[PATCH, i386, Pointer Bounds Checker 17/x] Pointer bounds constants support

[Ilya Enkovich]

Hi,

This patch adds support for pointer bounds constants to be used as DECL_INITIAL 
for constant bounds (like zero bounds).

Bootstrapped and tested on linux-x86_64.

Thanks,
Ilya
--
gcc/

2014-05-30  Ilya Enkovich  <ilya.enkov...@intel.com>

        * emit-rtl.c (immed_double_const): Support MODE_POINTER_BOUNDS.
        (init_emit_once): Build pointer bounds zero constants.
        * explow.c (trunc_int_for_mode): Likewise.
        * varpool.c (ctor_for_folding): Do not fold constant
        bounds vars.
        * varasm.c (output_constant_pool_2): Support MODE_POINTER_BOUNDS.
        * config/i386/i386.c (ix86_legitimate_constant_p): Mark
        bounds constant as not valid.


diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 6a99b6b..888f5ad 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -12443,8 +12443,12 @@ darwin_local_data_pic (rtx disp)
    satisfies CONSTANT_P.  */
 
 static bool
-ix86_legitimate_constant_p (enum machine_mode mode ATTRIBUTE_UNUSED, rtx x)
+ix86_legitimate_constant_p (enum machine_mode mode, rtx x)
 {
+  /* Pointer bounds constants are not valid.  */
+  if (POINTER_BOUNDS_MODE_P (mode))
+    return false;
+
   switch (GET_CODE (x))
     {
     case CONST:
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 4736f8d..f9484d5 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -505,7 +505,8 @@ immed_double_const (HOST_WIDE_INT i0, HOST_WIDE_INT i1, 
enum machine_mode mode)
                  || GET_MODE_CLASS (mode) == MODE_PARTIAL_INT
                  /* We can get a 0 for an error mark.  */
                  || GET_MODE_CLASS (mode) == MODE_VECTOR_INT
-                 || GET_MODE_CLASS (mode) == MODE_VECTOR_FLOAT);
+                 || GET_MODE_CLASS (mode) == MODE_VECTOR_FLOAT
+                 || GET_MODE_CLASS (mode) == MODE_POINTER_BOUNDS);
 
       if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
        return gen_int_mode (i0, mode);
@@ -5875,6 +5876,11 @@ init_emit_once (void)
   if (STORE_FLAG_VALUE == 1)
     const_tiny_rtx[1][(int) BImode] = const1_rtx;
 
+  for (mode = GET_CLASS_NARROWEST_MODE (MODE_POINTER_BOUNDS);
+       mode != VOIDmode;
+       mode = GET_MODE_WIDER_MODE (mode))
+    const_tiny_rtx[0][mode] = immed_double_const (0, 0, mode);
+
   pc_rtx = gen_rtx_fmt_ (PC, VOIDmode);
   ret_rtx = gen_rtx_fmt_ (RETURN, VOIDmode);
   simple_return_rtx = gen_rtx_fmt_ (SIMPLE_RETURN, VOIDmode);
diff --git a/gcc/explow.c b/gcc/explow.c
index 48e91a6..9661abb 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -53,7 +53,8 @@ trunc_int_for_mode (HOST_WIDE_INT c, enum machine_mode mode)
   int width = GET_MODE_PRECISION (mode);
 
   /* You want to truncate to a _what_?  */
-  gcc_assert (SCALAR_INT_MODE_P (mode));
+  gcc_assert (SCALAR_INT_MODE_P (mode)
+             || POINTER_BOUNDS_MODE_P (mode));
 
   /* Canonicalize BImode to 0 and STORE_FLAG_VALUE.  */
   if (mode == BImode)
diff --git a/gcc/varasm.c b/gcc/varasm.c
index af7fb4a..fcae2fa 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -3799,6 +3799,7 @@ output_constant_pool_2 (enum machine_mode mode, rtx x, 
unsigned int align)
     case MODE_UFRACT:
     case MODE_ACCUM:
     case MODE_UACCUM:
+    case MODE_POINTER_BOUNDS:
       assemble_integer (x, GET_MODE_SIZE (mode), align, 1);
       break;
 
diff --git a/gcc/varpool.c b/gcc/varpool.c
index 0eeb2b6..321165d 100644
--- a/gcc/varpool.c
+++ b/gcc/varpool.c
@@ -257,6 +257,12 @@ ctor_for_folding (tree decl)
       && TREE_CODE (decl) != CONST_DECL)
     return error_mark_node;
 
+  /* Static constant bounds are created to be
+     used instead of constants and therefore
+     do not let folding it.  */
+  if (POINTER_BOUNDS_P (decl))
+    return error_mark_node;
+
   if (TREE_CODE (decl) == CONST_DECL
       || DECL_IN_CONSTANT_POOL (decl))
     return DECL_INITIAL (decl);