#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*/ boundary_pressure();
double compute_error(double *, double *, double *, double *);
double fabs(double);
int /*<<< orphan*/ printf(char *, int, double);
void Gauss_siedel(double *P, double *fn, double *a_x, double *a_y) {
  long i, j, indx, indx_rght, indx_frnt, indx_lft, indx_bck, indx_ax, indx_ay;
  double P_old;
  double error;
  double tol = 1.0e-6;
  int iter = 0;
  for (;;) {
    boundary_pressure();
    for (i = 1; i < (65) - 1; i++) {
      for (j = 1; j < (65) - 1; j++) {
        indx = i * (65) + j;
        indx_rght = indx + 1;
        indx_frnt = indx + (65);
        indx_lft = indx - 1;
        indx_bck = indx - (65);
        indx_ax = i * ((65) - 1) + j;
        indx_ay = i * ((65) - 2) + j;
        if (((i + j) % 2) == 0) {
          P[indx] =
              -1.0 * (P[indx_lft] + P[indx_rght] + P[indx_bck] + P[indx_frnt]) +
              (1.0) * (1.0) * fn[indx];
          P[indx] = -1.0 * (a_x[indx_ax - 1] * P[indx_lft] +
                            a_x[indx_ax] * P[indx_rght] +
                            a_y[indx_ay - ((65) - 2)] * P[indx_bck] +
                            a_y[indx_ay] * P[indx_frnt]) +
                    (1.0) * (1.0) * fn[indx];
          P[indx] /= -1.0 * (a_x[indx_ax - 1] + a_x[indx_ax] +
                             a_y[indx_ay - ((65) - 2)] + a_y[indx_ay]);
        }
      }
    }
    for (i = 1; i < (65) - 1; i++) {
      for (j = 1; j < (65) - 1; j++) {
        indx = i * (65) + j;
        indx_rght = indx + 1;
        indx_frnt = indx + (65);
        indx_lft = indx - 1;
        indx_bck = indx - (65);
        indx_ax = i * ((65) - 1) + j;
        indx_ay = i * ((65) - 2) + j;
        if (((i + j) % 2) != 0) {
          P[indx] = -1.0 * (a_x[indx_ax - 1] * P[indx_lft] +
                            a_x[indx_ax] * P[indx_rght] +
                            a_y[indx_ay - ((65) - 2)] * P[indx_bck] +
                            a_y[indx_ay] * P[indx_frnt]) +
                    (1.0) * (1.0) * fn[indx];
          P[indx] /= -1.0 * (a_x[indx_ax - 1] + a_x[indx_ax] +
                             a_y[indx_ay - ((65) - 2)] + a_y[indx_ay]);
        }
      }
    }
    iter++;
    error = compute_error(a_x, a_y, P, fn);
    printf("iter=%d\terror=%lf\n", iter, error);
    if (fabs(error) < tol) {
      break;
    }
  }
}


x86 assembly (clang, -O0):
<Gauss_siedel>:
push   %rbp
mov    %rsp,%rbp
sub    $0x90,%rsp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    %rdx,-0x18(%rbp)
mov    %rcx,-0x20(%rbp)
movsd  0xead(%rip),%xmm0
movsd  %xmm0,-0x80(%rbp)
movl   $0x0,-0x84(%rbp)
mov    $0x0,%al
call   1040 <boundary_pressure@plt>
movq   $0x1,-0x28(%rbp)
cmpq   $0x40,-0x28(%rbp)
jge    1397 <Gauss_siedel+0x267>
movq   $0x1,-0x30(%rbp)
cmpq   $0x40,-0x30(%rbp)
jge    1381 <Gauss_siedel+0x251>
imul   $0x41,-0x28(%rbp),%rax
add    -0x30(%rbp),%rax
mov    %rax,-0x38(%rbp)
mov    -0x38(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x40(%rbp)
mov    -0x38(%rbp),%rax
add    $0x41,%rax
mov    %rax,-0x48(%rbp)
mov    -0x38(%rbp),%rax
sub    $0x1,%rax
mov    %rax,-0x50(%rbp)
mov    -0x38(%rbp),%rax
sub    $0x41,%rax
mov    %rax,-0x58(%rbp)
mov    -0x28(%rbp),%rax
shl    $0x6,%rax
add    -0x30(%rbp),%rax
mov    %rax,-0x60(%rbp)
imul   $0x3f,-0x28(%rbp),%rax
add    -0x30(%rbp),%rax
mov    %rax,-0x68(%rbp)
mov    -0x28(%rbp),%rax
add    -0x30(%rbp),%rax
mov    $0x2,%ecx
cqto
idiv   %rcx
cmp    $0x0,%rdx
jne    136b <Gauss_siedel+0x23b>
mov    -0x8(%rbp),%rax
mov    -0x50(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x40(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x58(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x48(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm1
