Don't bother looking through gep inbounds

Author: nikic

llvm/lib/Analysis/CaptureTracking.cpp

@@ -400,13 +400,8 @@ CaptureInfo llvm::DetermineUseCaptureKind(
       }
 
       // Check whether this is a comparison of the base pointer against
-      // null. We can also strip inbounds GEPs, as inbounds preserves
-      // the null-ness of the pointer.
-      Value *Stripped = U.get();
-      if (!NullPointerIsDefined(I->getFunction(),
-                                U->getType()->getPointerAddressSpace()))
-        Stripped = Stripped->stripInBoundsOffsets();
-      if (Stripped == Base)
+      // null.
+      if (U.get() == Base)
         return CaptureInfo::otherOnly(CaptureComponents::AddressIsNull);
     }
 

llvm/test/Transforms/FunctionAttrs/nocapture.ll

@@ -788,10 +788,12 @@ define i1 @captureICmpWrongPred(ptr %x) {
   ret i1 %1
 }
 
+; We could infer captures(address_is_null) here, but don't bother, because
+; InstCombine will optimize the GEP away.
 define i1 @nocaptureInboundsGEPICmp(ptr %x) {
 ; FNATTRS: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none)
 ; FNATTRS-LABEL: define i1 @nocaptureInboundsGEPICmp
-; FNATTRS-SAME: (ptr readnone captures(address_is_null) [[X:%.*]]) #[[ATTR0]] {
+; FNATTRS-SAME: (ptr readnone captures(address) [[X:%.*]]) #[[ATTR0]] {
 ; FNATTRS-NEXT:    [[TMP1:%.*]] = getelementptr inbounds i32, ptr [[X]], i32 5
 ; FNATTRS-NEXT:    [[TMP2:%.*]] = icmp eq ptr [[TMP1]], null
 ; FNATTRS-NEXT:    ret i1 [[TMP2]]
@@ -811,7 +813,7 @@ define i1 @nocaptureInboundsGEPICmp(ptr %x) {
 define i1 @nocaptureInboundsGEPICmpRev(ptr %x) {
 ; FNATTRS: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none)
 ; FNATTRS-LABEL: define i1 @nocaptureInboundsGEPICmpRev
-; FNATTRS-SAME: (ptr readnone captures(address_is_null) [[X:%.*]]) #[[ATTR0]] {
+; FNATTRS-SAME: (ptr readnone captures(address) [[X:%.*]]) #[[ATTR0]] {
 ; FNATTRS-NEXT:    [[TMP1:%.*]] = getelementptr inbounds i32, ptr [[X]], i32 5
 ; FNATTRS-NEXT:    [[TMP2:%.*]] = icmp eq ptr null, [[TMP1]]
 ; FNATTRS-NEXT:    ret i1 [[TMP2]]