#define NULL ((void *)0)
typedef unsigned long size_t; // Customize by platform.
typedef long intptr_t;
typedef unsigned long uintptr_t;
typedef long scalar_t__; // Either arithmetic or pointer type.
/* By default, we understand bool (as a convenience). */
typedef int bool;
#define false 0
#define true 1

/* Forward declarations */

/* Type definitions */

/* Variables and functions */
int /*<<< orphan*/ fprintf(int /*<<< orphan*/, char *, int, int);
int /*<<< orphan*/ stderr;
void LU_Gauss(int n, const double *a, double *lu) {
  int k;
  for (k = 0; k < n * n; k++) {
    lu[k] = a[k];
  }
  for (k = 0; k < (n - 1); k++) {
    if (lu[k * n + k] == 0.0) {
      fprintf(stderr, "LU_GAUSS : breakdown a[%d,%d] = 0\n", k, k);
    }
    int i, j;
    for (i = (k + 1); i < n; i++) {
      lu[i * n + k] = lu[i * n + k] / lu[k * n + k];
      for (j = (k + 1); j < n; j++) {
        lu[i * n + j] -= lu[i * n + k] * lu[k * n + j];
      }
    }
  }
}


x86 assembly (clang, -O0):
<LU_Gauss>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    %edi,-0x4(%rbp)
mov    %rsi,-0x10(%rbp)
mov    %rdx,-0x18(%rbp)
movl   $0x0,-0x1c(%rbp)
mov    -0x1c(%rbp),%eax
mov    -0x4(%rbp),%ecx
imul   -0x4(%rbp),%ecx
cmp    %ecx,%eax
jge    1164 <LU_Gauss+0x54>
mov    -0x10(%rbp),%rax
movslq -0x1c(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x18(%rbp),%rax
movslq -0x1c(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
mov    -0x1c(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x1c(%rbp)
jmp    112a <LU_Gauss+0x1a>
movl   $0x0,-0x1c(%rbp)
mov    -0x1c(%rbp),%eax
mov    -0x4(%rbp),%ecx
sub    $0x1,%ecx
cmp    %ecx,%eax
jge    12c6 <LU_Gauss+0x1b6>
mov    -0x18(%rbp),%rax
mov    -0x1c(%rbp),%ecx
imul   -0x4(%rbp),%ecx
add    -0x1c(%rbp),%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm0
xorps  %xmm1,%xmm1
ucomisd %xmm1,%xmm0
jne    11c0 <LU_Gauss+0xb0>
jp     11c0 <LU_Gauss+0xb0>
mov    0x2e34(%rip),%rax
mov    (%rax),%edi
mov    -0x1c(%rbp),%edx
mov    -0x1c(%rbp),%ecx
lea    0xe45(%rip),%rsi
call   1030 <fprintf@plt>
mov    -0x1c(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x20(%rbp)
mov    -0x20(%rbp),%eax
cmp    -0x4(%rbp),%eax
jge    12b3 <LU_Gauss+0x1a3>
mov    -0x18(%rbp),%rax
mov    -0x20(%rbp),%ecx
imul   -0x4(%rbp),%ecx
add    -0x1c(%rbp),%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x18(%rbp),%rax
mov    -0x1c(%rbp),%ecx
imul   -0x4(%rbp),%ecx
add    -0x1c(%rbp),%ecx
movslq %ecx,%rcx
divsd  (%rax,%rcx,8),%xmm0
mov    -0x18(%rbp),%rax
mov    -0x20(%rbp),%ecx
imul   -0x4(%rbp),%ecx
add    -0x1c(%rbp),%ecx
movslq %ecx,%rcx
movsd  %xmm0,(%rax,%rcx,8)
mov    -0x1c(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x24(%rbp)
mov    -0x24(%rbp),%eax
cmp    -0x4(%rbp),%eax
jge    12a0 <LU_Gauss+0x190>
mov    -0x18(%rbp),%rax
mov    -0x20(%rbp),%ecx
imul   -0x4(%rbp),%ecx
add    -0x1c(%rbp),%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x18(%rbp),%rax
mov    -0x1c(%rbp),%ecx
imul   -0x4(%rbp),%ecx
add    -0x24(%rbp),%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm2
mov    -0x18(%rbp),%rax
mov    -0x20(%rbp),%ecx
imul   -0x4(%rbp),%ecx
add    -0x24(%rbp),%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm1
movq   %xmm0,%rdx
movabs $0x8000000000000000,%rsi
xor    %rsi,%rdx
movq   %rdx,%xmm0
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,(%rax,%rcx,8)
mov    -0x24(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x24(%rbp)
jmp    1220 <LU_Gauss+0x110>
jmp    12a5 <LU_Gauss+0x195>
mov    -0x20(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x20(%rbp)
jmp    11c9 <LU_Gauss+0xb9>
jmp    12b8 <LU_Gauss+0x1a8>
mov    -0x1c(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x1c(%rbp)
