[llvm-dev] Query regarding LLVM IR is SSA

[gurbani dimpal via llvm-dev]

I read in LLVM language reference manual that LLVM IR is in SSA Form, but
when i compiled it using clang, it is giving me the below form which i
can't see in SSA form and even i found that there is a pass -mem2reg to
convert it into SSA form. Then, i am unable to understand that why it's
written in manual that it is in SSA form. I feel if it is in SSA then we
should not need to convert it. Could you please clarify my doubt, i am
stuck here.

.c Program:

int main() {
    int a=0, b=1, p=2, q=3, x, y, m, n, g;
    if (m > n) {
        x = a;
        y = b;
    }
    else {
        x = p;
        y = q;
    }
    g = x + y;
    return 0;
}

.ll Program:

define i32 @main() #0 {
  %1 = alloca i32, align 4
  %a = alloca i32, align 4
  %b = alloca i32, align 4
  %p = alloca i32, align 4
  %q = alloca i32, align 4
  %x = alloca i32, align 4
  %y = alloca i32, align 4
  %m = alloca i32, align 4
  %n = alloca i32, align 4
  %g = alloca i32, align 4
  store i32 0, i32* %1, align 4
  store i32 0, i32* %a, align 4
  store i32 1, i32* %b, align 4
  store i32 2, i32* %p, align 4
  store i32 3, i32* %q, align 4
  %2 = load i32, i32* %m, align 4
  %3 = load i32, i32* %n, align 4
  %4 = icmp sgt i32 %2, %3
  br i1 %4, label %5, label %8

; <label>:5                                       ; preds = %0
  %6 = load i32, i32* %a, align 4
  store i32 %6, i32* %x, align 4
  %7 = load i32, i32* %b, align 4
  store i32 %7, i32* %y, align 4
  br label %11

; <label>:8                                       ; preds = %0
  %9 = load i32, i32* %p, align 4
  store i32 %9, i32* %x, align 4
  %10 = load i32, i32* %q, align 4
  store i32 %10, i32* %y, align 4
  br label %11

; <label>:11                                      ; preds = %8, %5
  %12 = load i32, i32* %x, align 4
  %13 = load i32, i32* %y, align 4
  %14 = add nsw i32 %12, %13
  store i32 %14, i32* %g, align 4
  ret i32 0
}

-- 
Thanks and Regards,
Dimpal Gurabani
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