[Bug tree-optimization/59303] [4.9 Regression] uninit-pred-8_b.c and uninit-pred-9_b.c fail after better optimizations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59303 Jakub Jelinek jakub at gcc dot gnu.org changed: What|Removed |Added Status|NEW |RESOLVED Resolution|--- |FIXED --- Comment #12 from Jakub Jelinek jakub at gcc dot gnu.org --- Author: davidxl Date: Fri Jan 3 00:40:57 2014 New Revision: 206309 URL: http://gcc.gnu.org/viewcvs?rev=206309root=gccview=rev Log: Fix PR/59303 -- uninit analysis enhancement Modified: trunk/gcc/ChangeLog trunk/gcc/tree-ssa-uninit.c
[Bug tree-optimization/59303] [4.9 Regression] uninit-pred-8_b.c and uninit-pred-9_b.c fail after better optimizations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59303 --- Comment #8 from davidxl at google dot com --- Created attachment 31495 -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=31495action=edit Patch file : cleanup + more predicate simplification rules
[Bug tree-optimization/59303] [4.9 Regression] uninit-pred-8_b.c and uninit-pred-9_b.c fail after better optimizations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59303 Jakub Jelinek jakub at gcc dot gnu.org changed: What|Removed |Added CC||jakub at gcc dot gnu.org --- Comment #9 from Jakub Jelinek jakub at gcc dot gnu.org --- Created attachment 31496 -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=31496action=edit cleanups I had also a brief look at this recently, but haven't made progress beyond attached formatting/cleanup patch so far (plus only dumping details with *-details, otherwise the dumps are pretty much inconsistent). My conclusion has also been that to fix this up the predicates would need to be normalized before comparison, and simplified, at least if the initial subset check fails. On uninit-pred-8_b.c there has been additional complication because PRE decides to change the IL and we end up with: bb 3: pretmp_24 = r_10(D) = 19; goto bb 5; bb 4: _11 = r_10(D) = 19; _13 = l_12(D) != 0; _14 = _11 | _13; if (_14 != 0) goto bb 14; else goto bb 15; bb 14: goto bb 3; bb 15: bb 5: # v_1 = PHI v_15(D)(15), r_10(D)(3) # prephitmp_30 = PHI 0(15), pretmp_24(3) if (m_7(D) != 0) goto bb 6; else goto bb 7; bb 6: g.0_17 = g; g.1_18 = g.0_17 + 1; g = g.1_18; goto bb 8; bb 7: bar (); bb 8: _3 = prephitmp_30 | _9; if (_3 != 0) so the prephitmp_30 would need to be canonicalized into _14 != 0 r_10(D) = 19 aka (r_10(D) = 19 || l_12(D) != 0) r_10(D) = 19 and from there to r_10(D) = 19.
[Bug tree-optimization/59303] [4.9 Regression] uninit-pred-8_b.c and uninit-pred-9_b.c fail after better optimizations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59303 --- Comment #10 from davidxl at google dot com --- My patch does this. 1) it first does aggressive simplification iteratively (more rules can be added later). 2) it then does normalization by building up larger predicate trees by following ud chain and bitwise or/and operations. It handles simple PHIs including also degenerated phis. The new dump reports: in foo, predicate for def: m_7(D) 100 (.OR.) n_5(D) = 9 (.OR.) l_12(D) != 0 (.OR.) r_10(D) = 19 use1: m_7(D) 100 (.OR.) n_5(D) = 9 (.OR.) r_10(D) = 9 use2: m_7(D) 100 (.OR.) n_5(D) = 9 (.OR.) r_10(D) = 19 For foo2, the predicates are properly built, but the patch has a bug in predicate set inclusion testing leading to a false negative. David (In reply to Jakub Jelinek from comment #9) Created attachment 31496 [details] cleanups I had also a brief look at this recently, but haven't made progress beyond attached formatting/cleanup patch so far (plus only dumping details with *-details, otherwise the dumps are pretty much inconsistent). My conclusion has also been that to fix this up the predicates would need to be normalized before comparison, and simplified, at least if the initial subset check fails. On uninit-pred-8_b.c there has been additional complication because PRE decides to change the IL and we end up with: bb 3: pretmp_24 = r_10(D) = 19; goto bb 5; bb 4: _11 = r_10(D) = 19; _13 = l_12(D) != 0; _14 = _11 | _13; if (_14 != 0) goto bb 14; else goto bb 15; bb 14: goto bb 3; bb 15: bb 5: # v_1 = PHI v_15(D)(15), r_10(D)(3) # prephitmp_30 = PHI 0(15), pretmp_24(3) if (m_7(D) != 0) goto bb 6; else goto bb 7; bb 6: g.0_17 = g; g.1_18 = g.0_17 + 1; g = g.1_18; goto bb 8; bb 7: bar (); bb 8: _3 = prephitmp_30 | _9; if (_3 != 0) so the prephitmp_30 would need to be canonicalized into _14 != 0 r_10(D) = 19 aka (r_10(D) = 19 || l_12(D) != 0) r_10(D) = 19 and from there to r_10(D) = 19.
