7 files changed, 157 insertions, 3 deletions
diff --git a/llvm/lib/Analysis/CFLAliasAnalysis.cpp b/llvm/lib/Analysis/CFLAliasAnalysis.cpp
index db94f2868c4..0386afeb23a 100644
--- a/llvm/lib/Analysis/CFLAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/CFLAliasAnalysis.cpp
@@ -986,9 +986,17 @@ CFLAliasAnalysis::query(const AliasAnalysis::Location &LocA,
 
   auto AttrsA = Sets.getLink(SetA.Index).Attrs;
   auto AttrsB = Sets.getLink(SetB.Index).Attrs;
-  auto CombinedAttrs = AttrsA | AttrsB;
-  if (CombinedAttrs.any())
-    return AliasAnalysis::PartialAlias;
+  // Stratified set attributes are used as markets to signify whether a member
+  // of a StratifiedSet (or a member of a set above the current set) has 
+  // interacted with either arguments or globals. "Interacted with" meaning
+  // its value may be different depending on the value of an argument or 
+  // global. The thought behind this is that, because arguments and globals
+  // may alias each other, if AttrsA and AttrsB have touched args/globals,
+  // we must conservatively say that they alias. However, if at least one of 
+  // the sets has no values that could legally be altered by changing the value 
+  // of an argument or global, then we don't have to be as conservative.
+  if (AttrsA.any() && AttrsB.any())
+    return AliasAnalysis::MayAlias;
 
   return AliasAnalysis::NoAlias;
 }
diff --git a/llvm/test/Analysis/CFLAliasAnalysis/arguments-globals.ll b/llvm/test/Analysis/CFLAliasAnalysis/arguments-globals.ll
new file mode 100644
index 00000000000..18bbe8b6b41
--- /dev/null
+++ b/llvm/test/Analysis/CFLAliasAnalysis/arguments-globals.ll
@@ -0,0 +1,20 @@
+; This testcase ensures that CFL AA gives conservative answers on variables
+; that involve arguments.
+; (Everything should alias everything, because args can alias globals, so the
+; aliasing sets should of args+alloca+global should be combined)
+
+; RUN: opt < %s -cfl-aa -aa-eval -print-may-aliases -disable-output 2>&1 | FileCheck %s
+
+; CHECK:     Function: test
+
+@g = external global i32
+
+define void @test(i1 %c, i32* %arg1, i32* %arg2) {
+  ; CHECK: 15 Total Alias Queries Performed
+  ; CHECK: 0 no alias responses
+  %A = alloca i32, align 4
+  %B = select i1 %c, i32* %arg1, i32* %arg2
+  %C = select i1 %c, i32* @g, i32* %A
+
+  ret void
+}
diff --git a/llvm/test/Analysis/CFLAliasAnalysis/arguments.ll b/llvm/test/Analysis/CFLAliasAnalysis/arguments.ll
new file mode 100644
index 00000000000..f3e6679c35e
--- /dev/null
+++ b/llvm/test/Analysis/CFLAliasAnalysis/arguments.ll
@@ -0,0 +1,15 @@
+; This testcase ensures that CFL AA gives conservative answers on variables
+; that involve arguments.
+
+; RUN: opt < %s -cfl-aa -aa-eval -print-may-aliases -disable-output 2>&1 | FileCheck %s
+
+; CHECK:     Function: test
+
+define void @test(i1 %c, i32* %arg1, i32* %arg2) {
+  ; CHECK: 6 Total Alias Queries Performed
+  ; CHECK: 3 no alias responses
+  %a = alloca i32, align 4
+  %b = select i1 %c, i32* %arg1, i32* %arg2
+
+  ret void
+}
diff --git a/llvm/test/Analysis/CFLAliasAnalysis/basic-interproc-ret.ll b/llvm/test/Analysis/CFLAliasAnalysis/basic-interproc-ret.ll
new file mode 100644
index 00000000000..d56a4552b51
--- /dev/null
+++ b/llvm/test/Analysis/CFLAliasAnalysis/basic-interproc-ret.ll
@@ -0,0 +1,26 @@
+; This testcase ensures that CFL AA gives conservative answers on variables
+; that involve arguments.
+
+; RUN: opt < %s -cfl-aa -aa-eval -print-may-aliases -disable-output 2>&1 | FileCheck %s
+
+; CHECK:     Function: test
+; CHECK: 4 Total Alias Queries Performed
+; CHECK: 3 no alias responses
+; ^ The 1 MayAlias is due to %arg1. Sadly, we don't currently have machinery
+; in place to check whether %arg1 aliases %a, because BasicAA takes care of 
+; that for us.
