[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 Andrew Pinski changed: What|Removed |Added Keywords||TREE --- Comment #10 from Andrew Pinski --- So this is almost fixed on the trunk at -O2: d_4 = (signed char) a_2(D); if (d_4 < 0) goto ; [41.00%] else goto ; [59.00%] [local count: 633507680]: _6 = (signed char) a_2(D); [local count: 1073741824]: # prephitmp_8 = PHI <_6(3), d_4(2)> The only thing missing is seeing that d_4 and _6 are the same ... Maybe factor_out_conditional_operation could detect this ... d_4 = (signed char) a_2(D); if (d_4 < 0) goto ; [41.00%] else goto ; [59.00%] [local count: 633507680]: _6 = (signed char) a_2(D); [local count: 1073741824]: # prephitmp_8 = PHI <_6(3), d_4(2)> factor_out_conditional_operation could factor out the cast to the definition of d_4 ... Anyways the original code is now optimized (via RTL level) so maybe it is not as important.
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 Andrew Pinski changed: What|Removed |Added URL|https://gcc.gnu.org/piperma | |il/gcc-patches/2021-Novembe | |r/584411.html | Keywords|patch | --- Comment #9 from Andrew Pinski --- So to fix this in a better way I propose to extend the: `/* (zero_one == 0) ? y : z y -> ((typeof(y))zero_one * z) y */` patterns to handle not only zero_one but rather popcount(nz) == 1. also treat `signed < 0` as `(signed>>signbit)&1`. I will do that over the weekend.
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 mcccs at gmx dot com changed: What|Removed |Added CC||mcccs at gmx dot com --- Comment #8 from mcccs at gmx dot com --- *** Bug 86604 has been marked as a duplicate of this bug. ***
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 Bug 103216 depends on bug 103218, which changed state. Bug 103218 Summary: (a < 0) << signbit is not always optimized to a & signbitmask at the gimple level https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103218 What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 Andrew Pinski changed: What|Removed |Added Depends on||103218 URL||https://gcc.gnu.org/piperma ||il/gcc-patches/2021-Novembe ||r/584411.html Keywords||patch --- Comment #7 from Andrew Pinski --- With PR 103218 patch and the one which I submited here: https://gcc.gnu.org/pipermail/gcc-patches/2021-November/584411.html This is basically fixed (we run into PR 103220 but that is a gimple level missed optimization which should not matter really). Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103218 [Bug 103218] (a < 0) << signbit is not always optimized to a & signbitmask at the gimple level
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 --- Comment #6 from Andrew Pinski --- Created attachment 51786 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51786=edit Patch which I am testing I still need to add testcases (there are many) and finish up the changelog.
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 --- Comment #5 from Andrew Pinski --- (In reply to Andrew Pinski from comment #4) > (In reply to Andrew Pinski from comment #3) > > I am going to implement this. I think I only need the first conversion (and > > making sure cond goes away which leads to the second one) which should lead > > to the rest (after having fixed PR 103218 which I am doing first which is > > needed to get the 4th line). > > I was right and wrong. I still need to debug match-and-simplify for why ! > does not work in one case, I thought it would. Because it does not produce a leaf node, I needed to add a new flag ^ which is like ! but only checks to make sure not producing the same code again.
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 --- Comment #4 from Andrew Pinski --- (In reply to Andrew Pinski from comment #3) > I am going to implement this. I think I only need the first conversion (and > making sure cond goes away which leads to the second one) which should lead > to the rest (after having fixed PR 103218 which I am doing first which is > needed to get the 4th line). I was right and wrong. I still need to debug match-and-simplify for why ! does not work in one case, I thought it would. Also the last 5 steps did not happen either on the gimple level, I filed PR 103220 for that.
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 Andrew Pinski changed: What|Removed |Added Status|NEW |ASSIGNED
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 Andrew Pinski changed: What|Removed |Added Ever confirmed|0 |1 Last reconfirmed||2021-11-13 Status|UNCONFIRMED |NEW Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot gnu.org --- Comment #3 from Andrew Pinski --- b_3 = a_2(D) & 127; c_4 = (signed char) b_3; d_5 = (signed char) a_2(D); if (d_5 < 0) goto ; [INV] else goto ; [INV] : v_7 = c_4 | -128; : # v_1 = PHI (d<0) ? (c | -128) : c -> c | ((d<0) ? -128 : 0) -> c | ((d<0) << 7) -> c | (d & -128) -> (c|d) & c|-128 -> ((signed char)(b | a)) & ((singed char)a|128) -> ((signed char)((a&128) | a)) & ((singed char)a|128) -> ((signed char)a) & ((singed char)a|128) -> (signed char)(a & (a|128))-> (signed char)a Hopefully I did this right. I am going to implement this. I think I only need the first conversion (and making sure cond goes away which leads to the second one) which should lead to the rest (after having fixed PR 103218 which I am doing first which is needed to get the 4th line).
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 --- Comment #2 from Andrew Pinski --- (In reply to Andrew Pinski from comment #1) > For x86_64 we might be able to solve this at the RTL level during combine: > (set (reg/v:QI 84 [ ]) > (if_then_else:QI (lt (subreg:QI (reg:SI 86 [ a ]) 0) > (const_int 0 [0])) > (ior:QI (subreg:QI (reg:SI 86 [ a ]) 0) > (const_int -128 [0xff80])) > (reg/v:QI 84 [ ]))) > > That is optimize: > (a < 0) ? a | signbit : b > to > (a < 0) ? a : b That didn't work either because combine could put back into place the lt.
[Bug tree-optimization/103216] missed optimization, phiopt/vrp?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103216 --- Comment #1 from Andrew Pinski --- For x86_64 we might be able to solve this at the RTL level during combine: (set (reg/v:QI 84 [ ]) (if_then_else:QI (lt (subreg:QI (reg:SI 86 [ a ]) 0) (const_int 0 [0])) (ior:QI (subreg:QI (reg:SI 86 [ a ]) 0) (const_int -128 [0xff80])) (reg/v:QI 84 [ ]))) That is optimize: (a < 0) ? a | signbit : b to (a < 0) ? a : b And I suspect we need after that) (a < 0) ? a : a & ~signbit into: a