[Bug tree-optimization/59303] [4.9 Regression] uninit-pred-8_b.c and uninit-pred-9_b.c fail after better optimizations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59303 --- Comment #11 from davidxl at google dot com --- The false negative bug introduced in the patch is fixed. Will submit the patch for review soon. (In reply to davidxl from comment #10) My patch does this. 1) it first does aggressive simplification iteratively (more rules can be added later). 2) it then does normalization by building up larger predicate trees by following ud chain and bitwise or/and operations. It handles simple PHIs including also degenerated phis. The new dump reports: in foo, predicate for def: m_7(D) 100 (.OR.) n_5(D) = 9 (.OR.) l_12(D) != 0 (.OR.) r_10(D) = 19 use1: m_7(D) 100 (.OR.) n_5(D) = 9 (.OR.) r_10(D) = 9 use2: m_7(D) 100 (.OR.) n_5(D) = 9 (.OR.) r_10(D) = 19 For foo2, the predicates are properly built, but the patch has a bug in predicate set inclusion testing leading to a false negative. David (In reply to Jakub Jelinek from comment #9) Created attachment 31496 [details] cleanups I had also a brief look at this recently, but haven't made progress beyond attached formatting/cleanup patch so far (plus only dumping details with *-details, otherwise the dumps are pretty much inconsistent). My conclusion has also been that to fix this up the predicates would need to be normalized before comparison, and simplified, at least if the initial subset check fails. On uninit-pred-8_b.c there has been additional complication because PRE decides to change the IL and we end up with: bb 3: pretmp_24 = r_10(D) = 19; goto bb 5; bb 4: _11 = r_10(D) = 19; _13 = l_12(D) != 0; _14 = _11 | _13; if (_14 != 0) goto bb 14; else goto bb 15; bb 14: goto bb 3; bb 15: bb 5: # v_1 = PHI v_15(D)(15), r_10(D)(3) # prephitmp_30 = PHI 0(15), pretmp_24(3) if (m_7(D) != 0) goto bb 6; else goto bb 7; bb 6: g.0_17 = g; g.1_18 = g.0_17 + 1; g = g.1_18; goto bb 8; bb 7: bar (); bb 8: _3 = prephitmp_30 | _9; if (_3 != 0) so the prephitmp_30 would need to be canonicalized into _14 != 0 r_10(D) = 19 aka (r_10(D) = 19 || l_12(D) != 0) r_10(D) = 19 and from there to r_10(D) = 19.
[Bug tree-optimization/59303] [4.9 Regression] uninit-pred-8_b.c and uninit-pred-9_b.c fail after better optimizations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59303 Richard Biener rguenth at gcc dot gnu.org changed: What|Removed |Added Priority|P3 |P1
[Bug tree-optimization/59303] [4.9 Regression] uninit-pred-8_b.c and uninit-pred-9_b.c fail after better optimizations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59303 --- Comment #5 from davidxl xinliangli at gmail dot com --- Fixing this requires more powerful predicate analysis with the help of value equivalent classes. From the dump: Use in stmt blah (v_1); is guarded by : if (_23 != 0) _23 = pephitmp_22 | _8, so the use guard is prephitmp_22 != 0 || _8 != 0 prephitmp_22 = PHI 0(13), prephitmp_21(3), so the guard can be translated to prephitmp_21 != 0 || _8 != 0 prephitmp_21 = r_9(D) = 19, so the predicate becomes r_9(D) = 19 || _8 != 0 For the def: [CHECK] Found def edge 1 in v_1 = PHI v_14(D)(13), r_9(D)(3) Operand defs of phi v_1 = PHI v_14(D)(13), r_9(D)(3) is guarded by : if (_8 != 0) (.OR.) (.NOT.) if (_8 != 0) (.AND.) if (_13 != 0) the predicate is _8 != 0 || _13 != 0 where _13 = _10 | _12, 10_ = (r_9(D) = 19), _12 = l_11(D) != 0 so the predicate is _8 != 0 || r_9(D) = 19 || 1_11(D) != 0 which is the superset for the use. Perhaps we need to do around of predicate normalization before comparison. David
[Bug tree-optimization/59303] [4.9 Regression] uninit-pred-8_b.c and uninit-pred-9_b.c fail after better optimizations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59303 --- Comment #6 from davidxl xinliangli at gmail dot com --- I am working on a solution (and some cleanups). David
[Bug tree-optimization/59303] [4.9 Regression] uninit-pred-8_b.c and uninit-pred-9_b.c fail after better optimizations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59303 davidxl at google dot com changed: What|Removed |Added CC||davidxl at google dot com --- Comment #7 from davidxl at google dot com --- Testing a fix that addresses the problem. With the fix, the dump shows: Use in stmt: blah (v_1); is guarded by : m_6(D) 100 (.OR.) n_4(D) = 9 (.OR.) r_9(D) = 19 Operand defs of phi: v_1 = PHI v_14(D)(13), r_9(D)(3) is guarded by : m_6(D) 100 (.OR.) n_4(D) = 9 (.OR.) l_11(D) != 0 (.OR.) r_9(D) = 19 which is correct.
[Bug tree-optimization/59303] [4.9 Regression] uninit-pred-8_b.c and uninit-pred-9_b.c fail after better optimizations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59303 Richard Biener rguenth at gcc dot gnu.org changed: What|Removed |Added Target||arm, x86_64 Status|UNCONFIRMED |NEW Keywords||diagnostic Last reconfirmed||2013-11-27 CC||xinliangli at gmail dot com Ever confirmed|0 |1 Summary|uninit-pred-8_b.c and |[4.9 Regression] |uninit-pred-9_b.c fail |uninit-pred-8_b.c and |after better optimizations |uninit-pred-9_b.c fail ||after better optimizations Target Milestone|--- |4.9.0 --- Comment #4 from Richard Biener rguenth at gcc dot gnu.org --- Confirmed. They fail for quite some while. The uninit pass needs to cope with combined predicates.
