[PATCH] D118727: [MemoryBuiltins][FIX] Adjust index type size properly wrt. AS casts

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert updated this revision to Diff 405065.
jdoerfert added a comment.

Fix comments


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D118727/new/

https://reviews.llvm.org/D118727

Files:
  llvm/include/llvm/Analysis/MemoryBuiltins.h
  llvm/lib/Analysis/MemoryBuiltins.cpp


Index: llvm/lib/Analysis/MemoryBuiltins.cpp
===================================================================
--- llvm/lib/Analysis/MemoryBuiltins.cpp
+++ llvm/lib/Analysis/MemoryBuiltins.cpp
@@ -573,10 +573,34 @@
 }
 
 SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
+  unsigned InitialIntTyBits = DL.getIndexTypeSizeInBits(V->getType());
+
+  // Stripping pointer casts can strip address space casts which can change the
+  // index type size. The invariant is that we use the value type to determine
+  // the index type size. If we stripped address space casts we "repair" the
+  // APInt as we pass it upwards. For the caller, the APInt matches the type of
+  // the argument value V (or better the type of it).
+  V = V->stripPointerCasts();
+
+  // Later we use the index type size and zero but it will match the type of the
+  // value that is passed to computeImpl.
   IntTyBits = DL.getIndexTypeSizeInBits(V->getType());
   Zero = APInt::getZero(IntTyBits);
 
-  V = V->stripPointerCasts();
+  if (InitialIntTyBits == IntTyBits)
+    return computeImpl(V);
+
+  // We stripped an address space cast that changed the index type size.
+  // Readjust it to match the argument's index type size.
+  SizeOffsetType SOT = computeImpl(V);
+  if (knownSize(SOT) && !::CheckedZextOrTrunc(SOT.first, InitialIntTyBits))
+    return unknown();
+  if (knownOffset(SOT) && !::CheckedZextOrTrunc(SOT.second, InitialIntTyBits))
+    return unknown();
+  return SOT;
+}
+
+SizeOffsetType ObjectSizeOffsetVisitor::computeImpl(Value *V) {
   if (Instruction *I = dyn_cast<Instruction>(V)) {
     // If we have already seen this instruction, bail out. Cycles can happen in
     // unreachable code after constant propagation.
Index: llvm/include/llvm/Analysis/MemoryBuiltins.h
===================================================================
--- llvm/include/llvm/Analysis/MemoryBuiltins.h
+++ llvm/include/llvm/Analysis/MemoryBuiltins.h
@@ -221,6 +221,7 @@
   SizeOffsetType visitInstruction(Instruction &I);
 
 private:
+  SizeOffsetType computeImpl(Value *V);
   bool CheckedZextOrTrunc(APInt &I);
 };
 


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