[clang] [CIR] Implement cir.cmp3way Operation (PR #186294)

[Erich Keane via cfe-commits]

================
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s
+
+#include "Inputs/std-compare.h"
+
+int test_int_spaceship(int a, int b) {
+  auto result = a <=> b;
+  // CHECK: cir.cmp3way(%{{.*}} : !s32i, %{{.*}}, #cir.cmp3way_strong_info<strong, lt = -1, eq = 0, gt = 1>) : !s32i
+  return (result < 0) ? -1 : (result > 0) ? 1 : 0;
+}
+
+unsigned int test_uint_spaceship(unsigned int a, unsigned int b) {
+  auto result = a <=> b;
+  // CHECK: cir.cmp3way(%{{.*}} : !u32i, %{{.*}}, #cir.cmp3way_strong_info<strong, lt = -1, eq = 0, gt = 1>) : !s32i
+  return (result < 0) ? 0 : (result > 0) ? 2 : 1;
+}
+
+float test_float_spaceship(float a, float b) {
+  auto result = a <=> b;
+  // CHECK: cir.cmp3way(%{{.*}} : !cir.float, %{{.*}}, #cir.cmp3way_partial_info<partial, lt = -1, eq = 0, gt = 1, unordered = -127>)
+  return (result < 0) ? -1.0f : (result > 0) ? 1.0f : 0.0f;
+}
----------------
erichkeane wrote:

We need newlines at the bottom of each test.

https://github.com/llvm/llvm-project/pull/186294