[Bug tree-optimization/94234] missed ccp folding for (addr + 8 * n) - (addr + 8 * (n - 1))
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94234 Feng Xue changed: What|Removed |Added Resolution|--- |FIXED Status|NEW |RESOLVED --- Comment #6 from Feng Xue --- Fixed.
[Bug tree-optimization/94234] missed ccp folding for (addr + 8 * n) - (addr + 8 * (n - 1))
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94234 --- Comment #5 from CVS Commits --- The master branch has been updated by Feng Xue : https://gcc.gnu.org/g:8f0d743c2dee6afae5c6f861b0642b7b112a4a70 commit r11-3207-g8f0d743c2dee6afae5c6f861b0642b7b112a4a70 Author: Feng Xue Date: Mon Aug 17 23:00:35 2020 +0800 tree-optimization/94234 - add plusminus-with-convert pattern Add a rule (T)(A) +- (T)(B) -> (T)(A +- B), which works only when (A +- B) could be folded to a simple value. By this rule, a plusminus-mult-with-convert expression could be handed over to the rule (A * C) +- (B * C) -> (A +- B). 2020-09-15 Feng Xue gcc/ PR tree-optimization/94234 * match.pd (T)(A) +- (T)(B) -> (T)(A +- B): New simplification. gcc/testsuite/ PR tree-optimization/94234 * gcc.dg/pr94234-3.c: New test.
[Bug tree-optimization/94234] missed ccp folding for (addr + 8 * n) - (addr + 8 * (n - 1))
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94234 --- Comment #4 from CVS Commits --- The master branch has been updated by Feng Xue : https://gcc.gnu.org/g:f9d2def016410a2095df6b399097b482f82064a5 commit r11-3199-gf9d2def016410a2095df6b399097b482f82064a5 Author: Feng Xue Date: Tue Sep 1 17:17:58 2020 +0800 tree-optimization/94234 - Fold plusminus_mult expr with multi-use operands 2020-09-03 Feng Xue gcc/ PR tree-optimization/94234 * genmatch.c (dt_simplify::gen_1): Emit check on final simplification result when "!" is specified on toplevel output expr. * match.pd ((A * C) +- (B * C) -> (A +- B) * C): Allow folding on expr with multi-use operands if final result is a simple gimple value. gcc/testsuite/ PR tree-optimization/94234 * gcc.dg/pr94234-2.c: New test.
[Bug tree-optimization/94234] missed ccp folding for (addr + 8 * n) - (addr + 8 * (n - 1))
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94234 --- Comment #3 from CVS Commits --- The master branch has been updated by Feng Xue : https://gcc.gnu.org/g:459f6f68a75fe88e7c8309ca8ad3244a532b0d8e commit r11-2764-g459f6f68a75fe88e7c8309ca8ad3244a532b0d8e Author: Feng Xue Date: Mon Jun 1 11:57:35 2020 +0800 tree-optimization/94234 - add pattern for ptr-diff on addresses with same offset 2020-08-19 Feng Xue gcc/ PR tree-optimization/94234 * match.pd ((PTR_A + OFF) - (PTR_B + OFF)) -> (PTR_A - PTR_B): New simplification. gcc/testsuite/ PR tree-optimization/94234 * gcc.dg/pr94234-1.c: New test.
[Bug tree-optimization/94234] missed ccp folding for (addr + 8 * n) - (addr + 8 * (n - 1))
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94234 --- Comment #2 from Marc Glisse --- The closest we have is /* (A * C) +- (B * C) -> (A+-B) * C and (A * C) +- A -> A * (C+-1). which does not handle conversions, although it should be possible to add them.
[Bug tree-optimization/94234] missed ccp folding for (addr + 8 * n) - (addr + 8 * (n - 1))
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94234
Richard Biener changed:
What|Removed |Added
Ever confirmed|0 |1
Last reconfirmed||2020-03-20
Keywords||missed-optimization
Version|unknown |10.0
Status|UNCONFIRMED |NEW
--- Comment #1 from Richard Biener ---
Confirmed. Might be also a regression since POINTER_DIFF_EXPR introduction.
We have
(simplify
(pointer_diff (pointer_plus @@0 @1) (pointer_plus @0 @2))
/* The second argument of pointer_plus must be interpreted as signed, and
thus sign-extended if necessary. */
(with { tree stype = signed_type_for (TREE_TYPE (@1)); }
/* Use view_convert instead of convert here, as POINTER_PLUS_EXPR
second arg is unsigned even when we need to consider it as signed,
we don't want to diagnose overflow here. */
(minus (convert (view_convert:stype @1))
(convert (view_convert:stype @2)))
which triggers here but appearantly the resulting minus isn't simplified.
_1 = n_5(D) * 8;
b1_7 = a_6(D) + _1;
_2 = n_5(D) + 18446744073709551615;
_3 = _2 * 8;
b2_8 = a_6(D) + _3;
and we need to simplify _1 - _3. Possibly the excessive conversions above
mess with the constraint of CCP not wanting new stmts. You can see what
forwprop does which applies all foldings possible and computes:
_1 = n_5(D) * 8;
_2 = n_5(D) + 18446744073709551615;
_3 = _2 * 8;
_11 = (signed long) _1;
_12 = (signed long) _3;
_4 = _11 - _12;
_9 = (long unsigned int) _4;
return _9;
I don't think we have match.pd patterns simplifying that.
