[FunctionAttrs] Determine underlying object by getUnderlyingObjectAggressive (#100102)

Thanks to #99509, we can fix
rust-lang/rust#119573 too.

Author: dianqk

llvm/lib/Transforms/IPO/FunctionAttrs.cpp

@@ -118,7 +118,7 @@ static void addLocAccess(MemoryEffects &ME, const MemoryLocation &Loc,
   if (isNoModRef(MR))
     return;
 
-  const Value *UO = getUnderlyingObject(Loc.Ptr);
+  const Value *UO = getUnderlyingObjectAggressive(Loc.Ptr);
   assert(!isa<AllocaInst>(UO) &&
          "Should have been handled by getModRefInfoMask()");
   if (isa<Argument>(UO)) {

llvm/test/Transforms/FunctionAttrs/argmemonly.ll

@@ -489,3 +489,127 @@ define void @test_scc_argmem_read_2(ptr %p) {
   call void @test_scc_argmem_read_1(ptr %p)
   ret void
 }
+
+define i64 @select_same_obj(i1 %c, ptr %p, i64 %x) {
+; FNATTRS: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(argmem: read)
+; FNATTRS-LABEL: define i64 @select_same_obj
+; FNATTRS-SAME: (i1 [[C:%.*]], ptr nocapture readonly [[P:%.*]], i64 [[X:%.*]]) #[[ATTR1]] {
+; FNATTRS-NEXT:  entry:
+; FNATTRS-NEXT:    [[P2:%.*]] = getelementptr i8, ptr [[P]], i64 [[X]]
+; FNATTRS-NEXT:    [[P3:%.*]] = select i1 [[C]], ptr [[P]], ptr [[P2]]
+; FNATTRS-NEXT:    [[R:%.*]] = load i64, ptr [[P3]], align 4
+; FNATTRS-NEXT:    ret i64 [[R]]
+;
+; ATTRIBUTOR: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none)
+; ATTRIBUTOR-LABEL: define i64 @select_same_obj
+; ATTRIBUTOR-SAME: (i1 [[C:%.*]], ptr nocapture nofree readonly [[P:%.*]], i64 [[X:%.*]]) #[[ATTR0]] {
+; ATTRIBUTOR-NEXT:  entry:
+; ATTRIBUTOR-NEXT:    [[P2:%.*]] = getelementptr i8, ptr [[P]], i64 [[X]]
+; ATTRIBUTOR-NEXT:    [[P3:%.*]] = select i1 [[C]], ptr [[P]], ptr [[P2]]
+; ATTRIBUTOR-NEXT:    [[R:%.*]] = load i64, ptr [[P3]], align 4
+; ATTRIBUTOR-NEXT:    ret i64 [[R]]
+;
+entry:
+  %p2 = getelementptr i8, ptr %p, i64 %x
+  %p3 = select i1 %c, ptr %p, ptr %p2
+  %r = load i64, ptr %p3
+  ret i64 %r
+}
+
+; FIXME: This could be `memory(argmem: read)`.
+define i64 @select_different_obj(i1 %c, ptr %p, ptr %p2) {
+; FNATTRS: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(read, inaccessiblemem: none)
+; FNATTRS-LABEL: define i64 @select_different_obj
+; FNATTRS-SAME: (i1 [[C:%.*]], ptr nocapture readonly [[P:%.*]], ptr nocapture readonly [[P2:%.*]]) #[[ATTR3]] {
+; FNATTRS-NEXT:  entry:
+; FNATTRS-NEXT:    [[P3:%.*]] = select i1 [[C]], ptr [[P]], ptr [[P2]]
+; FNATTRS-NEXT:    [[R:%.*]] = load i64, ptr [[P3]], align 4
+; FNATTRS-NEXT:    ret i64 [[R]]
+;
+; ATTRIBUTOR: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none)
+; ATTRIBUTOR-LABEL: define i64 @select_different_obj
+; ATTRIBUTOR-SAME: (i1 [[C:%.*]], ptr nocapture nofree readonly [[P:%.*]], ptr nocapture nofree readonly [[P2:%.*]]) #[[ATTR0]] {
+; ATTRIBUTOR-NEXT:  entry:
+; ATTRIBUTOR-NEXT:    [[P3:%.*]] = select i1 [[C]], ptr [[P]], ptr [[P2]]
+; ATTRIBUTOR-NEXT:    [[R:%.*]] = load i64, ptr [[P3]], align 4
+; ATTRIBUTOR-NEXT:    ret i64 [[R]]
+;
+entry:
+  %p3 = select i1 %c, ptr %p, ptr %p2
+  %r = load i64, ptr %p3
+  ret i64 %r
+}
+
+define i64 @phi_same_obj(i1 %c, ptr %p, i64 %x) {
