Use fibers on windows

Cargo.toml

@@ -22,5 +22,9 @@ test = false
 cfg-if = "0.1"
 libc = "0.2"
 
+[target.'cfg(windows)'.dependencies]
+kernel32-sys = "0.2.2"
+winapi = "0.2.8"
+
 [build-dependencies]
 cc = "1.0"

README.md

@@ -7,7 +7,7 @@
 
 A stack-growth library for Rust. Enables annotating fixed points in programs
 where the stack may want to grow larger. Spills over to the heap if the stack
-has it its limit.
+has hit its limit.
 
 This library is intended on helping implement recursive algorithms.
 

build.rs

@@ -4,7 +4,6 @@ use std::env;
 
 fn main() {
     let target = env::var("TARGET").unwrap();
-    let msvc = target.contains("msvc");
 
     let mut cfg = cc::Build::new();
 
@@ -19,15 +18,19 @@ fn main() {
                 stacker: {}\n\n", target);
     }
 
-    if target.starts_with("x86_64") {
-        cfg.file(if msvc {"src/arch/x86_64.asm"} else {"src/arch/x86_64.S"});
-        cfg.define("X86_64", None);
-    } else if target.contains("i686") {
-        cfg.file(if msvc {"src/arch/i686.asm"} else {"src/arch/i686.S"});
-        cfg.define("X86", None);
+    if target.contains("windows") {
+        cfg.file("src/arch/windows.c");
     } else {
-        panic!("\n\nusing currently unsupported target triple with \
-                stacker: {}\n\n", target);
+        if target.starts_with("x86_64") {
+            cfg.file("src/arch/x86_64.S");
+            cfg.define("X86_64", None);
+        } else if target.contains("i686") {
+            cfg.file("src/arch/i686.S");
+            cfg.define("X86", None);
+        } else {
+            panic!("\n\nusing currently unsupported target triple with \
+                    stacker: {}\n\n", target);
+        }
     }
 
     cfg.include("src/arch").compile("libstacker.a");

src/arch/asm.h

@@ -1,4 +1,4 @@
-#if defined(APPLE) || (defined(WINDOWS) && defined(X86))
+#if defined(APPLE)
 #define GLOBAL(name) .globl _ ## name; _ ## name
 #else
 #define GLOBAL(name) .globl name; name

src/arch/i686.S

@@ -2,26 +2,25 @@
 
 .text
 
-GLOBAL(__stacker_black_box):
-    ret
-
 GLOBAL(__stacker_stack_pointer):
     mov %esp, %eax
     ret
 
-#if defined(WINDOWS)
-GLOBAL(__stacker_get_tib_32):
-    mov %fs:0x18, %eax
+GLOBAL(__stacker_black_box):
     ret
-#endif
 
 GLOBAL(__stacker_switch_stacks):
+    .cfi_startproc
     push %ebp
+    .cfi_def_cfa_offset 8
+    .cfi_offset ebp, -8
     mov %esp, %ebp
-    mov 8(%ebp), %esp   // switch to our new stack
+    .cfi_def_cfa_register ebp
+    mov 16(%ebp), %esp  // switch to our new stack
     mov 12(%ebp), %eax  // load function we're going to call
-    push 16(%ebp)       // push argument to first function
+    push 8(%ebp)        // push argument to first function
     call *%eax          // call our function pointer
     mov %ebp, %esp      // restore the old stack pointer
     pop %ebp
     ret
+    .cfi_endproc

src/arch/windows.c

@@ -0,0 +1,30 @@
+#include <windows.h>
+
+void __stacker_black_box() {}
+
+PVOID __stacker_get_current_fiber() {
+    return GetCurrentFiber();
+}
+
+static size_t calc_stack_limit(size_t stack_low, size_t stack_guarantee) {
+    return stack_low +
+           max(stack_guarantee, sizeof(void *) == 4 ? 0x1000 : 0x2000) + // The guaranteed pages on a stack overflow
+           0x1000; // The guard page
+}
+
+// Fast paths for x86
+// magic numbers are from https://en.wikipedia.org/wiki/Win32_Thread_Information_Block
+
+#if defined(_M_X64)
+size_t __stacker_get_stack_limit() {
+    return calc_stack_limit(__readgsqword(0x1478), // The base address of the stack. Referenced in GetCurrentThreadStackLimits
+                            __readgsqword(0x1748)); // The guaranteed pages on a stack overflow. Referenced in SetThreadStackGuarantee
+}
+#endif
+
+#ifdef _M_IX86
+size_t __stacker_get_stack_limit() {
+    return calc_stack_limit(__readfsdword(0xE0C), // The base address of the stack. Referenced in GetCurrentThreadStackLimits
+                            __readfsdword(0xF78)); // The guaranteed pages on a stack overflow. Referenced in SetThreadStackGuarantee
+}
+#endif

src/arch/x86_64.S

@@ -4,33 +4,20 @@
 
 GLOBAL(__stacker_black_box):
     ret
-
 GLOBAL(__stacker_stack_pointer):
     movq %rsp, %rax
     ret
 
-#if defined(WINDOWS)
-#define ARG1 %rcx
-#define ARG2 %rdx
-#define ARG3 %r8
-#else
-#define ARG1 %rdi
-#define ARG2 %rsi
-#define ARG3 %rdx
-#endif
-
-#if defined(WINDOWS)
-GLOBAL(__stacker_get_tib_64):
-    mov %gs:0x30, %rax
-    ret
-#endif
-
 GLOBAL(__stacker_switch_stacks):
+    .cfi_startproc
     push %rbp
+    .cfi_def_cfa_offset 16
+    .cfi_offset rbp, -16
     mov %rsp, %rbp
-    mov ARG1, %rsp      // switch to our new stack
-    mov ARG3, ARG1      // move the data pointer to the first argument
-    call *ARG2          // call our function pointer
+    .cfi_def_cfa_register rbp
+    mov %rdx, %rsp      // switch to our new stack
+    call *%rsi          // call our function pointer, data argument in %rdi
     mov %rbp, %rsp      // restore the old stack pointer
     pop %rbp
     ret
+    .cfi_endproc