Constant Fold Logf128 calls (#84501)

This patch enables constant folding for 128 bit floating-point logf
calls. This is achieved by querying if the host system has the logf128()
symbol available with a CMake test. If so, replace the runtime call with
the compile time value returned from logf128.

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index 749374a..e292ff3 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -2089,6 +2089,17 @@ static Constant *ConstantFoldScalarCall1(StringRef Name,
     if (IntrinsicID == Intrinsic::canonicalize)
       return constantFoldCanonicalize(Ty, Call, U);
 
+#if defined(__FLOAT128__) && defined(HAS_LOGF128)
+    if (Ty->isFP128Ty()) {
+      switch (IntrinsicID) {
+      default:
+        return nullptr;
+      case Intrinsic::log:
+        return ConstantFP::get(Ty, logf128(Op->getValueAPF().convertToQuad()));
+      }
+    }
+#endif
+
     if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
       return nullptr;