+; FNATTRS: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(argmem: read)
+; FNATTRS-LABEL: define i64 @phi_same_obj
+; FNATTRS-SAME: (i1 [[C:%.*]], ptr nocapture readonly [[P:%.*]], i64 [[X:%.*]]) #[[ATTR1]] {
+; FNATTRS-NEXT:  entry:
+; FNATTRS-NEXT:    [[P2:%.*]] = getelementptr i8, ptr [[P]], i64 [[X]]
+; FNATTRS-NEXT:    br i1 [[C]], label [[IF:%.*]], label [[JOIN:%.*]]
+; FNATTRS:       if:
+; FNATTRS-NEXT:    br label [[JOIN]]
+; FNATTRS:       join:
+; FNATTRS-NEXT:    [[P3:%.*]] = phi ptr [ [[P]], [[IF]] ], [ [[P2]], [[ENTRY:%.*]] ]
+; FNATTRS-NEXT:    [[R:%.*]] = load i64, ptr [[P3]], align 4
+; FNATTRS-NEXT:    ret i64 [[R]]
+;
+; ATTRIBUTOR: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(argmem: read)
+; ATTRIBUTOR-LABEL: define i64 @phi_same_obj
+; ATTRIBUTOR-SAME: (i1 [[C:%.*]], ptr nocapture nofree readonly [[P:%.*]], i64 [[X:%.*]]) #[[ATTR1]] {
+; ATTRIBUTOR-NEXT:  entry:
+; ATTRIBUTOR-NEXT:    [[P2:%.*]] = getelementptr i8, ptr [[P]], i64 [[X]]
+; ATTRIBUTOR-NEXT:    br i1 [[C]], label [[IF:%.*]], label [[JOIN:%.*]]
+; ATTRIBUTOR:       if:
+; ATTRIBUTOR-NEXT:    br label [[JOIN]]
+; ATTRIBUTOR:       join:
+; ATTRIBUTOR-NEXT:    [[P3:%.*]] = phi ptr [ [[P]], [[IF]] ], [ [[P2]], [[ENTRY:%.*]] ]
+; ATTRIBUTOR-NEXT:    [[R:%.*]] = load i64, ptr [[P3]], align 4
+; ATTRIBUTOR-NEXT:    ret i64 [[R]]
+;
+entry:
+  %p2 = getelementptr i8, ptr %p, i64 %x
+  br i1 %c, label %if, label %join
+if:
+  br label %join
+join:
+  %p3 = phi ptr [ %p, %if ], [ %p2, %entry ]
+  %r = load i64, ptr %p3
+  ret i64 %r
+}
+
+; FIXME: This could be `memory(argmem: read)`.
+define i64 @phi_different_obj(i1 %c, ptr %p, ptr %p2) {
+; FNATTRS: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(read, inaccessiblemem: none)
+; FNATTRS-LABEL: define i64 @phi_different_obj
+; FNATTRS-SAME: (i1 [[C:%.*]], ptr nocapture readonly [[P:%.*]], ptr nocapture readonly [[P2:%.*]]) #[[ATTR3]] {
+; FNATTRS-NEXT:  entry:
+; FNATTRS-NEXT:    br i1 [[C]], label [[IF:%.*]], label [[JOIN:%.*]]
+; FNATTRS:       if:
+; FNATTRS-NEXT:    br label [[JOIN]]
+; FNATTRS:       join:
+; FNATTRS-NEXT:    [[P3:%.*]] = phi ptr [ [[P]], [[IF]] ], [ [[P2]], [[ENTRY:%.*]] ]
+; FNATTRS-NEXT:    [[R:%.*]] = load i64, ptr [[P3]], align 4
+; FNATTRS-NEXT:    ret i64 [[R]]
+;
+; ATTRIBUTOR: Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(argmem: read)
+; ATTRIBUTOR-LABEL: define i64 @phi_different_obj
+; ATTRIBUTOR-SAME: (i1 [[C:%.*]], ptr nocapture nofree readonly [[P:%.*]], ptr nocapture nofree readonly [[P2:%.*]]) #[[ATTR1]] {
+; ATTRIBUTOR-NEXT:  entry:
+; ATTRIBUTOR-NEXT:    br i1 [[C]], label [[IF:%.*]], label [[JOIN:%.*]]
+; ATTRIBUTOR:       if:
+; ATTRIBUTOR-NEXT:    br label [[JOIN]]
+; ATTRIBUTOR:       join:
+; ATTRIBUTOR-NEXT:    [[P3:%.*]] = phi ptr [ [[P]], [[IF]] ], [ [[P2]], [[ENTRY:%.*]] ]
+; ATTRIBUTOR-NEXT:    [[R:%.*]] = load i64, ptr [[P3]], align 4
+; ATTRIBUTOR-NEXT:    ret i64 [[R]]
+;
+entry:
+  br i1 %c, label %if, label %join
+if:
+  br label %join
+join:
+  %p3 = phi ptr [ %p, %if ], [ %p2, %entry ]
+  %r = load i64, ptr %p3
+  ret i64 %r
+}