commit 14041afe24556efd5845564aa183b6451fd9d6cc

Author: law <law@138bc75d-0d04-0410-961f-82ee72b054a4>

Date:   Thu Feb 1 16:22:56 2018 +0000

            PR target/84128

            * config/i386/i386.c (release_scratch_register_on_entry): Add new

            OFFSET and RELEASE_VIA_POP arguments.  Use SP+OFFSET to restore

            the scratch if RELEASE_VIA_POP is false.

            (ix86_adjust_stack_and_probe_stack_clash): Un-constify SIZE.

            If we have to save a temporary register, decrement SIZE appropriately.

            Pass new arguments to release_scratch_register_on_entry.

            (ix86_adjust_stack_and_probe): Likewise.

            (ix86_emit_probe_stack_range): Pass new arguments to

            release_scratch_register_on_entry.

            PR target/84128

            * gcc.target/i386/pr84128.c: New test.

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c

index 2fe2a0c..c25d26c 100644

--- a/gcc/config/i386/i386.c

+++ b/gcc/config/i386/i386.c

@@ -10182,22 +10182,39 @@ get_scratch_register_on_entry (struct scratch_reg *sr)

     }

 }

-/* Release a scratch register obtained from the preceding function.  */

+/* Release a scratch register obtained from the preceding function.

+

+   If RELEASE_VIA_POP is true, we just pop the register off the stack

+   to release it.  This is what non-Linux systems use with -fstack-check.

+

+   Otherwise we use OFFSET to locate the saved register and the

+   allocated stack space becomes part of the local frame and is

+   deallcated by the epilogue.  */

 static void

-release_scratch_register_on_entry (struct scratch_reg *sr)

+release_scratch_register_on_entry (struct scratch_reg *sr, HOST_WIDE_INT offset,

+				   bool release_via_pop)

 {

   if (sr->saved)

     {

-      struct machine_function *m = cfun->machine;

-      rtx x, insn = emit_insn (gen_pop (sr->reg));

+      if (release_via_pop)

+	{

+	  struct machine_function *m = cfun->machine;

+	  rtx x, insn = emit_insn (gen_pop (sr->reg));

-      /* The RTX_FRAME_RELATED_P mechanism doesn't know about pop.  */

-      RTX_FRAME_RELATED_P (insn) = 1;

-      x = gen_rtx_PLUS (Pmode, stack_pointer_rtx, GEN_INT (UNITS_PER_WORD));

-      x = gen_rtx_SET (VOIDmode, stack_pointer_rtx, x);

-      add_reg_note (insn, REG_FRAME_RELATED_EXPR, x);

-      m->fs.sp_offset -= UNITS_PER_WORD;

+	  /* The RTX FRAME_RELATED_P mechanism doesn't know about pop.  */

+	  RTX_FRAME_RELATED_P (insn) = 1;

+	  x = gen_rtx_PLUS (Pmode, stack_pointer_rtx, GEN_INT (UNITS_PER_WORD));

+	  x = gen_rtx_SET (VOIDmode, stack_pointer_rtx, x);

+	  add_reg_note (insn, REG_FRAME_RELATED_EXPR, x);

+	  m->fs.sp_offset -= UNITS_PER_WORD;

+	}

+      else

+	{

+	  rtx x = gen_rtx_PLUS (Pmode, stack_pointer_rtx, GEN_INT (offset));

+	  x = gen_rtx_SET (VOIDmode, sr->reg, gen_rtx_MEM (word_mode, x));

+	  emit_insn (x);

+	}

     }

 }

@@ -10212,7 +10229,7 @@ release_scratch_register_on_entry (struct scratch_reg *sr)

    pushed on the stack.  */

 static void

-ix86_adjust_stack_and_probe_stack_clash (const HOST_WIDE_INT size,

+ix86_adjust_stack_and_probe_stack_clash (HOST_WIDE_INT size,

 					 const bool int_registers_saved)

 {

   struct machine_function *m = cfun->machine;

