[PATCH] D61607: Introduce an option to stripPointerCasts to force the same bit pattern

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert updated this revision to Diff 198375.
jdoerfert added a comment.

Use a new function for the new behavior


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D61607/new/

https://reviews.llvm.org/D61607

Files:
  llvm/include/llvm/IR/Value.h
  llvm/lib/Analysis/LazyValueInfo.cpp
  llvm/lib/IR/Value.cpp


Index: llvm/lib/IR/Value.cpp
===================================================================
--- llvm/lib/IR/Value.cpp
+++ llvm/lib/IR/Value.cpp
@@ -460,6 +460,7 @@
 enum PointerStripKind {
   PSK_ZeroIndices,
   PSK_ZeroIndicesAndAliases,
+  PSK_ZeroIndicesAndAliasesSameBitPattern,
   PSK_ZeroIndicesAndAliasesAndInvariantGroups,
   PSK_InBoundsConstantIndices,
   PSK_InBounds
@@ -479,6 +480,7 @@
     if (auto *GEP = dyn_cast<GEPOperator>(V)) {
       switch (StripKind) {
       case PSK_ZeroIndicesAndAliases:
+      case PSK_ZeroIndicesAndAliasesSameBitPattern:
       case PSK_ZeroIndicesAndAliasesAndInvariantGroups:
       case PSK_ZeroIndices:
         if (!GEP->hasAllZeroIndices())
@@ -494,7 +496,9 @@
         break;
       }
       V = GEP->getPointerOperand();
-    } else if (Operator::getOpcode(V) == Instruction::BitCast ||
+    } else if (Operator::getOpcode(V) == Instruction::BitCast) {
+      V = cast<Operator>(V)->getOperand(0);
+    } else if (StripKind != PSK_ZeroIndicesAndAliasesSameBitPattern &&
                Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
       V = cast<Operator>(V)->getOperand(0);
     } else if (auto *GA = dyn_cast<GlobalAlias>(V)) {
@@ -530,6 +534,11 @@
   return stripPointerCastsAndOffsets<PSK_ZeroIndicesAndAliases>(this);
 }
 
+const Value *Value::stripPointerCastsSameBitPattern() const {
+  return stripPointerCastsAndOffsets<PSK_ZeroIndicesAndAliasesSameBitPattern>(
+      this);
+}
+
 const Value *Value::stripPointerCastsNoFollowAliases() const {
   return stripPointerCastsAndOffsets<PSK_ZeroIndices>(this);
 }
Index: llvm/lib/Analysis/LazyValueInfo.cpp
===================================================================
--- llvm/lib/Analysis/LazyValueInfo.cpp
+++ llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1739,7 +1739,7 @@
   // through would still be correct.
   const DataLayout &DL = CxtI->getModule()->getDataLayout();
   if (V->getType()->isPointerTy() && C->isNullValue() &&
-      isKnownNonZero(V->stripPointerCasts(), DL)) {
+      isKnownNonZero(V->stripPointerCastsSameBitPattern(), DL)) {
     if (Pred == ICmpInst::ICMP_EQ)
       return LazyValueInfo::False;
     else if (Pred == ICmpInst::ICMP_NE)
Index: llvm/include/llvm/IR/Value.h
===================================================================
--- llvm/include/llvm/IR/Value.h
+++ llvm/include/llvm/IR/Value.h
@@ -493,7 +493,7 @@
   /// swifterror attribute.
   bool isSwiftError() const;
 
-  /// Strip off pointer casts, all-zero GEPs, and aliases.
+  /// Strip off pointer casts, all-zero GEPs, address space casts, and aliases.
   ///
   /// Returns the original uncasted value.  If this is called on a non-pointer
   /// value, it returns 'this'.
@@ -503,6 +503,18 @@
                          static_cast<const Value *>(this)->stripPointerCasts());
   }
 
+  /// Strip off pointer casts, all-zero GEPs, address space casts, and aliases
+  /// but ensures the bit pattern of the result is equal to the bit pattern of
+  /// the underlying value.
+  ///
+  /// Returns the original uncasted value with the same bit pattern. If this is
+  /// called on a non-pointer value, it returns 'this'.
+  const Value *stripPointerCastsSameBitPattern() const;
+  Value *stripPointerCastsSameBitPattern() {
+    return const_cast<Value *>(
+        static_cast<const Value *>(this)->stripPointerCastsSameBitPattern());
+  }
+
   /// Strip off pointer casts, all-zero GEPs, aliases and invariant group
   /// info.
   ///


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