[llvm] 8aa52b1 - [APInt] set all bits for getBitsSetWithWrap if loBit == hiBit

[Chen Zheng via llvm-commits]

Author: Chen Zheng
Date: 2020-06-08T22:55:24-04:00
New Revision: 8aa52b19a7f1be25e38c851cfe861233ca66900a

URL: https://github.com/llvm/llvm-project/commit/8aa52b19a7f1be25e38c851cfe861233ca66900a
DIFF: https://github.com/llvm/llvm-project/commit/8aa52b19a7f1be25e38c851cfe861233ca66900a.diff

LOG: [APInt] set all bits for getBitsSetWithWrap if loBit == hiBit

differentiate getBitsSetWithWrap & getBitsSet when loBit == hiBit
getBitsSetWithWrap sets all bits;
getBitsSet does nothing.

Reviewed By: lkail, RKSimon, lebedev.ri

Differential Revision: https://reviews.llvm.org/D81325

Added: 
    

Modified: 
    llvm/include/llvm/ADT/APInt.h
    llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
    llvm/unittests/ADT/APIntTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/ADT/APInt.h b/llvm/include/llvm/ADT/APInt.h
index 9f0fb04794ea..c88d9651d68d 100644
--- a/llvm/include/llvm/ADT/APInt.h
+++ b/llvm/include/llvm/ADT/APInt.h
@@ -616,9 +616,11 @@ class LLVM_NODISCARD APInt {
   }
 
   /// Wrap version of getBitsSet.
-  /// If \p hiBit is no less than \p loBit, this is same with getBitsSet.
-  /// If \p hiBit is less than \p loBit, the set bits "wrap". For example, with
-  /// parameters (32, 28, 4), you would get 0xF000000F.
+  /// If \p hiBit is bigger than \p loBit, this is same with getBitsSet.
+  /// If \p hiBit is not bigger than \p loBit, the set bits "wrap". For example,
+  /// with parameters (32, 28, 4), you would get 0xF000000F.
+  /// If \p hiBit is equal to \p loBit, you would get a result with all bits
+  /// set.
   static APInt getBitsSetWithWrap(unsigned numBits, unsigned loBit,
                                   unsigned hiBit) {
     APInt Res(numBits, 0);
@@ -1448,12 +1450,13 @@ class LLVM_NODISCARD APInt {
   }
 
   /// Set the bits from loBit (inclusive) to hiBit (exclusive) to 1.
-  /// This function handles "wrap" case when \p loBit > \p hiBit, and calls
-  /// setBits when \p loBit <= \p hiBit.
+  /// This function handles "wrap" case when \p loBit >= \p hiBit, and calls
+  /// setBits when \p loBit < \p hiBit.
+  /// For \p loBit == \p hiBit wrap case, set every bit to 1.
   void setBitsWithWrap(unsigned loBit, unsigned hiBit) {
     assert(hiBit <= BitWidth && "hiBit out of range");
     assert(loBit <= BitWidth && "loBit out of range");
-    if (loBit <= hiBit) {
+    if (loBit < hiBit) {
       setBits(loBit, hiBit);
       return;
     }

diff  --git a/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp b/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
index 7b42830070c8..d2aba6bd6e8d 100644
--- a/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
+++ b/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
@@ -906,11 +906,6 @@ bool PPCMIPeephole::simplifyCode(void) {
         // while in PowerPC ISA, lowerest bit is at index 63.
         APInt MaskSrc =
             APInt::getBitsSetWithWrap(32, 32 - MESrc - 1, 32 - MBSrc);
-        // Current APInt::getBitsSetWithWrap sets all bits to 0 if loBit is
-        // equal to highBit.
-        // If MBSrc - MESrc == 1, we expect a full set mask instead of Null.
-        if (SrcMaskFull && (MBSrc - MESrc == 1))
-          MaskSrc.setAllBits();
 
         APInt RotatedSrcMask = MaskSrc.rotl(SHMI);
         APInt FinalMask = RotatedSrcMask & MaskMI;

diff  --git a/llvm/unittests/ADT/APIntTest.cpp b/llvm/unittests/ADT/APIntTest.cpp
index 0efb10f9b32d..37ab21bcfaf2 100644
--- a/llvm/unittests/ADT/APIntTest.cpp
+++ b/llvm/unittests/ADT/APIntTest.cpp
@@ -2099,6 +2099,14 @@ TEST(APIntTest, getBitsSetWithWrap) {
   EXPECT_EQ(0u, i127hi1lo1wrap.countTrailingZeros());
   EXPECT_EQ(1u, i127hi1lo1wrap.countTrailingOnes());
   EXPECT_EQ(2u, i127hi1lo1wrap.countPopulation());
+
+  APInt i32hiequallowrap = APInt::getBitsSetWithWrap(32, 10, 10);
+  EXPECT_EQ(32u, i32hiequallowrap.countLeadingOnes());
+  EXPECT_EQ(0u, i32hiequallowrap.countLeadingZeros());
+  EXPECT_EQ(32u, i32hiequallowrap.getActiveBits());
+  EXPECT_EQ(0u, i32hiequallowrap.countTrailingZeros());
+  EXPECT_EQ(32u, i32hiequallowrap.countTrailingOnes());
+  EXPECT_EQ(32u, i32hiequallowrap.countPopulation());
 }
 
 TEST(APIntTest, getHighBitsSet) {