jmp    116b <LU_Gauss+0x5b>
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<LU_Gauss>:
push   %rbp
push   %r15
push   %r14
push   %r13
push   %r12
push   %rbx
sub    $0xf8,%rsp
mov    %rdx,%r15
mov    %rdi,%rax
mov    %rdi,0x18(%rsp)
mov    %edi,%ecx
imul   %edi,%ecx
test   %ecx,%ecx
je     12a9 <LU_Gauss+0x199>
mov    %ecx,%eax
cmp    $0x4,%ecx
jb     1156 <LU_Gauss+0x46>
lea    (%rsi,%rax,8),%rcx
cmp    %r15,%rcx
jbe    11d0 <LU_Gauss+0xc0>
lea    (%r15,%rax,8),%rcx
cmp    %rsi,%rcx
jbe    11d0 <LU_Gauss+0xc0>
xor    %ecx,%ecx
mov    %rcx,%rdx
not    %rdx
add    %rax,%rdx
mov    %rax,%rdi
and    $0x3,%rdi
je     1185 <LU_Gauss+0x75>
nopw   0x0(%rax,%rax,1)
movsd  (%rsi,%rcx,8),%xmm0
movsd  %xmm0,(%r15,%rcx,8)
add    $0x1,%rcx
add    $0xffffffffffffffff,%rdi
jne    1170 <LU_Gauss+0x60>
cmp    $0x3,%rdx
jb     12a9 <LU_Gauss+0x199>
nop
movsd  (%rsi,%rcx,8),%xmm0
movsd  %xmm0,(%r15,%rcx,8)
movsd  0x8(%rsi,%rcx,8),%xmm0
movsd  %xmm0,0x8(%r15,%rcx,8)
movsd  0x10(%rsi,%rcx,8),%xmm0
movsd  %xmm0,0x10(%r15,%rcx,8)
movsd  0x18(%rsi,%rcx,8),%xmm0
movsd  %xmm0,0x18(%r15,%rcx,8)
add    $0x4,%rcx
cmp    %rcx,%rax
jne    1190 <LU_Gauss+0x80>
jmp    12a9 <LU_Gauss+0x199>
mov    %eax,%ecx
and    $0xfffffffc,%ecx
lea    -0x4(%rcx),%rbp
mov    %rbp,%rdi
shr    $0x2,%rdi
add    $0x1,%rdi
mov    %edi,%edx
and    $0x3,%edx
cmp    $0xc,%rbp
jae    11f3 <LU_Gauss+0xe3>
xor    %ebp,%ebp
jmp    1264 <LU_Gauss+0x154>
and    $0xfffffffffffffffc,%rdi
xor    %ebp,%ebp
nopl   0x0(%rax)
movups (%rsi,%rbp,8),%xmm0
movups 0x10(%rsi,%rbp,8),%xmm1
movups %xmm0,(%r15,%rbp,8)
movups %xmm1,0x10(%r15,%rbp,8)
movups 0x20(%rsi,%rbp,8),%xmm0
movups 0x30(%rsi,%rbp,8),%xmm1
movups %xmm0,0x20(%r15,%rbp,8)
movups %xmm1,0x30(%r15,%rbp,8)
movups 0x40(%rsi,%rbp,8),%xmm0
movups 0x50(%rsi,%rbp,8),%xmm1
movups %xmm0,0x40(%r15,%rbp,8)
movups %xmm1,0x50(%r15,%rbp,8)
movupd 0x60(%rsi,%rbp,8),%xmm0
movupd 0x70(%rsi,%rbp,8),%xmm1
movupd %xmm0,0x60(%r15,%rbp,8)
movupd %xmm1,0x70(%r15,%rbp,8)
add    $0x10,%rbp
add    $0xfffffffffffffffc,%rdi
jne    1200 <LU_Gauss+0xf0>
test   %rdx,%rdx
je     12a0 <LU_Gauss+0x190>
lea    (%r15,%rbp,8),%rdi
add    $0x10,%rdi
lea    (%rsi,%rbp,8),%rbp
add    $0x10,%rbp
shl    $0x5,%rdx
xor    %ebx,%ebx
nop
movupd -0x10(%rbp,%rbx,1),%xmm0
movupd 0x0(%rbp,%rbx,1),%xmm1
movupd %xmm0,-0x10(%rdi,%rbx,1)
movupd %xmm1,(%rdi,%rbx,1)
add    $0x20,%rbx
cmp    %rbx,%rdx
jne    1280 <LU_Gauss+0x170>
cmp    %rax,%rcx
jne    1158 <LU_Gauss+0x48>
cmpl   $0x2,0x18(%rsp)
jl     1719 <LU_Gauss+0x609>
mov    0x18(%rsp),%rax
lea    -0x1(%rax),%ecx
mov    %rcx,0x70(%rsp)
mov    %eax,%ebp
lea    0x2(%rbp),%rax
mov    %rax,0xa8(%rsp)
lea    0x0(,%rbp,8),%rax
mov    %rax,0x50(%rsp)
lea    0x8(,%rbp,8),%rax
mov    %rax,0x40(%rsp)
lea    0x0(%rbp,%rbp,1),%rax
mov    %rax,0x68(%rsp)
lea    0x1(%rbp),%rax
mov    %rax,0xa0(%rsp)
lea    0x10(%r15),%rax
mov    %rax,0x60(%rsp)
lea    -0x2(%rbp),%rax
mov    %rbp,%rcx
neg    %rcx
mov    %rcx,0xd0(%rsp)
lea    0x20(%r15),%r13
lea    (%r15,%rbp,8),%rcx
add    $0x20,%rcx
mov    %rcx,0x38(%rsp)
lea    (%r15,%rbp,8),%rcx
mov    %rcx,0x30(%rsp)
mov    $0x1,%ecx
mov    %rcx,0x20(%rsp)
xor    %ecx,%ecx
movapd 0xcb8(%rip),%xmm5
mov    %r15,%rbx
mov    %rax,0x58(%rsp)
mov    %rax,0x28(%rsp)
jmp    1396 <LU_Gauss+0x286>
nopw   0x0(%rax,%rax,1)
addq   $0x1,0x20(%rsp)
addq   $0xffffffffffffffff,0x28(%rsp)
mov    0x40(%rsp),%rax
add    %rax,%r13
add    %rax,0x38(%rsp)
mov    0x50(%rsp),%rax
add    %rax,0x30(%rsp)
add    %rax,%rbx
mov    0x78(%rsp),%rcx
cmp    0x70(%rsp),%rcx
je     1719 <LU_Gauss+0x609>
mov    %rcx,%r12
mov    %r12d,%eax
imul   0x18(%rsp),%eax
cltq
add    %rcx,%rax
