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* [PATCH v2] Enable __memcmpeq after seeing __memcmpeq prototype
@ 2022-06-20 15:44 H.J. Lu
  2022-07-01  7:51 ` Richard Biener
  0 siblings, 1 reply; 3+ messages in thread
From: H.J. Lu @ 2022-06-20 15:44 UTC (permalink / raw)
  To: gcc-patches

extern int __memcmpeq (const void *, const void *, size_t);

was was added to GLIBC 2.35.  Expand BUILT_IN_MEMCMP_EQ to __memcmpeq
after seeing __memcmpeq prototype

gcc/

	* builtins.cc (have_memcmpeq_prototype): New.
	(expand_builtin): Issue an error for BUILT_IN___MEMCMPEQ if
	there is no __memcmpeq prototype.  Expand BUILT_IN_MEMCMP_EQ
	to BUILT_IN___MEMCMP_EQ if there is __memcmpeq prototype.
	* builtins.def (BUILT_IN___MEMCMPEQ): New.
	* builtins.h (have_memcmpeq_prototype): New.

gcc/c/

	* c-decl.cc (diagnose_mismatched_decls): Set
	have_memcmpeq_prototype to true after seeing __memcmpeq prototype.

gcc/cp/

	*  decl.cc (duplicate_decls): Set have_memcmpeq_prototype to true
	after seeing __memcmpeq prototype.

gcc/testsuite/

	* c-c++-common/memcmpeq-1.c: New test.
	* c-c++-common/memcmpeq-2.c: Likewise.
	* c-c++-common/memcmpeq-3.c: Likewise.
	* c-c++-common/memcmpeq-4.c: Likewise.
	* c-c++-common/memcmpeq-5.c: Likewise.
	* c-c++-common/memcmpeq-6.c: Likewise.
	* c-c++-common/memcmpeq.h: Likewise.
---
 gcc/builtins.cc                         | 17 ++++++++++++++++-
 gcc/builtins.def                        |  3 +++
 gcc/builtins.h                          |  3 +++
 gcc/c/c-decl.cc                         | 25 ++++++++++++++++++-------
 gcc/cp/decl.cc                          |  5 +++++
 gcc/testsuite/c-c++-common/memcmpeq-1.c | 11 +++++++++++
 gcc/testsuite/c-c++-common/memcmpeq-2.c | 11 +++++++++++
 gcc/testsuite/c-c++-common/memcmpeq-3.c | 11 +++++++++++
 gcc/testsuite/c-c++-common/memcmpeq-4.c | 11 +++++++++++
 gcc/testsuite/c-c++-common/memcmpeq-5.c | 11 +++++++++++
 gcc/testsuite/c-c++-common/memcmpeq-6.c | 10 ++++++++++
 gcc/testsuite/c-c++-common/memcmpeq.h   | 11 +++++++++++
 12 files changed, 121 insertions(+), 8 deletions(-)
 create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-1.c
 create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-2.c
 create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-3.c
 create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-4.c
 create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-5.c
 create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-6.c
 create mode 100644 gcc/testsuite/c-c++-common/memcmpeq.h

diff --git a/gcc/builtins.cc b/gcc/builtins.cc
index 971b18c3745..96e283e5847 100644
--- a/gcc/builtins.cc
+++ b/gcc/builtins.cc
@@ -104,6 +104,9 @@ builtin_info_type builtin_info[(int)END_BUILTINS];
 /* Non-zero if __builtin_constant_p should be folded right away.  */
 bool force_folding_builtin_constant_p;
 
+/* True if there is a __memcmpeq prototype.  */
+bool have_memcmpeq_prototype;
+
 static int target_char_cast (tree, char *);
 static int apply_args_size (void);
 static int apply_result_size (void);
@@ -7392,6 +7395,15 @@ expand_builtin (tree exp, rtx target, rtx subtarget, machine_mode mode,
 	return target;
       break;
 
