[llvm] r275340 - [DAG] Correctly chain masked loads

[Michael Kuperstein via llvm-commits]

Author: mkuper
Date: Wed Jul 13 18:23:40 2016
New Revision: 275340

URL: http://llvm.org/viewvc/llvm-project?rev=275340&view=rev
Log:
[DAG] Correctly chain masked loads

If a masked loads is not added to the chain, it should not reset the chain's
root.

This fixes the remaining part of PR28515.

Added:
    llvm/trunk/test/CodeGen/X86/pr28515.ll
Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=275340&r1=275339&r2=275340&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Wed Jul 13 18:23:40 2016
@@ -3831,13 +3831,10 @@ void SelectionDAGBuilder::visitMaskedLoa
   I.getAAMetadata(AAInfo);
   const MDNode *Ranges = I.getMetadata(LLVMContext::MD_range);
 
-  SDValue InChain = DAG.getRoot();
-  if (AA->pointsToConstantMemory(MemoryLocation(
-          PtrOperand, DAG.getDataLayout().getTypeStoreSize(I.getType()),
-          AAInfo))) {
-    // Do not serialize (non-volatile) loads of constant memory with anything.
-    InChain = DAG.getEntryNode();
-  }
+  // Do not serialize masked loads of constant memory with anything.
+  bool AddToChain = !AA->pointsToConstantMemory(MemoryLocation(
+      PtrOperand, DAG.getDataLayout().getTypeStoreSize(I.getType()), AAInfo));
+  SDValue InChain = AddToChain ? DAG.getRoot() : InChain = DAG.getEntryNode();
 
   MachineMemOperand *MMO =
     DAG.getMachineFunction().
@@ -3847,8 +3844,10 @@ void SelectionDAGBuilder::visitMaskedLoa
 
   SDValue Load = DAG.getMaskedLoad(VT, sdl, InChain, Ptr, Mask, Src0, VT, MMO,
                                    ISD::NON_EXTLOAD);
-  SDValue OutChain = Load.getValue(1);
-  DAG.setRoot(OutChain);
+  if (AddToChain) {
+    SDValue OutChain = Load.getValue(1);
+    DAG.setRoot(OutChain);
+  }
   setValue(&I, Load);
 }
 

Added: llvm/trunk/test/CodeGen/X86/pr28515.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/pr28515.ll?rev=275340&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/pr28515.ll (added)
+++ llvm/trunk/test/CodeGen/X86/pr28515.ll Wed Jul 13 18:23:40 2016
@@ -0,0 +1,16 @@
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -mattr=+avx2 | FileCheck %s
+
+ at 0 = private constant [8 x i32] zeroinitializer
+
+; CHECK-LABEL: foo:
+; CHECK: movl  %esi, (%rdi)
+; CHECK-NEXT: retq
+define void @foo(i32* %p, i32 %v, <8 x i1> %mask) {
+  store i32 %v, i32* %p
+  %wide.masked.load = call <8 x i32> @llvm.masked.load.v8i32.p0v8i32(<8 x i32>* bitcast (i32* getelementptr ([8 x i32], [8 x i32]* @0, i64 0, i64 0) to <8 x i32>*), i32 4, <8 x i1> %mask, <8 x i32> undef)  
+  ret void
+}
+
+declare <8 x i32> @llvm.masked.load.v8i32.p0v8i32(<8 x i32>*, i32, <8 x i1>, <8 x i32>) #0
+
+attributes #0 = { argmemonly nounwind readonly }