From 87bfd7a670ab64a0f02d1b088a2f43a572024e29 Mon Sep 17 00:00:00 2001
From: Manman Ren <manman.ren@gmail.com>
Date: Tue, 22 Oct 2013 01:40:25 +0000
Subject: [PATCH] TBAA: fix PR17620.

We can have a struct type with a single field and the field does not start
with 0. In that case, we should correctly update the offset.

llvm-svn: 193137
---
 lib/Analysis/TypeBasedAliasAnalysis.cpp       |  6 ++-
 .../TypeBasedAliasAnalysis/PR17620.ll         | 51 +++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 test/Analysis/TypeBasedAliasAnalysis/PR17620.ll

diff --git a/lib/Analysis/TypeBasedAliasAnalysis.cpp b/lib/Analysis/TypeBasedAliasAnalysis.cpp
index 9026dc91143..6791d4b9102 100644
--- a/lib/Analysis/TypeBasedAliasAnalysis.cpp
+++ b/lib/Analysis/TypeBasedAliasAnalysis.cpp
@@ -231,8 +231,12 @@ namespace {
       if (Node->getNumOperands() < 2)
         return TBAAStructTypeNode();
 
-      // Special handling for a scalar type node. 
+      // Fast path for a scalar type node and a struct type node with a single
+      // field.
       if (Node->getNumOperands() <= 3) {
+        uint64_t Cur = Node->getNumOperands() == 2 ? 0 :
+                       cast<ConstantInt>(Node->getOperand(2))->getZExtValue();
+        Offset -= Cur;
         MDNode *P = dyn_cast_or_null<MDNode>(Node->getOperand(1));
         if (!P)
           return TBAAStructTypeNode();
diff --git a/test/Analysis/TypeBasedAliasAnalysis/PR17620.ll b/test/Analysis/TypeBasedAliasAnalysis/PR17620.ll
new file mode 100644
index 00000000000..a2e96d8948e
--- /dev/null
+++ b/test/Analysis/TypeBasedAliasAnalysis/PR17620.ll
@@ -0,0 +1,51 @@
+; RUN: opt < %s -O2 -S | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
+%"structA" = type { %"structB" }
+%"structB" = type { i32*, %classT }
+%classT = type { %classO, %classJ*, i8 }
+%classO = type { i32 }
+%classJ = type { i8 }
+%"classA" = type { %"classB" }
+%"classB" = type { i8 }
+%"classC" = type { %"classD", %"structA" }
+%"classD" = type { %"structA"* }
+
+; Function Attrs: ssp uwtable
+define %"structA"** @test(%"classA"* %this, i32** %p1) #0 align 2 {
+entry:
+; CHECK-LABEL: @test
+; CHECK: load i32** %p1, align 8, !tbaa
+; CHECK: load i32** inttoptr (i64 8 to i32**), align 8, !tbaa
+; CHECK: call void @callee
+  %p1.addr = alloca i32**, align 8
+  store i32** %p1, i32*** %p1.addr, align 8, !tbaa !1
+  %0 = load i32*** %p1.addr, align 8
+  %1 = load i32** %0, align 8, !tbaa !4
+  %__value_ = getelementptr inbounds %"classC"* null, i32 0, i32 1
+  %__cc = getelementptr inbounds %"structA"* %__value_, i32 0, i32 0
+  %first = getelementptr inbounds %"structB"* %__cc, i32 0, i32 0
+  %2 = load i32** %first, align 8, !tbaa !6
+  call void @callee(i32* %1, i32* %2)
+  unreachable
+}
+
+declare void @callee(i32*, i32*) #1
+
+attributes #0 = { ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.ident = !{!0}
+
+!0 = metadata !{metadata !"clang version 3.4"}
+!1 = metadata !{metadata !2, metadata !2, i64 0}
+!2 = metadata !{metadata !"omnipotent char", metadata !3, i64 0}
+!3 = metadata !{metadata !"Simple C/C++ TBAA"}
+!4 = metadata !{metadata !5, metadata !5, i64 0}
+!5 = metadata !{metadata !"any pointer", metadata !2, i64 0}
+!6 = metadata !{metadata !7, metadata !5, i64 8}
+!7 = metadata !{metadata !"_ZTSN12_GLOBAL__N_11RINS_1FIPi8TreeIterN1I1S1LENS_1KINS_1DIKS2_S3_EEEEE1GEPSD_EE", metadata !8, i64 8}
+!8 = metadata !{metadata !"_ZTSN12_GLOBAL__N_11FIPi8TreeIterN1I1S1LENS_1KINS_1DIKS1_S2_EEEEE1GE", metadata !9, i64 0}
+!9 = metadata !{metadata !"_ZTSN12_GLOBAL__N_11DIKPi8TreeIterEE", metadata !5, i64 0, metadata !10, i64 8}
+!10 = metadata !{metadata !"_ZTS8TreeIter", metadata !5, i64 8, metadata !11, i64 16}
+!11 = metadata !{metadata !"bool", metadata !2, i64 0}