+    case BUILT_IN___MEMCMPEQ:
+      if (!have_memcmpeq_prototype)
+	{
+	  error ("use of %<__builtin___memcmpeq ()%> without "
+		 "%<__memcmpeq%> prototype");
+	  return const0_rtx;
+	}
+      break;
+
     /* Expand it as BUILT_IN_MEMCMP_EQ first. If not successful, change it
        back to a BUILT_IN_STRCMP. Remember to delete the 3rd parameter
        when changing it to a strcmp call.  */
@@ -7445,7 +7457,10 @@ expand_builtin (tree exp, rtx target, rtx subtarget, machine_mode mode,
 	return target;
       if (fcode == BUILT_IN_MEMCMP_EQ)
 	{
-	  tree newdecl = builtin_decl_explicit (BUILT_IN_MEMCMP);
+	  tree newdecl = builtin_decl_explicit
+	    (have_memcmpeq_prototype
+	     ? BUILT_IN___MEMCMPEQ
+	     : BUILT_IN_MEMCMP);
 	  TREE_OPERAND (exp, 1) = build_fold_addr_expr (newdecl);
 	}
       break;
diff --git a/gcc/builtins.def b/gcc/builtins.def
index 005976f34e9..95642c6acdf 100644
--- a/gcc/builtins.def
+++ b/gcc/builtins.def
@@ -965,6 +965,9 @@ DEF_BUILTIN_STUB (BUILT_IN_ALLOCA_WITH_ALIGN_AND_MAX, "__builtin_alloca_with_ali
    equality with zero.  */
 DEF_BUILTIN_STUB (BUILT_IN_MEMCMP_EQ, "__builtin_memcmp_eq")
 
+/* Similar to BUILT_IN_MEMCMP_EQ, but is mapped to __memcmpeq.  */
+DEF_EXT_LIB_BUILTIN (BUILT_IN___MEMCMPEQ, "__memcmpeq", BT_FN_INT_CONST_PTR_CONST_PTR_SIZE, ATTR_PURE_NOTHROW_NONNULL_LEAF)
+
 /* An internal version of strcmp/strncmp, used when the result is only 
    tested for equality with zero.  */
 DEF_BUILTIN_STUB (BUILT_IN_STRCMP_EQ, "__builtin_strcmp_eq")
diff --git a/gcc/builtins.h b/gcc/builtins.h
index 5ad830c9fbf..e3e80b33f6d 100644
--- a/gcc/builtins.h
+++ b/gcc/builtins.h
@@ -49,6 +49,9 @@ extern struct target_builtins *this_target_builtins;
 /* Non-zero if __builtin_constant_p should be folded right away.  */
 extern bool force_folding_builtin_constant_p;
 
+/* True if there is a __memcmpeq prototype.  */
+extern bool have_memcmpeq_prototype;
+
 extern bool called_as_built_in (tree);
 extern bool get_object_alignment_1 (tree, unsigned int *,
 				    unsigned HOST_WIDE_INT *);
diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index ae8990c138f..cc66d254017 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -2140,13 +2140,24 @@ diagnose_mismatched_decls (tree newdecl, tree olddecl,
 	  return false;
 	}
     }
-  /* Warn about enum/integer type mismatches.  They are compatible types
-     (C2X 6.7.2.2/5), but may pose portability problems.  */
-  else if (enum_and_int_p && TREE_CODE (newdecl) != TYPE_DECL)
-    warned = warning_at (DECL_SOURCE_LOCATION (newdecl),
-			 OPT_Wenum_int_mismatch,
-			 "conflicting types for %q+D due to enum/integer "
-			 "mismatch; have %qT", newdecl, newtype);
+  else
+    {
+      /* Enable __memcmpeq after seeing its prototype.  */
+      if (TREE_CODE (olddecl) == FUNCTION_DECL
+	  && fndecl_built_in_p (olddecl, BUILT_IN_NORMAL)
+	  && !C_DECL_DECLARED_BUILTIN (olddecl)
+	  && DECL_FUNCTION_CODE (olddecl) == BUILT_IN___MEMCMPEQ)
+	have_memcmpeq_prototype = true;
+
+      /* Warn about enum/integer type mismatches.  They are compatible
+	 types (C2X 6.7.2.2/5), but may pose portability problems.  */
+      if (enum_and_int_p && TREE_CODE (newdecl) != TYPE_DECL)
+	warned = warning_at (DECL_SOURCE_LOCATION (newdecl),
+			     OPT_Wenum_int_mismatch,
+			     "conflicting types for %q+D due to "
+			     "enum/integer mismatch; have %qT",
+			     newdecl, newtype);
+    }
 
