[Fixed Point Arithmetic] Add APFixedPoint to APValue

This adds APFixedPoint to the union of values that can be represented with an APValue.

Differential Revision: https://reviews.llvm.org/D56746

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@351368 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 27 insertions, 0 deletions

diff --git a/lib/Basic/FixedPoint.cpp b/lib/Basic/FixedPoint.cpp
index 0aaa9af191..e3cffe628f 100644
--- a/lib/Basic/FixedPoint.cpp
+++ b/lib/Basic/FixedPoint.cpp
@@ -137,4 +137,31 @@ FixedPointSemantics FixedPointSemantics::getCommonSemantics(
                              ResultIsSaturated, ResultHasUnsignedPadding);
 }
 
+void APFixedPoint::toString(llvm::SmallVectorImpl<char> &Str) const {
+  llvm::APSInt Val = getValue();
+  unsigned Scale = getScale();
+
+  if (Val.isSigned() && Val.isNegative() && Val != -Val) {
+    Val = -Val;
+    Str.push_back('-');
+  }
+
+  llvm::APSInt IntPart = Val >> Scale;
+
+  // Add 4 digits to hold the value after multiplying 10 (the radix)
+  unsigned Width = Val.getBitWidth() + 4;
+  llvm::APInt FractPart = Val.zextOrTrunc(Scale).zext(Width);
+  llvm::APInt FractPartMask = llvm::APInt::getAllOnesValue(Scale).zext(Width);
+  llvm::APInt RadixInt = llvm::APInt(Width, 10);
+
+  IntPart.toString(Str, /*radix=*/10);
+  Str.push_back('.');
+  do {
+    (FractPart * RadixInt)
+        .lshr(Scale)
+        .toString(Str, /*radix=*/10, Val.isSigned());
+    FractPart = (FractPart * RadixInt) & FractPartMask;
+  } while (FractPart != 0);
+}
+
 }  // namespace clang