mov    -0x10(%rbp),%rax
mov    -0x38(%rbp),%rcx
movsd  0xdc7(%rip),%xmm0
mulsd  (%rax,%rcx,8),%xmm0
subsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x38(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%rcx
sub    $0x1,%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x50(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm2
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x8(%rbp),%rax
mov    -0x40(%rbp),%rcx
mulsd  (%rax,%rcx,8),%xmm0
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
sub    $0x3f,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x8(%rbp),%rax
mov    -0x58(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x48(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm2
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
mov    -0x10(%rbp),%rax
mov    -0x38(%rbp),%rcx
movsd  0xd19(%rip),%xmm0
mulsd  (%rax,%rcx,8),%xmm0
subsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x38(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%rcx
sub    $0x1,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm0
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
sub    $0x3f,%rcx
addsd  (%rax,%rcx,8),%xmm0
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm0
movsd  0xcb7(%rip),%xmm1
mulsd  %xmm0,%xmm1
mov    -0x8(%rbp),%rax
mov    -0x38(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
divsd  %xmm1,%xmm0
movsd  %xmm0,(%rax,%rcx,8)
jmp    1370 <Gauss_siedel+0x240>
mov    -0x30(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x30(%rbp)
jmp    1184 <Gauss_siedel+0x54>
jmp    1386 <Gauss_siedel+0x256>
mov    -0x28(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x28(%rbp)
jmp    1171 <Gauss_siedel+0x41>
movq   $0x1,-0x28(%rbp)
cmpq   $0x40,-0x28(%rbp)
jge    156b <Gauss_siedel+0x43b>
movq   $0x1,-0x30(%rbp)
cmpq   $0x40,-0x30(%rbp)
jge    1555 <Gauss_siedel+0x425>
imul   $0x41,-0x28(%rbp),%rax
add    -0x30(%rbp),%rax
mov    %rax,-0x38(%rbp)
mov    -0x38(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x40(%rbp)
mov    -0x38(%rbp),%rax
add    $0x41,%rax
mov    %rax,-0x48(%rbp)
mov    -0x38(%rbp),%rax
sub    $0x1,%rax
mov    %rax,-0x50(%rbp)
mov    -0x38(%rbp),%rax
sub    $0x41,%rax
mov    %rax,-0x58(%rbp)
mov    -0x28(%rbp),%rax
shl    $0x6,%rax
add    -0x30(%rbp),%rax
mov    %rax,-0x60(%rbp)
imul   $0x3f,-0x28(%rbp),%rax
add    -0x30(%rbp),%rax
mov    %rax,-0x68(%rbp)
mov    -0x28(%rbp),%rax
add    -0x30(%rbp),%rax
mov    $0x2,%ecx
cqto
idiv   %rcx
cmp    $0x0,%rdx
je     153f <Gauss_siedel+0x40f>
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%rcx
sub    $0x1,%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x50(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm2
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x8(%rbp),%rax
mov    -0x40(%rbp),%rcx
mulsd  (%rax,%rcx,8),%xmm0
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
sub    $0x3f,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x8(%rbp),%rax
mov    -0x58(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x48(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm2
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
mov    -0x10(%rbp),%rax
mov    -0x38(%rbp),%rcx
movsd  0xb45(%rip),%xmm0
mulsd  (%rax,%rcx,8),%xmm0
subsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x38(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%rcx
sub    $0x1,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm0
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
sub    $0x3f,%rcx
addsd  (%rax,%rcx,8),%xmm0
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm0