+
+define i32* @test2(i32* %arg1) {
+  store i32 0, i32* %arg1
+
+  %a = alloca i32, align 4
+  ret i32* %a
+}
+
+define void @test() {
+  %a = alloca i32, align 4
+  %b = alloca i32, align 4
+  %c = call i32* @test2(i32* %a)
+
+  ret void
+}
diff --git a/llvm/test/Analysis/CFLAliasAnalysis/basic-interproc.ll b/llvm/test/Analysis/CFLAliasAnalysis/basic-interproc.ll
new file mode 100644
index 00000000000..c0a5404eab6
--- /dev/null
+++ b/llvm/test/Analysis/CFLAliasAnalysis/basic-interproc.ll
@@ -0,0 +1,24 @@
+; This testcase ensures that CFL AA gives conservative answers on variables
+; that involve arguments.
+
+; RUN: opt < %s -cfl-aa -aa-eval -print-may-aliases -disable-output 2>&1 | FileCheck %s
+
+; CHECK:     Function: test
+; CHECK: 2 Total Alias Queries Performed
+; CHECK: 1 no alias responses
+; ^^ In @test2, %arg1 and %arg2 may alias
+
+define void @test2(i32* %arg1, i32* %arg2) {
+  store i32 0, i32* %arg1
+  store i32 0, i32* %arg2
+
+  ret void
+}
+
+define void @test() {
+  %a = alloca i32, align 4
+  %b = alloca i32, align 4
+  call void @test2(i32* %a, i32* %b)
+
+  ret void
+}
diff --git a/llvm/test/Analysis/CFLAliasAnalysis/multilevel-combine.ll b/llvm/test/Analysis/CFLAliasAnalysis/multilevel-combine.ll
new file mode 100644
index 00000000000..9bbc721a7b1
--- /dev/null
+++ b/llvm/test/Analysis/CFLAliasAnalysis/multilevel-combine.ll
@@ -0,0 +1,31 @@
+; This testcase ensures that CFL AA responds conservatively when we union 
+; groups of pointers together through ternary/conditional operations
+; Derived from:
+; void foo(bool c) {
+;   char a, b;
+;   char *m = c ? &a : &b;
+;   *m;
+; }
+;
+
+; RUN: opt < %s -cfl-aa -aa-eval -print-may-aliases -disable-output 2>&1 | FileCheck %s
+
+%T = type { i32, [10 x i8] }
+
+; CHECK:     Function: test
+
+define void @test(i1 %C) {
+; CHECK: 10 Total Alias Queries Performed
+; CHECK: 4 no alias responses
+  %M = alloca %T*, align 8 ; NoAlias with %A, %B, %MS, %AP
+  %A = alloca %T, align 8
+  %B = alloca %T, align 8
+
+  %MS = select i1 %C, %T* %B, %T* %A
+
+  store %T* %MS, %T** %M
+
+  %AP = load %T** %M ; PartialAlias with %A, %B
+
+  ret void
+}
diff --git a/llvm/test/Analysis/CFLAliasAnalysis/multilevel.ll b/llvm/test/Analysis/CFLAliasAnalysis/multilevel.ll
new file mode 100644
index 00000000000..9c9eb9a4977
--- /dev/null
+++ b/llvm/test/Analysis/CFLAliasAnalysis/multilevel.ll
@@ -0,0 +1,30 @@
+; This testcase ensures that CFL AA handles trivial cases with storing 
+; pointers in pointers appropriately.
+; Derived from:
+; char a, b;
+; char *m = &a, *n = &b;
+; *m;
+; *n;
+
+; RUN: opt < %s -cfl-aa -aa-eval -print-may-aliases -disable-output 2>&1 | FileCheck %s
+
+%T = type { i32, [10 x i8] }
+
+; CHECK:     Function: test
+
+define void @test() {
+; CHECK: 15 Total Alias Queries Performed
+; CHECK: 13 no alias responses
+  %M = alloca %T*, align 8
+  %N = alloca %T*, align 8
+  %A = alloca %T, align 8
+  %B = alloca %T, align 8
+
+  store %T* %A, %T** %M
+  store %T* %B, %T** %N
+
+  %AP = load %T** %M ; PartialAlias with %A
+  %BP = load %T** %N ; PartialAlias with %B
+
+  ret void
+}