[llvm-bugs] [Bug 40629] New: (manual) fixed point math: scale reduction

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https://bugs.llvm.org/show_bug.cgi?id=40629

            Bug ID: 40629
           Summary: (manual) fixed point math: scale reduction
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: lebedev.ri at gmail.com
                CC: llvm-bugs at lists.llvm.org

int yy(int x) {
  return (((10 * x) / 3) + 5) / 10;
}

int yy2(int x) {
  return (((2 * x) / 3) + 1) / 2;
}

yy and yy2 are equivalent: https://rise4fun.com/Alive/tF61
yy2 results in better codegen.

I don't //really// expect this to be solved,
just thought i'd report for completeness

Refs https://github.com/google/souper/issues/438 (more TLDR)

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