re PR tree-optimization/47179 (SPU: errno misoptimization around malloc call)

2011-01-14  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/47179
	* target.def (ref_may_alias_errno): New target hook.
	* targhooks.h (default_ref_may_alias_errno): Declare.
	* targhooks.c: Include tree-ssa-alias.h and tree-flow.h.
	(default_ref_may_alias_errno): New function.
	* target.h (struct ao_ref_s): Declare.
	* tree-ssa-alias.c: Include target.h.
	(call_may_clobber_ref_p_1): Use the ref_may_alias_errno target hook.
	* Makefile.in (tree-ssa-alias.o): Adjust dependencies.
	(targhooks.o): Likewise.
	* doc/tm.texi.in (TARGET_REF_MAY_ALIAS_ERRNO): Document.
	* doc/tm.texi (TARGET_REF_MAY_ALIAS_ERRNO): Copy documentation.

From-SVN: r168788

9 files changed, 72 insertions, 19 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 00a7b11..9a6f58b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,20 @@
 2011-01-14  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/47179
+	* target.def (ref_may_alias_errno): New target hook.
+	* targhooks.h (default_ref_may_alias_errno): Declare.
+	* targhooks.c: Include tree-ssa-alias.h and tree-flow.h.
+	(default_ref_may_alias_errno): New function.
+	* target.h (struct ao_ref_s): Declare.
+	* tree-ssa-alias.c: Include target.h.
+	(call_may_clobber_ref_p_1): Use the ref_may_alias_errno target hook.
+	* Makefile.in (tree-ssa-alias.o): Adjust dependencies.
+	(targhooks.o): Likewise.
+	* doc/tm.texi.in (TARGET_REF_MAY_ALIAS_ERRNO): Document.
+	* doc/tm.texi (TARGET_REF_MAY_ALIAS_ERRNO): Copy documentation.
+
+2011-01-14  Richard Guenther  <rguenther@suse.de>
+
 	* tree-ssa-structalias.c  (new_var_info): Use DECL_HARD_REGISTER.
 
 2011-01-14  Richard Guenther  <rguenther@suse.de>
diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index de3bde9..188f8d5 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -2614,7 +2614,7 @@ tree-ssa-alias.o : tree-ssa-alias.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
    $(TREE_H) $(TM_P_H) $(EXPR_H) $(GGC_H) $(TREE_INLINE_H) $(FLAGS_H) \
    $(FUNCTION_H) $(TIMEVAR_H) convert.h $(TM_H) coretypes.h langhooks.h \
    $(TREE_DUMP_H) $(TREE_PASS_H) $(PARAMS_H) $(BASIC_BLOCK_H) $(DIAGNOSTIC_H) \
-   $(GIMPLE_H) $(VEC_H) \
+   $(GIMPLE_H) $(VEC_H) $(TARGET_H) \
    $(IPA_TYPE_ESCAPE_H) vecprim.h pointer-set.h alloc-pool.h \
    tree-pretty-print.h
 tree-ssa-reassoc.o : tree-ssa-reassoc.c $(TREE_FLOW_H) $(CONFIG_H) \
@@ -2796,7 +2796,8 @@ opts-common.o : opts-common.c $(OPTS_H) $(FLAGS_H) $(CONFIG_H) $(SYSTEM_H) \
 targhooks.o : targhooks.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TREE_H) \
    $(EXPR_H) $(TM_H) $(RTL_H) $(TM_P_H) $(FUNCTION_H) output.h $(DIAGNOSTIC_CORE_H) \
    $(MACHMODE_H) $(TARGET_DEF_H) $(TARGET_H) $(GGC_H) gt-targhooks.h \
-   $(OPTABS_H) $(RECOG_H) reload.h hard-reg-set.h intl.h $(OPTS_H)
+   $(OPTABS_H) $(RECOG_H) reload.h hard-reg-set.h intl.h $(OPTS_H) \
+   tree-ssa-alias.h $(TREE_FLOW_H)
 
 bversion.h: s-bversion; @true
 s-bversion: BASE-VER
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 139c5a7..010e77b 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -4295,6 +4295,10 @@ with machine mode @var{mode}.  The default version of this
 hook returns true for both @code{ptr_mode} and @code{Pmode}.
 @end deftypefn
 
+@deftypefn {Target Hook} bool TARGET_REF_MAY_ALIAS_ERRNO (struct ao_ref_s *@var{ref})
+Define this to return nonzero if the memory reference @var{ref}  may alias with the system C library errno location.  The default  version of this hook assumes the system C library errno location  is either a declaration of type int or accessed by dereferencing  a pointer to int.
+@end deftypefn
+
 @deftypefn {Target Hook} bool TARGET_SCALAR_MODE_SUPPORTED_P (enum machine_mode @var{mode})
 Define this to return nonzero if the port is prepared to handle
 insns involving scalar mode @var{mode}.  For a scalar mode to be
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 2085816..3298c3d 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -4283,6 +4283,8 @@ with machine mode @var{mode}.  The default version of this
 hook returns true for both @code{ptr_mode} and @code{Pmode}.
 @end deftypefn
 