movsd  0xae3(%rip),%xmm1
mulsd  %xmm0,%xmm1
mov    -0x8(%rbp),%rax
mov    -0x38(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
divsd  %xmm1,%xmm0
movsd  %xmm0,(%rax,%rcx,8)
jmp    1544 <Gauss_siedel+0x414>
mov    -0x30(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x30(%rbp)
jmp    13b2 <Gauss_siedel+0x282>
jmp    155a <Gauss_siedel+0x42a>
mov    -0x28(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x28(%rbp)
jmp    139f <Gauss_siedel+0x26f>
mov    -0x84(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x84(%rbp)
mov    -0x18(%rbp),%rdi
mov    -0x20(%rbp),%rsi
mov    -0x8(%rbp),%rdx
mov    -0x10(%rbp),%rcx
call   1050 <compute_error@plt>
movsd  %xmm0,-0x78(%rbp)
mov    -0x84(%rbp),%esi
movsd  -0x78(%rbp),%xmm0
lea    0xa8a(%rip),%rdi
call   1030 <printf@plt>
movsd  -0x78(%rbp),%xmm1
movaps 0xa69(%rip),%xmm0
pand   %xmm0,%xmm1
movsd  -0x80(%rbp),%xmm0
ucomisd %xmm1,%xmm0
jbe    15cf <Gauss_siedel+0x49f>
jmp    15d4 <Gauss_siedel+0x4a4>
jmp    1162 <Gauss_siedel+0x32>
add    $0x90,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<Gauss_siedel>:
push   %rbp
push   %r15
push   %r14
push   %r13
push   %r12
push   %rbx
sub    $0x48,%rsp
mov    %rcx,0x28(%rsp)
lea    0x200(%rcx),%rax
mov    %rax,0x8(%rsp)
mov    %rdx,0x20(%rsp)
lea    0x208(%rdx),%r14
mov    %rdi,0x10(%rsp)
lea    0x418(%rdi),%r15
mov    %rsi,0x18(%rsp)
lea    0x210(%rsi),%r12
xor    %r13d,%r13d
jmp    11d2 <Gauss_siedel+0xa2>
nopl   0x0(%rax,%rax,1)
add    $0x1,%r13d
mov    0x20(%rsp),%rdi
mov    0x28(%rsp),%rsi
mov    0x10(%rsp),%rdx
mov    0x18(%rsp),%rcx
call   1050 <compute_error@plt>
movapd %xmm0,0x30(%rsp)
lea    0xe7e(%rip),%rdi
mov    %r13d,%esi
call   1030 <printf@plt>
movapd 0x30(%rsp),%xmm1
andpd  0xe50(%rip),%xmm1
movsd  0xe58(%rip),%xmm0
ucomisd %xmm1,%xmm0
ja     13f7 <Gauss_siedel+0x2c7>
xor    %eax,%eax
call   1040 <boundary_pressure@plt>
mov    $0x1,%r8d
mov    $0x2,%ecx
mov    %r12,%rdx
mov    %r15,%rsi
mov    %r14,%rdi
mov    0x8(%rsp),%rbx
movapd 0xe06(%rip),%xmm6
jmp    122e <Gauss_siedel+0xfe>
nopl   0x0(%rax)
add    $0x1,%r8
add    $0x1,%rcx
add    $0x1f8,%rbx
add    $0x200,%rdi
add    $0x208,%rsi
add    $0x208,%rdx
cmp    $0x40,%r8
je     1300 <Gauss_siedel+0x1d0>
xor    %ebp,%ebp
jmp    124a <Gauss_siedel+0x11a>
cs nopw 0x0(%rax,%rax,1)
nopl   0x0(%rax)
add    $0x1,%rbp
cmp    $0x3f,%rbp
je     1200 <Gauss_siedel+0xd0>
lea    (%rcx,%rbp,1),%eax
test   $0x1,%al
jne    1240 <Gauss_siedel+0x110>
movsd  -0x410(%rsi,%rbp,8),%xmm0
ff ff
movsd  -0x210(%rsi,%rbp,8),%xmm1
ff ff
movsd  -0x200(%rsi,%rbp,8),%xmm2
ff ff
movapd %xmm1,%xmm3
addsd  %xmm2,%xmm3
addsd  %xmm0,%xmm3
movsd  (%rsi,%rbp,8),%xmm4
addsd  %xmm4,%xmm3
movsd  (%rdx,%rbp,8),%xmm5
subsd  %xmm3,%xmm5
movsd  %xmm5,-0x208(%rsi,%rbp,8)
ff ff
mulsd  (%rdi,%rbp,8),%xmm2
mulsd  -0x8(%rdi,%rbp,8),%xmm1
addsd  %xmm2,%xmm1
mulsd  -0x1f8(%rbx,%rbp,8),%xmm0
ff ff
mulsd  (%rbx,%rbp,8),%xmm4
addsd  %xmm1,%xmm0
addsd  %xmm0,%xmm4
movsd  (%rdx,%rbp,8),%xmm0
subsd  %xmm4,%xmm0
movsd  %xmm0,-0x208(%rsi,%rbp,8)
ff ff
movsd  -0x8(%rdi,%rbp,8),%xmm1
addsd  (%rdi,%rbp,8),%xmm1
addsd  -0x1f8(%rbx,%rbp,8),%xmm1
ff ff
addsd  (%rbx,%rbp,8),%xmm1
xorpd  %xmm6,%xmm1
divsd  %xmm1,%xmm0
movsd  %xmm0,-0x208(%rsi,%rbp,8)
ff ff
jmp    1240 <Gauss_siedel+0x110>
nopl   0x0(%rax)
mov    $0x1,%r8d
mov    $0x2,%ecx
mov    %r12,%rdx
mov    %r15,%rsi
mov    %r14,%rdi
mov    0x8(%rsp),%rbx
jmp    134e <Gauss_siedel+0x21e>
nopl   0x0(%rax,%rax,1)
add    $0x1,%r8
add    $0x1,%rcx
add    $0x1f8,%rbx
add    $0x200,%rdi
add    $0x208,%rsi
add    $0x208,%rdx
cmp    $0x40,%r8
je     1180 <Gauss_siedel+0x50>
xor    %ebp,%ebp