mov    %rax,0xf0(%rsp)
movsd  (%r15,%rax,8),%xmm0
ucomisd 0xc54(%rip),%xmm0
mov    %rcx,0x8(%rsp)
jne    13f1 <LU_Gauss+0x2e1>
jp     13f1 <LU_Gauss+0x2e1>
mov    0x2c14(%rip),%rax
mov    (%rax),%edi
lea    0xc43(%rip),%rsi
mov    0x8(%rsp),%rdx
mov    0x8(%rsp),%rcx
call   1030 <fprintf@plt>
mov    0x8(%rsp),%r12
movapd 0xc0f(%rip),%xmm5
lea    0x1(%r12),%rax
mov    %rax,0x78(%rsp)
cmp    %rbp,%rax
jae    1360 <LU_Gauss+0x250>
mov    %r12,%rdx
imul   %rbp,%rdx
mov    0x40(%rsp),%rdi
imul   %r12,%rdi
lea    (%rdx,%rbp,1),%rax
mov    0x28(%rsp),%rcx
and    $0xfffffffffffffffc,%rcx
mov    %rcx,0x90(%rsp)
mov    0x58(%rsp),%rsi
sub    %r12,%rsi
mov    0x68(%rsp),%rcx
add    %rdx,%rcx
mov    %rcx,0xc0(%rsp)
mov    0x60(%rsp),%rcx
mov    %rdi,0xc8(%rsp)
lea    (%rcx,%rdi,1),%rcx
mov    %rcx,0xb8(%rsp)
lea    (%r15,%rax,8),%rax
mov    %rax,0xb0(%rsp)
mov    0x20(%rsp),%rdi
mov    %rdx,0x98(%rsp)
lea    (%rdi,%rdx,1),%rax
mov    %rax,0xe8(%rsp)
lea    0x1(%rdi),%rax
mov    %rax,0x10(%rsp)
mov    %rsi,0x48(%rsp)
and    $0xfffffffffffffffc,%rsi
mov    %rsi,0x88(%rsp)
lea    (%rdi,%rsi,1),%rax
add    $0x1,%rax
mov    %rax,0x80(%rsp)
mov    0x30(%rsp),%r9
mov    0x38(%rsp),%r10
xor    %r11d,%r11d
jmp    14dc <LU_Gauss+0x3cc>
nopl   0x0(%rax,%rax,1)
add    $0x1,%rdi
add    $0x1,%r11
mov    0x50(%rsp),%rax
add    %rax,%r10
add    %rax,%r9
cmp    %rbp,%rdi
je     1360 <LU_Gauss+0x250>
mov    %rdi,%rcx
imul   %rbp,%rcx
lea    (%rcx,%r12,1),%rdx
movsd  (%r15,%rdx,8),%xmm0
mov    0xf0(%rsp),%rax
divsd  (%r15,%rax,8),%xmm0
mov    0x20(%rsp),%rax
add    %rcx,%rax
movsd  %xmm0,(%r15,%rdx,8)
mov    0xe8(%rsp),%rsi
mulsd  (%r15,%rsi,8),%xmm0
movsd  (%r15,%rax,8),%xmm1
subsd  %xmm0,%xmm1
movsd  %xmm1,(%r15,%rax,8)
cmp    %rbp,0x10(%rsp)
je     14c0 <LU_Gauss+0x3b0>
mov    0x10(%rsp),%rax
cmpq   $0x4,0x48(%rsp)
jb     1670 <LU_Gauss+0x560>
mov    %r11,%rax
imul   %rbp,%rax
mov    0xa8(%rsp),%rsi
add    %rax,%rsi
lea    (%r15,%rsi,8),%rsi
mov    %rsi,0xd8(%rsp)
mov    0xc8(%rsp),%r12
add    %r12,%rsi
mov    %rsi,0xe0(%rsp)
mov    0xc0(%rsp),%rsi
lea    (%rsi,%rax,1),%r14
lea    (%rax,%rbp,1),%r8
lea    (%r15,%r8,8),%r8
add    %r12,%r8
add    0xa0(%rsp),%rax
lea    (%r15,%r14,8),%r14
lea    (%r15,%rax,8),%rax
cmp    %rax,0xd8(%rsp)
setb   %r12b
cmp    %r14,%r8
setb   %sil
mov    0xe0(%rsp),%rax
cmp    0xb0(%rsp),%rax
setb   %r8b
cmp    %r14,0xb8(%rsp)
setb   %r14b
mov    0x10(%rsp),%rax
test   %sil,%r12b
mov    0x8(%rsp),%r12
jne    1670 <LU_Gauss+0x560>
mov    0x10(%rsp),%rax
and    %r14b,%r8b
jne    1670 <LU_Gauss+0x560>
movsd  (%r15,%rdx,8),%xmm0
unpcklpd %xmm0,%xmm0
xorpd  %xmm5,%xmm0
xor    %eax,%eax
mov    0x90(%rsp),%rsi
cs nopw 0x0(%rax,%rax,1)
nopl   (%rax)
movupd -0x10(%r13,%rax,8),%xmm1
movupd 0x0(%r13,%rax,8),%xmm2
movupd -0x10(%r10,%rax,8),%xmm3
movupd (%r10,%rax,8),%xmm4
mulpd  %xmm0,%xmm1
addpd  %xmm3,%xmm1
mulpd  %xmm0,%xmm2
addpd  %xmm4,%xmm2
movupd %xmm1,-0x10(%r10,%rax,8)
movupd %xmm2,(%r10,%rax,8)
add    $0x4,%rax
cmp    %rax,%rsi
jne    1610 <LU_Gauss+0x500>
mov    0x80(%rsp),%rax
mov    0x88(%rsp),%rsi
cmp    %rsi,0x48(%rsp)
je     14c0 <LU_Gauss+0x3b0>
nopl   0x0(%rax)
mov    %ebp,%esi
sub    %eax,%esi
mov    %rax,%r8
test   $0x1,%sil
je     16ab <LU_Gauss+0x59b>
movsd  (%r15,%rdx,8),%xmm0
mov    0x98(%rsp),%rsi
add    %rax,%rsi
add    %rax,%rcx
mulsd  (%r15,%rsi,8),%xmm0
movsd  (%r15,%rcx,8),%xmm1
subsd  %xmm0,%xmm1
movsd  %xmm1,(%r15,%rcx,8)
lea    0x1(%rax),%r8
not    %rax
cmp    0xd0(%rsp),%rax
mov    0x8(%rsp),%r12
je     14c0 <LU_Gauss+0x3b0>
cs nopw 0x0(%rax,%rax,1)
nopl   0x0(%rax,%rax,1)
movsd  (%r15,%rdx,8),%xmm0
mulsd  (%rbx,%r8,8),%xmm0
movsd  (%r9,%r8,8),%xmm1
subsd  %xmm0,%xmm1