@@ -10331,6 +10348,12 @@ ix86_adjust_stack_and_probe_stack_clash (const HOST_WIDE_INT size,

       struct scratch_reg sr;

       get_scratch_register_on_entry (&sr);

+      /* If we needed to save a register, then account for any space

+	 that was pushed (we are not going to pop the register when

+	 we do the restore).  */

+      if (sr.saved)

+	size -= UNITS_PER_WORD;

+

       /* Step 1: round SIZE down to a multiple of the interval.  */

       HOST_WIDE_INT rounded_size = size & -probe_interval;

@@ -10379,7 +10402,9 @@ ix86_adjust_stack_and_probe_stack_clash (const HOST_WIDE_INT size,

 				   m->fs.cfa_reg == stack_pointer_rtx);

       dump_stack_clash_frame_info (PROBE_LOOP, size != rounded_size);

-      release_scratch_register_on_entry (&sr);

+      /* This does not deallocate the space reserved for the scratch

+	 register.  That will be deallocated in the epilogue.  */

+      release_scratch_register_on_entry (&sr, size, false);

     }

   /* Make sure nothing is scheduled before we are done.  */

@@ -10392,7 +10417,7 @@ ix86_adjust_stack_and_probe_stack_clash (const HOST_WIDE_INT size,

    pushed on the stack.  */

 static void

-ix86_adjust_stack_and_probe (const HOST_WIDE_INT size,

+ix86_adjust_stack_and_probe (HOST_WIDE_INT size,

 			     const bool int_registers_saved)

 {

   /* We skip the probe for the first interval + a small dope of 4 words and

@@ -10465,6 +10490,11 @@ ix86_adjust_stack_and_probe (const HOST_WIDE_INT size,

       get_scratch_register_on_entry (&sr);

+      /* If we needed to save a register, then account for any space

+	 that was pushed (we are not going to pop the register when

+	 we do the restore).  */

+      if (sr.saved)

+	size -= UNITS_PER_WORD;

       /* Step 1: round SIZE to the previous multiple of the interval.  */

@@ -10516,7 +10546,9 @@ ix86_adjust_stack_and_probe (const HOST_WIDE_INT size,

 						    (get_probe_interval ()

 						     + dope))));

-      release_scratch_register_on_entry (&sr);

+      /* This does not deallocate the space reserved for the scratch

+	 register.  That will be deallocated in the epilogue.  */

+      release_scratch_register_on_entry (&sr, size, false);

     }

   gcc_assert (cfun->machine->fs.cfa_reg != stack_pointer_rtx);

@@ -10669,7 +10701,7 @@ ix86_emit_probe_stack_range (HOST_WIDE_INT first, HOST_WIDE_INT size,

 						       sr.reg),

 					 rounded_size - size));

-      release_scratch_register_on_entry (&sr);

+      release_scratch_register_on_entry (&sr, size, true);

     }

   /* Make sure nothing is scheduled before we are done.  */

diff --git a/gcc/testsuite/gcc.target/i386/pr84128.c b/gcc/testsuite/gcc.target/i386/pr84128.c

new file mode 100644

index 0000000..a8323fd

--- /dev/null

+++ b/gcc/testsuite/gcc.target/i386/pr84128.c

@@ -0,0 +1,30 @@

+/* { dg-do run } */

+/* { dg-options "-O2 -march=i686 -mtune=generic -fstack-clash-protection" } */

+/* { dg-require-effective-target ia32 } */

+

+__attribute__ ((noinline, noclone, weak, regparm (3)))

+int

+f1 (long arg0, int (*pf) (long, void *))

+{

+  unsigned char buf[32768];

+  return pf (arg0, buf);

+}

+

+__attribute__ ((noinline, noclone, weak))

+int

+f2 (long arg0, void *ignored)

+{

+  if (arg0 != 17)

+    __builtin_abort ();

+  return 19;

+}

+

+int

+main (void)

+{

+  if (f1 (17, f2) != 19)

+    __builtin_abort ();

+  return 0;

+}

+

+