Add tests for C/C++ musttail attributes

Some adopted from the existing C musttail plugin tests.
Also extends the ability to query the sibcall capabilities of the
target.

gcc/testsuite/ChangeLog:

	* lib/target-supports.exp:
	(check_effective_target_struct_tail_call): New function.
	* c-c++-common/musttail1.c: New test.
	* c-c++-common/musttail12.c: New test.
	* c-c++-common/musttail13.c: New test.
	* c-c++-common/musttail2.c: New test.
	* c-c++-common/musttail3.c: New test.
	* c-c++-common/musttail4.c: New test.
	* c-c++-common/musttail5.c: New test.
	* c-c++-common/musttail7.c: New test.
	* c-c++-common/musttail8.c: New test.
	* g++.dg/musttail10.C: New test.
	* g++.dg/musttail11.C: New test.
	* g++.dg/musttail6.C: New test.
	* g++.dg/musttail9.C: New test.

gcc/testsuite/c-c++-common/musttail1.c

@@ -0,0 +1,14 @@
+/* { dg-do compile { target { tail_call && { c || c++11 } } } } */
+/* { dg-additional-options "-fdelayed-branch" { target sparc*-*-* } } */
+
+int __attribute__((noinline,noclone,noipa))
+callee (int i)
+{
+  return i * i;
+}
+
+int __attribute__((noinline,noclone,noipa))
+caller (int i)
+{
+  [[gnu::musttail]] return callee (i + 1);
+}

gcc/testsuite/c-c++-common/musttail12.c

@@ -0,0 +1,15 @@
+/* { dg-do compile { target { struct_tail_call && { c || c++11 } } } } */
+/* { dg-additional-options "-fdelayed-branch" { target sparc*-*-* } } */
+
+struct str
+{
+  int a, b;
+};
+struct str
+cstruct (int x)
+{
+  if (x < 10)
+    L:
+    [[gnu::musttail]] return cstruct (x + 1);
+  return ((struct str){ x, 0 });
+}

gcc/testsuite/c-c++-common/musttail13.c

@@ -0,0 +1,5 @@
+/* { dg-do compile { target { c || c++11 } } } */
+void f(void)
+{
+  [[gnu::musttail]] return; /* { dg-error "cannot tail-call.*return value must be a call" } */
+}

gcc/testsuite/c-c++-common/musttail2.c

@@ -0,0 +1,33 @@
+/* { dg-do compile { target { tail_call && { c || c++11 } } } } */
+
+struct box { char field[256]; int i; };
+
+int __attribute__((noinline,noclone,noipa))
+test_2_callee (int i, struct box b)
+{
+  if (b.field[0])
+    return 5;
+  return i * i;
+}
+
+int __attribute__((noinline,noclone,noipa))
+test_2_caller (int i)
+{
+  struct box b;
+  [[gnu::musttail]] return test_2_callee (i + 1, b); /* { dg-error "cannot tail-call: " } */
+}
+
+extern void setjmp (void);
+void
+test_3 (void)
+{
+  [[gnu::musttail]] return setjmp (); /* { dg-error "cannot tail-call: " } */
+}
+
+extern float f7(void);
+
+int
+test_6 (void)
+{
+  [[gnu::musttail]] return f7(); /* { dg-error "cannot tail-call: " } */
+}

gcc/testsuite/c-c++-common/musttail3.c

@@ -0,0 +1,29 @@
+/* { dg-do compile { target { tail_call && { c || c++11 } } } } */
+
+extern int foo2 (int x, ...);
+
+struct str
+{
+  int a, b;
+};
+
+struct str
+cstruct (int x)
+{
+  if (x < 10)
+    [[clang::musttail]] return cstruct (x + 1);
+  return ((struct str){ x, 0 });
+}
+
+int
+foo (int x)
+{
+  if (x < 10)
+    [[clang::musttail]] return foo2 (x, 29);
+  if (x < 100)
+    {
+      int k = foo (x + 1);
+      [[clang::musttail]] return k;	/* { dg-error "cannot tail-call: " } */
+    }
+  return x;
+}

