[Bug c++/114297] New: Yet more problems with "definition in block does not dominate use in block"

["dcb314 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114297

            Bug ID: 114297
           Summary: Yet more problems with "definition in block does not
                    dominate use in block"
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

For this C++ code:

void __assert_fail(char *, int, const char *) __attribute__((__noreturn__));
template <class T> void max(T, T);
template <class T> struct SimpleVector {
  T array;
  int num;
  T *getRef(int i) {
    num - i ? void() : __assert_fail("", 7, __PRETTY_FUNCTION__);
    return &array + i;
  }
};
struct Extremes {
  int minWidth;
  int maxWidth;
};
int forceCalcColumnExtremes_cs;
struct Table {
  SimpleVector<Extremes> colExtremes;
  void forceCalcColumnExtremes();
};
void Table::forceCalcColumnExtremes() {
  int minSumCols, maxSumCols;
  for (int i; i; ++i) {
    minSumCols += colExtremes.getRef(i)->minWidth;
    maxSumCols += colExtremes.getRef(i)->maxWidth;
  }
  max(forceCalcColumnExtremes_cs, minSumCols);
  max(forceCalcColumnExtremes_cs, maxSumCols);
}

compiled by recent gcc trunk, does this:

cvise $ ~/gcc/results/bin/g++ -c -w -O3 bug1022.cc
cvise $ ~/gcc/results/bin/g++ -c -w -O3 -march=znver3 bug1022.cc
bug1022.cc: In member function ‘void Table::forceCalcColumnExtremes()’:
bug1022.cc:20:6: error: definition in block 5 does not dominate use in block 3
   20 | void Table::forceCalcColumnExtremes() {
      |      ^~~~~
for SSA_NAME: vect_maxSumCols_16.16_76 in statement:
vect_maxSumCols_16.16_90 = PHI <vect_maxSumCols_16.16_76(3)>
PHI argument
vect_maxSumCols_16.16_76
for PHI node
vect_maxSumCols_16.16_90 = PHI <vect_maxSumCols_16.16_76(3)>
during GIMPLE pass: vect
bug1022.cc:20:6: internal compiler error: verify_ssa failed
0x159e432 verify_ssa(bool, bool)
        ../../trunk.20210101/gcc/tree-ssa.cc:1203
0x1204a9d execute_function_todo
        ../../trunk.20210101/gcc/passes.cc:2095

The bug first seems to occur sometime between g:71244316cf714725
and g:10cbfcd60f9e5bdb, which is a distance of 43 commits.