int isabbr(abbr, word)
register char *abbr;
register char *word;
{
  if (lowerit(*abbr) != lowerit(*word))
    return 0;
  ++word;
  while (*++abbr != '\0')
    do
      if (*word == '\0')
        return 0;
    while (lowerit(*word++) != lowerit(*abbr));
  return 1;
}


x86 assembly (clang, -O0):
<isabbr>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x10(%rbp)
mov    %rsi,-0x18(%rbp)
mov    -0x10(%rbp),%rax
movsbl (%rax),%edi
mov    $0x0,%al
call   1030 <lowerit@plt>
mov    %eax,-0x1c(%rbp)
mov    -0x18(%rbp),%rax
movsbl (%rax),%edi
mov    $0x0,%al
call   1030 <lowerit@plt>
mov    %eax,%ecx
mov    -0x1c(%rbp),%eax
cmp    %ecx,%eax
je     1158 <isabbr+0x48>
movl   $0x0,-0x4(%rbp)
jmp    11e9 <isabbr+0xd9>
mov    -0x18(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x18(%rbp)
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x1,%rcx
mov    %rcx,-0x10(%rbp)
movsbl 0x1(%rax),%eax
cmp    $0x0,%eax
je     11e2 <isabbr+0xd2>
jmp    1185 <isabbr+0x75>
mov    -0x18(%rbp),%rax
movsbl (%rax),%eax
cmp    $0x0,%eax
jne    11a1 <isabbr+0x91>
movl   $0x0,-0x4(%rbp)
jmp    11e9 <isabbr+0xd9>
jmp    11a6 <isabbr+0x96>
mov    -0x18(%rbp),%rax
mov    %rax,%rcx
add    $0x1,%rcx
mov    %rcx,-0x18(%rbp)
movsbl (%rax),%edi
mov    $0x0,%al
call   1030 <lowerit@plt>
mov    %eax,-0x20(%rbp)
mov    -0x10(%rbp),%rax
movsbl (%rax),%edi
mov    $0x0,%al
call   1030 <lowerit@plt>
mov    %eax,%ecx
mov    -0x20(%rbp),%eax
cmp    %ecx,%eax
jne    1185 <isabbr+0x75>
jmp    1164 <isabbr+0x54>
movl   $0x1,-0x4(%rbp)
mov    -0x4(%rbp),%eax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<isabbr>:
push   %rbp
push   %r15
push   %r14
push   %r12
push   %rbx
mov    %rsi,%rbx
mov    %rdi,%r12
movsbl (%rdi),%edi
xor    %r14d,%r14d
xor    %eax,%eax
call   1030 <lowerit@plt>
mov    %eax,%r15d
movsbl (%rbx),%edi
xor    %eax,%eax
call   1030 <lowerit@plt>
cmp    %eax,%r15d
jne    1196 <isabbr+0x86>
mov    $0x1,%r14d
cmpb   $0x0,0x1(%r12)
je     1196 <isabbr+0x86>
add    $0x1,%r12
add    $0x1,%rbx
cs nopw 0x0(%rax,%rax,1)
nopl   (%rax)
movsbl (%rbx),%edi
test   %edi,%edi
je     1193 <isabbr+0x83>
add    $0x1,%rbx
xor    %eax,%eax
call   1030 <lowerit@plt>
mov    %eax,%ebp
movsbl (%r12),%edi
xor    %eax,%eax
call   1030 <lowerit@plt>
cmp    %eax,%ebp
jne    1160 <isabbr+0x50>
cmpb   $0x0,0x1(%r12)
lea    0x1(%r12),%r12
jne    1160 <isabbr+0x50>
jmp    1196 <isabbr+0x86>
xor    %r14d,%r14d
mov    %r14d,%eax
pop    %rbx
pop    %r12
pop    %r14
pop    %r15
pop    %rbp
ret

