[llvm] 2c7b7ec - [ADT] Fix Incorrect rounding for APFixedPoint::getIntPart

[via llvm-commits]

Author: Tyker
Date: 2022-10-14T11:01:20-07:00
New Revision: 2c7b7eca85c2ccc9b0d5c65169213ce499652f92

URL: https://github.com/llvm/llvm-project/commit/2c7b7eca85c2ccc9b0d5c65169213ce499652f92
DIFF: https://github.com/llvm/llvm-project/commit/2c7b7eca85c2ccc9b0d5c65169213ce499652f92.diff

LOG: [ADT] Fix Incorrect rounding for APFixedPoint::getIntPart

Added: 
    

Modified: 
    llvm/include/llvm/ADT/APFixedPoint.h
    llvm/unittests/ADT/APFixedPointTest.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm/ADT/APFixedPoint.h b/llvm/include/llvm/ADT/APFixedPoint.h
index e151089b75bbf..0b72fcc76e121 100644
--- a/llvm/include/llvm/ADT/APFixedPoint.h
+++ b/llvm/include/llvm/ADT/APFixedPoint.h
@@ -214,7 +214,7 @@ class APFixedPoint {
     APSInt ExtVal =
         (getLsbWeight() > 0) ? Val.extend(getWidth() + getLsbWeight()) : Val;
     if (Val < 0 && Val != -Val) // Cover the case when we have the min val
-      return -(-ExtVal.relativeShl(getLsbWeight()));
+      return -((-ExtVal).relativeShl(getLsbWeight()));
     return ExtVal.relativeShl(getLsbWeight());
   }
 

diff  --git a/llvm/unittests/ADT/APFixedPointTest.cpp b/llvm/unittests/ADT/APFixedPointTest.cpp
index 0b85db531f739..3a197639f2ea0 100644
--- a/llvm/unittests/ADT/APFixedPointTest.cpp
+++ b/llvm/unittests/ADT/APFixedPointTest.cpp
@@ -276,6 +276,11 @@ void CheckIntPartMax(const FixedPointSemantics &Sema, uint64_t Expected) {
                                     APSInt::getUnsigned(Expected)) == 0);
 }
 
+void CheckIntPartRes(const FixedPointSemantics &Sema, int64_t Representation, int64_t Result) {
+  APFixedPoint Val(Representation, Sema);
+  ASSERT_EQ(Val.getIntPart().getZExtValue(), Result) ;
+}
+
 TEST(FixedPoint, getIntPart) {
   // Normal values
   CheckIntPart(getSAccumSema(), 2);
@@ -359,6 +364,12 @@ TEST(FixedPoint, getIntPart) {
   CheckIntPartMax(getPadUSFractSema(), 0);
   CheckIntPartMax(getPadUFractSema(), 0);
   CheckIntPartMax(getPadULFractSema(), 0);
+
+  // Rounded Towards Zero
+  CheckIntPartRes(getSFractSema(), -127, 0);
+  CheckIntPartRes(getFractSema(), -32767, 0);
+  CheckIntPartRes(getLFractSema(), -2147483647, 0);
+  CheckIntPartRes(getS16Neg18(), -32768, 0);
 }
 
 TEST(FixedPoint, compare) {