[llvm] 6a46c6c - Ensure KnownBits passed when calculating from range md has right size (#132985)

[via llvm-commits]

Author: LU-JOHN
Date: 2025-04-03T10:17:14+07:00
New Revision: 6a46c6c865270ceb01bcaef4a2e4c8df56a8800a

URL: https://github.com/llvm/llvm-project/commit/6a46c6c865270ceb01bcaef4a2e4c8df56a8800a
DIFF: https://github.com/llvm/llvm-project/commit/6a46c6c865270ceb01bcaef4a2e4c8df56a8800a.diff

LOG: Ensure KnownBits passed when calculating from range md has right size (#132985)

KnownBits passed to computeKnownBitsFromRangeMetadata must have the same
bit width as the range metadata bit width. Otherwise the calculated
results will be incorrect.

---------

Signed-off-by: John Lu <John.Lu at amd.com>

Added: 
    

Modified: 
    llvm/lib/Analysis/ValueTracking.cpp
    llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index fc0c74942c6d8..3b0249f91d6d7 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -430,6 +430,10 @@ void llvm::computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
     ConstantInt *Upper =
         mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 1));
     ConstantRange Range(Lower->getValue(), Upper->getValue());
+    // BitWidth must equal the Ranges BitWidth for the correct number of high
+    // bits to be set.
+    assert(BitWidth == Range.getBitWidth() &&
+           "Known bit width must match range bit width!");
 
     // The first CommonPrefixBits of all values in Range are equal.
     unsigned CommonPrefixBits =

diff  --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 3526beeb312ce..69548d0462318 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -9176,6 +9176,12 @@ SDValue SelectionDAG::getLoad(ISD::MemIndexedMode AM, ISD::LoadExtType ExtType,
            "Cannot use an ext load to change the number of vector elements!");
   }
 
+  assert((!MMO->getRanges() ||
+          (mdconst::extract<ConstantInt>(MMO->getRanges()->getOperand(0))
+                   ->getBitWidth() == MemVT.getScalarSizeInBits() &&
+           MemVT.isInteger())) &&
+         "Range metadata and load type must match!");
+
   bool Indexed = AM != ISD::UNINDEXED;
   assert((Indexed || Offset.isUndef()) && "Unindexed load with an offset!");