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Re: [PATCH][AARCH64] PR target/84521 Fix frame pointer corruption with -fomit-frame-pointer with __builtin_setjmp


On 19/03/18 12:11, James Greenhalgh wrote:
On Wed, Mar 14, 2018 at 05:40:49PM +0000, Sudi Das wrote:
Hi

This patch is another partial fix for PR 84521. This is adding a
definition to one of the target hooks used in the SJLJ implemetation so
that AArch64 defines the hard_frame_pointer_rtx as the
TARGET_BUILTIN_SETJMP_FRAME_VALUE. As pointed out by Wilco there is
still a lot more work to be done for these builtins in the future.

Testing: Bootstrapped and regtested on aarch64-none-linux-gnu and added
new test.

Is this ok for trunk?

OK.

Thanks James but I realized I marked this wrong as only AArch64 patch. This also has a mid change so cc'ing more people for approval.

Sudi


Thanks,
James

*** gcc/ChangeLog ***

2018-03-14  Sudakshina Das  <sudi.das@arm.com>

	* builtins.c (expand_builtin_setjmp_receiver): Update condition
	to restore frame pointer.
	* config/aarch64/aarch64.h (DONT_USE_BUILTIN_SETJMP): Update
	comment.
	* config/aarch64/aarch64.c (aarch64_builtin_setjmp_frame_value):
	New.
	(TARGET_BUILTIN_SETJMP_FRAME_VALUE): Define.

*** gcc/testsuite/ChangeLog ***

2018-03-14  Sudakshina Das  <sudi.das@arm.com>

	* gcc.c-torture/execute/pr84521.c: New test.

diff --git a/gcc/builtins.c b/gcc/builtins.c
index 85affa7..640f1a9 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -898,7 +898,8 @@ expand_builtin_setjmp_receiver (rtx receiver_label)
/* Now put in the code to restore the frame pointer, and argument
       pointer, if needed.  */
-  if (! targetm.have_nonlocal_goto ())
+  if (! targetm.have_nonlocal_goto ()
+      && targetm.builtin_setjmp_frame_value () != hard_frame_pointer_rtx)
      {
        /* First adjust our frame pointer to its actual value.  It was
  	 previously set to the start of the virtual area corresponding to
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index e3c52f6..7a21c14 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -474,7 +474,9 @@ extern unsigned aarch64_architecture_version;
  #define EH_RETURN_STACKADJ_RTX	gen_rtx_REG (Pmode, R4_REGNUM)
  #define EH_RETURN_HANDLER_RTX  aarch64_eh_return_handler_rtx ()
-/* Don't use __builtin_setjmp until we've defined it. */
+/* Don't use __builtin_setjmp until we've defined it.
+   CAUTION: This macro is only used during exception unwinding.
+   Don't fall for its name.  */
  #undef DONT_USE_BUILTIN_SETJMP
  #define DONT_USE_BUILTIN_SETJMP 1
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index e1fb87f..e7ac0fe 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -12128,6 +12128,13 @@ aarch64_expand_builtin_va_start (tree valist, rtx nextarg ATTRIBUTE_UNUSED)
    expand_expr (t, const0_rtx, VOIDmode, EXPAND_NORMAL);
  }
+/* Implement TARGET_BUILTIN_SETJMP_FRAME_VALUE. */
+static rtx
+aarch64_builtin_setjmp_frame_value (void)
+{
+  return hard_frame_pointer_rtx;
+}
+
  /* Implement TARGET_GIMPLIFY_VA_ARG_EXPR.  */
static tree
@@ -17505,6 +17512,9 @@ aarch64_run_selftests (void)
  #undef TARGET_FOLD_BUILTIN
  #define TARGET_FOLD_BUILTIN aarch64_fold_builtin
+#undef TARGET_BUILTIN_SETJMP_FRAME_VALUE
+#define TARGET_BUILTIN_SETJMP_FRAME_VALUE aarch64_builtin_setjmp_frame_value
+
  #undef TARGET_FUNCTION_ARG
  #define TARGET_FUNCTION_ARG aarch64_function_arg
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr84521.c b/gcc/testsuite/gcc.c-torture/execute/pr84521.c
new file mode 100644
index 0000000..76b10d2
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr84521.c
@@ -0,0 +1,49 @@
+/* { dg-require-effective-target indirect_jumps } */
+
+#include <setjmp.h>
+
+jmp_buf buf;
+
+int uses_longjmp (void)
+{
+  __builtin_longjmp (buf, 1);
+}
+
+int gl;
+void after_longjmp (void)
+{
+  gl = 5;
+}
+
+int
+test_1 (int n)
+{
+  volatile int *p = alloca (n);
+  if (__builtin_setjmp (buf))
+    {
+      after_longjmp ();
+    }
+  else
+    {
+      uses_longjmp ();
+    }
+
+  return 0;
+}
+
+int __attribute__ ((optimize ("no-omit-frame-pointer")))
+test_2 (int n)
+{
+  int i;
+  int *ptr = (int *)__builtin_alloca (sizeof (int) * n);
+  for (i = 0; i < n; i++)
+    ptr[i] = i;
+  test_1 (n);
+  return 0;
+}
+
+int main (int argc, const char **argv)
+{
+  __builtin_memset (&buf, 0xaf, sizeof (buf));
+  test_2 (100);
+}



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