jmp    136a <Gauss_siedel+0x23a>
cs nopw 0x0(%rax,%rax,1)
nopl   0x0(%rax)
add    $0x1,%rbp
cmp    $0x3f,%rbp
je     1320 <Gauss_siedel+0x1f0>
lea    (%rcx,%rbp,1),%eax
test   $0x1,%al
je     1360 <Gauss_siedel+0x230>
movsd  -0x8(%rdi,%rbp,8),%xmm0
movsd  (%rdi,%rbp,8),%xmm1
mulsd  -0x200(%rsi,%rbp,8),%xmm1
ff ff
mulsd  -0x210(%rsi,%rbp,8),%xmm0
ff ff
addsd  %xmm1,%xmm0
movsd  -0x1f8(%rbx,%rbp,8),%xmm1
ff ff
movsd  (%rbx,%rbp,8),%xmm2
mulsd  -0x410(%rsi,%rbp,8),%xmm1
ff ff
mulsd  (%rsi,%rbp,8),%xmm2
addsd  %xmm0,%xmm1
addsd  %xmm1,%xmm2
movsd  (%rdx,%rbp,8),%xmm0
subsd  %xmm2,%xmm0
movsd  %xmm0,-0x208(%rsi,%rbp,8)
ff ff
movsd  -0x8(%rdi,%rbp,8),%xmm1
addsd  (%rdi,%rbp,8),%xmm1
addsd  -0x1f8(%rbx,%rbp,8),%xmm1
ff ff
addsd  (%rbx,%rbp,8),%xmm1
xorpd  %xmm6,%xmm1
divsd  %xmm1,%xmm0
movsd  %xmm0,-0x208(%rsi,%rbp,8)
ff ff
jmp    1360 <Gauss_siedel+0x230>
add    $0x48,%rsp
pop    %rbx
pop    %r12
pop    %r13
pop    %r14
pop    %r15
pop    %rbp
ret

LLVM IR (-O0):
@.str = [19 x i8] c"iter=%d\09error=%lf\0A\00"
define void @Gauss_siedel(double* %0, double* %1, double* %2, double* %3) {
%5 = alloca double*
%6 = alloca double*
%7 = alloca double*
%8 = alloca double*
%9 = alloca i64
%10 = alloca i64
%11 = alloca i64
%12 = alloca i64
%13 = alloca i64
%14 = alloca i64
%15 = alloca i64
%16 = alloca i64
%17 = alloca i64
%18 = alloca double
%19 = alloca double
%20 = alloca double
%21 = alloca i32
store double* %0, double** %5
store double* %1, double** %6
store double* %2, double** %7
store double* %3, double** %8
store double 0x3EB0C6F7A0B5ED8D, double* %20
store i32 0, i32* %21
br label %22
22: ; preds = %301, %4
%23 = call i32 (...) @boundary_pressure()
store i64 1, i64* %9
br label %24
24: ; preds = %165, %22
%25 = load i64, i64* %9
%26 = icmp slt i64 %25, 64
br i1 %26, label %27, label %168
27: ; preds = %24
store i64 1, i64* %10
br label %28
28: ; preds = %161, %27
%29 = load i64, i64* %10
%30 = icmp slt i64 %29, 64
br i1 %30, label %31, label %164
31: ; preds = %28
%32 = load i64, i64* %9
%33 = mul nsw i64 %32, 65
%34 = load i64, i64* %10
%35 = add nsw i64 %33, %34
store i64 %35, i64* %11
%36 = load i64, i64* %11
%37 = add nsw i64 %36, 1
store i64 %37, i64* %12
%38 = load i64, i64* %11
%39 = add nsw i64 %38, 65
store i64 %39, i64* %13
%40 = load i64, i64* %11
%41 = sub nsw i64 %40, 1
store i64 %41, i64* %14
%42 = load i64, i64* %11
%43 = sub nsw i64 %42, 65
store i64 %43, i64* %15
%44 = load i64, i64* %9
%45 = mul nsw i64 %44, 64
%46 = load i64, i64* %10
%47 = add nsw i64 %45, %46
store i64 %47, i64* %16
%48 = load i64, i64* %9
%49 = mul nsw i64 %48, 63
%50 = load i64, i64* %10
%51 = add nsw i64 %49, %50
store i64 %51, i64* %17
%52 = load i64, i64* %9
%53 = load i64, i64* %10
%54 = add nsw i64 %52, %53
%55 = srem i64 %54, 2
%56 = icmp eq i64 %55, 0
br i1 %56, label %57, label %160
57: ; preds = %31
%58 = load double*, double** %5
%59 = load i64, i64* %14
%60 = getelementptr inbounds double, double* %58, i64 %59
%61 = load double, double* %60
%62 = load double*, double** %5
%63 = load i64, i64* %12
%64 = getelementptr inbounds double, double* %62, i64 %63
%65 = load double, double* %64
%66 = fadd double %61, %65
%67 = load double*, double** %5
%68 = load i64, i64* %15
%69 = getelementptr inbounds double, double* %67, i64 %68
%70 = load double, double* %69
%71 = fadd double %66, %70
%72 = load double*, double** %5
%73 = load i64, i64* %13
%74 = getelementptr inbounds double, double* %72, i64 %73
%75 = load double, double* %74
%76 = fadd double %71, %75
%77 = load double*, double** %6
%78 = load i64, i64* %11
%79 = getelementptr inbounds double, double* %77, i64 %78
%80 = load double, double* %79
