Handle the new !tbaa.struct metadata tags when converting a memcpy into scalar

loads and stores.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163844 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 1b389b92e8daf612d540ac1ff46ea41ba076bc93..486dd1312a4ca9faa2bb5e7c11aca81382ce82e9 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -94,6 +94,7 @@ Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
   // dest address will be promotable.  See if we can find a better type than the
   // integer datatype.
   Value *StrippedDest = MI->getArgOperand(0)->stripPointerCasts();
+  MDNode *CopyMD = 0;
   if (StrippedDest != MI->getArgOperand(0)) {
     Type *SrcETy = cast<PointerType>(StrippedDest->getType())
                                     ->getElementType();
@@ -105,6 +106,18 @@ Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
       if (SrcETy->isSingleValueType()) {
         NewSrcPtrTy = PointerType::get(SrcETy, SrcAddrSp);
         NewDstPtrTy = PointerType::get(SrcETy, DstAddrSp);
+
+        // If the memcpy has metadata describing the members, see if we can
+        // get the TBAA tag describing our copy.
+        if (MDNode *M = MI->getMetadata(LLVMContext::MD_tbaa_struct)) {
+          if (M->getNumOperands() == 3 &&
+              isa<ConstantInt>(M->getOperand(0)) &&
+              cast<ConstantInt>(M->getOperand(0))->isNullValue() &&
+              isa<ConstantInt>(M->getOperand(1)) &&
+              cast<ConstantInt>(M->getOperand(1))->getValue() == Size &&
+              isa<MDNode>(M->getOperand(2)))
+            CopyMD = cast<MDNode>(M->getOperand(2));
+        }
       }
     }
   }
@@ -118,8 +131,12 @@ Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
   Value *Dest = Builder->CreateBitCast(MI->getArgOperand(0), NewDstPtrTy);
   LoadInst *L = Builder->CreateLoad(Src, MI->isVolatile());
   L->setAlignment(SrcAlign);
+  if (CopyMD)
+    L->setMetadata(LLVMContext::MD_tbaa, CopyMD);
   StoreInst *S = Builder->CreateStore(L, Dest, MI->isVolatile());
   S->setAlignment(DstAlign);
+  if (CopyMD)
+    S->setMetadata(LLVMContext::MD_tbaa, CopyMD);
 
   // Set the size of the copy to 0, it will be deleted on the next iteration.
   MI->setArgOperand(2, Constant::getNullValue(MemOpLength->getType()));

diff --git a/test/Transforms/InstCombine/struct-assign-tbaa.ll b/test/Transforms/InstCombine/struct-assign-tbaa.ll
new file mode 100644 (file)
index 0000000..4fbdb0a
--- /dev/null
+++ b/test/Transforms/InstCombine/struct-assign-tbaa.ll
@@ -0,0 +1,26 @@
+; RUN: opt -instcombine -S < %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"
+
+%struct.foo = type { float }
+
+; Verify that instcombine preserves TBAA tags when converting a memcpy into
+; a scalar load and store.
+
+; CHECK: %2 = load float* %0, align 4, !tbaa !0
+; CHECK: store float %2, float* %1, align 4, !tbaa !0
+; CHECK: !0 = metadata !{metadata !"float", metadata !1}
+define void @test(%struct.foo* nocapture %a, %struct.foo* nocapture %b) {
+entry:
+  %0 = bitcast %struct.foo* %a to i8*
+  %1 = bitcast %struct.foo* %b to i8*
+  tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %0, i8* %1, i64 4, i32 4, i1 false), !tbaa.struct !3
+  ret void
+}
+
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind
+
+!0 = metadata !{metadata !"Simple C/C++ TBAA"}
+!1 = metadata !{metadata !"omnipotent char", metadata !0}
+!2 = metadata !{metadata !"float", metadata !0}
+!3 = metadata !{i64 0, i64 4, metadata !2}