[Clang] Add elementwise abs builtin.

This patch implements __builtin_elementwise_abs as specified in
D111529.

Reviewed By: aaron.ballman, scanon

Differential Revision: https://reviews.llvm.org/D111986
diff --git a/clang/test/Sema/builtins-elementwise-math.c b/clang/test/Sema/builtins-elementwise-math.c
index 7c3c1aa..1825d0c 100644
--- a/clang/test/Sema/builtins-elementwise-math.c
+++ b/clang/test/Sema/builtins-elementwise-math.c
@@ -2,6 +2,7 @@
 
 typedef float float4 __attribute__((ext_vector_type(4)));
 typedef int int3 __attribute__((ext_vector_type(3)));
+typedef unsigned unsigned4 __attribute__((ext_vector_type(4)));
 
 struct Foo {
   char *p;
@@ -11,6 +12,26 @@
 typedef int bar;
 bar b;
 
+void test_builtin_elementwise_abs(int i, double d, float4 v, int3 iv, unsigned u, unsigned4 uv) {
+  struct Foo s = __builtin_elementwise_abs(i);
+  // expected-error@-1 {{initializing 'struct Foo' with an expression of incompatible type 'int'}}
+
+  i = __builtin_elementwise_abs();
+  // expected-error@-1 {{too few arguments to function call, expected 1, have 0}}
+
+  i = __builtin_elementwise_abs(i, i);
+  // expected-error@-1 {{too many arguments to function call, expected 1, have 2}}
+
+  i = __builtin_elementwise_abs(v);
+  // expected-error@-1 {{assigning to 'int' from incompatible type 'float4' (vector of 4 'float' values)}}
+
+  u = __builtin_elementwise_abs(u);
+  // expected-error@-1 {{1st argument must be a signed integer or floating point type (was 'unsigned int')}}
+
+  uv = __builtin_elementwise_abs(uv);
+  // expected-error@-1 {{1st argument must be a signed integer or floating point type (was 'unsigned4' (vector of 4 'unsigned int' values))}}
+}
+
 void test_builtin_elementwise_max(int i, short s, double d, float4 v, int3 iv, int *p) {
   i = __builtin_elementwise_max(p, d);
   // expected-error@-1 {{arguments are of different types ('int *' vs 'double')}}