. But it seams not perfect to handle df_lr problem. When I fixed PR 57637 (https://gcc.gnu.org/ml/gcc-patches/2013-07/msg00897.html), we selected "if DF_LIVE doesn't exist, i.e. at -O1, just give up searching NEXT_BLOCK." Thanks! -Zhenqiang >> >> ChangeLog: >> 2014-05-23 Zhenqiang Chen <zhenqiang.c...@linaro.org> >> >> PR rtl-optimization/61278 >> * shrink-wrap.c (move_insn_for_shrink_wrap): Check df_live. >> >> testsuite/ChangeLog: >> 2014-05-23 Zhenqiang Chen <zhenqiang.c...@linaro.org> >> >> * gcc.dg/lto/pr61278_0.c: New test. >> * gcc.dg/lto/pr61278_1.c: New test. >> >> diff --git a/gcc/shrink-wrap.c b/gcc/shrink-wrap.c >> index f09cfe7..be17829 100644 >> --- a/gcc/shrink-wrap.c >> +++ b/gcc/shrink-wrap.c >> @@ -204,8 +204,15 @@ move_insn_for_shrink_wrap (basic_block bb, rtx insn, >> /* Create a new basic block on the edge. */ >> if (EDGE_COUNT (next_block->preds) == 2) >> { >> + /* If DF_LIVE doesn't exist, i.e. at -O1, just give up. */ >> + if (!df_live) >> + return false; >> + >> next_block = split_edge (live_edge); >> >> + /* We create a new basic block. Call df_grow_bb_info to make sure >> + all data structures are allocated. */ >> + df_grow_bb_info (df_live); >> bitmap_copy (df_get_live_in (next_block), df_get_live_out (bb)); >> df_set_bb_dirty (next_block); >> >> diff --git a/gcc/testsuite/gcc.dg/lto/pr61278_0.c >> b/gcc/testsuite/gcc.dg/lto/pr61278_0.c >> new file mode 100644 >> index 0000000..03a24ae >> --- /dev/null >> +++ b/gcc/testsuite/gcc.dg/lto/pr61278_0.c >> @@ -0,0 +1,30 @@ >> +/* { dg-lto-do link } */ >> +/* { dg-lto-options { { -flto -O0 } } } */ >> +/* { dg-extra-ld-options " -flto -O1 " } */ >> + >> +static unsigned int >> +fn1 (int p1, int p2) >> +{ >> + return 0; >> +} >> + >> +char a, b, c; >> + >> +char >> +foo (char *p) >> +{ >> + int i; >> + for (b = 1 ; b > 0; b++) >> + { >> + for (i = 0; i < 2; i++) >> + ; >> + for (a = 1; a > 0; a++) >> + { >> + char d[1] = { 0 }; >> + if (*p) >> + break; >> + c ^= fn1 (fn1 (fn1 (0, 0), 0), 0); >> + } >> + } >> + return 0; >> +} >> diff --git a/gcc/testsuite/gcc.dg/lto/pr61278_1.c >> b/gcc/testsuite/gcc.dg/lto/pr61278_1.c >> new file mode 100644 >> index 0000000..b02c8ac >> --- /dev/null >> +++ b/gcc/testsuite/gcc.dg/lto/pr61278_1.c >> @@ -0,0 +1,13 @@ >> +/* { dg-lto-do link } */ >> +/* { dg-lto-options { { -flto -O1 } } } */ >> + >> +extern char foo (char *); >> + >> +char d; >> + >> +int >> +main () >> +{ >> + foo (&d); >> + return 0; >> +}
