system/gcc: Fix ppc32 kernel build; POSIXise builtin snprintf

1 files changed, 80 insertions, 0 deletions

diff --git a/system/gcc/backport-r267157-posix-conformant-snprintf.patch b/system/gcc/backport-r267157-posix-conformant-snprintf.patch
new file mode 100644
index 000000000..adedf0ce9
--- /dev/null
+++ b/system/gcc/backport-r267157-posix-conformant-snprintf.patch
@@ -0,0 +1,80 @@
+https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87096
+
+GCC's "optimised" snprintf is not POSIX conformant
+
+--- trunk/gcc/gimple-ssa-sprintf.c	2018/12/07 17:02:11	266897
++++ trunk/gcc/gimple-ssa-sprintf.c	2018/12/14 22:38:08	267157
+@@ -3899,6 +3899,7 @@
+   /* True when the destination size is constant as opposed to the lower
+      or upper bound of a range.  */
+   bool dstsize_cst_p = true;
++  bool posunder4k = true;
+ 
+   if (idx_dstsize == HOST_WIDE_INT_M1U)
+     {
+@@ -3931,11 +3932,20 @@
+ 			    "specified bound %wu exceeds maximum object size "
+ 			    "%wu",
+ 			    dstsize, target_size_max () / 2);
++	      /* POSIX requires snprintf to fail if DSTSIZE is greater
++		 than INT_MAX.  Even though not all POSIX implementations
++		 conform to the requirement, avoid folding in this case.  */
++	      posunder4k = false;
+ 	    }
+ 	  else if (dstsize > target_int_max ())
+-	    warning_at (gimple_location (info.callstmt), info.warnopt (),
+-			"specified bound %wu exceeds %<INT_MAX%>",
+-			dstsize);
++	    {
++	      warning_at (gimple_location (info.callstmt), info.warnopt (),
++			  "specified bound %wu exceeds %<INT_MAX%>",
++			  dstsize);
++	      /* POSIX requires snprintf to fail if DSTSIZE is greater
++		 than INT_MAX.  Avoid folding in that case.  */
++	      posunder4k = false;
++	    }
+ 	}
+       else if (TREE_CODE (size) == SSA_NAME)
+ 	{
+@@ -3944,9 +3954,29 @@
+ 	  if (vr->type == VR_RANGE
+              && TREE_CODE (vr->min) == INTEGER_CST
+              && TREE_CODE (vr->max) == INTEGER_CST)
+-	    dstsize = (warn_level < 2
+-		       ? TREE_INT_CST_LOW (vr->max)
+-		       : TREE_INT_CST_LOW (vr->min));
++	    {
++	      unsigned HOST_WIDE_INT minsize = TREE_INT_CST_LOW (vr->min);
++	      unsigned HOST_WIDE_INT maxsize = TREE_INT_CST_LOW (vr->max);
++	      dstsize = warn_level < 2 ? maxsize : minsize;
++
++	      if (minsize > target_int_max ())
++		warning_at (gimple_location (info.callstmt), info.warnopt (),
++			    "specified bound range [%wu, %wu] exceeds "
++			    "%<INT_MAX%>",
++			    minsize, maxsize);
++
++	      /* POSIX requires snprintf to fail if DSTSIZE is greater
++		 than INT_MAX.  Avoid folding if that's possible.  */
++	      if (maxsize > target_int_max ())
++		posunder4k = false;
++	    }
++	  else if (vr->type == VR_VARYING)
++	    {
++	      /* POSIX requires snprintf to fail if DSTSIZE is greater
++		 than INT_MAX.  Since SIZE's range is unknown, avoid
++		 folding.  */
++	      posunder4k = false;
++	    }
+ 
+ 	  /* The destination size is not constant.  If the function is
+ 	     bounded (e.g., snprintf) a lower bound of zero doesn't
+@@ -4033,7 +4073,7 @@
+      the call.  Avoid this optimization when -frounding-math is in effect
+      and the format string contains a floating point directive.  */
+   bool call_removed = false;
+-  if (success && optimize > 0)
++  if (!posunder4k && success && optimize > 0)
+     {
+       /* Save a copy of the iterator pointing at the call.  The iterator
+          may change to point past the call in try_substitute_return_value