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

[Simon Pilgrim via cfe-commits]

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@@ -2940,6 +2940,134 @@ _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.
+///
+/// \headerfile <x86intrin.h>
+///
+/// \code
+/// __m128 _mm_cmp_ps(__m128 a, __m128 b, const int c);
+/// \endcode
+///
+/// This intrinsic corresponds to the <c> (V)CMPPS </c> instruction.
+///
+/// \param a
+///    A 128-bit vector of [4 x float].
+/// \param b
+///    A 128-bit vector of [4 x float].
+/// \param c
+///    An immediate integer operand, with bits [4:0] specifying which comparison
+///    operation to use: \n
+///    (Note that without avx enabled, only bits [2:0] are supported) \n
+///    0x00: Equal (ordered, non-signaling) \n
+///    0x01: Less-than (ordered, signaling) \n
+///    0x02: Less-than-or-equal (ordered, signaling) \n
+///    0x03: Unordered (non-signaling) \n
+///    0x04: Not-equal (unordered, non-signaling) \n
+///    0x05: Not-less-than (unordered, signaling) \n
+///    0x06: Not-less-than-or-equal (unordered, signaling) \n
+///    0x07: Ordered (non-signaling) \n
+///    0x08: Equal (unordered, non-signaling) \n
+///    0x09: Not-greater-than-or-equal (unordered, signaling) \n
+///    0x0A: Not-greater-than (unordered, signaling) \n
+///    0x0B: False (ordered, non-signaling) \n
+///    0x0C: Not-equal (ordered, non-signaling) \n
+///    0x0D: Greater-than-or-equal (ordered, signaling) \n
+///    0x0E: Greater-than (ordered, signaling) \n
+///    0x0F: True (unordered, non-signaling) \n
+///    0x10: Equal (ordered, signaling) \n
+///    0x11: Less-than (ordered, non-signaling) \n
+///    0x12: Less-than-or-equal (ordered, non-signaling) \n
+///    0x13: Unordered (signaling) \n
+///    0x14: Not-equal (unordered, signaling) \n
+///    0x15: Not-less-than (unordered, non-signaling) \n
+///    0x16: Not-less-than-or-equal (unordered, non-signaling) \n
+///    0x17: Ordered (signaling) \n
+///    0x18: Equal (unordered, signaling) \n
+///    0x19: Not-greater-than-or-equal (unordered, non-signaling) \n
+///    0x1A: Not-greater-than (unordered, non-signaling) \n
+///    0x1B: False (ordered, signaling) \n
+///    0x1C: Not-equal (ordered, signaling) \n
+///    0x1D: Greater-than-or-equal (ordered, non-signaling) \n
+///    0x1E: Greater-than (ordered, non-signaling) \n
+///    0x1F: True (unordered, signaling)
----------------
RKSimon wrote:

No objections, but I'd prefer to see the new macros (and tests) and comment removal to be done as a followup patch

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