%81 = fmul double 1.000000e+00, %80
%82 = call double @llvm.fmuladd.f64(double -1.000000e+00, double %76, double %81)
%83 = load double*, double** %5
%84 = load i64, i64* %11
%85 = getelementptr inbounds double, double* %83, i64 %84
store double %82, double* %85
%86 = load double*, double** %7
%87 = load i64, i64* %16
%88 = sub nsw i64 %87, 1
%89 = getelementptr inbounds double, double* %86, i64 %88
%90 = load double, double* %89
%91 = load double*, double** %5
%92 = load i64, i64* %14
%93 = getelementptr inbounds double, double* %91, i64 %92
%94 = load double, double* %93
%95 = load double*, double** %7
%96 = load i64, i64* %16
%97 = getelementptr inbounds double, double* %95, i64 %96
%98 = load double, double* %97
%99 = load double*, double** %5
%100 = load i64, i64* %12
%101 = getelementptr inbounds double, double* %99, i64 %100
%102 = load double, double* %101
%103 = fmul double %98, %102
%104 = call double @llvm.fmuladd.f64(double %90, double %94, double %103)
%105 = load double*, double** %8
%106 = load i64, i64* %17
%107 = sub nsw i64 %106, 63
%108 = getelementptr inbounds double, double* %105, i64 %107
%109 = load double, double* %108
%110 = load double*, double** %5
%111 = load i64, i64* %15
%112 = getelementptr inbounds double, double* %110, i64 %111
%113 = load double, double* %112
%114 = call double @llvm.fmuladd.f64(double %109, double %113, double %104)
%115 = load double*, double** %8
%116 = load i64, i64* %17
%117 = getelementptr inbounds double, double* %115, i64 %116
%118 = load double, double* %117
%119 = load double*, double** %5
%120 = load i64, i64* %13
%121 = getelementptr inbounds double, double* %119, i64 %120
%122 = load double, double* %121
%123 = call double @llvm.fmuladd.f64(double %118, double %122, double %114)
%124 = load double*, double** %6
%125 = load i64, i64* %11
%126 = getelementptr inbounds double, double* %124, i64 %125
%127 = load double, double* %126
%128 = fmul double 1.000000e+00, %127
%129 = call double @llvm.fmuladd.f64(double -1.000000e+00, double %123, double %128)
%130 = load double*, double** %5
%131 = load i64, i64* %11
%132 = getelementptr inbounds double, double* %130, i64 %131
store double %129, double* %132
%133 = load double*, double** %7
%134 = load i64, i64* %16
%135 = sub nsw i64 %134, 1
%136 = getelementptr inbounds double, double* %133, i64 %135
%137 = load double, double* %136
%138 = load double*, double** %7
%139 = load i64, i64* %16
%140 = getelementptr inbounds double, double* %138, i64 %139
%141 = load double, double* %140
%142 = fadd double %137, %141
%143 = load double*, double** %8
%144 = load i64, i64* %17
%145 = sub nsw i64 %144, 63
%146 = getelementptr inbounds double, double* %143, i64 %145
%147 = load double, double* %146
%148 = fadd double %142, %147
%149 = load double*, double** %8
%150 = load i64, i64* %17
%151 = getelementptr inbounds double, double* %149, i64 %150
%152 = load double, double* %151
%153 = fadd double %148, %152
%154 = fmul double -1.000000e+00, %153
%155 = load double*, double** %5
%156 = load i64, i64* %11
%157 = getelementptr inbounds double, double* %155, i64 %156
%158 = load double, double* %157
%159 = fdiv double %158, %154
store double %159, double* %157
br label %160
160: ; preds = %57, %31
br label %161
161: ; preds = %160
%162 = load i64, i64* %10
%163 = add nsw i64 %162, 1
store i64 %163, i64* %10
br label %28
164: ; preds = %28
br label %165
165: ; preds = %164
%166 = load i64, i64* %9
%167 = add nsw i64 %166, 1
store i64 %167, i64* %9
br label %24
168: ; preds = %24
store i64 1, i64* %9
br label %169
169: ; preds = %282, %168
%170 = load i64, i64* %9
