[clang] Add test cases for multiversion function overload scenarios in C.

This change adds test cases to validate diagnostics for overloaded sets
that contain declarations of multiversion functions. Many of the added test
cases exercise declarations that are intended to be valid. Others are
intended to be valid if and when restrictions on multiversion functions
being declared with the overloadable attribute are lifted.

Several of the new test cases currently trigger the following assertion
failure in SemaDecl.cpp; the relevant test is therefore marked as an
expected failure pending a fix.
```
Assertion `(Previous.empty() || llvm::any_of(Previous, [](const NamedDecl *ND) { return ND->hasAttr(); })) && "Non-redecls shouldn't happen without overloadable present"' failed.
```

Reviewed By: erichkeane

Differential Revision: https://reviews.llvm.org/D121954

clang/test/Sema/attr-cpuspecific.c

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -Wno-strict-prototypes -fsyntax-only -verify %s -Wnonnull
+// XFAIL: asserts
 
 void __attribute__((cpu_specific(ivybridge))) no_default(void);
 void __attribute__((cpu_specific(sandybridge)))  no_default(void);
@@ -118,3 +119,74 @@ int use3(void) {
 int __attribute__((cpu_dispatch(pentium_iii, pentium_iii_no_xmm_regs))) dupe_p3(void);
 
 void __attribute__((cpu_specific(atom), nothrow, nonnull(1))) addtl_attrs(int*);
+
+// FIXME: Declaration of a non-overloadable function when more than one
+// FIXME: multiversion function declarations are present results in an
+// FIXME: assertion failure.
+int __attribute__((cpu_specific(atom))) bad_overload1(void);
+int __attribute__((cpu_specific(ivybridge))) bad_overload1(void);
+// expected-error@+2 {{at most one overload for a given name may lack the 'overloadable' attribute}}
+// expected-note@-2 {{previous unmarked overload of function is here}}
+int bad_overload1(int);
+
+int bad_overload2(int);
+// expected-error@+2 {{conflicting types for 'bad_overload2'}}
+// expected-note@-2 {{previous declaration is here}}
+int __attribute__((cpu_specific(atom))) bad_overload2(void);
+int __attribute__((cpu_specific(ivybridge))) bad_overload2(void);
+
+// FIXME: Declaration of a non-overloadable function when more than one
+// FIXME: multiversion function declarations are present results in an
+// FIXME: assertion failure.
+int __attribute__((cpu_dispatch(generic))) bad_overload3(void);
+int __attribute__((cpu_specific(ivybridge))) bad_overload3(void);
+// expected-error@+2 {{at most one overload for a given name may lack the 'overloadable' attribute}}
+// expected-note@-2 {{previous unmarked overload of function is here}}
+int bad_overload3(int);
+
+int bad_overload4(int);
+// expected-error@+2 {{conflicting types for 'bad_overload4'}}
+// expected-note@-2 {{previous declaration is here}}
+int __attribute__((cpu_dispatch(generic))) bad_overload4(void);
+int __attribute__((cpu_specific(ivybridge))) bad_overload4(void);
+
+// expected-error@+1 {{attribute 'cpu_specific' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((cpu_specific(generic))) bad_overload5(void);
+int __attribute__((cpu_specific(ivybridge))) bad_overload5(void);
+
+int __attribute__((cpu_specific(generic))) bad_overload6(void);
+// expected-error@+1 {{attribute 'cpu_specific' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((cpu_specific(ivybridge))) bad_overload6(void);
+
+int __attribute__((cpu_specific(atom))) good_overload1(void);
+int __attribute__((cpu_specific(ivybridge))) good_overload1(void);
+int __attribute__((__overloadable__)) good_overload1(int);
+
+int __attribute__((__overloadable__)) good_overload2(int);
+int __attribute__((cpu_specific(atom))) good_overload2(void);
+int __attribute__((cpu_specific(ivybridge))) good_overload2(void);
+
+// expected-error@+1 {{attribute 'cpu_specific' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((cpu_specific(atom))) good_overload3(void);
+// expected-error@+1 {{attribute 'cpu_specific' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((cpu_specific(ivybridge))) good_overload3(void);
+int good_overload3(int);
+
+int good_overload4(int);
+// expected-error@+1 {{attribute 'cpu_specific' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((cpu_specific(atom))) good_overload4(void);
+// expected-error@+1 {{attribute 'cpu_specific' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((cpu_specific(ivybridge))) good_overload4(void);
+
+// expected-error@+1 {{attribute 'cpu_specific' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((cpu_specific(atom))) good_overload5(void);
+// expected-error@+1 {{attribute 'cpu_specific' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((cpu_specific(ivybridge))) good_overload5(int);
+
+int __attribute__((cpu_specific(atom))) good_overload6(void);
+// expected-error@+1 {{attribute 'cpu_specific' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((cpu_specific(ivybridge))) good_overload6(int);
+
+// expected-error@+1 {{attribute 'cpu_specific' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((cpu_specific(atom))) good_overload7(void);
+int __attribute__((cpu_specific(ivybridge))) good_overload7(int);

