#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 < 300 - 1; i++) {
      for (j = 1; j < 300 - 1; j++) {
        indx = i * 300 + j;
        indx_rght = indx + 1;
        indx_frnt = indx + 300;
        indx_lft = indx - 1;
        indx_bck = indx - 300;
        indx_ax = (i - 1) * (300 - 1) + (j - 1);
        indx_ay = (i - 1) * (300 - 2) + (j - 1);
        if (((i + j) % 2) == 0) {
          P[indx] = -1.0 * (a_x[indx_ax] * P[indx_lft] +
                            a_x[indx_ax + 1] * P[indx_rght] +
                            a_y[indx_ay] * P[indx_bck] +
                            a_y[indx_ay + (300 - 2)] * 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 + (300 - 2)] + a_y[indx_ay]);
        }
      }
    }
    for (i = 1; i < 300 - 1; i++) {
      for (j = 1; j < 300 - 1; j++) {
        indx = i * 300 + j;
        indx_rght = indx + 1;
        indx_frnt = indx + 300;
        indx_lft = indx - 1;
        indx_bck = indx - 300;
        indx_ax = (i - 1) * (300 - 1) + (j - 1);
        indx_ay = (i - 1) * (300 - 2) + (j - 1);
        if (((i + j) % 2) != 0) {
          P[indx] = -1.0 * (a_x[indx_ax] * P[indx_lft] +
                            a_x[indx_ax + 1] * P[indx_rght] +
                            a_y[indx_ay] * P[indx_bck] +
                            a_y[indx_ay + (300 - 2)] * P[indx_frnt]) +
                    (1.0) * (1.0) * fn[indx];
          P[indx] /= -1.0 * (a_x[indx_ax] + a_x[indx_ax + 1] + a_y[indx_ay] +
                             a_y[indx_ay + (300 - 2)]);
        }
      }
    }
    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   $0x12b,-0x28(%rbp)
jge    1363 <Gauss_siedel+0x233>
movq   $0x1,-0x30(%rbp)
cmpq   $0x12b,-0x30(%rbp)
jge    134d <Gauss_siedel+0x21d>
imul   $0x12c,-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    $0x12c,%rax
mov    %rax,-0x48(%rbp)
mov    -0x38(%rbp),%rax
sub    $0x1,%rax
mov    %rax,-0x50(%rbp)
mov    -0x38(%rbp),%rax
sub    $0x12c,%rax
mov    %rax,-0x58(%rbp)
mov    -0x28(%rbp),%rax
sub    $0x1,%rax
imul   $0x12b,%rax,%rax
mov    -0x30(%rbp),%rcx
sub    $0x1,%rcx
add    %rcx,%rax
mov    %rax,-0x60(%rbp)
mov    -0x28(%rbp),%rax
sub    $0x1,%rax
imul   $0x12a,%rax,%rax
mov    -0x30(%rbp),%rcx
sub    $0x1,%rcx
add    %rcx,%rax
mov    %rax,-0x68(%rbp)
mov    -0x28(%rbp),%rax
add    -0x30(%rbp),%rax
mov    $0x2,%ecx
cqto
idiv   %rcx
cmp    $0x0,%rdx
jne    1337 <Gauss_siedel+0x207>
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%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  0x8(%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
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  0x950(%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  0xd4a(%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
movsd  0x8(%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
addsd  0x950(%rax,%rcx,8),%xmm0
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm0
movsd  0xceb(%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    133c <Gauss_siedel+0x20c>
mov    -0x30(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x30(%rbp)
jmp    1187 <Gauss_siedel+0x57>
jmp    1352 <Gauss_siedel+0x222>
mov    -0x28(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x28(%rbp)
jmp    1171 <Gauss_siedel+0x41>
movq   $0x1,-0x28(%rbp)
cmpq   $0x12b,-0x28(%rbp)
jge    155d <Gauss_siedel+0x42d>
movq   $0x1,-0x30(%rbp)
cmpq   $0x12b,-0x30(%rbp)