%171 = icmp slt i64 %170, 64
br i1 %171, label %172, label %285
172: ; preds = %169
store i64 1, i64* %10
br label %173
173: ; preds = %278, %172
%174 = load i64, i64* %10
%175 = icmp slt i64 %174, 64
br i1 %175, label %176, label %281
176: ; preds = %173
%177 = load i64, i64* %9
%178 = mul nsw i64 %177, 65
%179 = load i64, i64* %10
%180 = add nsw i64 %178, %179
store i64 %180, i64* %11
%181 = load i64, i64* %11
%182 = add nsw i64 %181, 1
store i64 %182, i64* %12
%183 = load i64, i64* %11
%184 = add nsw i64 %183, 65
store i64 %184, i64* %13
%185 = load i64, i64* %11
%186 = sub nsw i64 %185, 1
store i64 %186, i64* %14
%187 = load i64, i64* %11
%188 = sub nsw i64 %187, 65
store i64 %188, i64* %15
%189 = load i64, i64* %9
%190 = mul nsw i64 %189, 64
%191 = load i64, i64* %10
%192 = add nsw i64 %190, %191
store i64 %192, i64* %16
%193 = load i64, i64* %9
%194 = mul nsw i64 %193, 63
%195 = load i64, i64* %10
%196 = add nsw i64 %194, %195
store i64 %196, i64* %17
%197 = load i64, i64* %9
%198 = load i64, i64* %10
%199 = add nsw i64 %197, %198
%200 = srem i64 %199, 2
%201 = icmp ne i64 %200, 0
br i1 %201, label %202, label %277
202: ; preds = %176
%203 = load double*, double** %7
%204 = load i64, i64* %16
%205 = sub nsw i64 %204, 1
%206 = getelementptr inbounds double, double* %203, i64 %205
%207 = load double, double* %206
%208 = load double*, double** %5
%209 = load i64, i64* %14
%210 = getelementptr inbounds double, double* %208, i64 %209
%211 = load double, double* %210
%212 = load double*, double** %7
%213 = load i64, i64* %16
%214 = getelementptr inbounds double, double* %212, i64 %213
%215 = load double, double* %214
%216 = load double*, double** %5
%217 = load i64, i64* %12
%218 = getelementptr inbounds double, double* %216, i64 %217
%219 = load double, double* %218
%220 = fmul double %215, %219
%221 = call double @llvm.fmuladd.f64(double %207, double %211, double %220)
%222 = load double*, double** %8
%223 = load i64, i64* %17
%224 = sub nsw i64 %223, 63
%225 = getelementptr inbounds double, double* %222, i64 %224
%226 = load double, double* %225
%227 = load double*, double** %5
%228 = load i64, i64* %15
%229 = getelementptr inbounds double, double* %227, i64 %228
%230 = load double, double* %229
%231 = call double @llvm.fmuladd.f64(double %226, double %230, double %221)
%232 = load double*, double** %8
%233 = load i64, i64* %17
%234 = getelementptr inbounds double, double* %232, i64 %233
%235 = load double, double* %234
%236 = load double*, double** %5
%237 = load i64, i64* %13
%238 = getelementptr inbounds double, double* %236, i64 %237
%239 = load double, double* %238
%240 = call double @llvm.fmuladd.f64(double %235, double %239, double %231)
%241 = load double*, double** %6
%242 = load i64, i64* %11
%243 = getelementptr inbounds double, double* %241, i64 %242
%244 = load double, double* %243
%245 = fmul double 1.000000e+00, %244
%246 = call double @llvm.fmuladd.f64(double -1.000000e+00, double %240, double %245)
%247 = load double*, double** %5
%248 = load i64, i64* %11
%249 = getelementptr inbounds double, double* %247, i64 %248
store double %246, double* %249
%250 = load double*, double** %7
%251 = load i64, i64* %16
%252 = sub nsw i64 %251, 1
%253 = getelementptr inbounds double, double* %250, i64 %252
%254 = load double, double* %253
%255 = load double*, double** %7
%256 = load i64, i64* %16
%257 = getelementptr inbounds double, double* %255, i64 %256
%258 = load double, double* %257
%259 = fadd double %254, %258
%260 = load double*, double** %8
%261 = load i64, i64* %17
%262 = sub nsw i64 %261, 63
%263 = getelementptr inbounds double, double* %260, i64 %262
