[ADT] Add APInt/MathExtras isShiftedMask variant returning mask offset/length

In many cases, calls to isShiftedMask are immediately followed with checks to determine the size and position of the bitmask.

This patch adds variants of APInt::isShiftedMask, isShiftedMask_32 and isShiftedMask_64 that return these values as additional arguments.

I've updated a number of cases that were either performing seperate size/position calculations or had created their own local wrapper versions of these.

Differential Revision: https://reviews.llvm.org/D119019

1 files changed, 22 insertions, 0 deletions

diff --git a/llvm/unittests/ADT/APIntTest.cpp b/llvm/unittests/ADT/APIntTest.cpp
index 95cb213..566ceab 100644
--- a/llvm/unittests/ADT/APIntTest.cpp
+++ b/llvm/unittests/ADT/APIntTest.cpp
@@ -1746,21 +1746,43 @@ TEST(APIntTest, isShiftedMask) {
   EXPECT_TRUE(APInt(32, 0xffff0000).isShiftedMask());
   EXPECT_TRUE(APInt(32, 0xff << 1).isShiftedMask());
 
+  unsigned MaskIdx, MaskLen;
+  EXPECT_FALSE(APInt(32, 0x01010101).isShiftedMask(MaskIdx, MaskLen));
+  EXPECT_TRUE(APInt(32, 0xf0000000).isShiftedMask(MaskIdx, MaskLen));
+  EXPECT_EQ(28, MaskIdx);
+  EXPECT_EQ(4, MaskLen);
+  EXPECT_TRUE(APInt(32, 0xffff0000).isShiftedMask(MaskIdx, MaskLen));
+  EXPECT_EQ(16, MaskIdx);
+  EXPECT_EQ(16, MaskLen);
+  EXPECT_TRUE(APInt(32, 0xff << 1).isShiftedMask(MaskIdx, MaskLen));
+  EXPECT_EQ(1, MaskIdx);
+  EXPECT_EQ(8, MaskLen);
+
   for (int N : { 1, 2, 3, 4, 7, 8, 16, 32, 64, 127, 128, 129, 256 }) {
     EXPECT_FALSE(APInt(N, 0).isShiftedMask());
+    EXPECT_FALSE(APInt(N, 0).isShiftedMask(MaskIdx, MaskLen));
 
     APInt One(N, 1);
     for (int I = 1; I < N; ++I) {
       APInt MaskVal = One.shl(I) - 1;
       EXPECT_TRUE(MaskVal.isShiftedMask());
+      EXPECT_TRUE(MaskVal.isShiftedMask(MaskIdx, MaskLen));
+      EXPECT_EQ(0, MaskIdx);
+      EXPECT_EQ(I, MaskLen);
     }
     for (int I = 1; I < N - 1; ++I) {
       APInt MaskVal = One.shl(I);
       EXPECT_TRUE(MaskVal.isShiftedMask());
+      EXPECT_TRUE(MaskVal.isShiftedMask(MaskIdx, MaskLen));
+      EXPECT_EQ(I, MaskIdx);
+      EXPECT_EQ(1, MaskLen);
     }
     for (int I = 1; I < N; ++I) {
       APInt MaskVal = APInt::getHighBitsSet(N, I);
       EXPECT_TRUE(MaskVal.isShiftedMask());
+      EXPECT_TRUE(MaskVal.isShiftedMask(MaskIdx, MaskLen));
+      EXPECT_EQ(N - I, MaskIdx);
+      EXPECT_EQ(I, MaskLen);
     }
   }
 }