jge    1547 <Gauss_siedel+0x417>
imul   $0x12c,-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    $0x12c,%rax
mov    %rax,-0x48(%rbp)
mov    -0x38(%rbp),%rax
sub    $0x1,%rax
mov    %rax,-0x50(%rbp)
mov    -0x38(%rbp),%rax
sub    $0x12c,%rax
mov    %rax,-0x58(%rbp)
mov    -0x28(%rbp),%rax
sub    $0x1,%rax
imul   $0x12b,%rax,%rax
mov    -0x30(%rbp),%rcx
sub    $0x1,%rcx
add    %rcx,%rax
mov    %rax,-0x60(%rbp)
mov    -0x28(%rbp),%rax
sub    $0x1,%rax
imul   $0x12a,%rax,%rax
mov    -0x30(%rbp),%rcx
sub    $0x1,%rcx
add    %rcx,%rax
mov    %rax,-0x68(%rbp)
mov    -0x28(%rbp),%rax
add    -0x30(%rbp),%rax
mov    $0x2,%ecx
cqto
idiv   %rcx
cmp    $0x0,%rdx
je     1531 <Gauss_siedel+0x401>
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%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  0x8(%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
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  0x950(%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  0xb50(%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
movsd  (%rax,%rcx,8),%xmm0
mov    -0x18(%rbp),%rax
mov    -0x60(%rbp),%rcx
addsd  0x8(%rax,%rcx,8),%xmm0
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm0
mov    -0x20(%rbp),%rax
mov    -0x68(%rbp),%rcx
addsd  0x950(%rax,%rcx,8),%xmm0
movsd  0xaf1(%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    1536 <Gauss_siedel+0x406>
mov    -0x30(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x30(%rbp)
jmp    1381 <Gauss_siedel+0x251>
jmp    154c <Gauss_siedel+0x41c>
mov    -0x28(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x28(%rbp)
jmp    136b <Gauss_siedel+0x23b>
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    0xa98(%rip),%rdi
call   1030 <printf@plt>
movsd  -0x78(%rbp),%xmm1
movaps 0xa77(%rip),%xmm0
pand   %xmm0,%xmm1
movsd  -0x80(%rbp),%xmm0
ucomisd %xmm1,%xmm0
jbe    15c1 <Gauss_siedel+0x491>
jmp    15c6 <Gauss_siedel+0x496>
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    $0x38,%rsp
mov    %rcx,%r12
mov    %rdi,0x8(%rsp)
lea    0x8(%rdi),%rax
mov    %rax,(%rsp)
mov    %rsi,0x10(%rsp)
lea    0x968(%rsi),%r14
mov    %rdx,0x18(%rsp)
lea    0x8(%rdx),%r15
xor    %r13d,%r13d
jmp    11c0 <Gauss_siedel+0x90>
nopl   0x0(%rax,%rax,1)
add    $0x1,%r13d
mov    0x18(%rsp),%rdi
mov    %r12,%rsi
mov    0x8(%rsp),%rdx
mov    0x10(%rsp),%rcx
call   1050 <compute_error@plt>
movapd %xmm0,0x20(%rsp)
lea    0xe90(%rip),%rdi
mov    %r13d,%esi
call   1030 <printf@plt>
movapd 0x20(%rsp),%xmm1
andpd  0xe62(%rip),%xmm1
movsd  0xe6a(%rip),%xmm0
ucomisd %xmm1,%xmm0
ja     13ca <Gauss_siedel+0x29a>
xor    %eax,%eax
call   1040 <boundary_pressure@plt>
mov    $0x1,%r8d
mov    $0x2,%ecx
mov    %r12,%rdx
mov    %r15,%rsi
mov    %r14,%rdi
mov    (%rsp),%rbx
movapd 0xe19(%rip),%xmm3
jmp    1221 <Gauss_siedel+0xf1>
nopl   0x0(%rax)
add    $0x1,%r8
add    $0x1,%rcx
add    $0x960,%rbx
add    $0x960,%rdi
add    $0x958,%rsi
add    $0x950,%rdx
cmp    $0x12b,%r8
je     12d0 <Gauss_siedel+0x1a0>
xor    %ebp,%ebp
jmp    123d <Gauss_siedel+0x10d>
cs nopw 0x0(%rax,%rax,1)
nop
add    $0x1,%rbp
cmp    $0x12a,%rbp
je     11f0 <Gauss_siedel+0xc0>
lea    (%rcx,%rbp,1),%eax
test   $0x1,%al
jne    1230 <Gauss_siedel+0x100>
movsd  -0x8(%rsi,%rbp,8),%xmm0
movsd  (%rsi,%rbp,8),%xmm1
mulsd  0x968(%rbx,%rbp,8),%xmm1
mulsd  0x958(%rbx,%rbp,8),%xmm0
movsd  (%rdx,%rbp,8),%xmm2
mulsd  (%rbx,%rbp,8),%xmm2