%264 = load double, double* %263
%265 = fadd double %259, %264
%266 = load double*, double** %8
%267 = load i64, i64* %17
%268 = getelementptr inbounds double, double* %266, i64 %267
%269 = load double, double* %268
%270 = fadd double %265, %269
%271 = fmul double -1.000000e+00, %270
%272 = load double*, double** %5
%273 = load i64, i64* %11
%274 = getelementptr inbounds double, double* %272, i64 %273
%275 = load double, double* %274
%276 = fdiv double %275, %271
store double %276, double* %274
br label %277
277: ; preds = %202, %176
br label %278
278: ; preds = %277
%279 = load i64, i64* %10
%280 = add nsw i64 %279, 1
store i64 %280, i64* %10
br label %173
281: ; preds = %173
br label %282
282: ; preds = %281
%283 = load i64, i64* %9
%284 = add nsw i64 %283, 1
store i64 %284, i64* %9
br label %169
285: ; preds = %169
%286 = load i32, i32* %21
%287 = add nsw i32 %286, 1
store i32 %287, i32* %21
%288 = load double*, double** %7
%289 = load double*, double** %8
%290 = load double*, double** %5
%291 = load double*, double** %6
%292 = call double @compute_error(double* %288, double* %289, double* %290, double* %291)
store double %292, double* %19
%293 = load i32, i32* %21
%294 = load double, double* %19
%295 = call i32 @printf(i8* getelementptr inbounds ([19 x i8], [19 x i8]* @.str, i64 0, i64 0), i32 %293, double %294)
%296 = load double, double* %19
%297 = call double @llvm.fabs.f64(double %296)
%298 = load double, double* %20
%299 = fcmp olt double %297, %298
br i1 %299, label %300, label %301
300: ; preds = %285
br label %302
301: ; preds = %285
br label %22
302: ; preds = %300
ret void
}

LLVM IR (-O2):
@.str = [19 x i8] c"iter=%d\09error=%lf\0A\00"
define void @Gauss_siedel(double* %0, double* %1, double* %2, double* %3) {
br label %5
5: ; preds = %131, %4
%6 = phi i32 [ 0, %4 ], [ %132, %131 ]
%7 = tail call i32 (...) @boundary_pressure()
br label %8
8: ; preds = %5, %69
%9 = phi i64 [ 1, %5 ], [ %70, %69 ]
%10 = mul nuw nsw i64 %9, 65
%11 = shl nsw i64 %9, 6
%12 = mul nuw nsw i64 %9, 63
br label %13
13: ; preds = %8, %66
%14 = phi i64 [ 1, %8 ], [ %67, %66 ]
%15 = add nuw nsw i64 %14, %10
%16 = add nuw nsw i64 %14, %11
%17 = add nuw nsw i64 %14, %12
%18 = add nuw nsw i64 %14, %9
%19 = and i64 %18, 1
%20 = icmp eq i64 %19, 0
br i1 %20, label %21, label %66
21: ; preds = %13
%22 = add nsw i64 %15, -65
%23 = add nsw i64 %15, -1
%24 = add nuw nsw i64 %15, 65
%25 = add nuw nsw i64 %15, 1
%26 = getelementptr inbounds double, double* %0, i64 %23
%27 = load double, double* %26
%28 = getelementptr inbounds double, double* %0, i64 %25
%29 = load double, double* %28
%30 = fadd double %27, %29
%31 = getelementptr inbounds double, double* %0, i64 %22
%32 = load double, double* %31
%33 = fadd double %30, %32
%34 = getelementptr inbounds double, double* %0, i64 %24
%35 = load double, double* %34
%36 = fadd double %33, %35
%37 = getelementptr inbounds double, double* %1, i64 %15
%38 = load double, double* %37
%39 = tail call double @llvm.fmuladd.f64(double %36, double -1.000000e+00, double %38)
%40 = getelementptr inbounds double, double* %0, i64 %15
store double %39, double* %40
%41 = add nsw i64 %16, -1
%42 = getelementptr inbounds double, double* %2, i64 %41
%43 = load double, double* %42
%44 = getelementptr inbounds double, double* %2, i64 %16
%45 = load double, double* %44
%46 = fmul double %29, %45
%47 = tail call double @llvm.fmuladd.f64(double %43, double %27, double %46)
%48 = add nsw i64 %17, -63
%49 = getelementptr inbounds double, double* %3, i64 %48
%50 = load double, double* %49
%51 = tail call double @llvm.fmuladd.f64(double %50, double %32, double %47)
