Re: Work around PR65873

[Jan Hubicka <hubicka@ucw.cz>]

Hi,
this is a variant of patch I backported to GCC 4.9.  It also includes the earlier
for for -fstrict-aliasing boundary.

Honza

Index: ChangeLog
===================================================================
--- ChangeLog	(revision 223269)
+++ ChangeLog	(working copy)
@@ -1,3 +1,10 @@
+2015-04-16  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR ipa/65873
+	* ipa-inline.c (can_inline_edge_p): Allow early inlining of always
+	inlines across optimization boundary; be tolerant about COMDAT;
+	allow inlining across -fstrict-aliasing boundary.
+
 2015-05-16  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	Backport from mainline
Index: ipa-inline.c
===================================================================
--- ipa-inline.c	(revision 223252)
+++ ipa-inline.c	(working copy)
@@ -427,49 +427,55 @@ can_inline_edge_p (struct cgraph_edge *e
 	      && lookup_attribute ("always_inline",
 				   DECL_ATTRIBUTES (callee->decl)));
 
+     /* Until GCC 4.9 we did not check the semantics alterning flags
+	bellow and inline across optimization boundry.
+	Enabling checks bellow breaks several packages by refusing
+	to inline library always_inline functions. See PR65873.
+	Disable the check for early inlining for now until better solution
+	is found.  */
+     if (always_inline && early)
+	;
       /* There are some options that change IL semantics which means
          we cannot inline in these cases for correctness reason.
 	 Not even for always_inline declared functions.  */
       /* Strictly speaking only when the callee contains signed integer
          math where overflow is undefined.  */
-      if ((check_maybe_up (flag_strict_overflow)
-	   /* this flag is set by optimize.  Allow inlining across
-	      optimize boundary.  */
-	   && (!opt_for_fn (caller->decl, optimize)
-	       == !opt_for_fn (callee->decl, optimize) || !always_inline))
-	  || check_match (flag_wrapv)
-	  || check_match (flag_trapv)
-	  /* Strictly speaking only when the callee contains memory
-	     accesses that are not using alias-set zero anyway.  */
-	  || check_maybe_down (flag_strict_aliasing)
-	  /* Strictly speaking only when the callee uses FP math.  */
-	  || check_maybe_up (flag_rounding_math)
-	  || check_maybe_up (flag_trapping_math)
-	  || check_maybe_down (flag_unsafe_math_optimizations)
-	  || check_maybe_down (flag_finite_math_only)
-	  || check_maybe_up (flag_signaling_nans)
-	  || check_maybe_down (flag_cx_limited_range)
-	  || check_maybe_up (flag_signed_zeros)
-	  || check_maybe_down (flag_associative_math)
-	  || check_maybe_down (flag_reciprocal_math)
-	  /* We do not want to make code compiled with exceptions to be brought
-	     into a non-EH function unless we know that the callee does not
-	     throw.  This is tracked by DECL_FUNCTION_PERSONALITY.  */
-	  || (check_match (flag_non_call_exceptions)
-	      /* TODO: We also may allow bringing !flag_non_call_exceptions
-		 to flag_non_call_exceptions function, but that may need
-		 extra work in tree-inline to add the extra EH edges.  */
-	      && (!opt_for_fn (callee->decl, flag_non_call_exceptions)
-		  || DECL_FUNCTION_PERSONALITY (callee->decl)))
-	  || (check_maybe_up (flag_exceptions)
-	      && DECL_FUNCTION_PERSONALITY (callee->decl))
-	  /* Strictly speaking only when the callee contains function
-	     calls that may end up setting errno.  */
-	  || check_maybe_up (flag_errno_math)
-	  /* When devirtualization is diabled for callee, it is not safe
-	     to inline it as we possibly mangled the type info.
-	     Allow early inlining of always inlines.  */
-	  || (!early && check_maybe_down (flag_devirtualize)))
+     else if ((check_maybe_up (flag_strict_overflow)
+	       /* this flag is set by optimize.  Allow inlining across
+		  optimize boundary.  */
+	       && (!opt_for_fn (caller->decl, optimize)
+		   == !opt_for_fn (callee->decl, optimize) || !always_inline))
+	      || check_match (flag_wrapv)
+	      || check_match (flag_trapv)
+	      /* Strictly speaking only when the callee uses FP math.  */
+	      || check_maybe_up (flag_rounding_math)
+	      || check_maybe_up (flag_trapping_math)
+	      || check_maybe_down (flag_unsafe_math_optimizations)
+	      || check_maybe_down (flag_finite_math_only)
+	      || check_maybe_up (flag_signaling_nans)
+	      || check_maybe_down (flag_cx_limited_range)
+	      || check_maybe_up (flag_signed_zeros)
+	      || check_maybe_down (flag_associative_math)
+	      || check_maybe_down (flag_reciprocal_math)
+	      /* We do not want to make code compiled with exceptions to be
+		 brought into a non-EH function unless we know that the callee
+		 does not throw.
+		 This is tracked by DECL_FUNCTION_PERSONALITY.  */
+	      || (check_match (flag_non_call_exceptions)
+		  /* TODO: We also may allow bringing !flag_non_call_exceptions
+		     to flag_non_call_exceptions function, but that may need
+		     extra work in tree-inline to add the extra EH edges.  */
+		  && (!opt_for_fn (callee->decl, flag_non_call_exceptions)
+		      || DECL_FUNCTION_PERSONALITY (callee->decl)))
+	      || (check_maybe_up (flag_exceptions)
+		  && DECL_FUNCTION_PERSONALITY (callee->decl))
+	      /* Strictly speaking only when the callee contains function
+		 calls that may end up setting errno.  */
+	      || check_maybe_up (flag_errno_math)
+	      /* When devirtualization is diabled for callee, it is not safe
+		 to inline it as we possibly mangled the type info.
+		 Allow early inlining of always inlines.  */
+	      || (!early && check_maybe_down (flag_devirtualize)))
 	{
 	  e->inline_failed = CIF_OPTIMIZATION_MISMATCH;
 	  inlinable = false;
@@ -484,6 +490,17 @@ can_inline_edge_p (struct cgraph_edge *e
 	  e->inline_failed = CIF_OPTIMIZATION_MISMATCH;
 	  inlinable = false;
 	}
+      /* If explicit optimize attribute are not used, the mismatch is caused
+	 by different command line options used to build different units.
+	 Do not care about COMDAT functions - those are intended to be
+         optimized with the optimization flags of module they are used in.
+	 Also do not care about mixing up size/speed optimization when
+	 DECL_DISREGARD_INLINE_LIMITS is set.  */
+      else if ((callee->merged
+	        && !lookup_attribute ("optimize",
+				      DECL_ATTRIBUTES (caller->decl)))
+	       || DECL_DISREGARD_INLINE_LIMITS (callee->decl))
+	;
       /* If mismatch is caused by merging two LTO units with different
 	 optimizationflags we want to be bit nicer.  However never inline
 	 if one of functions is not optimized at all.  */
@@ -515,7 +532,7 @@ can_inline_edge_p (struct cgraph_edge *e
       else if (opt_for_fn (callee->decl, optimize_size)
 	       < opt_for_fn (caller->decl, optimize_size)
 	       || (opt_for_fn (callee->decl, optimize)
-		   >= opt_for_fn (caller->decl, optimize)))
+		   > opt_for_fn (caller->decl, optimize)))
 	{
 	  if (estimate_edge_time (e)
 	      >= 20 + inline_edge_summary (e)->call_stmt_time)