[clang] [X86] Finally handle target of __builtin_ia32_cmp[p|s][s|d] from avx into sse/sse2/avx (PR #84136)

[Paul T Robinson via cfe-commits]

================
@@ -2940,6 +2940,84 @@ _mm_movemask_ps(__m128 __a)
   return __builtin_ia32_movmskps((__v4sf)__a);
 }
 
+/* Compare */
+#define _CMP_EQ_OQ    0x00 /* Equal (ordered, non-signaling)  */
+#define _CMP_LT_OS    0x01 /* Less-than (ordered, signaling)  */
+#define _CMP_LE_OS    0x02 /* Less-than-or-equal (ordered, signaling)  */
+#define _CMP_UNORD_Q  0x03 /* Unordered (non-signaling)  */
+#define _CMP_NEQ_UQ   0x04 /* Not-equal (unordered, non-signaling)  */
+#define _CMP_NLT_US   0x05 /* Not-less-than (unordered, signaling)  */
+#define _CMP_NLE_US   0x06 /* Not-less-than-or-equal (unordered, signaling)  */
+#define _CMP_ORD_Q    0x07 /* Ordered (non-signaling)   */
+
+/// Compares each of the corresponding values of two 128-bit vectors of
+///    [4 x float], using the operation specified by the immediate integer
+///    operand.
+///
+///    Returns a [4 x float] vector consisting of four floats corresponding to
+///    the four comparison results: zero if the comparison is false, and all 1's
+///    if the comparison is true.
----------------
pogo59 wrote:

```suggestion
///    Each comparison yields 0x0 for false, 0xFFFFFFFF for true.
```

https://github.com/llvm/llvm-project/pull/84136