addsd  %xmm1,%xmm0
movsd  0x950(%rdx,%rbp,8),%xmm1
mulsd  0x12c0(%rbx,%rbp,8),%xmm1
addsd  %xmm0,%xmm2
addsd  %xmm2,%xmm1
movsd  (%rdi,%rbp,8),%xmm0
subsd  %xmm1,%xmm0
movsd  %xmm0,0x960(%rbx,%rbp,8)
movsd  (%rsi,%rbp,8),%xmm1
addsd  -0x8(%rsi,%rbp,8),%xmm1
addsd  0x950(%rdx,%rbp,8),%xmm1
addsd  (%rdx,%rbp,8),%xmm1
xorpd  %xmm3,%xmm1
divsd  %xmm1,%xmm0
movsd  %xmm0,0x960(%rbx,%rbp,8)
jmp    1230 <Gauss_siedel+0x100>
nopw   0x0(%rax,%rax,1)
mov    $0x1,%r8d
mov    $0x2,%ecx
mov    %r12,%rdx
mov    %r15,%rsi
mov    %r14,%rdi
mov    (%rsp),%rbx
jmp    1321 <Gauss_siedel+0x1f1>
nopw   0x0(%rax,%rax,1)
add    $0x1,%r8
add    $0x1,%rcx
add    $0x960,%rbx
add    $0x960,%rdi
add    $0x958,%rsi
add    $0x950,%rdx
cmp    $0x12b,%r8
je     1170 <Gauss_siedel+0x40>
xor    %ebp,%ebp
jmp    133d <Gauss_siedel+0x20d>
cs nopw 0x0(%rax,%rax,1)
nop
add    $0x1,%rbp
cmp    $0x12a,%rbp
je     12f0 <Gauss_siedel+0x1c0>
lea    (%rcx,%rbp,1),%eax
test   $0x1,%al
je     1330 <Gauss_siedel+0x200>
movsd  -0x8(%rsi,%rbp,8),%xmm0
movsd  (%rsi,%rbp,8),%xmm1
mulsd  0x968(%rbx,%rbp,8),%xmm1
mulsd  0x958(%rbx,%rbp,8),%xmm0
movsd  (%rdx,%rbp,8),%xmm2
mulsd  (%rbx,%rbp,8),%xmm2
addsd  %xmm1,%xmm0
movsd  0x950(%rdx,%rbp,8),%xmm1
mulsd  0x12c0(%rbx,%rbp,8),%xmm1
addsd  %xmm0,%xmm2
addsd  %xmm2,%xmm1
movsd  (%rdi,%rbp,8),%xmm0
subsd  %xmm1,%xmm0
movsd  %xmm0,0x960(%rbx,%rbp,8)
movsd  -0x8(%rsi,%rbp,8),%xmm1
addsd  (%rsi,%rbp,8),%xmm1
addsd  (%rdx,%rbp,8),%xmm1
addsd  0x950(%rdx,%rbp,8),%xmm1
xorpd  %xmm3,%xmm1
divsd  %xmm1,%xmm0
movsd  %xmm0,0x960(%rbx,%rbp,8)
jmp    1330 <Gauss_siedel+0x200>
add    $0x38,%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 = %281, %4
%23 = call i32 (...) @boundary_pressure()
store i64 1, i64* %9
br label %24
24: ; preds = %141, %22
%25 = load i64, i64* %9
%26 = icmp slt i64 %25, 299
br i1 %26, label %27, label %144
27: ; preds = %24
store i64 1, i64* %10
br label %28
28: ; preds = %137, %27
%29 = load i64, i64* %10
%30 = icmp slt i64 %29, 299
br i1 %30, label %31, label %140
31: ; preds = %28
%32 = load i64, i64* %9
%33 = mul nsw i64 %32, 300
%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, 300
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, 300
store i64 %43, i64* %15
%44 = load i64, i64* %9
%45 = sub nsw i64 %44, 1
%46 = mul nsw i64 %45, 299
%47 = load i64, i64* %10
%48 = sub nsw i64 %47, 1
%49 = add nsw i64 %46, %48
store i64 %49, i64* %16
%50 = load i64, i64* %9
%51 = sub nsw i64 %50, 1
%52 = mul nsw i64 %51, 298
%53 = load i64, i64* %10
%54 = sub nsw i64 %53, 1
%55 = add nsw i64 %52, %54
store i64 %55, i64* %17
%56 = load i64, i64* %9
%57 = load i64, i64* %10
%58 = add nsw i64 %56, %57
%59 = srem i64 %58, 2
%60 = icmp eq i64 %59, 0
br i1 %60, label %61, label %136
61: ; preds = %31
%62 = load double*, double** %7
%63 = load i64, i64* %16
%64 = getelementptr inbounds double, double* %62, i64 %63
%65 = load double, double* %64
%66 = load double*, double** %5
%67 = load i64, i64* %14
%68 = getelementptr inbounds double, double* %66, i64 %67
%69 = load double, double* %68
%70 = load double*, double** %7
%71 = load i64, i64* %16
%72 = add nsw i64 %71, 1
%73 = getelementptr inbounds double, double* %70, i64 %72
%74 = load double, double* %73
%75 = load double*, double** %5
%76 = load i64, i64* %12
%77 = getelementptr inbounds double, double* %75, i64 %76
%78 = load double, double* %77
%79 = fmul double %74, %78
