[AssumeBundles] add cannonicalisation to the assume builder

Summary:
this reduces significantly the number of assumes generated without aftecting too much
the information that is preserved. this improves the compile-time cost
of enable-knowledge-retention significantly.

Reviewers: jdoerfert, sstefan1

Reviewed By: jdoerfert

Subscribers: hiraditya, asbirlea, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D79650

2 files changed, 34 insertions, 3 deletions

diff --git a/llvm/lib/IR/Operator.cpp b/llvm/lib/IR/Operator.cpp
index baf3a05..df6f08d 100644
--- a/llvm/lib/IR/Operator.cpp
+++ b/llvm/lib/IR/Operator.cpp
@@ -31,6 +31,33 @@ Type *GEPOperator::getResultElementType() const {
   return cast<GetElementPtrConstantExpr>(this)->getResultElementType();
 }
 
+Align GEPOperator::getMaxPreservedAlignment(const DataLayout &DL) const {
+  /// compute the worse possible offset for every level of the GEP et accumulate
+  /// the minimum alignment into Result.
+
+  Align Result = Align(llvm::Value::MaximumAlignment);
+  for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this);
+       GTI != GTE; ++GTI) {
+    int64_t Offset = 1;
+    ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
+
+    if (StructType *STy = GTI.getStructTypeOrNull()) {
+      const StructLayout *SL = DL.getStructLayout(STy);
+      Offset = SL->getElementOffset(OpC->getZExtValue());
+    } else {
+      assert(GTI.isSequential() && "should be sequencial");
+      /// If the index isn't know we take 1 because it is the index that will
+      /// give the worse alignment of the offset.
+      int64_t ElemCount = 1;
+      if (OpC)
+        ElemCount = OpC->getZExtValue();
+      Offset = DL.getTypeAllocSize(GTI.getIndexedType()) * ElemCount;
+    }
+    Result = Align(MinAlign(Offset, Result.value()));
+  }
+  return Result;
+}
+
 bool GEPOperator::accumulateConstantOffset(
     const DataLayout &DL, APInt &Offset,
     function_ref<bool(Value &, APInt &)> ExternalAnalysis) const {
diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index 70d4012..78c12f4 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -516,7 +516,9 @@ enum PointerStripKind {
 };
 
 template <PointerStripKind StripKind>
-static const Value *stripPointerCastsAndOffsets(const Value *V) {
+static const Value *stripPointerCastsAndOffsets(
+    const Value *V,
+    function_ref<void(const Value *)> Func = [](const Value *) {}) {
   if (!V->getType()->isPointerTy())
     return V;
 
@@ -526,6 +528,7 @@ static const Value *stripPointerCastsAndOffsets(const Value *V) {
 
   Visited.insert(V);
   do {
+    Func(V);
     if (auto *GEP = dyn_cast<GEPOperator>(V)) {
       switch (StripKind) {
       case PSK_ZeroIndices:
@@ -667,8 +670,9 @@ const Value *Value::stripAndAccumulateConstantOffsets(
   return V;
 }
 
-const Value *Value::stripInBoundsOffsets() const {
-  return stripPointerCastsAndOffsets<PSK_InBounds>(this);
+const Value *
+Value::stripInBoundsOffsets(function_ref<void(const Value *)> Func) const {
+  return stripPointerCastsAndOffsets<PSK_InBounds>(this, Func);
 }
 
 uint64_t Value::getPointerDereferenceableBytes(const DataLayout &DL,