[PATCH] D109233: [hwasan] Respect returns attribute when tracking values.

[Florian Mayer via Phabricator via llvm-commits]

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fmayer retitled this revision from "[hwasan] Respect returns attribute when following to Alloca." to "[hwasan] Respect returns attribute when tracking values.".
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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D109233

Files:
  llvm/lib/Analysis/StackSafetyAnalysis.cpp
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Instrumentation/HWAddressSanitizer/stack-safety-analysis.ll


Index: llvm/test/Instrumentation/HWAddressSanitizer/stack-safety-analysis.ll
===================================================================
--- llvm/test/Instrumentation/HWAddressSanitizer/stack-safety-analysis.ll
+++ llvm/test/Instrumentation/HWAddressSanitizer/stack-safety-analysis.ll
@@ -136,6 +136,24 @@
   ret i32 0
 }
 
+; Check whether we see through the returns attribute of functions.
+define i32 @test_retptr(i32* %a) sanitize_hwaddress {
+entry:
+  ; CHECK-LABEL: @test_retptr
+  ; NOSAFETY: call {{.*}}__hwasan_generate_tag
+  ; NOSAFETY: call {{.*}}__hwasan_store
+  ; SAFETY: call {{.*}}__hwasan_generate_tag
+  ; SAFETY-NOT: call {{.*}}__hwasan_store
+  ; NOSTACK-NOT: call {{.*}}__hwasan_generate_tag
+  ; NOSTACK-NOT: call {{.*}}__hwasan_store
+  %buf.sroa.0 = alloca i8, align 4
+  call void @llvm.lifetime.start.p0i8(i64 1, i8* nonnull %buf.sroa.0)
+  %ptr = call i8* @retptr(i8* %buf.sroa.0)
+  store volatile i8 0, i8* %ptr, align 4, !tbaa !8
+  call void @llvm.lifetime.end.p0i8(i64 1, i8* nonnull %buf.sroa.0)
+  ret i32 0
+}
+
 ; Function Attrs: argmemonly mustprogress nofree nosync nounwind willreturn
 declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture)
 
@@ -145,6 +163,7 @@
 declare void @use(i8* nocapture)
 declare i32 @getoffset()
 declare i8* @getptr(i8* nocapture)
+declare i8* @retptr(i8* returned)
 
 !8 = !{!9, !9, i64 0}
 !9 = !{!"omnipotent char", !10, i64 0}
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4533,6 +4533,12 @@
       if (OffsetZero && !GEP->hasAllZeroIndices())
         return nullptr;
       AddWork(GEP->getPointerOperand());
+    } else if (CallBase *CB = dyn_cast<CallBase>(V)) {
+      Value *Returned = CB->getReturnedArgOperand();
+      if (Returned)
+        AddWork(Returned);
+      else
+        return nullptr;
     } else {
       return nullptr;
     }
Index: llvm/lib/Analysis/StackSafetyAnalysis.cpp
===================================================================
--- llvm/lib/Analysis/StackSafetyAnalysis.cpp
+++ llvm/lib/Analysis/StackSafetyAnalysis.cpp
@@ -414,6 +414,11 @@
         }
 
         const auto &CB = cast<CallBase>(*I);
+        if (CB.getReturnedArgOperand() == V) {
+          if (Visited.insert(I).second)
+            WorkList.push_back(cast<const Instruction>(I));
+        }
+
         if (!CB.isArgOperand(&UI)) {
           US.addRange(I, UnknownRange);
           break;


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