Add handling of !invariant.load to PropagateMetadata.

[jlebar]

Summary

This will let e.g. the load/store vectorizer propagate this metadata
appropriately.

[mzolotukhin]

Looks good to me, thanks!

[jlebar]

FYI I haven't landed this yet because the test relies on D23477. There may be another way to test it, but the dependent patches are getting reviewed now, so unless someone else needs this in the meantime I'll probably just wait for those to get in.

llvm/trunk/lib/Analysis/VectorUtils.cpp

 }
 
 /// \returns \p I after propagating metadata from \p VL.
 Instruction *llvm::propagateMetadata(Instruction *Inst, ArrayRef<Value *> VL) {
   Instruction *I0 = cast<Instruction>(VL[0]);
   SmallVector<std::pair<unsigned, MDNode *>, 4> Metadata;
   I0->getAllMetadataOtherThanDebugLoc(Metadata);
 
-  for (auto Kind : { LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
-                     LLVMContext::MD_noalias, LLVMContext::MD_fpmath,
-                     LLVMContext::MD_nontemporal }) {
+  for (auto Kind :
+       {LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
+        LLVMContext::MD_nontemporal, LLVMContext::MD_invariant_load}) {
     MDNode *MD = I0->getMetadata(Kind);
 
     for (int J = 1, E = VL.size(); MD && J != E; ++J) {
       const Instruction *IJ = cast<Instruction>(VL[J]);
       MDNode *IMD = IJ->getMetadata(Kind);
       switch (Kind) {
       case LLVMContext::MD_tbaa:
         MD = MDNode::getMostGenericTBAA(MD, IMD);
         break;
       case LLVMContext::MD_alias_scope:
         MD = MDNode::getMostGenericAliasScope(MD, IMD);
         break;
-      case LLVMContext::MD_noalias:
-        MD = MDNode::intersect(MD, IMD);
-        break;
       case LLVMContext::MD_fpmath:
         MD = MDNode::getMostGenericFPMath(MD, IMD);
         break;
+      case LLVMContext::MD_noalias:
       case LLVMContext::MD_nontemporal:
+      case LLVMContext::MD_invariant_load:
         MD = MDNode::intersect(MD, IMD);
         break;
       default:
         llvm_unreachable("unhandled metadata");
       }
     }
 
     Inst->setMetadata(Kind, MD);
   }
 
   return Inst;
 }

llvm/trunk/test/Transforms/LoadStoreVectorizer/NVPTX/propagate-invariance-metadata.ll

+; RUN: opt -load-store-vectorizer -march=nvptx64 -mcpu=sm_35 -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-v16:16:16-v32:32:32-v64:64:64-v128:128:128-n16:32:64"
+target triple = "nvptx64-nvidia-cuda"
+
+; CHECK-LABEL: @foo
+define i32 @foo(i32* %ptr) {
+  %ptr1 = getelementptr i32, i32* %ptr, i32 1
+  %p1 = addrspacecast i32* %ptr1 to i32 addrspace(1)*
+  ; CHECK: load <2 x i32>, <2 x i32>* %{{[0-9]+}}, align 8, !invariant.load !0
+  %v0 = load i32, i32* %ptr, align 8, !invariant.load !0
+  %v1 = load i32, i32* %ptr1, align 4, !invariant.load !0
+  %sum = add i32 %v0, %v1
+  ret i32 %sum
+}
+
+!0 = !{}