[llvm] r278836 - Don't passively concatenate MDNodes

[David Majnemer via llvm-commits]

Author: majnemer
Date: Tue Aug 16 13:48:34 2016
New Revision: 278836

URL: http://llvm.org/viewvc/llvm-project?rev=278836&view=rev
Log:
Don't passively concatenate MDNodes

I have audited all the callers of concatenate and none require duplicate
entries to service concatenation.
These duplicates serve no purpose but to needlessly embiggen the IR.

N.B. Layering getMostGenericAliasScope on top of concatenate makes it
O(nlogn + mlogm) instead of O(n*m).

Modified:
    llvm/trunk/lib/IR/Metadata.cpp
    llvm/trunk/test/Transforms/InstCombine/fold-phi-load-metadata.ll

Modified: llvm/trunk/lib/IR/Metadata.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Metadata.cpp?rev=278836&r1=278835&r2=278836&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Metadata.cpp (original)
+++ llvm/trunk/lib/IR/Metadata.cpp Tue Aug 16 13:48:34 2016
@@ -16,6 +16,7 @@
 #include "MetadataImpl.h"
 #include "SymbolTableListTraitsImpl.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/IR/ConstantRange.h"
@@ -862,14 +863,12 @@ MDNode *MDNode::concatenate(MDNode *A, M
   if (!B)
     return A;
 
-  SmallVector<Metadata *, 4> MDs;
-  MDs.reserve(A->getNumOperands() + B->getNumOperands());
-  MDs.append(A->op_begin(), A->op_end());
-  MDs.append(B->op_begin(), B->op_end());
+  SmallSetVector<Metadata *, 4> MDs(A->op_begin(), A->op_end());
+  MDs.insert(B->op_begin(), B->op_end());
 
   // FIXME: This preserves long-standing behaviour, but is it really the right
   // behaviour?  Or was that an unintended side-effect of node uniquing?
-  return getOrSelfReference(A->getContext(), MDs);
+  return getOrSelfReference(A->getContext(), MDs.getArrayRef());
 }
 
 MDNode *MDNode::intersect(MDNode *A, MDNode *B) {
@@ -890,14 +889,7 @@ MDNode *MDNode::getMostGenericAliasScope
   if (!A || !B)
     return nullptr;
 
-  SmallVector<Metadata *, 4> MDs(B->op_begin(), B->op_end());
-  for (Metadata *MD : A->operands())
-    if (!is_contained(B->operands(), MD))
-      MDs.push_back(MD);
-
-  // FIXME: This preserves long-standing behaviour, but is it really the right
-  // behaviour?  Or was that an unintended side-effect of node uniquing?
-  return getOrSelfReference(A->getContext(), MDs);
+  return concatenate(A, B);
 }
 
 MDNode *MDNode::getMostGenericFPMath(MDNode *A, MDNode *B) {

Modified: llvm/trunk/test/Transforms/InstCombine/fold-phi-load-metadata.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/fold-phi-load-metadata.ll?rev=278836&r1=278835&r2=278836&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/fold-phi-load-metadata.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/fold-phi-load-metadata.ll Tue Aug 16 13:48:34 2016
@@ -40,10 +40,10 @@ return:
 ; CHECK: ![[TBAA]] = !{![[TAG1:[0-9]+]], ![[TAG1]], i64 0}
 ; CHECK: ![[TAG1]] = !{!"int", !{{[0-9]+}}, i64 0}
 ; CHECK: ![[RANGE]] = !{i32 10, i32 25}
-; CHECK: ![[ALIAS_SCOPE]] = !{![[SCOPE0:[0-9]+]], ![[SCOPE1:[0-9]+]], ![[SCOPE2:[0-9]+]]}
+; CHECK: ![[ALIAS_SCOPE]] = !{![[SCOPE0:[0-9]+]], ![[SCOPE2:[0-9]+]], ![[SCOPE1:[0-9]+]]}
 ; CHECK: ![[SCOPE0]] = distinct !{![[SCOPE0]], !{{[0-9]+}}, !"scope0"}
-; CHECK: ![[SCOPE1]] = distinct !{![[SCOPE1]], !{{[0-9]+}}, !"scope1"}
 ; CHECK: ![[SCOPE2]] = distinct !{![[SCOPE2]], !{{[0-9]+}}, !"scope2"}
+; CHECK: ![[SCOPE1]] = distinct !{![[SCOPE1]], !{{[0-9]+}}, !"scope1"}
 ; CHECK: ![[NOALIAS]] = !{![[SCOPE3:[0-9]+]]}
 ; CHECK: ![[SCOPE3]] = distinct !{![[SCOPE3]], !{{[0-9]+}}, !"scope3"}