%80 = call double @llvm.fmuladd.f64(double %65, double %69, double %79)
%81 = load double*, double** %8
%82 = load i64, i64* %17
%83 = getelementptr inbounds double, double* %81, i64 %82
%84 = load double, double* %83
%85 = load double*, double** %5
%86 = load i64, i64* %15
%87 = getelementptr inbounds double, double* %85, i64 %86
%88 = load double, double* %87
%89 = call double @llvm.fmuladd.f64(double %84, double %88, double %80)
%90 = load double*, double** %8
%91 = load i64, i64* %17
%92 = add nsw i64 %91, 298
%93 = getelementptr inbounds double, double* %90, i64 %92
%94 = load double, double* %93
%95 = load double*, double** %5
%96 = load i64, i64* %13
%97 = getelementptr inbounds double, double* %95, i64 %96
%98 = load double, double* %97
%99 = call double @llvm.fmuladd.f64(double %94, double %98, double %89)
%100 = load double*, double** %6
%101 = load i64, i64* %11
%102 = getelementptr inbounds double, double* %100, i64 %101
%103 = load double, double* %102
%104 = fmul double 1.000000e+00, %103
%105 = call double @llvm.fmuladd.f64(double -1.000000e+00, double %99, double %104)
%106 = load double*, double** %5
%107 = load i64, i64* %11
%108 = getelementptr inbounds double, double* %106, i64 %107
store double %105, double* %108
%109 = load double*, double** %7
%110 = load i64, i64* %16
%111 = add nsw i64 %110, 1
%112 = getelementptr inbounds double, double* %109, i64 %111
%113 = load double, double* %112
%114 = load double*, double** %7
%115 = load i64, i64* %16
%116 = getelementptr inbounds double, double* %114, i64 %115
%117 = load double, double* %116
%118 = fadd double %113, %117
%119 = load double*, double** %8
%120 = load i64, i64* %17
%121 = add nsw i64 %120, 298
%122 = getelementptr inbounds double, double* %119, i64 %121
%123 = load double, double* %122
%124 = fadd double %118, %123
%125 = load double*, double** %8
%126 = load i64, i64* %17
%127 = getelementptr inbounds double, double* %125, i64 %126
%128 = load double, double* %127
%129 = fadd double %124, %128
%130 = fmul double -1.000000e+00, %129
%131 = load double*, double** %5
%132 = load i64, i64* %11
%133 = getelementptr inbounds double, double* %131, i64 %132
%134 = load double, double* %133
%135 = fdiv double %134, %130
store double %135, double* %133
br label %136
136: ; preds = %61, %31
br label %137
137: ; preds = %136
%138 = load i64, i64* %10
%139 = add nsw i64 %138, 1
store i64 %139, i64* %10
br label %28
140: ; preds = %28
br label %141
141: ; preds = %140
%142 = load i64, i64* %9
%143 = add nsw i64 %142, 1
store i64 %143, i64* %9
br label %24
144: ; preds = %24
store i64 1, i64* %9
br label %145
145: ; preds = %262, %144
%146 = load i64, i64* %9
%147 = icmp slt i64 %146, 299
br i1 %147, label %148, label %265
148: ; preds = %145
store i64 1, i64* %10
br label %149
149: ; preds = %258, %148
%150 = load i64, i64* %10
%151 = icmp slt i64 %150, 299
br i1 %151, label %152, label %261
152: ; preds = %149
%153 = load i64, i64* %9
%154 = mul nsw i64 %153, 300
%155 = load i64, i64* %10
%156 = add nsw i64 %154, %155
store i64 %156, i64* %11
%157 = load i64, i64* %11
%158 = add nsw i64 %157, 1
store i64 %158, i64* %12
%159 = load i64, i64* %11
%160 = add nsw i64 %159, 300
store i64 %160, i64* %13
%161 = load i64, i64* %11
%162 = sub nsw i64 %161, 1
store i64 %162, i64* %14
%163 = load i64, i64* %11
%164 = sub nsw i64 %163, 300
store i64 %164, i64* %15