%52 = getelementptr inbounds double, double* %3, i64 %17
%53 = load double, double* %52
%54 = tail call double @llvm.fmuladd.f64(double %53, double %35, double %51)
%55 = load double, double* %37
%56 = tail call double @llvm.fmuladd.f64(double %54, double -1.000000e+00, double %55)
store double %56, double* %40
%57 = load double, double* %42
%58 = load double, double* %44
%59 = fadd double %57, %58
%60 = load double, double* %49
%61 = fadd double %59, %60
%62 = load double, double* %52
%63 = fadd double %61, %62
%64 = fneg double %63
%65 = fdiv double %56, %64
store double %65, double* %40
br label %66
66: ; preds = %13, %21
%67 = add nuw nsw i64 %14, 1
%68 = icmp eq i64 %67, 64
br i1 %68, label %69, label %13
69: ; preds = %66
%70 = add nuw nsw i64 %9, 1
%71 = icmp eq i64 %70, 64
br i1 %71, label %72, label %8
72: ; preds = %69, %128
%73 = phi i64 [ %129, %128 ], [ 1, %69 ]
%74 = mul nuw nsw i64 %73, 65
%75 = shl nsw i64 %73, 6
%76 = mul nuw nsw i64 %73, 63
br label %77
77: ; preds = %72, %125
%78 = phi i64 [ 1, %72 ], [ %126, %125 ]
%79 = add nuw nsw i64 %78, %74
%80 = add nuw nsw i64 %78, %75
%81 = add nuw nsw i64 %78, %76
%82 = add nuw nsw i64 %78, %73
%83 = and i64 %82, 1
%84 = icmp eq i64 %83, 0
br i1 %84, label %125, label %85
85: ; preds = %77
%86 = add nsw i64 %79, -65
%87 = add nsw i64 %79, -1
%88 = add nuw nsw i64 %79, 65
%89 = add nuw nsw i64 %79, 1
%90 = add nsw i64 %80, -1
%91 = getelementptr inbounds double, double* %2, i64 %90
%92 = load double, double* %91
%93 = getelementptr inbounds double, double* %0, i64 %87
%94 = load double, double* %93
%95 = getelementptr inbounds double, double* %2, i64 %80
%96 = load double, double* %95
%97 = getelementptr inbounds double, double* %0, i64 %89
%98 = load double, double* %97
%99 = fmul double %96, %98
%100 = tail call double @llvm.fmuladd.f64(double %92, double %94, double %99)
%101 = add nsw i64 %81, -63
%102 = getelementptr inbounds double, double* %3, i64 %101
%103 = load double, double* %102
%104 = getelementptr inbounds double, double* %0, i64 %86
%105 = load double, double* %104
%106 = tail call double @llvm.fmuladd.f64(double %103, double %105, double %100)
%107 = getelementptr inbounds double, double* %3, i64 %81
%108 = load double, double* %107
%109 = getelementptr inbounds double, double* %0, i64 %88
%110 = load double, double* %109
%111 = tail call double @llvm.fmuladd.f64(double %108, double %110, double %106)
%112 = getelementptr inbounds double, double* %1, i64 %79
%113 = load double, double* %112
%114 = tail call double @llvm.fmuladd.f64(double %111, double -1.000000e+00, double %113)
%115 = getelementptr inbounds double, double* %0, i64 %79
store double %114, double* %115
%116 = load double, double* %91
%117 = load double, double* %95
%118 = fadd double %116, %117
%119 = load double, double* %102
%120 = fadd double %118, %119
%121 = load double, double* %107
%122 = fadd double %120, %121
%123 = fneg double %122
%124 = fdiv double %114, %123
store double %124, double* %115
br label %125
125: ; preds = %77, %85
%126 = add nuw nsw i64 %78, 1
%127 = icmp eq i64 %126, 64
br i1 %127, label %128, label %77
128: ; preds = %125
%129 = add nuw nsw i64 %73, 1
%130 = icmp eq i64 %129, 64
br i1 %130, label %131, label %72
131: ; preds = %128
%132 = add nuw nsw i32 %6, 1
%133 = tail call double @compute_error(double* %2, double* %3, double* %0, double* %1)
%134 = tail call i32 @printf(i8* getelementptr inbounds ([19 x i8], [19 x i8]* @.str, i64 0, i64 0), i32 %132, double %133)
%135 = tail call double @llvm.fabs.f64(double %133)
%136 = fcmp olt double %135, 0x3EB0C6F7A0B5ED8D
br i1 %136, label %137, label %5
137: ; preds = %131
ret void
}