[InstCombine] Retain TBAA when narrowing memory accesses
Summary:
As discussed on the mailing list it is legal to propagate TBAA to loads/stores
from/to smaller regions of a larger load tagged with TBAA. Do so for
(load->extractvalue)=>(gep->load) and similar foldings.
Reviewed By: sanjoy
Differential Revision: https://reviews.llvm.org/D31954
llvm-svn: 306615
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index ca370c7..26bee20 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -661,6 +661,9 @@
if (NumElements == 1) {
LoadInst *NewLoad = combineLoadToNewType(IC, LI, ST->getTypeAtIndex(0U),
".unpack");
+ AAMDNodes AAMD;
+ LI.getAAMetadata(AAMD);
+ NewLoad->setAAMetadata(AAMD);
return IC.replaceInstUsesWith(LI, IC.Builder->CreateInsertValue(
UndefValue::get(T), NewLoad, 0, Name));
}
@@ -690,6 +693,10 @@
Name + ".elt");
auto EltAlign = MinAlign(Align, SL->getElementOffset(i));
auto *L = IC.Builder->CreateAlignedLoad(Ptr, EltAlign, Name + ".unpack");
+ // Propagate AA metadata. It'll still be valid on the narrowed load.
+ AAMDNodes AAMD;
+ LI.getAAMetadata(AAMD);
+ L->setAAMetadata(AAMD);
V = IC.Builder->CreateInsertValue(V, L, i);
}
@@ -702,6 +709,9 @@
auto NumElements = AT->getNumElements();
if (NumElements == 1) {
LoadInst *NewLoad = combineLoadToNewType(IC, LI, ET, ".unpack");
+ AAMDNodes AAMD;
+ LI.getAAMetadata(AAMD);
+ NewLoad->setAAMetadata(AAMD);
return IC.replaceInstUsesWith(LI, IC.Builder->CreateInsertValue(
UndefValue::get(T), NewLoad, 0, Name));
}
@@ -734,6 +744,9 @@
Name + ".elt");
auto *L = IC.Builder->CreateAlignedLoad(Ptr, MinAlign(Align, Offset),
Name + ".unpack");
+ AAMDNodes AAMD;
+ LI.getAAMetadata(AAMD);
+ L->setAAMetadata(AAMD);
V = IC.Builder->CreateInsertValue(V, L, i);
Offset += EltSize;
}
@@ -1192,7 +1205,11 @@
AddrName);
auto *Val = IC.Builder->CreateExtractValue(V, i, EltName);
auto EltAlign = MinAlign(Align, SL->getElementOffset(i));
- IC.Builder->CreateAlignedStore(Val, Ptr, EltAlign);
+ llvm::Instruction *NS =
+ IC.Builder->CreateAlignedStore(Val, Ptr, EltAlign);
+ AAMDNodes AAMD;
+ SI.getAAMetadata(AAMD);
+ NS->setAAMetadata(AAMD);
}
return true;
@@ -1239,7 +1256,10 @@
AddrName);
auto *Val = IC.Builder->CreateExtractValue(V, i, EltName);
auto EltAlign = MinAlign(Align, Offset);
- IC.Builder->CreateAlignedStore(Val, Ptr, EltAlign);
+ Instruction *NS = IC.Builder->CreateAlignedStore(Val, Ptr, EltAlign);
+ AAMDNodes AAMD;
+ SI.getAAMetadata(AAMD);
+ NS->setAAMetadata(AAMD);
Offset += EltSize;
}
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 02fac4f..7234146 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2425,9 +2425,15 @@
Builder->SetInsertPoint(L);
Value *GEP = Builder->CreateInBoundsGEP(L->getType(),
L->getPointerOperand(), Indices);
+ Instruction *NL = Builder->CreateLoad(GEP);
+ // Whatever aliasing information we had for the orignal load must also
+ // hold for the smaller load, so propagate the annotations.
+ AAMDNodes Nodes;
+ L->getAAMetadata(Nodes);
+ NL->setAAMetadata(Nodes);
// Returning the load directly will cause the main loop to insert it in
// the wrong spot, so use replaceInstUsesWith().
- return replaceInstUsesWith(EV, Builder->CreateLoad(GEP));
+ return replaceInstUsesWith(EV, NL);
}
// We could simplify extracts from other values. Note that nested extracts may
// already be simplified implicitly by the above: extract (extract (insert) )