%165 = load i64, i64* %9
%166 = sub nsw i64 %165, 1
%167 = mul nsw i64 %166, 299
%168 = load i64, i64* %10
%169 = sub nsw i64 %168, 1
%170 = add nsw i64 %167, %169
store i64 %170, i64* %16
%171 = load i64, i64* %9
%172 = sub nsw i64 %171, 1
%173 = mul nsw i64 %172, 298
%174 = load i64, i64* %10
%175 = sub nsw i64 %174, 1
%176 = add nsw i64 %173, %175
store i64 %176, i64* %17
%177 = load i64, i64* %9
%178 = load i64, i64* %10
%179 = add nsw i64 %177, %178
%180 = srem i64 %179, 2
%181 = icmp ne i64 %180, 0
br i1 %181, label %182, label %257
182: ; preds = %152
%183 = load double*, double** %7
%184 = load i64, i64* %16
%185 = getelementptr inbounds double, double* %183, i64 %184
%186 = load double, double* %185
%187 = load double*, double** %5
%188 = load i64, i64* %14
%189 = getelementptr inbounds double, double* %187, i64 %188
%190 = load double, double* %189
%191 = load double*, double** %7
%192 = load i64, i64* %16
%193 = add nsw i64 %192, 1
%194 = getelementptr inbounds double, double* %191, i64 %193
%195 = load double, double* %194
%196 = load double*, double** %5
%197 = load i64, i64* %12
%198 = getelementptr inbounds double, double* %196, i64 %197
%199 = load double, double* %198
%200 = fmul double %195, %199
%201 = call double @llvm.fmuladd.f64(double %186, double %190, double %200)
%202 = load double*, double** %8
%203 = load i64, i64* %17
%204 = getelementptr inbounds double, double* %202, i64 %203
%205 = load double, double* %204
%206 = load double*, double** %5
%207 = load i64, i64* %15
%208 = getelementptr inbounds double, double* %206, i64 %207
%209 = load double, double* %208
%210 = call double @llvm.fmuladd.f64(double %205, double %209, double %201)
%211 = load double*, double** %8
%212 = load i64, i64* %17
%213 = add nsw i64 %212, 298
%214 = getelementptr inbounds double, double* %211, i64 %213
%215 = load double, double* %214
%216 = load double*, double** %5
%217 = load i64, i64* %13
%218 = getelementptr inbounds double, double* %216, i64 %217
%219 = load double, double* %218
%220 = call double @llvm.fmuladd.f64(double %215, double %219, double %210)
%221 = load double*, double** %6
%222 = load i64, i64* %11
%223 = getelementptr inbounds double, double* %221, i64 %222
%224 = load double, double* %223
%225 = fmul double 1.000000e+00, %224
%226 = call double @llvm.fmuladd.f64(double -1.000000e+00, double %220, double %225)
%227 = load double*, double** %5
%228 = load i64, i64* %11
%229 = getelementptr inbounds double, double* %227, i64 %228
store double %226, double* %229
%230 = load double*, double** %7
%231 = load i64, i64* %16
%232 = getelementptr inbounds double, double* %230, i64 %231
%233 = load double, double* %232
%234 = load double*, double** %7
%235 = load i64, i64* %16
%236 = add nsw i64 %235, 1
%237 = getelementptr inbounds double, double* %234, i64 %236
%238 = load double, double* %237
%239 = fadd double %233, %238
%240 = load double*, double** %8
%241 = load i64, i64* %17
%242 = getelementptr inbounds double, double* %240, i64 %241
%243 = load double, double* %242
%244 = fadd double %239, %243
%245 = load double*, double** %8
%246 = load i64, i64* %17
%247 = add nsw i64 %246, 298
%248 = getelementptr inbounds double, double* %245, i64 %247
%249 = load double, double* %248
%250 = fadd double %244, %249
%251 = fmul double -1.000000e+00, %250
%252 = load double*, double** %5