movsd  0x8(%r9,%r8,8),%xmm0
movsd  %xmm1,(%r9,%r8,8)
movsd  (%r15,%rdx,8),%xmm1
mulsd  0x8(%rbx,%r8,8),%xmm1
subsd  %xmm1,%xmm0
movsd  %xmm0,0x8(%r9,%r8,8)
add    $0x2,%r8
cmp    %r8,%rbp
jne    16d0 <LU_Gauss+0x5c0>
jmp    14c0 <LU_Gauss+0x3b0>
add    $0xf8,%rsp
pop    %rbx
pop    %r12
pop    %r13
pop    %r14
pop    %r15
pop    %rbp
ret

LLVM IR (-O0):
@stderr = global i32 0
@.str = [35 x i8] c"LU_GAUSS : breakdown a[%d,%d] = 0\0A\00"
define void @LU_Gauss(i32 %0, double* %1, double* %2) {
%4 = alloca i32
%5 = alloca double*
%6 = alloca double*
%7 = alloca i32
%8 = alloca i32
%9 = alloca i32
store i32 %0, i32* %4
store double* %1, double** %5
store double* %2, double** %6
store i32 0, i32* %7
br label %10
10: ; preds = %26, %3
%11 = load i32, i32* %7
%12 = load i32, i32* %4
%13 = load i32, i32* %4
%14 = mul nsw i32 %12, %13
%15 = icmp slt i32 %11, %14
br i1 %15, label %16, label %29
16: ; preds = %10
%17 = load double*, double** %5
%18 = load i32, i32* %7
%19 = sext i32 %18 to i64
%20 = getelementptr inbounds double, double* %17, i64 %19
%21 = load double, double* %20
%22 = load double*, double** %6
%23 = load i32, i32* %7
%24 = sext i32 %23 to i64
%25 = getelementptr inbounds double, double* %22, i64 %24
store double %21, double* %25
br label %26
26: ; preds = %16
%27 = load i32, i32* %7
%28 = add nsw i32 %27, 1
store i32 %28, i32* %7
br label %10
29: ; preds = %10
store i32 0, i32* %7
br label %30
30: ; preds = %130, %29
%31 = load i32, i32* %7
%32 = load i32, i32* %4
%33 = sub nsw i32 %32, 1
%34 = icmp slt i32 %31, %33
br i1 %34, label %35, label %133
35: ; preds = %30
%36 = load double*, double** %6
%37 = load i32, i32* %7
%38 = load i32, i32* %4
%39 = mul nsw i32 %37, %38
%40 = load i32, i32* %7
%41 = add nsw i32 %39, %40
%42 = sext i32 %41 to i64
%43 = getelementptr inbounds double, double* %36, i64 %42
%44 = load double, double* %43
%45 = fcmp oeq double %44, 0.000000e+00
br i1 %45, label %46, label %51
46: ; preds = %35
%47 = load i32, i32* @stderr
%48 = load i32, i32* %7
%49 = load i32, i32* %7
%50 = call i32 @fprintf(i32 %47, i8* getelementptr inbounds ([35 x i8], [35 x i8]* @.str, i64 0, i64 0), i32 %48, i32 %49)
br label %51
51: ; preds = %46, %35
%52 = load i32, i32* %7
%53 = add nsw i32 %52, 1
store i32 %53, i32* %8
br label %54
54: ; preds = %126, %51
%55 = load i32, i32* %8
%56 = load i32, i32* %4
%57 = icmp slt i32 %55, %56
br i1 %57, label %58, label %129
58: ; preds = %54
%59 = load double*, double** %6
%60 = load i32, i32* %8
%61 = load i32, i32* %4
%62 = mul nsw i32 %60, %61
%63 = load i32, i32* %7
%64 = add nsw i32 %62, %63
%65 = sext i32 %64 to i64
%66 = getelementptr inbounds double, double* %59, i64 %65
%67 = load double, double* %66
%68 = load double*, double** %6
%69 = load i32, i32* %7
%70 = load i32, i32* %4
%71 = mul nsw i32 %69, %70
%72 = load i32, i32* %7
%73 = add nsw i32 %71, %72
%74 = sext i32 %73 to i64
%75 = getelementptr inbounds double, double* %68, i64 %74
%76 = load double, double* %75
%77 = fdiv double %67, %76
%78 = load double*, double** %6
%79 = load i32, i32* %8
%80 = load i32, i32* %4
%81 = mul nsw i32 %79, %80
%82 = load i32, i32* %7
%83 = add nsw i32 %81, %82
%84 = sext i32 %83 to i64
%85 = getelementptr inbounds double, double* %78, i64 %84
store double %77, double* %85
%86 = load i32, i32* %7
%87 = add nsw i32 %86, 1
store i32 %87, i32* %9
br label %88
88: ; preds = %122, %58
%89 = load i32, i32* %9
%90 = load i32, i32* %4
%91 = icmp slt i32 %89, %90
br i1 %91, label %92, label %125
92: ; preds = %88
%93 = load double*, double** %6
%94 = load i32, i32* %8
%95 = load i32, i32* %4
%96 = mul nsw i32 %94, %95
%97 = load i32, i32* %7
%98 = add nsw i32 %96, %97