LLVM IR (-O0):
define i32 @isabbr(i8* %0, i8* %1) {
%3 = alloca i32
%4 = alloca i8*
%5 = alloca i8*
store i8* %0, i8** %4
store i8* %1, i8** %5
%6 = load i8*, i8** %4
%7 = load i8, i8* %6
%8 = sext i8 %7 to i32
%9 = call i32 (i32, ...) bitcast (i32 (...)* @lowerit to i32 (i32, ...)*)(i32 %8)
%10 = load i8*, i8** %5
%11 = load i8, i8* %10
%12 = sext i8 %11 to i32
%13 = call i32 (i32, ...) bitcast (i32 (...)* @lowerit to i32 (i32, ...)*)(i32 %12)
%14 = icmp ne i32 %9, %13
br i1 %14, label %15, label %16
15: ; preds = %2
store i32 0, i32* %3
br label %46
16: ; preds = %2
%17 = load i8*, i8** %5
%18 = getelementptr inbounds i8, i8* %17, i32 1
store i8* %18, i8** %5
br label %19
19: ; preds = %44, %16
%20 = load i8*, i8** %4
%21 = getelementptr inbounds i8, i8* %20, i32 1
store i8* %21, i8** %4
%22 = load i8, i8* %21
%23 = sext i8 %22 to i32
%24 = icmp ne i32 %23, 0
br i1 %24, label %25, label %45
25: ; preds = %19
br label %26
26: ; preds = %33, %25
%27 = load i8*, i8** %5
%28 = load i8, i8* %27
%29 = sext i8 %28 to i32
%30 = icmp eq i32 %29, 0
br i1 %30, label %31, label %32
31: ; preds = %26
store i32 0, i32* %3
br label %46
32: ; preds = %26
br label %33
33: ; preds = %32
%34 = load i8*, i8** %5
%35 = getelementptr inbounds i8, i8* %34, i32 1
store i8* %35, i8** %5
%36 = load i8, i8* %34
%37 = sext i8 %36 to i32
%38 = call i32 (i32, ...) bitcast (i32 (...)* @lowerit to i32 (i32, ...)*)(i32 %37)
%39 = load i8*, i8** %4
%40 = load i8, i8* %39
%41 = sext i8 %40 to i32
%42 = call i32 (i32, ...) bitcast (i32 (...)* @lowerit to i32 (i32, ...)*)(i32 %41)
%43 = icmp ne i32 %38, %42
br i1 %43, label %26, label %44
44: ; preds = %33
br label %19
45: ; preds = %19
store i32 1, i32* %3
br label %46
46: ; preds = %45, %31, %15
%47 = load i32, i32* %3
ret i32 %47
}

LLVM IR (-O2):
define i32 @isabbr(i8* nocapture %0, i8* nocapture %1) {
%3 = load i8, i8* %0
%4 = sext i8 %3 to i32
%5 = tail call i32 (i32, ...) bitcast (i32 (...)* @lowerit to i32 (i32, ...)*)(i32 %4)
%6 = load i8, i8* %1
%7 = sext i8 %6 to i32
%8 = tail call i32 (i32, ...) bitcast (i32 (...)* @lowerit to i32 (i32, ...)*)(i32 %7)
%9 = icmp eq i32 %5, %8
br i1 %9, label %10, label %35
10: ; preds = %2
%11 = getelementptr inbounds i8, i8* %0, i64 1
%12 = load i8, i8* %11
%13 = icmp eq i8 %12, 0
br i1 %13, label %35, label %14
14: ; preds = %10
%15 = getelementptr inbounds i8, i8* %1, i64 1
br label %20
16: ; preds = %27
%17 = getelementptr inbounds i8, i8* %21, i64 1
%18 = load i8, i8* %17
%19 = icmp eq i8 %18, 0
br i1 %19, label %35, label %20
20: ; preds = %14, %16
%21 = phi i8* [ %17, %16 ], [ %11, %14 ]
%22 = phi i8* [ %29, %16 ], [ %15, %14 ]
br label %23
23: ; preds = %20, %27
%24 = phi i8* [ %29, %27 ], [ %22, %20 ]
%25 = load i8, i8* %24
%26 = icmp eq i8 %25, 0
br i1 %26, label %35, label %27
27: ; preds = %23
%28 = sext i8 %25 to i32
%29 = getelementptr inbounds i8, i8* %24, i64 1
%30 = tail call i32 (i32, ...) bitcast (i32 (...)* @lowerit to i32 (i32, ...)*)(i32 %28)
%31 = load i8, i8* %21
%32 = sext i8 %31 to i32
%33 = tail call i32 (i32, ...) bitcast (i32 (...)* @lowerit to i32 (i32, ...)*)(i32 %32)
%34 = icmp eq i32 %30, %33
br i1 %34, label %16, label %23
35: ; preds = %16, %23, %10, %2
%36 = phi i32 [ 0, %2 ], [ 1, %10 ], [ 0, %23 ], [ 1, %16 ]
ret i32 %36
}