Patchwork For asm "n" and similar constraints use maybe_const_value (PR c++/56302)

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Submitter Jakub Jelinek
Date Feb. 13, 2013, 3:50 p.m.
Message ID <20130213155055.GV4385@tucnak.redhat.com>
Download mbox | patch
Permalink /patch/220177/
State New
Headers show

Comments

Jakub Jelinek - Feb. 13, 2013, 3:50 p.m.
Hi!

My SIZEOF_EXPR deferred folding changes regressed some sys/sdt.h macros
at -O0, the sizeof in there is no longer folded, so instead of
say "n" (-8) we ended up with "n" (-1 * (int) sizeof (void *)) and similar,
and as at -O0 we don't really optimize, the asm got rejected.

Fixed thusly, constexpr-56302.C is a bonus, something that didn't work
before but now works.  Bootstrapped/regtested on x86_64-linux and
i686-linux, ok for trunk?

2013-02-13  Jakub Jelinek  <jakub@redhat.com>

	PR c++/56302
	* semantics.c (finish_asm_stmt): If input constraints allow
	neither register nor memory, try maybe_constant_value to get
	a constant if possible.

	* g++.dg/torture/pr56302.C: New test.
	* g++.dg/cpp0x/constexpr-56302.C: New test.
	* c-c++-common/pr56302.c: New test.


	Jakub
Jason Merrill - Feb. 13, 2013, 3:55 p.m.
OK.

Patch

--- gcc/cp/semantics.c.jj	2013-02-12 19:02:48.000000000 +0100
+++ gcc/cp/semantics.c	2013-02-13 10:04:14.615998647 +0100
@@ -1402,6 +1402,14 @@  finish_asm_stmt (int volatile_p, tree st
 		  if (!cxx_mark_addressable (operand))
 		    operand = error_mark_node;
 		}
+	      else if (!allows_reg && !allows_mem)
+		{
+		  /* If constraint allows neither register nor memory,
+		     try harder to get a constant.  */
+		  tree constop = maybe_constant_value (operand);
+		  if (TREE_CONSTANT (constop))
+		    operand = constop;
+		}
 	    }
 	  else
 	    operand = error_mark_node;
--- gcc/testsuite/g++.dg/torture/pr56302.C.jj	2013-02-13 10:18:58.785974294 +0100
+++ gcc/testsuite/g++.dg/torture/pr56302.C	2013-02-13 10:22:19.901837358 +0100
@@ -0,0 +1,41 @@ 
+// PR c++/56302
+// { dg-do compile }
+
+typedef __SIZE_TYPE__ size_t;
+# define STAP_SDT_ARG_CONSTRAINT        nor
+# define _SDT_STRINGIFY(x)              #x
+# define _SDT_ARG_CONSTRAINT_STRING(x)  _SDT_STRINGIFY(x)
+# define _SDT_ARG(n, x)			\
+  [_SDT_S##n] "n" ((_SDT_ARGSIGNED (x) ? 1 : -1) * (int) _SDT_ARGSIZE (x)), \
+  [_SDT_A##n] _SDT_ARG_CONSTRAINT_STRING (STAP_SDT_ARG_CONSTRAINT) (_SDT_ARGVAL (x))
+#define _SDT_ARGARRAY(x)	(__builtin_classify_type (x) == 14	\
+				 || __builtin_classify_type (x) == 5)
+# define _SDT_ARGSIGNED(x)	(!_SDT_ARGARRAY (x) \
+				 && __sdt_type<__typeof (x)>::__sdt_signed)
+# define _SDT_ARGSIZE(x)	(_SDT_ARGARRAY (x) \
+				 ? sizeof (void *) : sizeof (x))
+# define _SDT_ARGVAL(x)		(x)
+template<typename __sdt_T>
+struct __sdt_type
+{
+  static const bool __sdt_signed = false;
+};
+#define __SDT_ALWAYS_SIGNED(T) \
+template<> struct __sdt_type<T> { static const bool __sdt_signed = true; };
+__SDT_ALWAYS_SIGNED(signed char)
+__SDT_ALWAYS_SIGNED(short)
+__SDT_ALWAYS_SIGNED(int)
+__SDT_ALWAYS_SIGNED(long)
+__SDT_ALWAYS_SIGNED(long long)
+template<typename __sdt_E>
+struct __sdt_type<__sdt_E[]> : public __sdt_type<__sdt_E *> {};
+template<typename __sdt_E, size_t __sdt_N>
+struct __sdt_type<__sdt_E[__sdt_N]> : public __sdt_type<__sdt_E *> {};
+
+struct S { char p[8]; };
+
+void
+foo (const S &str)
+{
+  __asm__ __volatile__ ("" : : _SDT_ARG (0, &str));
+}
--- gcc/testsuite/g++.dg/cpp0x/constexpr-56302.C	2012-11-17 15:43:17.572007394 +0100
+++ gcc/testsuite/g++.dg/cpp0x/constexpr-56302.C	2013-02-13 10:28:41.462666774 +0100
@@ -0,0 +1,12 @@ 
+// PR c++/56302
+// { dg-do compile }
+// { dg-options "-std=c++11 -O0" }
+
+constexpr int foo () { return 42; }
+constexpr int x = foo () + 2;
+
+void
+bar ()
+{
+  __asm ("" : : "n" (x), "n" (foo () * 7 + x));
+}
--- gcc/testsuite/c-c++-common/pr56302.c.jj	2013-02-13 10:10:42.980799956 +0100
+++ gcc/testsuite/c-c++-common/pr56302.c	2013-02-13 10:11:17.906598785 +0100
@@ -0,0 +1,9 @@ 
+/* PR c++/56302 */
+/* { dg-do compile } */
+/* { dg-options "-O0" } */
+
+void
+foo (int x)
+{
+  __asm__ __volatile__ ("" : : "n" (-1 * (int) sizeof (&x)));
+}