%99 = sext i32 %98 to i64
%100 = getelementptr inbounds double, double* %93, i64 %99
%101 = load double, double* %100
%102 = load double*, double** %6
%103 = load i32, i32* %7
%104 = load i32, i32* %4
%105 = mul nsw i32 %103, %104
%106 = load i32, i32* %9
%107 = add nsw i32 %105, %106
%108 = sext i32 %107 to i64
%109 = getelementptr inbounds double, double* %102, i64 %108
%110 = load double, double* %109
%111 = load double*, double** %6
%112 = load i32, i32* %8
%113 = load i32, i32* %4
%114 = mul nsw i32 %112, %113
%115 = load i32, i32* %9
%116 = add nsw i32 %114, %115
%117 = sext i32 %116 to i64
%118 = getelementptr inbounds double, double* %111, i64 %117
%119 = load double, double* %118
%120 = fneg double %101
%121 = call double @llvm.fmuladd.f64(double %120, double %110, double %119)
store double %121, double* %118
br label %122
122: ; preds = %92
%123 = load i32, i32* %9
%124 = add nsw i32 %123, 1
store i32 %124, i32* %9
br label %88
125: ; preds = %88
br label %126
126: ; preds = %125
%127 = load i32, i32* %8
%128 = add nsw i32 %127, 1
store i32 %128, i32* %8
br label %54
129: ; preds = %54
br label %130
130: ; preds = %129
%131 = load i32, i32* %7
%132 = add nsw i32 %131, 1
store i32 %132, i32* %7
br label %30
133: ; preds = %30
ret void
}

LLVM IR (-O2):
@stderr = global i32 0
@.str = [35 x i8] c"LU_GAUSS : breakdown a[%d,%d] = 0\0A\00"
define void @LU_Gauss(i32 %0, double* nocapture %1, double* nocapture %2) {
%4 = mul i32 %0, %0
%5 = icmp eq i32 %4, 0
br i1 %5, label %112, label %6
6: ; preds = %3
%7 = zext i32 %4 to i64
%8 = icmp ult i32 %4, 4
br i1 %8, label %94, label %9
9: ; preds = %6
%10 = getelementptr double, double* %2, i64 %7
%11 = getelementptr double, double* %1, i64 %7
%12 = icmp ugt double* %11, %2
%13 = icmp ugt double* %10, %1
%14 = and i1 %12, %13
br i1 %14, label %94, label %15
15: ; preds = %9
%16 = and i64 %7, 4294967292
%17 = add nsw i64 %16, -4
%18 = lshr exact i64 %17, 2
%19 = add nuw nsw i64 %18, 1
%20 = and i64 %19, 3
%21 = icmp ult i64 %17, 12
br i1 %21, label %73, label %22
22: ; preds = %15
%23 = and i64 %19, 9223372036854775804
br label %24
24: ; preds = %24, %22
%25 = phi i64 [ 0, %22 ], [ %70, %24 ]
%26 = phi i64 [ 0, %22 ], [ %71, %24 ]
%27 = getelementptr inbounds double, double* %1, i64 %25
%28 = bitcast double* %27 to <2 x double>*
%29 = load <2 x double>, <2 x double>* %28
%30 = getelementptr inbounds double, double* %27, i64 2
%31 = bitcast double* %30 to <2 x double>*
%32 = load <2 x double>, <2 x double>* %31
%33 = getelementptr inbounds double, double* %2, i64 %25
%34 = bitcast double* %33 to <2 x double>*
store <2 x double> %29, <2 x double>* %34
%35 = getelementptr inbounds double, double* %33, i64 2
%36 = bitcast double* %35 to <2 x double>*
store <2 x double> %32, <2 x double>* %36
%37 = or i64 %25, 4
%38 = getelementptr inbounds double, double* %1, i64 %37
%39 = bitcast double* %38 to <2 x double>*
%40 = load <2 x double>, <2 x double>* %39
%41 = getelementptr inbounds double, double* %38, i64 2
%42 = bitcast double* %41 to <2 x double>*
%43 = load <2 x double>, <2 x double>* %42
%44 = getelementptr inbounds double, double* %2, i64 %37
%45 = bitcast double* %44 to <2 x double>*
store <2 x double> %40, <2 x double>* %45
%46 = getelementptr inbounds double, double* %44, i64 2
%47 = bitcast double* %46 to <2 x double>*
store <2 x double> %43, <2 x double>* %47
%48 = or i64 %25, 8
%49 = getelementptr inbounds double, double* %1, i64 %48
%50 = bitcast double* %49 to <2 x double>*
%51 = load <2 x double>, <2 x double>* %50
%52 = getelementptr inbounds double, double* %49, i64 2
%53 = bitcast double* %52 to <2 x double>*
%54 = load <2 x double>, <2 x double>* %53
