[llvm-bugs] [Bug 51783] New: Missed arithmetic fold

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51783

            Bug ID: 51783
           Summary: Missed arithmetic fold
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: llvm at rifkin.dev
                CC: llvm-bugs at lists.llvm.org

LLVM optimizes bar into tgt here but not foo.

https://godbolt.org/z/jdeT7jbjd

int foo(int a, int b) {
    return b * (1 + a / b) - a;
}
int bar(int a, int b) {
    return b * (a / b) + b - a;
}
int tgt(int a, int b) {
    return b - a % b;
}

https://alive2.llvm.org/ce/z/axgBxW

GCC appears to miss this too.

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