[clang] [clang] Add support for new loop attribute [[clang::code_align()]] (PR #70762)

[Erich Keane via cfe-commits]

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@@ -0,0 +1,124 @@
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,c-local %s
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cpp-local -pedantic -x c++ -std=c++11 %s 
+
+// Add diagnostics tests for Loop attribute: [[clang::code_align()]].
+
+void foo() {
+  int i;
+  int a[10], b[10];
+
+  [[clang::code_align(8)]]
+  for (i = 0; i < 10; ++i) {  // this is OK
+    a[i] = b[i] = 0;
+  }
+  // expected-error at +1 {{'code_align' attribute only applies to 'for', 'while', and 'do' statements}}
+  [[clang::code_align(4)]]
+  i = 7;
+  for (i = 0; i < 10; ++i) {
+    a[i] = b[i] = 0;
+  }
+
+  // expected-error at +1{{'code_align' attribute cannot be applied to a declaration}}
+  [[clang::code_align(12)]] int n[10];
+}
+
+void bar(int);
+#if __cplusplus >= 201103L
+// cpp-local-note at +2 {{declared here}}
+#endif
+void foo1(int A)
+{
+  // expected-error at +1 {{'code_align' attribute requires a positive integral compile time constant expression}}
+  [[clang::code_align(0)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+  // expected-error at +1{{'code_align' attribute requires a positive integral compile time constant expression}}
+  [[clang::code_align(-4)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+#if __cplusplus >= 201103L
+    // cpp-local-error at +4 {{integral constant expression must have integral or unscoped enumeration type, not 'double'}}
+#else
+    // c-local-error at +2 {{integer constant expression must have integer type, not 'double'}}
+#endif
+  [[clang::code_align(64.0)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+  // expected-error at +1 {{'code_align' attribute takes one argument}}
+  [[clang::code_align()]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+  // expected-error at +1 {{'code_align' attribute takes one argument}}
+  [[clang::code_align(4,8)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+  // no diagnostic is expected
+  [[clang::code_align(32)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+#if __cplusplus >= 201103L
+  // cpp-local-error at +4 {{integral constant expression must have integral or unscoped enumeration type, not 'const char[4]'}}
+#else  
+  // c-local-error at +2 {{integer constant expression must have integer type, not 'char[4]'}}
+#endif
+  [[clang::code_align("abc")]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+  [[clang::code_align(64)]]
+  // expected-error at +1 {{duplicate loop attribute 'code_align'}}
+  [[clang::code_align(64)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+  // expected-error at +1 {{'code_align' attribute argument must be a constant power of two greater than zero}}
+  [[clang::code_align(7)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+#if __cplusplus >= 201103L
+  // cpp-local-error at +5 {{expression is not an integral constant expression}}
+  // cpp-local-note at +4 {{function parameter 'A' with unknown value cannot be used in a constant expression}}
+#else
+  // c-local-error at +2 {{expression is not an integer constant expression}}
+#endif  
+  [[clang::code_align(A)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+}
+
+#if __cplusplus >= 201103L
+void check_code_align_expression() {
+  int a[10];
+
+  // Test that checks expression is not a constant expression.
+  int foo2; // cpp-local-note {{declared here}}
+  // cpp-local-error at +2{{expression is not an integral constant expression}}
+  // cpp-local-note at +1{{read of non-const variable 'foo2' is not allowed in a constant expression}}
+  [[clang::code_align(foo2 + 1)]]
+  for (int i = 0; i != 10; ++i)
+    a[i] = 0;
+
+  // Test that checks expression is a constant expression.
+  constexpr int bars = 0;
+  [[clang::code_align(bars + 1)]]
+  for (int i = 0; i != 10; ++i)
+    a[i] = 0;
+}
+
+template <int A, int B, int C, int D>
+void code_align_dependent() {
+  [[clang::code_align(C)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+  [[clang::code_align(A)]]
+  // cpp-local-error at +1 {{duplicate loop attribute 'code_align'}}
+  [[clang::code_align(B)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+
+  // cpp-local-error at +1{{'code_align' attribute requires a positive integral compile time constant expression}}
+  [[clang::code_align(D)]]
+  for(int I=0; I<128; ++I) { bar(I); }
+}
+
+int main() {
+  code_align_dependent<8, 16, 32, -10>(); // cpp-local-note{{in instantiation of function template specialization 'code_align_dependent<8, 16, 32, -10>' requested here}}
----------------
erichkeane wrote:

Please use bookmarks to put the notes on instantiations next to the error, that way they are possible to read.

https://github.com/llvm/llvm-project/pull/70762