%55 = getelementptr inbounds double, double* %2, i64 %48
%56 = bitcast double* %55 to <2 x double>*
store <2 x double> %51, <2 x double>* %56
%57 = getelementptr inbounds double, double* %55, i64 2
%58 = bitcast double* %57 to <2 x double>*
store <2 x double> %54, <2 x double>* %58
%59 = or i64 %25, 12
%60 = getelementptr inbounds double, double* %1, i64 %59
%61 = bitcast double* %60 to <2 x double>*
%62 = load <2 x double>, <2 x double>* %61
%63 = getelementptr inbounds double, double* %60, i64 2
%64 = bitcast double* %63 to <2 x double>*
%65 = load <2 x double>, <2 x double>* %64
%66 = getelementptr inbounds double, double* %2, i64 %59
%67 = bitcast double* %66 to <2 x double>*
store <2 x double> %62, <2 x double>* %67
%68 = getelementptr inbounds double, double* %66, i64 2
%69 = bitcast double* %68 to <2 x double>*
store <2 x double> %65, <2 x double>* %69
%70 = add nuw i64 %25, 16
%71 = add nuw i64 %26, 4
%72 = icmp eq i64 %71, %23
br i1 %72, label %73, label %24
73: ; preds = %24, %15
%74 = phi i64 [ 0, %15 ], [ %70, %24 ]
%75 = icmp eq i64 %20, 0
br i1 %75, label %92, label %76
76: ; preds = %73, %76
%77 = phi i64 [ %89, %76 ], [ %74, %73 ]
%78 = phi i64 [ %90, %76 ], [ 0, %73 ]
%79 = getelementptr inbounds double, double* %1, i64 %77
%80 = bitcast double* %79 to <2 x double>*
%81 = load <2 x double>, <2 x double>* %80
%82 = getelementptr inbounds double, double* %79, i64 2
%83 = bitcast double* %82 to <2 x double>*
%84 = load <2 x double>, <2 x double>* %83
%85 = getelementptr inbounds double, double* %2, i64 %77
%86 = bitcast double* %85 to <2 x double>*
store <2 x double> %81, <2 x double>* %86
%87 = getelementptr inbounds double, double* %85, i64 2
%88 = bitcast double* %87 to <2 x double>*
store <2 x double> %84, <2 x double>* %88
%89 = add nuw i64 %77, 4
%90 = add i64 %78, 1
%91 = icmp eq i64 %90, %20
br i1 %91, label %92, label %76
92: ; preds = %76, %73
%93 = icmp eq i64 %16, %7
br i1 %93, label %112, label %94
94: ; preds = %9, %6, %92
%95 = phi i64 [ 0, %9 ], [ 0, %6 ], [ %16, %92 ]
%96 = xor i64 %95, -1
%97 = add nsw i64 %96, %7
%98 = and i64 %7, 3
%99 = icmp eq i64 %98, 0
br i1 %99, label %109, label %100
100: ; preds = %94, %100
%101 = phi i64 [ %106, %100 ], [ %95, %94 ]
%102 = phi i64 [ %107, %100 ], [ 0, %94 ]
%103 = getelementptr inbounds double, double* %1, i64 %101
%104 = load double, double* %103
%105 = getelementptr inbounds double, double* %2, i64 %101
store double %104, double* %105
%106 = add nuw nsw i64 %101, 1
%107 = add i64 %102, 1
%108 = icmp eq i64 %107, %98
br i1 %108, label %109, label %100
109: ; preds = %100, %94
%110 = phi i64 [ %95, %94 ], [ %106, %100 ]
%111 = icmp ult i64 %97, 3
br i1 %111, label %112, label %128
112: ; preds = %109, %128, %92, %3
%113 = icmp sgt i32 %0, 1
br i1 %113, label %114, label %301
114: ; preds = %112
%115 = add nsw i32 %0, -1
%116 = zext i32 %0 to i64
%117 = zext i32 %115 to i64
%118 = zext i32 %0 to i64
%119 = add nuw nsw i64 %118, 2
%120 = shl nuw nsw i64 %118, 3
%121 = add nuw nsw i64 %120, 8
%122 = shl nuw nsw i64 %118, 1
%123 = add nuw nsw i64 %118, 1
%124 = getelementptr double, double* %2, i64 2
%125 = bitcast double* %124 to i8*
%126 = add nsw i64 %118, -2
%127 = sub nsw i64 0, %116
br label %150
128: ; preds = %109, %128
%129 = phi i64 [ %145, %128 ], [ %110, %109 ]
%130 = getelementptr inbounds double, double* %1, i64 %129
%131 = load double, double* %130
%132 = getelementptr inbounds double, double* %2, i64 %129
store double %131, double* %132
%133 = add nuw nsw i64 %129, 1
%134 = getelementptr inbounds double, double* %1, i64 %133
%135 = load double, double* %134
%136 = getelementptr inbounds double, double* %2, i64 %133