+@hook TARGET_REF_MAY_ALIAS_ERRNO
+
 @hook TARGET_SCALAR_MODE_SUPPORTED_P
 Define this to return nonzero if the port is prepared to handle
 insns involving scalar mode @var{mode}.  For a scalar mode to be
diff --git a/gcc/target.def b/gcc/target.def
index 9d96e65..bdd7662 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -1519,6 +1519,17 @@ DEFHOOK
  bool, (enum machine_mode mode),
  default_valid_pointer_mode)
 
+/* Disambiguate with errno.  */
+DEFHOOK
+(ref_may_alias_errno,
+ "Define this to return nonzero if the memory reference @var{ref}\
+  may alias with the system C library errno location.  The default\
+  version of this hook assumes the system C library errno location\
+  is either a declaration of type int or accessed by dereferencing\
+  a pointer to int.",
+ bool, (struct ao_ref_s *ref),
+ default_ref_may_alias_errno)
+
 /* Support for named address spaces.  */
 #undef HOOK_PREFIX
 #define HOOK_PREFIX "TARGET_ADDR_SPACE_"
diff --git a/gcc/target.h b/gcc/target.h
index f93699f..eaf7aad 100644
--- a/gcc/target.h
+++ b/gcc/target.h
@@ -100,6 +100,9 @@ struct ddg;
 /* This is defined in cfgloop.h .  */
 struct loop;
 
+/* This is defined in tree-ssa-alias.h.  */
+struct ao_ref_s;
+
 /* Assembler instructions for creating various kinds of integer object.  */
 
 struct asm_int_op
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index 30a5891..225831b 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -69,6 +69,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "recog.h"
 #include "intl.h"
 #include "opts.h"
+#include "tree-flow.h"
+#include "tree-ssa-alias.h"
 
 
 bool
@@ -1035,6 +1037,33 @@ default_valid_pointer_mode (enum machine_mode mode)
   return (mode == ptr_mode || mode == Pmode);
 }
 
+/* Determine whether the memory reference specified by REF may alias
+   the C libraries errno location.  */
+bool
+default_ref_may_alias_errno (ao_ref *ref)
+{
+  tree base = ao_ref_base (ref);
+  /* The default implementation assumes the errno location is
+     a declaration of type int or is always accessed via a
+     pointer to int.  We assume that accesses to errno are
+     not deliberately obfuscated (even in conforming ways).  */
+  if (TYPE_UNSIGNED (TREE_TYPE (base))
+      || TYPE_MODE (TREE_TYPE (base)) != TYPE_MODE (integer_type_node))
+    return false;
+  /* The default implementation assumes an errno location
+     declaration is never defined in the current compilation unit.  */
+  if (DECL_P (base)
+      && !TREE_STATIC (base))
+    return true;
+  else if (TREE_CODE (base) == MEM_REF
+	   && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
+    {
+      struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
+      return !pi || pi->pt.anything || pi->pt.nonlocal;
+    }
+  return false;
+}
+
 /* Return the mode for a pointer to a given ADDRSPACE, defaulting to ptr_mode
    for the generic address space only.  */
 
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index d34ad9f..a8dbb11 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -143,6 +143,7 @@ extern bool default_target_option_valid_attribute_p (tree, tree, tree, int);
 extern bool default_target_option_pragma_parse (tree, tree);
 extern bool default_target_can_inline_p (tree, tree);
 extern bool default_valid_pointer_mode (enum machine_mode);
+extern bool default_ref_may_alias_errno (struct ao_ref_s *);
 extern enum machine_mode default_addr_space_pointer_mode (addr_space_t);
 extern enum machine_mode default_addr_space_address_mode (addr_space_t);
 extern bool default_addr_space_valid_pointer_mode (enum machine_mode,
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index d990a02..3f6fec1 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -25,6 +25,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tm.h"
 #include "tree.h"
 #include "tm_p.h"
+#include "target.h"
 #include "basic-block.h"
 #include "timevar.h"
 #include "ggc.h"
@@ -1417,24 +1418,10 @@ call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
 	   being the definition point for the pointer.  */
 	case BUILT_IN_MALLOC:
 	case BUILT_IN_CALLOC:
-	  /* Unix98 specifies that errno is set on allocation failure.
-	     Until we properly can track the errno location assume it
-	     is not a local decl but external or anonymous storage in
-	     a different translation unit.  Also assume it is of
-	     type int as required by the standard.  */
+	  /* Unix98 specifies that errno is set on allocation failure.  */
 	  if (flag_errno_math
-	      && TREE_TYPE (base) == integer_type_node)
-	    {
-	      struct ptr_info_def *pi;
-	      if (DECL_P (base)
-		  && !TREE_STATIC (base))
-		return true;
-	      else if ((INDIRECT_REF_P (base)
-			|| TREE_CODE (base) == MEM_REF)
-		       && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME
-		       && (pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0))))
-		return pi->pt.anything || pi->pt.nonlocal;
-	    }
+	      && targetm.ref_may_alias_errno (ref))
+	    return true;
 	  return false;
 	/* Freeing memory kills the pointed-to memory.  More importantly
 	   the call has to serve as a barrier for moving loads and stores