   /* Redeclaration of a type is a constraint violation (6.7.2.3p1),
      but silently ignore the redeclaration if either is in a system
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 29fc36534c2..051e83e3540 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -1719,6 +1719,11 @@ duplicate_decls (tree newdecl, tree olddecl, bool hiding, bool was_hidden)
 
 	  type = cp_build_type_attribute_variant (type, attribs);
 	  TREE_TYPE (newdecl) = TREE_TYPE (olddecl) = type;
+
+	  /* Enable __memcmpeq after seeing its prototype.  */
+	  if (fndecl_built_in_p (olddecl, BUILT_IN_NORMAL)
+	      && DECL_FUNCTION_CODE (olddecl) == BUILT_IN___MEMCMPEQ)
+	    have_memcmpeq_prototype = true;
 	}
 
       /* If a function is explicitly declared "throw ()", propagate that to
diff --git a/gcc/testsuite/c-c++-common/memcmpeq-1.c b/gcc/testsuite/c-c++-common/memcmpeq-1.c
new file mode 100644
index 00000000000..14622f0d765
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/memcmpeq-1.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler "__memcmpeq" } } */
+
+#include "memcmpeq.h"
+
+int
+foo (const char *s1, const char *s2, size_t len)
+{
+  return __builtin_memcmp (s1, s2, len) != 0;
+}
diff --git a/gcc/testsuite/c-c++-common/memcmpeq-2.c b/gcc/testsuite/c-c++-common/memcmpeq-2.c
new file mode 100644
index 00000000000..f57f279f173
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/memcmpeq-2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler "__memcmpeq" } } */
+
+#include "memcmpeq.h"
+
+int
+foo (const char *s1, const char *s2, size_t len)
+{
+  return memcmp (s1, s2, len) == 0;
+}
diff --git a/gcc/testsuite/c-c++-common/memcmpeq-3.c b/gcc/testsuite/c-c++-common/memcmpeq-3.c
new file mode 100644
index 00000000000..2ca2131c23a
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/memcmpeq-3.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-not "__memcmpeq" } } */
+
+#include "memcmpeq.h"
+
+int
+foo (const char *s1, const char *s2, size_t len)
+{
+  return memcmp (s1, s2, len);
+}
diff --git a/gcc/testsuite/c-c++-common/memcmpeq-4.c b/gcc/testsuite/c-c++-common/memcmpeq-4.c
new file mode 100644
index 00000000000..d59765894e7
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/memcmpeq-4.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-not "__memcmpeq" } } */
+
+#include <stddef.h>
+
+int
+foo (const char *s1, const char *s2, size_t len)
+{
+  return __builtin_memcmp_eq (s1, s2, len) != 0;
+}
diff --git a/gcc/testsuite/c-c++-common/memcmpeq-5.c b/gcc/testsuite/c-c++-common/memcmpeq-5.c
new file mode 100644
index 00000000000..cb12358cd87
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/memcmpeq-5.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler "__memcmpeq" } } */
+
+#include "memcmpeq.h"
+
+int
+foo (const char *s1, const char *s2, size_t len)
+{
+  return __builtin___memcmpeq (s1, s2, len) != 0;
+}
diff --git a/gcc/testsuite/c-c++-common/memcmpeq-6.c b/gcc/testsuite/c-c++-common/memcmpeq-6.c
new file mode 100644
index 00000000000..8f983c05a44
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/memcmpeq-6.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+#include <stddef.h>
+
+int
+foo (const char *s1, const char *s2, size_t len)
+{
+  return __builtin___memcmpeq (s1, s2, len) != 0; /* { dg-error "__builtin___memcmpeq" } */
+}
diff --git a/gcc/testsuite/c-c++-common/memcmpeq.h b/gcc/testsuite/c-c++-common/memcmpeq.h
new file mode 100644
index 00000000000..3f731a4806b
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/memcmpeq.h
@@ -0,0 +1,11 @@
+#include <string.h>
+
+#if __cplusplus
+extern "C" {
+#endif
+
+extern int __memcmpeq (const void *, const void *, size_t);
+
+#if __cplusplus
+}
+#endif
-- 
2.36.1


^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-07-05 16:28 UTC | newest]

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2022-06-20 15:44 [PATCH v2] Enable __memcmpeq after seeing __memcmpeq prototype H.J. Lu
2022-07-01  7:51 ` Richard Biener
2022-07-05 16:28   ` H.J. Lu

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