store double %135, double* %136
%137 = add nuw nsw i64 %129, 2
%138 = getelementptr inbounds double, double* %1, i64 %137
%139 = load double, double* %138
%140 = getelementptr inbounds double, double* %2, i64 %137
store double %139, double* %140
%141 = add nuw nsw i64 %129, 3
%142 = getelementptr inbounds double, double* %1, i64 %141
%143 = load double, double* %142
%144 = getelementptr inbounds double, double* %2, i64 %141
store double %143, double* %144
%145 = add nuw nsw i64 %129, 4
%146 = icmp eq i64 %145, %7
br i1 %146, label %112, label %128
147: ; preds = %297, %172
%148 = add nuw nsw i64 %152, 1
%149 = icmp eq i64 %173, %117
br i1 %149, label %301, label %150
150: ; preds = %114, %147
%151 = phi i64 [ 0, %114 ], [ %173, %147 ]
%152 = phi i64 [ 1, %114 ], [ %148, %147 ]
%153 = sub i64 %126, %151
%154 = mul i64 %121, %151
%155 = mul i64 %151, %118
%156 = add i64 %122, %155
%157 = getelementptr i8, i8* %125, i64 %154
%158 = add i64 %155, %118
%159 = getelementptr double, double* %2, i64 %158
%160 = bitcast double* %159 to i8*
%161 = trunc i64 %151 to i32
%162 = mul nsw i64 %151, %116
%163 = mul nsw i32 %161, %0
%164 = sext i32 %163 to i64
%165 = add nsw i64 %151, %164
%166 = getelementptr inbounds double, double* %2, i64 %165
%167 = load double, double* %166
%168 = fcmp oeq double %167, 0.000000e+00
br i1 %168, label %169, label %172
169: ; preds = %150
%170 = load i32, i32* @stderr
%171 = tail call i32 @fprintf(i32 %170, i8* getelementptr inbounds ([35 x i8], [35 x i8]* @.str, i64 0, i64 0), i32 %161, i32 %161)
br label %172
172: ; preds = %169, %150
%173 = add nuw nsw i64 %151, 1
%174 = icmp ult i64 %173, %116
br i1 %174, label %175, label %147
175: ; preds = %172
%176 = add nuw nsw i64 %152, %162
%177 = getelementptr inbounds double, double* %2, i64 %176
%178 = add nuw nsw i64 %152, 1
%179 = icmp eq i64 %178, %118
%180 = icmp ult i64 %153, 4
%181 = and i64 %153, -4
%182 = add i64 %178, %181
%183 = icmp eq i64 %153, %181
br label %184
184: ; preds = %175, %297
%185 = phi i64 [ %300, %297 ], [ 0, %175 ]
%186 = phi i64 [ %298, %297 ], [ %152, %175 ]
%187 = mul i64 %185, %118
%188 = add i64 %119, %187
%189 = getelementptr double, double* %2, i64 %188
%190 = bitcast double* %189 to i8*
%191 = getelementptr i8, i8* %190, i64 %154
%192 = add i64 %156, %187
%193 = getelementptr double, double* %2, i64 %192
%194 = bitcast double* %193 to i8*
%195 = add i64 %187, %118
%196 = getelementptr double, double* %2, i64 %195
%197 = bitcast double* %196 to i8*
%198 = getelementptr i8, i8* %197, i64 %154
%199 = add i64 %123, %187
%200 = getelementptr double, double* %2, i64 %199
%201 = mul nsw i64 %186, %116
%202 = add nuw nsw i64 %201, %151
%203 = getelementptr inbounds double, double* %2, i64 %202
%204 = load double, double* %203
%205 = load double, double* %166
%206 = fdiv double %204, %205
store double %206, double* %203
%207 = load double, double* %177
%208 = add nuw nsw i64 %152, %201
%209 = getelementptr inbounds double, double* %2, i64 %208
%210 = load double, double* %209
%211 = fneg double %206
%212 = tail call double @llvm.fmuladd.f64(double %211, double %207, double %210)
store double %212, double* %209
br i1 %179, label %297, label %213
213: ; preds = %184
br i1 %180, label %254, label %214
214: ; preds = %213
%215 = icmp ult double* %189, %200
%216 = icmp ult i8* %198, %194
%217 = and i1 %215, %216
%218 = icmp ult i8* %191, %160
%219 = icmp ult i8* %157, %194
%220 = and i1 %218, %219
%221 = or i1 %217, %220
br i1 %221, label %254, label %222
222: ; preds = %214
%223 = load double, double* %203
%224 = insertelement <2 x double> poison, double %223, i64 0
