[llvm-branch-commits] [clang] [ConstantTime][Clang] Add __builtin_ct_select for constant-time selection (PR #166703)

[Matt Arsenault via llvm-branch-commits]

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+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// Diagnostic coverage for the __builtin_ct_select Sema checks. Codegen
+// behavior is tested separately in clang/test/CodeGen/builtin-ct-select.c.
+
+struct S {
+  int x;
+};
+
+// A well-formed call must not diagnose.
+int test_valid(int c, int a, int b) {
+  return __builtin_ct_select(c, a, b);
+}
+
+// The builtin requires exactly three arguments.
+void test_too_few(int c, int a) {
+  __builtin_ct_select(c, a); // expected-error {{too few arguments to function call, expected at least 3, have 2}}
+}
+
+void test_too_many(int c, int a, int b, int d) {
+  __builtin_ct_select(c, a, b, d); // expected-error {{too many arguments to function call, expected 3, have 4}}
+}
+
+// The condition must be an integer type.
+void test_noninteger_cond(struct S s, int a, int b) {
+  __builtin_ct_select(s, a, b); // expected-error {{used type 'struct S' where arithmetic or pointer type is required}}
+}
+
+// The value operands must be scalar or vector types.
+void test_nonscalar_operands(int c, struct S s) {
+  __builtin_ct_select(c, s, s); // expected-error {{incompatible operand types ('struct S' and 'struct S')}}
+}
+
+// The two value operands must have the same type.
+void test_mismatched_operands(int c, int a, int *p) {
+  __builtin_ct_select(c, a, p); // expected-error {{incompatible operand types ('int' and 'int *')}}
+}
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arsenm wrote:

Test vector cases 

https://github.com/llvm/llvm-project/pull/166703