gcc/testsuite/c-c++-common/musttail4.c

@@ -0,0 +1,17 @@
+/* { dg-do compile { target { tail_call && { c || c++11 } } } } */
+
+struct box { char field[64]; int i; };
+
+struct box __attribute__((noinline,noclone,noipa))
+returns_struct (int i)
+{
+  struct box b;
+  b.i = i * i;
+  return b;
+}
+
+int __attribute__((noinline,noclone))
+test_1 (int i)
+{
+  [[gnu::musttail]] return returns_struct (i * 5).i; /* { dg-error "cannot tail-call: " } */
+}

gcc/testsuite/c-c++-common/musttail5.c

@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c23" { target c } } */
+/* { dg-options "-std=gnu++11" { target c++ } } */
+
+[[musttail]] int j; /* { dg-warning "attribute" } */
+__attribute__((musttail)) int k; /* { dg-warning "attribute" } */
+
+void foo(void)
+{
+  [[gnu::musttail]] j++; /* { dg-warning "attribute" } */
+  [[gnu::musttail]] if (k > 0) /* { dg-warning "attribute" } */
+    [[gnu::musttail]] k++; /* { dg-warning "attribute" } */
+}
+
+int foo2(int p)
+{
+  [[gnu::musttail(1)]] return foo2(p + 1); /* { dg-error "\(before numeric constant|attribute\)" } */
+}
+
+int i;
+
+int foo3(void)
+{
+  [[musttail]] i++; /* { dg-warning "attribute" } */
+  [[musttail]] if (i > 10) /* { dg-warning "attribute" } */
+    [[musttail]] return foo2(i); /* { dg-warning "attribute" } */
+  return 0;
+}

gcc/testsuite/c-c++-common/musttail7.c

@@ -0,0 +1,14 @@
+/* { dg-do compile { target { tail_call && { c || c++11 } } } } */
+/* { dg-additional-options "-fdelayed-branch" { target sparc*-*-* } } */
+
+void __attribute__((noipa)) f() {}
+
+void f2()
+{
+  [[gnu::musttail]] return f2();
+}
+
+void f3()
+{
+  [[gnu::musttail]] return f();
+}

gcc/testsuite/c-c++-common/musttail8.c

@@ -0,0 +1,17 @@
+/* { dg-do compile { target { tail_call && { c || c++11 } } } } */
+
+float f1(void);
+
+int f2(void)
+{
+  [[gnu::musttail]] return f1 (); /* { dg-error "changed after call" } */
+}
+
+
+int f3(int *);
+
+int f4(void)
+{
+  int x;
+  [[gnu::musttail]] return f3(&x); /* { dg-error "\(refers to locals|other reasons\)" } */
+}

gcc/testsuite/g++.dg/musttail10.C

@@ -0,0 +1,40 @@
+/* { dg-do compile { target { tail_call } } } */
+/* { dg-options "-std=gnu++11" } */
+/* { dg-additional-options "-fdelayed-branch" { target sparc*-*-* } } */
+
+template <class T> T f();
+
+double g() { [[gnu::musttail]] return f<int>(); } /* { dg-error "cannot tail-call" } */
+
+template <class T>
+__attribute__((noinline, noclone, noipa))
+T g1() { [[gnu::musttail]] return f<T>(); } /* { dg-error "target is not able" "" { target powerpc*-*-* } } */
+
+template <class T>
+__attribute__((noinline, noclone, noipa))
+T g2() { [[gnu::musttail]] return f<T>(); }
+
+template <class T>
+__attribute__((noinline, noclone, noipa))
+/* Would work with -O1.  */
+T g3() { [[gnu::musttail]] return f<T>(); } /* { dg-error "cannot tail-call" } */
+
+template <class T>
+__attribute__((noinline, noclone, noipa))
+T g4() { [[gnu::musttail]] return f<double>(); } /* { dg-error "cannot tail-call" } */
+
+class C
+{
+  double x;
+public:
+  C(double x) : x(x) {}
+  ~C() { asm("":::"memory"); }
+};
+
+int main()
+{
+  g1<int>();
+  g2<double>();
+  g3<C>();
+  g4<int>();
+}

