[llvm] r304275 - [CFLAA] Add missing break; note things are broken.

[George Burgess IV via llvm-commits]

Author: gbiv
Date: Tue May 30 21:35:26 2017
New Revision: 304275

URL: http://llvm.org/viewvc/llvm-project?rev=304275&view=rev
Log:
[CFLAA] Add missing break; note things are broken.

Thanks to Galina Kistanova for finding the missing break!

When trying to make a test for this, I realized our logic for handling
extractvalue/insertvalue/... is somewhat broken. This makes constructing
a test-case for this missing break nontrivial.

Added:
    llvm/trunk/test/Analysis/CFLAliasAnalysis/Andersen/struct.ll
Modified:
    llvm/trunk/lib/Analysis/CFLGraph.h

Modified: llvm/trunk/lib/Analysis/CFLGraph.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/CFLGraph.h?rev=304275&r1=304274&r2=304275&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/CFLGraph.h (original)
+++ llvm/trunk/lib/Analysis/CFLGraph.h Tue May 30 21:35:26 2017
@@ -210,6 +210,11 @@ template <typename CFLAA> class CFLGraph
 
     void addDerefEdge(Value *From, Value *To, bool IsRead) {
       assert(From != nullptr && To != nullptr);
+      // FIXME: This is subtly broken, due to how we model some instructions
+      // (e.g. extractvalue, extractelement) as loads. Since those take
+      // non-pointer operands, we'll entirely skip adding edges for those.
+      //
+      // addAssignEdge seems to have a similar issue with insertvalue, etc.
       if (!From->getType()->isPointerTy() || !To->getType()->isPointerTy())
         return;
       addNode(From);
@@ -540,6 +545,7 @@ template <typename CFLAA> class CFLGraph
       case Instruction::ExtractValue: {
         auto *Ptr = CE->getOperand(0);
         addLoadEdge(Ptr, CE);
+        break;
       }
       case Instruction::ShuffleVector: {
         auto *From1 = CE->getOperand(0);

Added: llvm/trunk/test/Analysis/CFLAliasAnalysis/Andersen/struct.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/CFLAliasAnalysis/Andersen/struct.ll?rev=304275&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/CFLAliasAnalysis/Andersen/struct.ll (added)
+++ llvm/trunk/test/Analysis/CFLAliasAnalysis/Andersen/struct.ll Tue May 30 21:35:26 2017
@@ -0,0 +1,18 @@
+; Ensures that our struct ops are sane.
+
+; RUN: opt < %s -disable-basicaa -cfl-anders-aa -aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
+; RUN: opt < %s -aa-pipeline=cfl-anders-aa -passes=aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
+
+; Since we ignore non-pointer values, we effectively ignore extractvalue
+; instructions. This means that %c "doesn't exist" in test_structure's graph,
+; so we currently get MayAlias.
+; XFAIL: *
+
+; CHECK-LABEL: Function: test_structure
+; CHECK: NoAlias: i64** %c, { i64**, i64** }* %a
+define void @test_structure() {
+  %a = alloca {i64**, i64**}, align 8
+  %b = load {i64**, i64**}, {i64**, i64**}* %a
+  %c = extractvalue {i64**, i64**} %b, 0
+  ret void
+}