fcall(c1, c2, c3) char c1, c2, c3;
{
  if (c1 != 1)
    e(1);
  if (c2 != 2)
    e(2);
  c_alter(&c1, 127);
  if (c1 != 127)
    e(3);
  c_alter(&c3, 0);
  if (c3)
    e(4);
}


x86 assembly (clang, -O0):
<fcall>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
mov    %edx,%eax
mov    %dil,%dl
mov    %sil,%cl
mov    %dl,-0x5(%rbp)
mov    %cl,-0x6(%rbp)
mov    %al,-0x7(%rbp)
movsbl -0x5(%rbp),%eax
cmp    $0x1,%eax
je     1152 <fcall+0x32>
mov    $0x1,%edi
mov    $0x0,%al
call   1030 <e@plt>
movsbl -0x6(%rbp),%eax
cmp    $0x2,%eax
je     116b <fcall+0x4b>
mov    $0x2,%edi
mov    $0x0,%al
call   1030 <e@plt>
lea    -0x5(%rbp),%rdi
mov    $0x7f,%esi
mov    $0x0,%al
call   1040 <c_alter@plt>
movsbl -0x5(%rbp),%eax
cmp    $0x7f,%eax
je     1194 <fcall+0x74>
mov    $0x3,%edi
mov    $0x0,%al
call   1030 <e@plt>
lea    -0x7(%rbp),%rdi
xor    %esi,%esi
mov    $0x0,%al
call   1040 <c_alter@plt>
cmpb   $0x0,-0x7(%rbp)
je     11b7 <fcall+0x97>
mov    $0x4,%edi
mov    $0x0,%al
call   1030 <e@plt>
mov    -0x4(%rbp),%eax
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<fcall>:
push   %rbx
sub    $0x10,%rsp
mov    %esi,%ebx
mov    %dil,0xf(%rsp)
mov    %dl,0xe(%rsp)
cmp    $0x1,%dil
je     1142 <fcall+0x22>
mov    $0x1,%edi
xor    %eax,%eax
call   1030 <e@plt>
cmp    $0x2,%bl
je     1153 <fcall+0x33>
mov    $0x2,%edi
xor    %eax,%eax
call   1030 <e@plt>
lea    0xf(%rsp),%rdi
mov    $0x7f,%esi
xor    %eax,%eax
call   1040 <c_alter@plt>
cmpb   $0x7f,0xf(%rsp)
je     1177 <fcall+0x57>
mov    $0x3,%edi
xor    %eax,%eax
call   1030 <e@plt>
lea    0xe(%rsp),%rdi
xor    %esi,%esi
xor    %eax,%eax
call   1040 <c_alter@plt>
cmpb   $0x0,0xe(%rsp)
je     1198 <fcall+0x78>
mov    $0x4,%edi
xor    %eax,%eax
call   1030 <e@plt>
add    $0x10,%rsp
pop    %rbx
ret

LLVM IR (-O0):
define i32 @fcall(i32 %0, i32 %1, i32 %2) {
%4 = alloca i32
%5 = alloca i8
%6 = alloca i8
%7 = alloca i8
%8 = trunc i32 %0 to i8
%9 = trunc i32 %1 to i8
%10 = trunc i32 %2 to i8
store i8 %8, i8* %5
store i8 %9, i8* %6
store i8 %10, i8* %7
%11 = load i8, i8* %5
%12 = sext i8 %11 to i32
%13 = icmp ne i32 %12, 1
br i1 %13, label %14, label %16
14: ; preds = %3
%15 = call i32 (i32, ...) bitcast (i32 (...)* @e to i32 (i32, ...)*)(i32 1)
br label %16
16: ; preds = %14, %3
%17 = load i8, i8* %6
%18 = sext i8 %17 to i32
%19 = icmp ne i32 %18, 2
br i1 %19, label %20, label %22
20: ; preds = %16
%21 = call i32 (i32, ...) bitcast (i32 (...)* @e to i32 (i32, ...)*)(i32 2)
br label %22
22: ; preds = %20, %16
%23 = call i32 (i8*, i32, ...) bitcast (i32 (...)* @c_alter to i32 (i8*, i32, ...)*)(i8* %5, i32 127)
%24 = load i8, i8* %5
%25 = sext i8 %24 to i32
%26 = icmp ne i32 %25, 127
br i1 %26, label %27, label %29
27: ; preds = %22
%28 = call i32 (i32, ...) bitcast (i32 (...)* @e to i32 (i32, ...)*)(i32 3)
br label %29
29: ; preds = %27, %22
%30 = call i32 (i8*, i32, ...) bitcast (i32 (...)* @c_alter to i32 (i8*, i32, ...)*)(i8* %7, i32 0)
%31 = load i8, i8* %7
%32 = icmp ne i8 %31, 0
br i1 %32, label %33, label %35
33: ; preds = %29
%34 = call i32 (i32, ...) bitcast (i32 (...)* @e to i32 (i32, ...)*)(i32 4)
br label %35
35: ; preds = %33, %29
%36 = load i32, i32* %4
ret i32 %36
}

LLVM IR (-O2):
define i32 @fcall(i32 %0, i32 %1, i32 %2) {
%4 = alloca i8
%5 = alloca i8
%6 = trunc i32 %0 to i8
%7 = trunc i32 %2 to i8
store i8 %6, i8* %4
store i8 %7, i8* %5
%8 = and i32 %0, 255
%9 = icmp eq i32 %8, 1
br i1 %9, label %12, label %10
10: ; preds = %3
%11 = tail call i32 (i32, ...) bitcast (i32 (...)* @e to i32 (i32, ...)*)(i32 1)
br label %12
12: ; preds = %10, %3
%13 = and i32 %1, 255
%14 = icmp eq i32 %13, 2
br i1 %14, label %17, label %15
15: ; preds = %12
%16 = tail call i32 (i32, ...) bitcast (i32 (...)* @e to i32 (i32, ...)*)(i32 2)
br label %17
17: ; preds = %15, %12
%18 = call i32 (i8*, i32, ...) bitcast (i32 (...)* @c_alter to i32 (i8*, i32, ...)*)(i8* %4, i32 127)
%19 = load i8, i8* %4
%20 = icmp eq i8 %19, 127
br i1 %20, label %23, label %21
21: ; preds = %17
%22 = call i32 (i32, ...) bitcast (i32 (...)* @e to i32 (i32, ...)*)(i32 3)
br label %23
23: ; preds = %21, %17
%24 = call i32 (i8*, i32, ...) bitcast (i32 (...)* @c_alter to i32 (i8*, i32, ...)*)(i8* %5, i32 0)
%25 = load i8, i8* %5
%26 = icmp eq i8 %25, 0
br i1 %26, label %29, label %27
27: ; preds = %23
%28 = call i32 (i32, ...) bitcast (i32 (...)* @e to i32 (i32, ...)*)(i32 4)
br label %29
29: ; preds = %27, %23
ret i32 undef
}