Copy noalias metadata from call sites to inlined instructions

When a call site with noalias metadata is inlined, that metadata can be
propagated directly to the inlined instructions (only those that might access
memory because it is not useful on the others). Prior to inlining, the noalias
metadata could express that a call would not alias with some other memory
access, which implies that no instruction within that called function would
alias. By propagating the metadata to the inlined instructions, we preserve
that knowledge.

This should complete the enhancements requested in PR20500.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215676 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Utils/InlineFunction.cpp

@@ -356,11 +356,35 @@ static void CloneAliasScopeMetadata(CallSite CS, ValueToValueMapTy &VMap) {
     if (!NI)
       continue;
 
-    if (MDNode *M = NI->getMetadata(LLVMContext::MD_alias_scope))
-      NI->setMetadata(LLVMContext::MD_alias_scope, MDMap[M]);
+    if (MDNode *M = NI->getMetadata(LLVMContext::MD_alias_scope)) {
+      MDNode *NewMD = MDMap[M];
+      // If the call site also had alias scope metadata (a list of scopes to
+      // which instructions inside it might belong), propagate those scopes to
+      // the inlined instructions.
+      if (MDNode *CSM =
+          CS.getInstruction()->getMetadata(LLVMContext::MD_alias_scope))
+        NewMD = MDNode::concatenate(NewMD, CSM);
+      NI->setMetadata(LLVMContext::MD_alias_scope, NewMD);
+    } else if (NI->mayReadOrWriteMemory()) {
+      if (MDNode *M =
+          CS.getInstruction()->getMetadata(LLVMContext::MD_alias_scope))
+        NI->setMetadata(LLVMContext::MD_alias_scope, M);
+    }
 
-    if (MDNode *M = NI->getMetadata(LLVMContext::MD_noalias))
-      NI->setMetadata(LLVMContext::MD_noalias, MDMap[M]);
+    if (MDNode *M = NI->getMetadata(LLVMContext::MD_noalias)) {
+      MDNode *NewMD = MDMap[M];
+      // If the call site also had noalias metadata (a list of scopes with
+      // which instructions inside it don't alias), propagate those scopes to
+      // the inlined instructions.
+      if (MDNode *CSM =
+          CS.getInstruction()->getMetadata(LLVMContext::MD_noalias))
+        NewMD = MDNode::concatenate(NewMD, CSM);
+      NI->setMetadata(LLVMContext::MD_noalias, NewMD);
+    } else if (NI->mayReadOrWriteMemory()) {
+      if (MDNode *M =
+          CS.getInstruction()->getMetadata(LLVMContext::MD_noalias))
+        NI->setMetadata(LLVMContext::MD_noalias, M);
+    }
   }
 
   // Now that everything has been replaced, delete the dummy nodes.

