[X86] Add test suite for stack realignment.

[LuoYuanke]

Summary

These test case is created to test D145650 and D146862 which create extra prolog and epilog when base pointer register is clobbered.

[LuoYuanke]

Add test case to check function can return correctly with
extra prolog and epilog.

[pengfei]

LGTM.

SingleSource/UnitTests/dyn_stack_alloc_realign.cpp

30 ↗

(On Diff #508287)

Why don't use aligned?

[LuoYuanke]

SingleSource/UnitTests/dyn_stack_alloc_realign.cpp

30 ↗

(On Diff #508287)

Yes, using aligned looks better.

[LuoYuanke]

Address Phoebe's comments.

[omjavaid]

Hi This change has broken LLVM testsuite on various buildbots

https://lab.llvm.org/buildbot/#/builders/178
https://lab.llvm.org/buildbot/#/builders/185
https://lab.llvm.org/buildbot/#/builders/179

Kindly have a look. Thanks!

[LuoYuanke]

It should be caused by x86 inline assembly. Let me create a X86 fold for these test.

[LuoYuanke]

Let me revert the patch first.

SingleSource/Regression/C++/dyn_stack_alloc_realign.cpp

+#include <stdlib.h>
+
+int
+check_int (int *i, int align)
+{
+  *i = 20;
+  if ((((size_t) i) & (align - 1)) != 0)
+    {
+      printf ("\nUnalign address (%d): %p!\n", align, i);
+      abort ();
+    }
+  return *i;
+}
+
+#ifndef ALIGNMENT
+#define ALIGNMENT    64
+#endif
+ 
+typedef int aligned __attribute__((aligned(ALIGNMENT)));
+ 
+int global;
+ 
+void
+bar (char *p, int size)
+{
+  __builtin_strncpy (p, "good", size);
+}
+ 
+class Base {};
+ 
+struct A : virtual public Base
+{
+  A() {}
+};
+ 
+struct B {};
+ 
+void
+foo (int size)
+#if __cplusplus <= 201402L
+throw (B,A)            // { dg-warning "deprecated" "" { target { c++11 && { ! c++17 } } } }
+#endif
+{
+  __attribute__((__aligned__(64))) int a;
+  char *p = (char*) __builtin_alloca (size + 1);
+  aligned i;
+ 
+  asm volatile ("nop"::"S"(405):);
+  asm volatile ("nop"::"b"(405):);
+  bar (p, size);
+  if (__builtin_strncmp (p, "good", size) != 0)
+    {
+      p[size] = '\0';
+      printf ("Failed: %s != good\n", p);
+      abort ();
+    }
+ 
+  if (check_int (&i,  __alignof__(i)) != i)
+    abort ();
+ 
+  asm volatile ("movl %0, %1"::"r"(size), "m"(a):);
+  throw A();
+}
+ 
+int
+main()
+{
+  try {    foo (5); }
+  catch (A& a) { }
+  return 0;
+}