Mac support

[margnus1]

I create this issue to document and track progress on mac support, since I'm currently out of time to take it further.

• configure picks mismatched clang (configure: Look for clang in LLVM prefix #65)
• Mac does not have mallopt (Make mallopt() optional #66)
• Mac stdlib needs assignable VecSet iterator (vecset: Don't use reference in iterator #67)
• pthread_t is not an integer type on mac, but nidhugg assumes it is (Allow pthread_t to be implemented as a pointer #71)
• pthread_join links against "\01_pthread_join" on mac
• Some of the regex-related unit tests fail on mac

Currently, nidhugg can be compiled on mac by installing llvm and boost from homebrew, and then configuring with ./configure --with-llvm=$(brew --prefix llvm) --with-boost=$(brew --prefix boost)

The last issue can be reproduced by trying to run tests/smoke/C-tests/mutex_hard.c on nidhuggc on mac. The LLVM IR produced for this test on mac is:

; ModuleID = 'tests/smoke/C-tests/mutex_hard.c'
source_filename = "tests/smoke/C-tests/mutex_hard.c"
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.13.0"
%struct._opaque_pthread_mutex_t = type { i64, [56 x i8] }
%struct._opaque_pthread_t = type { i64, %struct.__darwin_pthread_handler_rec*, [8176 x i8] }
%struct.__darwin_pthread_handler_rec = type { void (i8*)*, i8*, %struct.__darwin_pthread_handler_rec* }
%struct._opaque_pthread_mutexattr_t = type { i64, [8 x i8] }
%struct._opaque_pthread_attr_t = type { i64, [56 x i8] }
@x = global i32 0, align 4
@m = common global %struct._opaque_pthread_mutex_t zeroinitializer, align 8
; Function Attrs: noinline nounwind optnone ssp uwtable
define i32 @main() #0 {
  %1 = alloca i32, align 4
  %2 = alloca [3 x %struct._opaque_pthread_t*], align 16
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  store i32 0, i32* %1, align 4
  %5 = call i32 @pthread_mutex_init(%struct._opaque_pthread_mutex_t* @m, %struct._opaque_pthread_mutexattr_t* null)
  store i32 0, i32* %3, align 4
  br label %6
6:                                                ; preds = %18, %0
  %7 = load i32, i32* %3, align 4
  %8 = icmp ult i32 %7, 3
  br i1 %8, label %9, label %21
9:                                                ; preds = %6
  %10 = getelementptr inbounds [3 x %struct._opaque_pthread_t*], [3 x %struct._opaque_pthread_t*]* %2, i64 0, i64 0
  %11 = load i32, i32* %3, align 4
  %12 = zext i32 %11 to i64
  %13 = getelementptr inbounds %struct._opaque_pthread_t*, %struct._opaque_pthread_t** %10, i64 %12
  %14 = load i32, i32* %3, align 4
  %15 = zext i32 %14 to i64
  %16 = inttoptr i64 %15 to i8*
  %17 = call i32 @pthread_create(%struct._opaque_pthread_t** %13, %struct._opaque_pthread_attr_t* null, i8* (i8*)* @t, i8* %16)
  br label %18
18:                                               ; preds = %9
  %19 = load i32, i32* %3, align 4
  %20 = add i32 %19, 1
  store i32 %20, i32* %3, align 4
  br label %6
21:                                               ; preds = %6
  store i32 0, i32* %4, align 4
  br label %22
22:                                               ; preds = %31, %21
  %23 = load i32, i32* %4, align 4
  %24 = icmp ult i32 %23, 3
  br i1 %24, label %25, label %34
25:                                               ; preds = %22
  %26 = load i32, i32* %4, align 4
  %27 = zext i32 %26 to i64
  %28 = getelementptr inbounds [3 x %struct._opaque_pthread_t*], [3 x %struct._opaque_pthread_t*]* %2, i64 0, i64 %27
  %29 = load %struct._opaque_pthread_t*, %struct._opaque_pthread_t** %28, align 8
  %30 = call i32 @"\01_pthread_join"(%struct._opaque_pthread_t* %29, i8** null)
  br label %31
31:                                               ; preds = %25
  %32 = load i32, i32* %4, align 4
  %33 = add i32 %32, 1
  store i32 %33, i32* %4, align 4
  br label %22
34:                                               ; preds = %22
  ret i32 0
}
declare i32 @pthread_mutex_init(%struct._opaque_pthread_mutex_t*, %struct._opaque_pthread_mutexattr_t*) #1
declare !callback !3 i32 @pthread_create(%struct._opaque_pthread_t**, %struct._opaque_pthread_attr_t*, i8* (i8*)*, i8*) #1
; Function Attrs: noinline nounwind optnone ssp uwtable
define internal i8* @t(i8*) #0 {
  %2 = alloca i8*, align 8
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  store i8* %0, i8** %2, align 8
  %6 = load i8*, i8** %2, align 8
  %7 = ptrtoint i8* %6 to i64
  %8 = trunc i64 %7 to i32
  store i32 %8, i32* %3, align 4
  %9 = call i32 @pthread_mutex_lock(%struct._opaque_pthread_mutex_t* @m)
  store i32 1, i32* %4, align 4
  %10 = load i32, i32* %4, align 4
  %11 = atomicrmw add i32* @x, i32 %10 seq_cst
  store i32 %11, i32* %5, align 4
  %12 = load i32, i32* %5, align 4
  %13 = load i32, i32* %3, align 4
  %14 = icmp eq i32 %12, %13
  br i1 %14, label %15, label %17
15:                                               ; preds = %1
  %16 = call i32 @pthread_mutex_unlock(%struct._opaque_pthread_mutex_t* @m)
  br label %17
17:                                               ; preds = %15, %1
  ret i8* null
}

declare i32 @"\01_pthread_join"(%struct._opaque_pthread_t*, i8**) #1
declare i32 @pthread_mutex_lock(%struct._opaque_pthread_mutex_t*) #1
declare i32 @pthread_mutex_unlock(%struct._opaque_pthread_mutex_t*) #1
attributes #0 = { noinline nounwind optnone ssp uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="penryn" "target-features"="+cx16,+cx8,+fxsr,+mmx,+sahf,+sse,+sse2,+sse3,+sse4.1,+ssse3,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="penryn" "target-features"="+cx16,+cx8,+fxsr,+mmx,+sahf,+sse,+sse2,+sse3,+sse4.1,+ssse3,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
!llvm.module.flags = !{!0, !1}
!llvm.ident = !{!2}
!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 7, !"PIC Level", i32 2}
!2 = !{!"clang version 9.0.0 (tags/RELEASE_900/final)"}
!3 = !{!4}
!4 = !{i64 2, i64 3, i1 false}