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Common LLVM IR Instructions

Assembly(x86_64) asm.s

 // Your Assembly(x86_64) code here
    .global     _fib
    .p2align    4, 0x90
_fib:
    pushq       %rbp
    movq        %rsp, %rbp
    pushq       %r14
    pushq       %rbx
    movq        %rdi, %rbx
    cmpq        $2, %rbx
    jge         LBB0_1
    movq        %rbx, %rax
    jmp         LBB0_3
LBB0_1:
    leaq        -1(%rbx), %rdi
    callq       _fib
    movq        %rax, %r14
    addq        $-2, %rbx
    movq        %rbx, %rdi
    addq        %r14, %rax
LBB0_3:
    popq        %rbx
    poqp        %r14
    popq        %rbp
    retq

   // Your Bash code here
$ clang -O3 fib.c -S -emit-llvm

// fib.c

int64_t fib(int64_t n) {
    if (n < 2) return n;
    return (fib(n-1) + fib(n-2));
}


// LLVM IR code fib.ll
define i64 @fib(i64) local_unnamed_addr #0 {
    %2 = icmp slt i64 %0, 2
    br i1 %2, label %9, label %3

; <label>:3:        ; preds = %1
    %4 = add nsw i64 %0, -1
    %5 = tail call i64 @fib(i64 %4)
    %6 = add nsw i64 %0, -2
    %7 = tail call i64 @fib(i64 %6)
    %8 = add nsw i64 %7, %5
ret i64 %8

; <label>:9:        ; preds = %1
    ret i64 %0
}