clang/test/Sema/attr-target-clones.c

@@ -86,3 +86,31 @@ int useage(void) {
 // expected-error@+1 {{function declaration cannot become a multiversioned function after first usage}}
 int __attribute__((target_clones("sse4.2", "default"))) mv_after_use(void) { return 1; }
 
+void bad_overload1(void) __attribute__((target_clones("mmx", "sse4.2", "default")));
+void bad_overload1(int p) {}
+
+void bad_overload2(int p) {}
+void bad_overload2(void) __attribute__((target_clones("mmx", "sse4.2", "default")));
+
+void bad_overload3(void) __attribute__((target_clones("mmx", "sse4.2", "default")));
+void bad_overload3(int) __attribute__((target_clones("mmx", "sse4.2", "default")));
+
+void good_overload1(void) __attribute__((target_clones("mmx", "sse4.2", "default")));
+void __attribute__((__overloadable__)) good_overload1(int p) {}
+
+// expected-error@+1 {{attribute 'target_clones' multiversioning cannot be combined with attribute 'overloadable'}}
+void __attribute__((__overloadable__)) good_overload2(void) __attribute__((target_clones("mmx", "sse4.2", "default")));
+void good_overload2(int p) {}
+
+// expected-error@+1 {{attribute 'target_clones' multiversioning cannot be combined with attribute 'overloadable'}}
+void __attribute__((__overloadable__)) good_overload3(void) __attribute__((target_clones("mmx", "sse4.2", "default")));
+// expected-error@+1 {{attribute 'target_clones' multiversioning cannot be combined with attribute 'overloadable'}}
+void __attribute__((__overloadable__)) good_overload3(int) __attribute__((target_clones("mmx", "sse4.2", "default")));
+
+void good_overload4(void) __attribute__((target_clones("mmx", "sse4.2", "default")));
+// expected-error@+1 {{attribute 'target_clones' multiversioning cannot be combined with attribute 'overloadable'}}
+void __attribute__((__overloadable__)) good_overload4(int) __attribute__((target_clones("mmx", "sse4.2", "default")));
+
+// expected-error@+1 {{attribute 'target_clones' multiversioning cannot be combined with attribute 'overloadable'}}
+void __attribute__((__overloadable__)) good_overload5(void) __attribute__((target_clones("mmx", "sse4.2", "default")));
+void good_overload5(int) __attribute__((target_clones("mmx", "sse4.2", "default")));

clang/test/Sema/attr-target-mv.c

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -Wno-strict-prototypes -fsyntax-only -verify %s
+// XFAIL: asserts
 
 void __attribute__((target("sse4.2"))) no_default(void);
 void __attribute__((target("arch=sandybridge")))  no_default(void);
@@ -108,3 +109,60 @@ void __attribute__((target("arch=sandybridge"))) addtl_attrs5(int*);
 void __attribute__((target("sse4.2"))) addtl_attrs6(int*);
 void __attribute__((target("arch=sandybridge"), nothrow, used, nonnull)) addtl_attrs6(int*);
 
