[APInt] Add the truncOrSelf resizing operator to APInt

Truncates the APInt if the bit width is greater than the width specified,
otherwise do nothing

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D91445

diff --git a/llvm/include/llvm/ADT/APInt.h b/llvm/include/llvm/ADT/APInt.h
index f5860f6..b97ea2c 100644 (file)
--- a/llvm/include/llvm/ADT/APInt.h
+++ b/llvm/include/llvm/ADT/APInt.h
@@ -1403,6 +1403,12 @@ public:
   /// extended, truncated, or left alone to make it that width.
   APInt zextOrTrunc(unsigned width) const;
 
+  /// Truncate to width
+  ///
+  /// Make this APInt have the bit width given by \p width. The value is
+  /// truncated or left alone to make it that width.
+  APInt truncOrSelf(unsigned width) const;
+
   /// Sign extend or truncate to width
   ///
   /// Make this APInt have the bit width given by \p width. The value is sign

diff --git a/llvm/lib/Support/APInt.cpp b/llvm/lib/Support/APInt.cpp
index fc339de..12ceb2d 100644 (file)
--- a/llvm/lib/Support/APInt.cpp
+++ b/llvm/lib/Support/APInt.cpp
@@ -961,6 +961,12 @@ APInt APInt::sextOrTrunc(unsigned width) const {
   return *this;
 }
 
+APInt APInt::truncOrSelf(unsigned width) const {
+  if (BitWidth > width)
+    return trunc(width);
+  return *this;
+}
+
 APInt APInt::zextOrSelf(unsigned width) const {
   if (BitWidth < width)
     return zext(width);

diff --git a/llvm/unittests/ADT/APIntTest.cpp b/llvm/unittests/ADT/APIntTest.cpp
index 673a211..ef5423e 100644 (file)
--- a/llvm/unittests/ADT/APIntTest.cpp
+++ b/llvm/unittests/ADT/APIntTest.cpp
@@ -2598,6 +2598,13 @@ TEST(APIntTest, sext) {
   EXPECT_EQ(63U, i32_neg1.countPopulation());
 }
 
+TEST(APIntTest, truncOrSelf) {
+  APInt val(32, 0xFFFFFFFF);
+  EXPECT_EQ(0xFFFF, val.truncOrSelf(16));
+  EXPECT_EQ(0xFFFFFFFF, val.truncOrSelf(32));
+  EXPECT_EQ(0xFFFFFFFF, val.truncOrSelf(64));
+}
+
 TEST(APIntTest, multiply) {
   APInt i64(64, 1234);