[llvm-bugs] [Bug 40851] New: Inline jump tables

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=40851

            Bug ID: 40851
           Summary: Inline jump tables
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Interprocedural Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: llvm-bugs at lists.llvm.org

int square(int x) {
    return x*x;
}

int add(int x) {
    return x + x;
}

typedef int (*p) (int);

p arr[4] = {square, add};

int test(int x) {
    int res = arr[1](x);
    return res;
}

Expected:
test(int):
        lea     eax, [rdi+rdi]
        ret

Currently:
test(int):
        jmp     [QWORD PTR arr[rip+8]]


------------
If the index to the jump table isn't a constant, should not be better to expand
"if else" chain like:
if (x==1)  arr[1](x);
else if (x==2)  arr[2](x);

..and then take an opportunity to inline functions?

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