[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

31

Why don't use aligned?

[LuoYuanke]

SingleSource/UnitTests/dyn_stack_alloc_realign.cpp

31

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/UnitTests/dyn_stack_alloc_realign.cpp

+#include <stdio.h>
+#include <stdlib.h>
+
+int checkInt(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)));
+
+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) {
+  aligned Var;
+  char *Ptr = (char *)__builtin_alloca(size + 1);
+  aligned I;
+
+  // clobber 32-bit base pointer.
+  asm volatile("nop" ::"S"(405) :);
+  // clobber 64-bit base pointer.
+  asm volatile("nop" ::"b"(405) :);
+  bar(Ptr, size);
+  if (__builtin_strncmp(Ptr, "good", size) != 0) {
+    Ptr[size] = '\0';
+    printf("Failed: %s != good\n", Ptr);
+    abort();
+  }
+
+  if (checkInt(&I, __alignof__(I)) != I)
+    abort();
+
+  // access argument and local variable.
+  asm volatile("movl %0, %1" ::"r"(size), "m"(Var) :);
+  throw A();
+}
+
+int main() {
+  try {
+    foo(5);
+  } catch (A &a) {
+  }
+  return 0;
+}

SingleSource/UnitTests/dyn_stack_alloc_realign.reference_output

+exit 0

SingleSource/UnitTests/dyn_stack_alloc_realign2.cpp

+#include <stdio.h>
+#include <stdlib.h>
+
+int checkInt(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)));
+
+void bar(char *p, int size) { __builtin_strncpy(p, "good", size); }
+
+class Base {};
+
+struct A : virtual public Base {
+  A() {}
+};
+
+struct B {};
+
+__attribute__((noinline))
+void foo(int size) {
+  aligned Var;
+  char *Ptr = (char *)__builtin_alloca(size + 1);
+  aligned I;
+
+  // clobber 32-bit base pointer.
+  asm volatile("nop" ::"S"(405) :);
+  // clobber 64-bit base pointer.
+  asm volatile("nop" ::"b"(405) :);
+  bar(Ptr, size);
+  if (__builtin_strncmp(Ptr, "good", size) != 0) {
+    Ptr[size] = '\0';
+    printf("Failed: %s != good\n", Ptr);
+    abort();
+  }
+
+  if (checkInt(&I, __alignof__(I)) != I)
+    abort();
+
+  // access argument and local variable.
+  asm volatile("movl %0, %1" ::"r"(size), "m"(Var) :);
+}
+
+int main() {
+  try {
+    foo(5);
+  } catch (A &a) {
+  }
+  return 0;
+}

SingleSource/UnitTests/dyn_stack_alloc_realign2.reference_output

+exit 0