[Clang][X86] Add avx512 __builtin_ia32_select* constexpr handling (#152705)

This should allow us to constexpr many avx512 predicated intrinsics where they wrap basic intrinsics that are already constexpr

Fixes #152321

1 files changed, 45 insertions, 0 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index cc631d73e8bd..e933918c182c 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -11783,6 +11783,51 @@ bool VectorExprEvaluator::VisitCallExpr(const CallExpr *E) {
 
     return Success(APValue(ResultElements.data(), ResultElements.size()), E);
   }
+  case X86::BI__builtin_ia32_selectb_128:
+  case X86::BI__builtin_ia32_selectb_256:
+  case X86::BI__builtin_ia32_selectb_512:
+  case X86::BI__builtin_ia32_selectw_128:
+  case X86::BI__builtin_ia32_selectw_256:
+  case X86::BI__builtin_ia32_selectw_512:
+  case X86::BI__builtin_ia32_selectd_128:
+  case X86::BI__builtin_ia32_selectd_256:
+  case X86::BI__builtin_ia32_selectd_512:
+  case X86::BI__builtin_ia32_selectq_128:
+  case X86::BI__builtin_ia32_selectq_256:
+  case X86::BI__builtin_ia32_selectq_512:
+  case X86::BI__builtin_ia32_selectph_128:
+  case X86::BI__builtin_ia32_selectph_256:
+  case X86::BI__builtin_ia32_selectph_512:
+  case X86::BI__builtin_ia32_selectpbf_128:
+  case X86::BI__builtin_ia32_selectpbf_256:
+  case X86::BI__builtin_ia32_selectpbf_512:
+  case X86::BI__builtin_ia32_selectps_128:
+  case X86::BI__builtin_ia32_selectps_256:
+  case X86::BI__builtin_ia32_selectps_512:
+  case X86::BI__builtin_ia32_selectpd_128:
+  case X86::BI__builtin_ia32_selectpd_256:
+  case X86::BI__builtin_ia32_selectpd_512: {
+    // AVX512 predicated move: "Result = Mask[] ? LHS[] : RHS[]".
+    APValue SourceMask, SourceLHS, SourceRHS;
+    if (!EvaluateAsRValue(Info, E->getArg(0), SourceMask) ||
+        !EvaluateAsRValue(Info, E->getArg(1), SourceLHS) ||
+        !EvaluateAsRValue(Info, E->getArg(2), SourceRHS))
+      return false;
+
+    APSInt Mask = SourceMask.getInt();
+    QualType DestEltTy = E->getType()->castAs<VectorType>()->getElementType();
+    unsigned SourceLen = SourceLHS.getVectorLength();
+    SmallVector<APValue, 4> ResultElements;
+    ResultElements.reserve(SourceLen);
+
+    for (unsigned EltNum = 0; EltNum < SourceLen; ++EltNum) {
+      const APValue &LHS = SourceLHS.getVectorElt(EltNum);
+      const APValue &RHS = SourceRHS.getVectorElt(EltNum);
+      ResultElements.push_back(Mask[EltNum] ? LHS : RHS);
+    }
+
+    return Success(APValue(ResultElements.data(), ResultElements.size()), E);
+  }
   }
 }