Subzero. Native 64-bit int arithmetic on x86-64.

crosstest/stack_hack.x8664.c

+//===- subzero/crosstest/stack_hack.x8664.c.h - X8664 stack hack ----------===//

[Jim Stichnoth, 2015/08/10 16:08:04]

no .h

[John, 2015/08/10 20:41:16]

Done.

+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implements main() for crosstests in x86-64.
+//
+//===----------------------------------------------------------------------===//
+#include <assert.h>
+#include <stdint.h>
+
+#include <sys/mman.h>
+
+// X8664_STACK_HACK needs to be defined before xdefs.h is included.
+#define X8664_STACK_HACK
+#include "xdefs.h"
+
+/// xSetStack is used to set %rsp to NewRsp. OldRsp is a pointer that will be
+/// used to save the old %rsp value.
+#define xSetStack(NewRsp, OldRsp)                                              \
+  do {                                                                         \
+    __asm__ volatile("xchgq   %1, %%rsp\n\t"                                   \
+                     "xchgq   %1, %0"                                          \
+                     : "=r"(*(OldRsp))                                         \
+                     : "r"(NewRsp));                                           \
+  } while (0)
+
+extern int wrapped_main(int argc, char *argv[]);
+
+unsigned char *xStackStart(uint32 StackEnd, uint32 Size) {
+  const uint32 PageBoundary = 4 << 20; // 4 MB.

[Jim Stichnoth, 2015/08/10 16:08:04]

May want to "(void)PageBoundary;" in case we ever ramp up the warning/error
levels.

[John, 2015/08/10 20:41:16]

Done.

+  const uint64 StackStart = StackEnd - Size;
+  assert(StackStart + (PageBoundary - 1) & ~(PageBoundary - 1) &&
+         "StackStart not aligned to page boundary.");
+  assert((StackStart & 0xFFFFFFFF00000000ull) == 0 && "StackStart wraps.");
+  return (unsigned char *)StackStart;
+}
+
+unsigned char *xAllocStack(uint64 StackEnd, uint32 Size) {
+  assert((StackEnd & 0xFFFFFFFF00000000ull) == 0 && "Invalid StackEnd.");
+  void *Foo = xStackStart(StackEnd, Size);

[Jim Stichnoth, 2015/08/10 16:08:04]

Foo?

[John, 2015/08/10 20:41:16]

Bar instead?

[Jim Stichnoth, 2015/08/11 16:01:36]

Made me look, well played sir.

+  void *Stack =
+      mmap(xStackStart(StackEnd, Size), Size, PROT_READ | PROT_WRITE,
+           MAP_FIXED | MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS, -1, 0);
+  assert(Stack != MAP_FAILED && "mmap failed. no stack.");
+  return Stack;
+}
+
+void xDeallocStack(uint64 StackEnd, uint32 Size) {
+  assert((StackEnd & 0xFFFFFFFF00000000ull) == 0 && "Invalid StackEnd.");
+  munmap(xStackStart(StackEnd, Size), Size);
+}
+
+int main(int argc, char *argv[]) {
+  // These "locals" need to live **NOT** in the stack.
+  static int Argc;
+  static char **Argv;
+  static const uint32_t StackEnd = 0x80000000;
+  static const uint32_t StackSize = 40 * 1024 * 1024;
+  static unsigned char *new_rsp;
+  static unsigned char *old_rsp;
+  static unsigned char *dummy_rsp;
+  static int Failures;
+  Argc = argc;
+  Argv = argv;
+  new_rsp = xAllocStack(StackEnd, StackSize) + StackSize;
+  xSetStack(new_rsp, &old_rsp);
+  Failures = wrapped_main(Argc, Argv);
+  xSetStack(old_rsp, &new_rsp);
+  xDeallocStack(StackEnd, StackSize);
+  return Failures;
+}