%253 = load i64, i64* %11
%254 = getelementptr inbounds double, double* %252, i64 %253
%255 = load double, double* %254
%256 = fdiv double %255, %251
store double %256, double* %254
br label %257
257: ; preds = %182, %152
br label %258
258: ; preds = %257
%259 = load i64, i64* %10
%260 = add nsw i64 %259, 1
store i64 %260, i64* %10
br label %149
261: ; preds = %149
br label %262
262: ; preds = %261
%263 = load i64, i64* %9
%264 = add nsw i64 %263, 1
store i64 %264, i64* %9
br label %145
265: ; preds = %145
%266 = load i32, i32* %21
%267 = add nsw i32 %266, 1
store i32 %267, i32* %21
%268 = load double*, double** %7
%269 = load double*, double** %8
%270 = load double*, double** %5
%271 = load double*, double** %6
%272 = call double @compute_error(double* %268, double* %269, double* %270, double* %271)
store double %272, double* %19
%273 = load i32, i32* %21
%274 = load double, double* %19
%275 = call i32 @printf(i8* getelementptr inbounds ([19 x i8], [19 x i8]* @.str, i64 0, i64 0), i32 %273, double %274)
%276 = load double, double* %19
%277 = call double @llvm.fabs.f64(double %276)
%278 = load double, double* %20
%279 = fcmp olt double %277, %278
br i1 %279, label %280, label %281
280: ; preds = %265
br label %282
281: ; preds = %265
br label %22
282: ; preds = %280
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 = %130, %4
%6 = phi i32 [ 0, %4 ], [ %131, %130 ]
%7 = tail call i32 (...) @boundary_pressure()
br label %8
8: ; preds = %5, %66
%9 = phi i64 [ 1, %5 ], [ %67, %66 ]
%10 = mul nuw nsw i64 %9, 300
%11 = add nsw i64 %9, -1
%12 = mul nuw nsw i64 %11, 299
%13 = mul nuw nsw i64 %11, 298
br label %14
14: ; preds = %8, %63
%15 = phi i64 [ 1, %8 ], [ %64, %63 ]
%16 = add nuw nsw i64 %15, %10
%17 = add nsw i64 %15, -1
%18 = add nuw nsw i64 %17, %13
%19 = add nuw nsw i64 %15, %9
%20 = and i64 %19, 1
%21 = icmp eq i64 %20, 0
br i1 %21, label %22, label %63
22: ; preds = %14
%23 = add nuw nsw i64 %17, %12
%24 = add nsw i64 %16, -300
%25 = add nsw i64 %16, -1
%26 = add nuw nsw i64 %16, 300
%27 = add nuw nsw i64 %16, 1
%28 = getelementptr inbounds double, double* %2, i64 %23
%29 = load double, double* %28
%30 = getelementptr inbounds double, double* %0, i64 %25
%31 = load double, double* %30
%32 = add nuw nsw i64 %15, %12
%33 = getelementptr inbounds double, double* %2, i64 %32
%34 = load double, double* %33
%35 = getelementptr inbounds double, double* %0, i64 %27
%36 = load double, double* %35
%37 = fmul double %34, %36
%38 = tail call double @llvm.fmuladd.f64(double %29, double %31, double %37)
%39 = getelementptr inbounds double, double* %3, i64 %18
%40 = load double, double* %39
%41 = getelementptr inbounds double, double* %0, i64 %24
%42 = load double, double* %41
%43 = tail call double @llvm.fmuladd.f64(double %40, double %42, double %38)
%44 = add nuw nsw i64 %18, 298
%45 = getelementptr inbounds double, double* %3, i64 %44
%46 = load double, double* %45
%47 = getelementptr inbounds double, double* %0, i64 %26
%48 = load double, double* %47
%49 = tail call double @llvm.fmuladd.f64(double %46, double %48, double %43)
%50 = getelementptr inbounds double, double* %1, i64 %16
%51 = load double, double* %50
%52 = tail call double @llvm.fmuladd.f64(double %49, double -1.000000e+00, double %51)
%53 = getelementptr inbounds double, double* %0, i64 %16
store double %52, double* %53
%54 = load double, double* %33
