[clang] [llvm] [CaptureTracking][FunctionAttrs] Add support for CaptureInfo (PR #125880)

[via llvm-commits]

================
@@ -358,49 +360,64 @@ UseCaptureKind llvm::DetermineUseCaptureKind(
     // Volatile stores make the address observable.
     auto *ACXI = cast<AtomicCmpXchgInst>(I);
     if (U.getOperandNo() == 1 || U.getOperandNo() == 2 || ACXI->isVolatile())
-      return UseCaptureKind::MAY_CAPTURE;
-    return UseCaptureKind::NO_CAPTURE;
+      return CaptureInfo::otherOnly();
+    return CaptureInfo::none();
   }
   case Instruction::GetElementPtr:
     // AA does not support pointers of vectors, so GEP vector splats need to
     // be considered as captures.
     if (I->getType()->isVectorTy())
-      return UseCaptureKind::MAY_CAPTURE;
-    return UseCaptureKind::PASSTHROUGH;
+      return CaptureInfo::otherOnly();
+    return CaptureInfo::retOnly();
   case Instruction::BitCast:
   case Instruction::PHI:
   case Instruction::Select:
   case Instruction::AddrSpaceCast:
     // The original value is not captured via this if the new value isn't.
-    return UseCaptureKind::PASSTHROUGH;
+    return CaptureInfo::retOnly();
   case Instruction::ICmp: {
     unsigned Idx = U.getOperandNo();
     unsigned OtherIdx = 1 - Idx;
-    if (auto *CPN = dyn_cast<ConstantPointerNull>(I->getOperand(OtherIdx))) {
+    if (isa<ConstantPointerNull>(I->getOperand(OtherIdx)) &&
+        cast<ICmpInst>(I)->isEquality()) {
+      // TODO(captures): Remove these special cases once we make use of
+      // captures(address_is_null).
+
       // Don't count comparisons of a no-alias return value against null as
       // captures. This allows us to ignore comparisons of malloc results
       // with null, for example.
-      if (CPN->getType()->getAddressSpace() == 0)
+      if (U->getType()->getPointerAddressSpace() == 0)
----------------
goldsteinn wrote:

I get that this is pre-existing, but isn't this (and the below) case also incorrect when applied to a non-inbounds GEP?

https://github.com/llvm/llvm-project/pull/125880