+// FIXME: Declaration of a non-overloadable function when more than one
+// FIXME: multiversion function declarations are present results in an
+// FIXME: assertion failure.
+int __attribute__((target("sse4.2"))) bad_overload1(void);
+int __attribute__((target("arch=sandybridge"))) bad_overload1(void);
+// expected-error@+2 {{at most one overload for a given name may lack the 'overloadable' attribute}}
+// expected-note@-2 {{previous unmarked overload of function is here}}
+int bad_overload1(int);
+
+int bad_overload2(int);
+// expected-error@+2 {{conflicting types for 'bad_overload2'}}
+// expected-note@-2 {{previous declaration is here}}
+int __attribute__((target("sse4.2"))) bad_overload2(void);
+// expected-error@+2 {{conflicting types for 'bad_overload2'}}
+// expected-note@-5 {{previous declaration is here}}
+int __attribute__((target("arch=sandybridge"))) bad_overload2(void);
+
+// expected-error@+2 {{attribute 'target' multiversioning cannot be combined with attribute 'overloadable'}}
+// expected-note@+2 {{function multiversioning caused by this declaration}}
+int __attribute__((__overloadable__)) __attribute__((target("sse4.2"))) bad_overload3(void);
+int __attribute__((target("arch=sandybridge"))) bad_overload3(void);
+
+int __attribute__((target("sse4.2"))) bad_overload4(void);
+// expected-error@+1 {{attribute 'target' multiversioning cannot be combined with attribute 'overloadable'}}
+int __attribute__((__overloadable__)) __attribute__((target("arch=sandybridge"))) bad_overload4(void);
+
+int __attribute__((target("sse4.2"))) bad_overload5(void);
+int __attribute__((target("arch=sandybridge"))) bad_overload5(int);
+
+int __attribute__((target("sse4.2"))) good_overload1(void);
+int __attribute__((target("arch=sandybridge"))) good_overload1(void);
+int __attribute__((__overloadable__)) good_overload1(int);
+
+int __attribute__((__overloadable__)) good_overload2(int);
+int __attribute__((target("sse4.2"))) good_overload2(void);
+int __attribute__((target("arch=sandybridge"))) good_overload2(void);
+
+// expected-error@+2 {{attribute 'target' multiversioning cannot be combined with attribute 'overloadable'}}
+// expected-note@+2 {{function multiversioning caused by this declaration}}
+int __attribute__((__overloadable__)) __attribute__((target("sse4.2"))) good_overload3(void);
+int __attribute__((__overloadable__)) __attribute__((target("arch=sandybridge"))) good_overload3(void);
+int good_overload3(int);
+
+int good_overload4(int);
+// expected-error@+2 {{attribute 'target' multiversioning cannot be combined with attribute 'overloadable'}}
+// expected-note@+2 {{function multiversioning caused by this declaration}}
+int __attribute__((__overloadable__)) __attribute__((target("sse4.2"))) good_overload4(void);
+int __attribute__((__overloadable__)) __attribute__((target("arch=sandybridge"))) good_overload4(void);
+
+int __attribute__((__overloadable__)) __attribute__((target("sse4.2"))) good_overload5(void);
+int __attribute__((__overloadable__)) __attribute__((target("arch=sandybridge"))) good_overload5(int);
+
+int __attribute__((target("sse4.2"))) good_overload6(void);
+int __attribute__((__overloadable__)) __attribute__((target("arch=sandybridge"))) good_overload6(int);
+
+int __attribute__((__overloadable__)) __attribute__((target("sse4.2"))) good_overload7(void);
+int __attribute__((target("arch=sandybridge"))) good_overload7(int);