test/Transforms/Inline/noalias-cs.ll

@@ -0,0 +1,84 @@
+; RUN: opt -inline -enable-noalias-to-md-conversion -S < %s | FileCheck %s
+target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind uwtable
+define void @foo2(float* nocapture %a, float* nocapture %b, float* nocapture readonly %c) #0 {
+entry:
+  %0 = load float* %c, align 4, !noalias !3
+  %arrayidx.i = getelementptr inbounds float* %a, i64 5
+  store float %0, float* %arrayidx.i, align 4, !alias.scope !7, !noalias !8
+  %arrayidx1.i = getelementptr inbounds float* %b, i64 8
+  store float %0, float* %arrayidx1.i, align 4, !alias.scope !8, !noalias !7
+  %1 = load float* %c, align 4
+  %arrayidx = getelementptr inbounds float* %a, i64 7
+  store float %1, float* %arrayidx, align 4
+  ret void
+}
+
+define void @foo(float* nocapture %a, float* nocapture %b, float* nocapture readonly %c) #0 {
+entry:
+  call void @foo2(float* %a, float* %b, float* %c), !noalias !0
+  call void @foo2(float* %b, float* %b, float* %a), !alias.scope !0
+  ret void
+}
+
+; CHECK: define void @foo(float* nocapture %a, float* nocapture %b, float* nocapture readonly %c) #0 {
+; CHECK: entry:
+; CHECK:   %0 = load float* %c, align 4, !noalias !6
+; CHECK:   %arrayidx.i.i = getelementptr inbounds float* %a, i64 5
+; CHECK:   store float %0, float* %arrayidx.i.i, align 4, !alias.scope !12, !noalias !13
+; CHECK:   %arrayidx1.i.i = getelementptr inbounds float* %b, i64 8
+; CHECK:   store float %0, float* %arrayidx1.i.i, align 4, !alias.scope !14, !noalias !15
+; CHECK:   %1 = load float* %c, align 4, !noalias !16
+; CHECK:   %arrayidx.i = getelementptr inbounds float* %a, i64 7
+; CHECK:   store float %1, float* %arrayidx.i, align 4, !noalias !16
+; CHECK:   %2 = load float* %a, align 4, !alias.scope !16, !noalias !17
+; CHECK:   %arrayidx.i.i1 = getelementptr inbounds float* %b, i64 5
+; CHECK:   store float %2, float* %arrayidx.i.i1, align 4, !alias.scope !21, !noalias !22
+; CHECK:   %arrayidx1.i.i2 = getelementptr inbounds float* %b, i64 8
+; CHECK:   store float %2, float* %arrayidx1.i.i2, align 4, !alias.scope !23, !noalias !24
+; CHECK:   %3 = load float* %a, align 4, !alias.scope !16
+; CHECK:   %arrayidx.i3 = getelementptr inbounds float* %b, i64 7
+; CHECK:   store float %3, float* %arrayidx.i3, align 4, !alias.scope !16
+; CHECK:   ret void
+; CHECK: }
+
+attributes #0 = { nounwind uwtable }
+
+!0 = metadata !{metadata !1}
+!1 = metadata !{metadata !1, metadata !2, metadata !"hello: %a"}
+!2 = metadata !{metadata !2, metadata !"hello"}
+!3 = metadata !{metadata !4, metadata !6}
+!4 = metadata !{metadata !4, metadata !5, metadata !"hello2: %a"}
+!5 = metadata !{metadata !5, metadata !"hello2"}
+!6 = metadata !{metadata !6, metadata !5, metadata !"hello2: %b"}
+!7 = metadata !{metadata !4}
+!8 = metadata !{metadata !6}
+
+; CHECK: !0 = metadata !{metadata !1, metadata !3}
+; CHECK: !1 = metadata !{metadata !1, metadata !2, metadata !"hello2: %a"}
+; CHECK: !2 = metadata !{metadata !2, metadata !"hello2"}
+; CHECK: !3 = metadata !{metadata !3, metadata !2, metadata !"hello2: %b"}
+; CHECK: !4 = metadata !{metadata !1}
+; CHECK: !5 = metadata !{metadata !3}
+; CHECK: !6 = metadata !{metadata !7, metadata !9, metadata !10}
+; CHECK: !7 = metadata !{metadata !7, metadata !8, metadata !"hello2: %a"}
+; CHECK: !8 = metadata !{metadata !8, metadata !"hello2"}
+; CHECK: !9 = metadata !{metadata !9, metadata !8, metadata !"hello2: %b"}
+; CHECK: !10 = metadata !{metadata !10, metadata !11, metadata !"hello: %a"}
+; CHECK: !11 = metadata !{metadata !11, metadata !"hello"}
+; CHECK: !12 = metadata !{metadata !7}
+; CHECK: !13 = metadata !{metadata !9, metadata !10}
+; CHECK: !14 = metadata !{metadata !9}
+; CHECK: !15 = metadata !{metadata !7, metadata !10}
+; CHECK: !16 = metadata !{metadata !10}
+; CHECK: !17 = metadata !{metadata !18, metadata !20}
+; CHECK: !18 = metadata !{metadata !18, metadata !19, metadata !"hello2: %a"}
+; CHECK: !19 = metadata !{metadata !19, metadata !"hello2"}
+; CHECK: !20 = metadata !{metadata !20, metadata !19, metadata !"hello2: %b"}
+; CHECK: !21 = metadata !{metadata !18, metadata !10}
+; CHECK: !22 = metadata !{metadata !20}
+; CHECK: !23 = metadata !{metadata !20, metadata !10}
+; CHECK: !24 = metadata !{metadata !18}
+