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| author | Segher Boessenkool <segher@kernel.crashing.org> | 2017-04-01 00:49:53 +0200 |
|---|---|---|
| committer | Jeff Law <law@gcc.gnu.org> | 2017-03-31 16:49:53 -0600 |
| commit | a5a9046deb1a43c09e53b7e406319ac7936c2e07 (patch) | |
| tree | bf4be001d4d273f6547bada534c9faa1206afa85 /gcc/fwprop.c | |
| parent | eee3756de395ab6220f78b471a7cd877301455a2 (diff) | |
| download | gcc-a5a9046deb1a43c09e53b7e406319ac7936c2e07.zip gcc-a5a9046deb1a43c09e53b7e406319ac7936c2e07.tar.gz gcc-a5a9046deb1a43c09e53b7e406319ac7936c2e07.tar.bz2 | |
re PR rtl-optimization/79405 (Infinite loop in fwprop)
PR rtl-optimization/79405
* fwprop.c (propagations_left): New variable.
(forward_propagate_into): Decrement it.
(fwprop_init): Initialize it.
(fw_prop): If the variable has reached zero, stop propagating.
(fwprop_addr): Ditto.
gcc/testsuite/
PR rtl-optimization/79405
gcc.dg/pr79405.c: New testcase.
From-SVN: r246627
Diffstat (limited to 'gcc/fwprop.c')
| -rw-r--r-- | gcc/fwprop.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/gcc/fwprop.c b/gcc/fwprop.c index 285fb1a..0ab25ef 100644 --- a/gcc/fwprop.c +++ b/gcc/fwprop.c @@ -120,6 +120,13 @@ static vec<df_ref> use_def_ref; static vec<df_ref> reg_defs; static vec<df_ref> reg_defs_stack; +/* The maximum number of propagations that are still allowed. If we do + more propagations than originally we had uses, we must have ended up + in a propagation loop, as in PR79405. Until the algorithm fwprop + uses can obviously not get into such loops we need a workaround like + this. */ +static int propagations_left; + /* The MD bitmaps are trimmed to include only live registers to cut memory usage on testcases like insn-recog.c. Track live registers in the basic block and do not perform forward propagation if the @@ -1407,6 +1414,8 @@ forward_propagate_into (df_ref use) if (forward_propagate_and_simplify (use, def_insn, def_set) || forward_propagate_subreg (use, def_insn, def_set)) { + propagations_left--; + if (cfun->can_throw_non_call_exceptions && find_reg_note (use_insn, REG_EH_REGION, NULL_RTX) && purge_dead_edges (DF_REF_BB (use))) @@ -1434,6 +1443,8 @@ fwprop_init (void) active_defs = XNEWVEC (df_ref, max_reg_num ()); if (flag_checking) active_defs_check = sparseset_alloc (max_reg_num ()); + + propagations_left = DF_USES_TABLE_SIZE (); } static void @@ -1480,6 +1491,9 @@ fwprop (void) for (i = 0; i < DF_USES_TABLE_SIZE (); i++) { + if (!propagations_left) + break; + df_ref use = DF_USES_GET (i); if (use) if (DF_REF_TYPE (use) == DF_REF_REG_USE @@ -1540,6 +1554,9 @@ fwprop_addr (void) end, and we'll go through them as well. */ for (i = 0; i < DF_USES_TABLE_SIZE (); i++) { + if (!propagations_left) + break; + df_ref use = DF_USES_GET (i); if (use) if (DF_REF_TYPE (use) != DF_REF_REG_USE |