[llvm-bugs] [Bug 32289] New: LoopStrengthReduce generates incorrect IR

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=32289

            Bug ID: 32289
           Summary: LoopStrengthReduce generates incorrect IR
           Product: new-bugs
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: anna at azul.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 18100
  --> https://bugs.llvm.org/attachment.cgi?id=18100&action=edit
Original IR

Steps to reproduce (on trunk):
opt -loop-reduce test2.ll -S > test2_lsr.ll 

Source code snippet:
vMeth1(long longarg, int intarg) {

        int ivar, jvar;
        boolean bArr[]=new boolean[N];

        ivar = 1;

        do {
            intarg += (((ivar * ivar) + intarg) - Test.instanceCount);
            bArr[ivar] = (((Test.dFld - Test.instanceCount) /
(((long)(-(Test.fFld
* Test.instanceCount))) | 1)) !=
                    (--intarg));
            Test.iArrFld[ivar] = (int)(intarg *= (int)longarg);
            longarg += (++Test.iArrFld[ivar]);
        } while (++ivar < 98);

        jvar = 68;

        while (--jvar > 0) {
            intarg += (int)(intarg -= (int)(-(++Test.fFld)));
            try {
                intarg = (Test.iArrFld[jvar - 1] % -82);
            } catch (ArithmeticException a_e) {}

        }

        sum += longarg + ivar + jvar;
}
This is in effect: sum += longarg + 98 + 0. 

Both the loops above are transformed through LSR. When LSR is enabled, the
longarg value for the sum is calculated incorrectly.

I have attached the original and transformed IR, along with detailed comments
on how the value is calculated (and where the difference occurs).
The result (sum) is calculated in the `ResultBB`.

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