%225 = shufflevector <2 x double> %224, <2 x double> poison, <2 x i32> zeroinitializer
%226 = insertelement <2 x double> poison, double %223, i64 0
%227 = shufflevector <2 x double> %226, <2 x double> poison, <2 x i32> zeroinitializer
%228 = fneg <2 x double> %225
%229 = fneg <2 x double> %227
br label %230
230: ; preds = %230, %222
%231 = phi i64 [ 0, %222 ], [ %251, %230 ]
%232 = add i64 %178, %231
%233 = add nuw nsw i64 %232, %162
%234 = getelementptr inbounds double, double* %2, i64 %233
%235 = bitcast double* %234 to <2 x double>*
%236 = load <2 x double>, <2 x double>* %235
%237 = getelementptr inbounds double, double* %234, i64 2
%238 = bitcast double* %237 to <2 x double>*
%239 = load <2 x double>, <2 x double>* %238
%240 = add nuw nsw i64 %232, %201
%241 = getelementptr inbounds double, double* %2, i64 %240
%242 = bitcast double* %241 to <2 x double>*
%243 = load <2 x double>, <2 x double>* %242
%244 = getelementptr inbounds double, double* %241, i64 2
%245 = bitcast double* %244 to <2 x double>*
%246 = load <2 x double>, <2 x double>* %245
%247 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %228, <2 x double> %236, <2 x double> %243)
%248 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %229, <2 x double> %239, <2 x double> %246)
%249 = bitcast double* %241 to <2 x double>*
store <2 x double> %247, <2 x double>* %249
%250 = bitcast double* %244 to <2 x double>*
store <2 x double> %248, <2 x double>* %250
%251 = add nuw i64 %231, 4
%252 = icmp eq i64 %251, %181
br i1 %252, label %253, label %230
253: ; preds = %230
br i1 %183, label %297, label %254
254: ; preds = %214, %213, %253
%255 = phi i64 [ %178, %214 ], [ %178, %213 ], [ %182, %253 ]
%256 = sub i64 %116, %255
%257 = xor i64 %255, -1
%258 = and i64 %256, 1
%259 = icmp eq i64 %258, 0
br i1 %259, label %271, label %260
260: ; preds = %254
%261 = load double, double* %203
%262 = add nuw nsw i64 %255, %162
%263 = getelementptr inbounds double, double* %2, i64 %262
%264 = load double, double* %263
%265 = add nuw nsw i64 %255, %201
%266 = getelementptr inbounds double, double* %2, i64 %265
%267 = load double, double* %266
%268 = fneg double %261
%269 = tail call double @llvm.fmuladd.f64(double %268, double %264, double %267)
store double %269, double* %266
%270 = add nuw nsw i64 %255, 1
br label %271
271: ; preds = %260, %254
%272 = phi i64 [ %255, %254 ], [ %270, %260 ]
%273 = icmp eq i64 %257, %127
br i1 %273, label %297, label %274
274: ; preds = %271, %274
%275 = phi i64 [ %295, %274 ], [ %272, %271 ]
%276 = load double, double* %203
%277 = add nuw nsw i64 %275, %162
%278 = getelementptr inbounds double, double* %2, i64 %277
%279 = load double, double* %278
%280 = add nuw nsw i64 %275, %201
%281 = getelementptr inbounds double, double* %2, i64 %280
%282 = load double, double* %281
%283 = fneg double %276
%284 = tail call double @llvm.fmuladd.f64(double %283, double %279, double %282)
store double %284, double* %281
%285 = add nuw nsw i64 %275, 1
%286 = load double, double* %203
%287 = add nuw nsw i64 %285, %162
%288 = getelementptr inbounds double, double* %2, i64 %287
%289 = load double, double* %288
%290 = add nuw nsw i64 %285, %201
%291 = getelementptr inbounds double, double* %2, i64 %290
%292 = load double, double* %291
%293 = fneg double %286
%294 = tail call double @llvm.fmuladd.f64(double %293, double %289, double %292)
store double %294, double* %291
%295 = add nuw nsw i64 %275, 2
%296 = icmp eq i64 %295, %118
br i1 %296, label %297, label %274
297: ; preds = %271, %274, %253, %184
%298 = add nuw nsw i64 %186, 1
%299 = icmp eq i64 %298, %118
%300 = add i64 %185, 1
br i1 %299, label %147, label %184
301: ; preds = %147, %112
ret void
}