Add __builtin_ia32_interrupt_data

The interrupt and exception handlers are called by x86 processors.  X86
hardware pushes information onto stack and calls the handler.  We need
a builtin function to access interrupt or exception data from the
interrupt and exception handlers which are void function without
arguments.  This patch adds __builtin_ia32_interrupt_data so that
interrupt or exception data can be retrieved from the interrupt and
exception handlers.

gcc/

	PR target/66960
	* config/i386/i386.c (ix86_expand_prologue): Sorry if DRAP is
	used and the address of interrupt/exception data has been
	taken.
	(ix86_builtins): Add IX86_BUILTIN_INTERRUPT_DATA.
	(ix86_expand_builtin): Handle IX86_BUILTIN_INTERRUPT_DATA.
	* config/i386/i386.h (machine_function): Add interrupt_data_taken.
	* doc/extend.texi: Document __builtin_ia32_interrupt_data.

gcc/testsuite/

	PR target/66960
	* gcc.target/i386/pr66960-1.c: New test.
	* gcc.target/i386/pr66960-2.c: Likewise.
	* gcc.target/i386/pr66960-3.c: Likewise.

6 files changed, 101 insertions, 0 deletions

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index d78f4e7f175..7a97f3725d2 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -11577,6 +11577,13 @@ ix86_expand_prologue (void)
     {
       int align_bytes = crtl->stack_alignment_needed / BITS_PER_UNIT;
 
+      /* Can't use DRAP if the address of interrupt/exception data has
+         been taken.  */
+      if (cfun->machine->interrupt_data_taken)
+	sorry ("%<__builtin_ia32_interrupt_data%> not supported with"
+	       " stack realignment.  This may be worked around by"
+	       " adding -maccumulate-outgoing-arg.");
+
       /* Only need to push parameter pointer reg if it is caller saved.  */
       if (!call_used_regs[REGNO (crtl->drap_reg)])
 	{
@@ -30747,6 +30754,9 @@ enum ix86_builtins
   IX86_BUILTIN_READ_FLAGS,
   IX86_BUILTIN_WRITE_FLAGS,
 
+  /* Get the address of interrupt or exception data.  */
+  IX86_BUILTIN_INTERRUPT_DATA,
+
   IX86_BUILTIN_MAX
 };
 
@@ -34374,6 +34384,10 @@ ix86_init_mmx_sse_builtins (void)
   def_builtin (OPTION_MASK_ISA_MWAITX, "__builtin_ia32_mwaitx",
 	       VOID_FTYPE_UNSIGNED_UNSIGNED_UNSIGNED, IX86_BUILTIN_MWAITX);
 
+  /* Get the stack address when the function is called.  */
+  def_builtin (0, "__builtin_ia32_interrupt_data",
+	       PVOID_FTYPE_VOID, IX86_BUILTIN_INTERRUPT_DATA);
+
   /* Add FMA4 multi-arg argument instructions */
   for (i = 0, d = bdesc_multi_arg; i < ARRAY_SIZE (bdesc_multi_arg); i++, d++)
     {
@@ -40298,6 +40312,21 @@ rdseed_step:
       emit_insn (gen_xabort (op0));
       return 0;
 
+    case IX86_BUILTIN_INTERRUPT_DATA:
+      cfun->machine->interrupt_data_taken = true;
+
+      if (!target
+	  || GET_MODE (target) != Pmode
+	  || !register_operand (target, Pmode))
+	target = gen_reg_rtx (Pmode);
+
+      /* After the prologue, he address of interrupt or exception data
+	 is at -WORD(AP) in the current frame.  */
+      emit_insn (gen_rtx_SET (target,
+			      plus_constant (Pmode, arg_pointer_rtx,
+					     -UNITS_PER_WORD)));
+      return target;
+
     default:
       break;
     }
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index 7bd23ecadef..d838acb536a 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -2492,6 +2492,10 @@ struct GTY(()) machine_function {
   /* If true, it is safe to not save/restore DRAP register.  */
   BOOL_BITFIELD no_drap_save_restore : 1;
 
