From e09b2a0d4964e6a34ea6393e94a9f5a76ba56f1a Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Fri, 30 Sep 2011 23:19:55 +0000
Subject: [PATCH] When inferring the pointer alignment, if the global doesn't
 have an initializer and the alignment is 0 (i.e., it's defined globally in
 one file and declared in another file) it could get an alignment which is
 larger than the ABI allows for that type, resulting in aligned moves being
 used for unaligned loads.

For instance, in file A.c:

   struct S s;

In file B.c:
   struct {
     // something long
   };
   extern S s;

   void foo() {
     struct S p = s;
     // ...
   }

this copy is a 'memcpy' which is turned into a series of 'movaps' instructions
on X86. But this is wrong, because 'struct S' has alignment of 4, not 16.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140902 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/SelectionDAG.cpp |  2 ++
 test/CodeGen/X86/alignment-2.ll           | 26 +++++++++++++++++++++++
 2 files changed, 28 insertions(+)
 create mode 100644 test/CodeGen/X86/alignment-2.ll

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index d617d6710c0..6a549e8760a 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -6537,6 +6537,8 @@ unsigned SelectionDAG::InferPtrAlignment(SDValue Ptr) const {
           Align = TD->getPreferredAlignment(GVar);
         }
       }
+      if (!Align)
+        Align = TLI.getTargetData()->getABITypeAlignment(GV->getType());
     }
     return MinAlign(Align, GVOffset);
   }
diff --git a/test/CodeGen/X86/alignment-2.ll b/test/CodeGen/X86/alignment-2.ll
new file mode 100644
index 00000000000..835cf6275b2
--- /dev/null
+++ b/test/CodeGen/X86/alignment-2.ll
@@ -0,0 +1,26 @@
+; RUN: llc < %s -mtriple i386-apple-darwin10 | not grep movaps
+; <rdar://problem/10058036>
+
+%struct._psqlSettings = type { %struct.pg_conn*, i32, %struct.__sFILE*, i8, %struct.printQueryOpt, i8*, i8, i32, %struct.__sFILE*, i8, i32, i8*, i8*, i8*, i64, i8, %struct.__sFILE*, %struct._variable*, i8, i8, i8, i8, i8, i32, i32, i32, i32, i32, i8*, i8*, i8*, i32 }
+%struct.pg_conn = type opaque
+%struct.__sFILE = type { i8*, i32, i32, i16, i16, %struct.__sbuf, i32, i8*, i32 (i8*)*, i32 (i8*, i8*, i32)*, i64 (i8*, i64, i32)*, i32 (i8*, i8*, i32)*, %struct.__sbuf, %struct.__sFILEX*, i32, [3 x i8], [1 x i8], %struct.__sbuf, i32, i64 }
+%struct.__sbuf = type { i8*, i32 }
+%struct.__sFILEX = type opaque
+%struct.printQueryOpt = type { %struct.printTableOpt, i8*, i8, i8*, i8**, i8, i8, i8* }
+%struct.printTableOpt = type { i32, i8, i16, i16, i8, i8, i8, i32, %struct.printTextFormat*, i8*, i8*, i8, i8*, i32, i32, i32 }
+%struct.printTextFormat = type { i8*, [4 x %struct.printTextLineFormat], i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8 }
+%struct.printTextLineFormat = type { i8*, i8*, i8*, i8* }
+%struct._variable = type { i8*, i8*, void (i8*)*, %struct._variable* }
+%struct.pg_result = type opaque
+
+@pset = external global %struct._psqlSettings
+
+define signext i8 @do_lo_list() nounwind optsize ssp {
+bb:
+  %myopt = alloca %struct.printQueryOpt, align 4
+  %tmp = bitcast %struct.printQueryOpt* %myopt to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %tmp, i8* bitcast (%struct.printQueryOpt* getelementptr inbounds (%struct._psqlSettings* @pset, i32 0, i32 4) to i8*), i32 76, i32 4, i1 false)
+  ret i8 0
+}
+
+declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
-- 
2.34.1