[Bug target/115934] New: [15 Regression] nvptx vs. ivopts: replace constant_multiple_of with aff_combination_constant_multiple_p [PR114932]

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115934

            Bug ID: 115934
           Summary: [15 Regression] nvptx vs. ivopts: replace
                    constant_multiple_of with
                    aff_combination_constant_multiple_p [PR114932]
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: testsuite-fail
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tschwinge at gcc dot gnu.org
                CC: tnfchris at gcc dot gnu.org, vries at gcc dot gnu.org
  Target Milestone: ---
            Target: nvptx

Recent commit r15-1809-g735edbf1e2479fa2323a2b4a9714fae1a0925f74 "ivopts:
replace constant_multiple_of with aff_combination_constant_multiple_p
[PR114932]" is causing one regression for nvptx target:

    PASS: gcc.dg/tree-ssa/pr43378.c (test for excess errors)
    PASS: gcc.dg/tree-ssa/pr43378.c scan-tree-dump-times ivopts "rite_[0-9]* =
rite_[0-9]* - element" 1
    [-PASS:-]{+FAIL:+} gcc.dg/tree-ssa/pr43378.c scan-tree-dump-times ivopts
"left_[0-9]* = left_[0-9]* \\+ element|left_[0-9]* = element_[0-9]*\\(D\\) \\+
left" 1

Before (or, with this commit locally reverted), we have no 'diff' between the
previous dump file: 'pr43378.c.186t.slp1' vs. 'pr43378.c.188t.ivopts', but now
there's this:

    --- pr43378.c.186t.slp1       2024-07-15 11:48:57.498943077 +0200
    +++ pr43378.c.188t.ivopts     2024-07-15 11:48:57.498943077 +0200
    @@ -3,6 +3,18 @@

     void foo (int left, int rite, int element)
     {
    +  unsigned int _1;
    +  unsigned int _2;
    +  unsigned int _11;
    +  unsigned int _12;
    +  unsigned int _13;
    +  unsigned int _17;
    +  unsigned int _19;
    +  unsigned int _20;
    +  unsigned int _21;
    +  unsigned int _22;
    +  unsigned int _23;
    +  
       <bb 2> [local count: 118111600]:
       if (left_4(D) <= rite_5(D))
         goto <bb 5>; [89.00%]
    @@ -12,12 +24,23 @@
       <bb 5> [local count: 105119324]:

       <bb 3> [local count: 955630224]:
    -  # left_14 = PHI <left_10(6), left_4(D)(5)>
       # rite_15 = PHI <rite_8(6), rite_5(D)(5)>
    +  _17 = (unsigned int) left_4(D);
    +  _2 = (unsigned int) rite_5(D);
    +  _1 = _2 + _17;
    +  _13 = (unsigned int) rite_15;
    +  _11 = -_13;
    +  _12 = _1 + _11;
    +  left_14 = (int) _12;
       rite_8 = rite_15 - element_7(D);
       bar (left_14, rite_8, element_7(D));
    -  left_10 = element_7(D) + left_14;
    -  if (rite_8 >= left_10)
    +  _19 = (unsigned int) left_4(D);
    +  _20 = (unsigned int) rite_5(D);
    +  _21 = _19 + _20;
    +  _22 = (unsigned int) rite_8;
    +  _23 = _21 - _22;
    +  left_18 = (int) _23;
    +  if (rite_8 >= left_18)
         goto <bb 6>; [89.00%]
       else
         goto <bb 4>; [11.00%]

(I've not yet looked any deeper.)