2 files changed, 23 insertions, 0 deletions

diff --git a/contrib/llvm-project/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/contrib/llvm-project/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 6bbb0251f2bc..2aab79e89078 100644
--- a/contrib/llvm-project/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/contrib/llvm-project/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1961,6 +1961,12 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
       }
     }
 
+    // If this 'and' clears the sign-bits added by ashr, replace with lshr:
+    // and (ashr X, ShiftC), C --> lshr X, ShiftC
+    if (match(Op0, m_AShr(m_Value(X), m_APInt(ShiftC))) && ShiftC->ult(Width) &&
+        C->isMask(Width - ShiftC->getZExtValue()))
+      return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, *ShiftC));
+
     const APInt *AddC;
     if (match(Op0, m_Add(m_Value(X), m_APInt(AddC)))) {
       // If we add zeros to every bit below a mask, the add has no effect:
diff --git a/contrib/llvm-project/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/contrib/llvm-project/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 65e60498ff95..881b00f2a55a 100644
--- a/contrib/llvm-project/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/contrib/llvm-project/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1572,6 +1572,23 @@ Instruction *InstCombinerImpl::foldSelectInstWithICmp(SelectInst &SI,
     }
   }
 
+  // Canonicalize a signbit condition to use zero constant by swapping:
+  // (CmpLHS > -1) ? TV : FV --> (CmpLHS < 0) ? FV : TV
+  // To avoid conflicts (infinite loops) with other canonicalizations, this is
+  // not applied with any constant select arm.
+  if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes()) &&
+      !match(TrueVal, m_Constant()) && !match(FalseVal, m_Constant()) &&
+      ICI->hasOneUse()) {
+    InstCombiner::BuilderTy::InsertPointGuard Guard(Builder);
+    Builder.SetInsertPoint(&SI);
+    Value *IsNeg = Builder.CreateICmpSLT(
+        CmpLHS, ConstantInt::getNullValue(CmpLHS->getType()), ICI->getName());
+    replaceOperand(SI, 0, IsNeg);
+    SI.swapValues();
+    SI.swapProfMetadata();
+    return &SI;
+  }
+
   // FIXME: This code is nearly duplicated in InstSimplify. Using/refactoring
   // decomposeBitTestICmp() might help.
   {