+  /* If true, the address of interrupt or exception data has been
+     taken.  */
+  BOOL_BITFIELD interrupt_data_taken : 1;
+
   /* If true, there is register available for argument passing.  This
      is used only in ix86_function_ok_for_sibcall by 32-bit to determine
      if there is scratch register available for indirect sibcall.  In
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 23e6a76b8a8..7ddf8bfd455 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -16815,6 +16815,15 @@ The following built-in function is always available.
 @item void __builtin_ia32_pause (void)
 Generates the @code{pause} machine instruction with a compiler memory
 barrier.
+
+@item void *__builtin_ia32_interrupt_data (void)
+Returns a pointer to interrupt or exception data pushed onto the stack
+by processor.
+
+The @code{__builtin_frame_address} builtin isn't suitable for interrupt
+and exception handlers since it returns the stack frame address on the
+callee side and compiler may generate a new stack frame for stack
+alignment.
 @end table
 
 The following floating-point built-in functions are made available in the
diff --git a/gcc/testsuite/gcc.target/i386/pr66960-1.c b/gcc/testsuite/gcc.target/i386/pr66960-1.c
new file mode 100644
index 00000000000..eeb67d2aadf
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr66960-1.c
@@ -0,0 +1,21 @@
+/* { dg-do link } */
+/* { dg-options "-O" } */
+
+extern void link_error (void);
+
+__attribute__ ((noinline, noclone))
+void
+foo (void)
+{
+  void **p = __builtin_ia32_interrupt_data ();
+  void *ra = __builtin_return_address (0);
+  if (*p != ra)
+    link_error ();
+}
+
+int
+main (void)
+{
+  foo ();
+  return 0;
+} 
diff --git a/gcc/testsuite/gcc.target/i386/pr66960-2.c b/gcc/testsuite/gcc.target/i386/pr66960-2.c
new file mode 100644
index 00000000000..2ed6e2a2447
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr66960-2.c
@@ -0,0 +1,21 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -maccumulate-outgoing-args" { target { lp64 } } } */
+/* { dg-options "-O2 -maccumulate-outgoing-args -maddress-mode=short" { target { x32 } } } */
+/* { dg-options "-O2 -maccumulate-outgoing-args -miamcu" { target { ia32 } } } */
+
+extern void abort (void);
+extern int check_int (int *i, int align);
+typedef int aligned __attribute__((aligned(64)));
+
+void *
+foo (void)
+{
+  aligned j;
+  if (check_int (&j, __alignof__(j)) != j)
+    abort ();
+  return __builtin_ia32_interrupt_data ();
+}
+
+/* { dg-final { scan-assembler "leaq\[ \t\]8\\(%rbp\\), %rax" { target lp64 } } } */
+/* { dg-final { scan-assembler "leal\[ \t\]8\\(%rbp\\), %eax" { target x32 } } } */
+/* { dg-final { scan-assembler "leal\[ \t\]4\\(%ebp\\), %eax" { target ia32 } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr66960-3.c b/gcc/testsuite/gcc.target/i386/pr66960-3.c
new file mode 100644
index 00000000000..b08400de07b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr66960-3.c
@@ -0,0 +1,17 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -mno-accumulate-outgoing-args" { target { lp64 } } } */
+/* { dg-options "-O2 -mno-accumulate-outgoing-args -maddress-mode=short" { target { x32 } } } */
+/* { dg-options "-O2 -mno-accumulate-outgoing-args -miamcu" { target { ia32 } } } */
+
+extern void abort (void);
+extern int check_int (int *i, int align);
+typedef int aligned __attribute__((aligned(64)));
+
+void *
+foo (void)
+{
+  aligned j;
+  if (check_int (&j, __alignof__(j)) != j)
+    abort ();
+  return __builtin_ia32_interrupt_data ();
+} /* { dg-message "sorry, unimplemented: .__builtin_ia32_interrupt_data. not supported" } */