[clang][x86] Add constexpr support for _mm_cvtsi32_ss/_mm_cvt_si2ss/_mm_cvtsi64_ss SSE1 intrinsics

Followup to llvm#111001

Author: RKSimon

clang/lib/Headers/xmmintrin.h

@@ -1618,9 +1618,8 @@ _mm_cvtt_ps2pi(__m128 __a)
 /// \returns A 128-bit vector of [4 x float] whose lower 32 bits contain the
 ///    converted value of the second operand. The upper 96 bits are copied from
 ///    the upper 96 bits of the first operand.
-static __inline__ __m128 __DEFAULT_FN_ATTRS
-_mm_cvtsi32_ss(__m128 __a, int __b)
-{
+static __inline__ __m128 __DEFAULT_FN_ATTRS_CONSTEXPR _mm_cvtsi32_ss(__m128 __a,
+                                                                     int __b) {
   __a[0] = __b;
   return __a;
 }
@@ -1641,9 +1640,8 @@ _mm_cvtsi32_ss(__m128 __a, int __b)
 /// \returns A 128-bit vector of [4 x float] whose lower 32 bits contain the
 ///    converted value of the second operand. The upper 96 bits are copied from
 ///    the upper 96 bits of the first operand.
-static __inline__ __m128 __DEFAULT_FN_ATTRS
-_mm_cvt_si2ss(__m128 __a, int __b)
-{
+static __inline__ __m128 __DEFAULT_FN_ATTRS_CONSTEXPR _mm_cvt_si2ss(__m128 __a,
+                                                                    int __b) {
   return _mm_cvtsi32_ss(__a, __b);
 }
 
@@ -1665,9 +1663,8 @@ _mm_cvt_si2ss(__m128 __a, int __b)
 /// \returns A 128-bit vector of [4 x float] whose lower 32 bits contain the
 ///    converted value of the second operand. The upper 96 bits are copied from
 ///    the upper 96 bits of the first operand.
-static __inline__ __m128 __DEFAULT_FN_ATTRS
-_mm_cvtsi64_ss(__m128 __a, long long __b)
-{
+static __inline__ __m128 __DEFAULT_FN_ATTRS_CONSTEXPR
+_mm_cvtsi64_ss(__m128 __a, long long __b) {
   __a[0] = __b;
   return __a;
 }

clang/test/CodeGen/X86/sse-builtins.c

@@ -948,6 +948,15 @@ void test_constexpr() {
   constexpr __m128 v_mm_movelh_ps = _mm_movelh_ps(k1, k2);
   static_assert(v_mm_movelh_ps[0] == +1.0f && v_mm_movelh_ps[1] == +0.0f && v_mm_movelh_ps[2] == +8.0f && v_mm_movelh_ps[3] == +4.0f);
 
+  constexpr __m128 v_mm_cvtsi32_ss = _mm_cvtsi32_ss(k1, 42);
+  static_assert(v_mm_cvtsi32_ss[0] == 42.0f && v_mm_cvtsi32_ss[1] == +0.0f && v_mm_cvtsi32_ss[2] == +2.0f && v_mm_cvtsi32_ss[3] == +4.0f);
+
+  constexpr __m128 v_mm_cvt_si2ss = _mm_cvt_si2ss(k2, -99);
+  static_assert(v_mm_cvt_si2ss[0] == -99.0f && v_mm_cvt_si2ss[1] == +4.0f && v_mm_cvt_si2ss[2] == +2.0f && v_mm_cvt_si2ss[3] == +1.0f);
+
+  constexpr __m128 v_mm_cvtsi64_ss = _mm_cvtsi64_ss(k3, 555);
+  static_assert(v_mm_cvtsi64_ss[0] == 555.0f && v_mm_cvtsi64_ss[1] == -5.0f && v_mm_cvtsi64_ss[2] == +6.0f && v_mm_cvtsi64_ss[3] == +7.0f);
+
   static_assert(_mm_cvtss_f32(k2) == +8.0f);
 }