gcc/testsuite/g++.dg/musttail11.C

@@ -0,0 +1,33 @@
+/* { dg-do compile { target { tail_call } } } */
+/* { dg-options "-std=gnu++11" } */
+/* { dg-additional-options "-fdelayed-branch" { target sparc*-*-* } } */
+
+template <class T> T f();
+
+class C
+{
+  double x;
+public:
+  C(double x) : x(x) {}
+  ~C() { asm("":::"memory"); }
+  operator int() { return x; }
+};
+
+template <class T>
+__attribute__((noinline, noclone, noipa))
+T g5() { [[gnu::musttail]] return f<C> (); } /* { dg-error "cannot tail-call" } */
+
+C h();
+
+__attribute__((noinline, noclone, noipa))
+int g6() { [[gnu::musttail]] return h (); }  /* { dg-error "cannot tail-call" } */
+
+__attribute__((noinline, noclone, noipa))
+C g7() { [[gnu::musttail]] return h (); } /* { dg-error "cannot tail-call" } */
+
+int main()
+{
+  g5<int> ();
+  g6 ();
+  g7 ();
+}

gcc/testsuite/g++.dg/musttail6.C

@@ -0,0 +1,60 @@
+/* { dg-do compile { target { struct_tail_call } } } */
+/* A lot of architectures will not build this due to PR115606 and PR115607 */
+/* { dg-skip-if "powerpc does not support sibcall to templates" { powerpc*-*-* } } */
+/* { dg-options "-std=gnu++11" } */
+/* { dg-additional-options "-fdelayed-branch" { target sparc*-*-* } } */
+
+class Foo {
+public:
+  int a, b;
+  Foo(int a, int b) : a(a), b(b) {}
+};
+
+Foo __attribute__((noinline,noclone,noipa))
+callee (int i)
+{
+  return Foo(i, i+1);
+}
+
+Foo __attribute__((noinline,noclone,noipa))
+caller (int i)
+{
+  [[gnu::musttail]] return callee (i + 1);
+}
+
+template<typename T>
+T __attribute__((noinline,noclone,noipa)) foo (T i)
+{
+  return i + 1;
+}
+
+int
+caller2 (int k)
+{
+  [[gnu::musttail]] return foo<int>(1);
+}
+
+template<typename T>
+T caller3 (T v)
+{
+  [[gnu::musttail]] return foo<T>(v);
+}
+
+int call3(int i)
+{
+  [[gnu::musttail]] return caller3<int>(i + 1);
+}
+
+struct Bar {
+  int a;
+  Bar(int a) : a(a) {}
+  Bar operator+(Bar o) { return Bar(a + o.a); }
+};
+
+#if __OPTIMIZE__ >= 1
+Bar
+caller4 (Bar k)
+{
+  [[gnu::musttail]] return caller3<Bar>(Bar(99));
+}
+#endif

gcc/testsuite/g++.dg/musttail9.C

@@ -0,0 +1,10 @@
+/* { dg-do compile { target { tail_call } } } */
+/* { dg-options "-std=gnu++11" } */
+/* { dg-additional-options "-fdelayed-branch" { target sparc*-*-* } } */
+
+extern void foo();
+
+void f() noexcept
+{
+  [[gnu::musttail]] return foo(); /* { dg-error "call may throw exception that does not propagate" } */
+}

gcc/testsuite/lib/target-supports.exp

@@ -12744,6 +12744,18 @@ proc check_effective_target_tail_call { } {
     } {-O2 -fdump-rtl-expand-all}] ;# The "SIBCALL" note requires a detailed dump.
 }
 
+# Return 1 if the target can perform tail-call optimizations for structures
+# checking with C++ because the C++ compiler has less tail call ability
+# due to PR115606 on some targets
+proc check_effective_target_struct_tail_call { } {
+    return [check_no_messages_and_pattern tail_call ",SIBCALL" rtl-expand {
+	// C++
+	struct foo { int a, b; };
+	__attribute__((__noipa__)) struct foo foo (void) { return {}; }
+	__attribute__((__noipa__)) struct foo bar (void) { return foo(); }
+    } {-O2 -fdump-rtl-expand-all}] ;# The "SIBCALL" note requires a detailed dump.
+}
+
 # Return 1 if the target's calling sequence or its ABI
 # create implicit stack probes at or prior to function entry.
 proc check_effective_target_caller_implicit_probes { } {