%55 = load double, double* %28
%56 = fadd double %54, %55
%57 = load double, double* %45
%58 = fadd double %56, %57
%59 = load double, double* %39
%60 = fadd double %58, %59
%61 = fneg double %60
%62 = fdiv double %52, %61
store double %62, double* %53
br label %63
63: ; preds = %14, %22
%64 = add nuw nsw i64 %15, 1
%65 = icmp eq i64 %64, 299
br i1 %65, label %66, label %14
66: ; preds = %63
%67 = add nuw nsw i64 %9, 1
%68 = icmp eq i64 %67, 299
br i1 %68, label %69, label %8
69: ; preds = %66, %127
%70 = phi i64 [ %128, %127 ], [ 1, %66 ]
%71 = mul nuw nsw i64 %70, 300
%72 = add nsw i64 %70, -1
%73 = mul nuw nsw i64 %72, 299
%74 = mul nuw nsw i64 %72, 298
br label %75
75: ; preds = %69, %124
%76 = phi i64 [ 1, %69 ], [ %125, %124 ]
%77 = add nuw nsw i64 %76, %71
%78 = add nsw i64 %76, -1
%79 = add nuw nsw i64 %78, %74
%80 = add nuw nsw i64 %76, %70
%81 = and i64 %80, 1
%82 = icmp eq i64 %81, 0
br i1 %82, label %124, label %83
83: ; preds = %75
%84 = add nuw nsw i64 %78, %73
%85 = add nsw i64 %77, -300
%86 = add nsw i64 %77, -1
%87 = add nuw nsw i64 %77, 300
%88 = add nuw nsw i64 %77, 1
%89 = getelementptr inbounds double, double* %2, i64 %84
%90 = load double, double* %89
%91 = getelementptr inbounds double, double* %0, i64 %86
%92 = load double, double* %91
%93 = add nuw nsw i64 %76, %73
%94 = getelementptr inbounds double, double* %2, i64 %93
%95 = load double, double* %94
%96 = getelementptr inbounds double, double* %0, i64 %88
%97 = load double, double* %96
%98 = fmul double %95, %97
%99 = tail call double @llvm.fmuladd.f64(double %90, double %92, double %98)
%100 = getelementptr inbounds double, double* %3, i64 %79
%101 = load double, double* %100
%102 = getelementptr inbounds double, double* %0, i64 %85
%103 = load double, double* %102
%104 = tail call double @llvm.fmuladd.f64(double %101, double %103, double %99)
%105 = add nuw nsw i64 %79, 298
%106 = getelementptr inbounds double, double* %3, i64 %105
%107 = load double, double* %106
%108 = getelementptr inbounds double, double* %0, i64 %87
%109 = load double, double* %108
%110 = tail call double @llvm.fmuladd.f64(double %107, double %109, double %104)
%111 = getelementptr inbounds double, double* %1, i64 %77
%112 = load double, double* %111
%113 = tail call double @llvm.fmuladd.f64(double %110, double -1.000000e+00, double %112)
%114 = getelementptr inbounds double, double* %0, i64 %77
store double %113, double* %114
%115 = load double, double* %89
%116 = load double, double* %94
%117 = fadd double %115, %116
%118 = load double, double* %100
%119 = fadd double %117, %118
%120 = load double, double* %106
%121 = fadd double %119, %120
%122 = fneg double %121
%123 = fdiv double %113, %122
store double %123, double* %114
br label %124
124: ; preds = %75, %83
%125 = add nuw nsw i64 %76, 1
%126 = icmp eq i64 %125, 299
br i1 %126, label %127, label %75
127: ; preds = %124
%128 = add nuw nsw i64 %70, 1
%129 = icmp eq i64 %128, 299
br i1 %129, label %130, label %69
130: ; preds = %127
%131 = add nuw nsw i32 %6, 1
%132 = tail call double @compute_error(double* %2, double* %3, double* %0, double* %1)
%133 = tail call i32 @printf(i8* getelementptr inbounds ([19 x i8], [19 x i8]* @.str, i64 0, i64 0), i32 %131, double %132)
%134 = tail call double @llvm.fabs.f64(double %132)
%135 = fcmp olt double %134, 0x3EB0C6F7A0B5ED8D
br i1 %135, label %136, label %5
136: ; preds = %130
ret void
}