[PATCH] D37028: [IRBuilder] Only emit alias scop metadata for arrays, but not scalars

[Tobias Grosser via Phabricator via llvm-commits]

grosser created this revision.
grosser added a project: Polly.

There is no need to emit alias metadata for scalars, as basicaa will easily
distinguish them from arrays. This reduces the size of the metadata we generate.
This is especially useful after we moved to -polly-position=before-vectorizer,
where a lot more scalar dependences are introduced, which increased the size of
the alias analysis metadata and made us commonly reach the limits after which
we do not emit alias metadata that have been introduced to prevent quadratic
growth of this alias metadata.


https://reviews.llvm.org/D37028

Files:
  lib/CodeGen/IRBuilder.cpp
  test/Isl/CodeGen/MemAccess/create_arrays.ll
  test/ScheduleOptimizer/pattern-matching-based-opts_10.ll


Index: test/ScheduleOptimizer/pattern-matching-based-opts_10.ll
===================================================================
--- test/ScheduleOptimizer/pattern-matching-based-opts_10.ll
+++ test/ScheduleOptimizer/pattern-matching-based-opts_10.ll
@@ -12,13 +12,13 @@
 ; This test case checks whether Polly generates second level alias metadata
 ; to distinguish the specific accesses in case of the ublas gemm kernel.
 ;
-; CHECK: !13 = distinct !{!13, !0, !"second level alias metadata"}
+; CHECK: !11 = distinct !{!11, !0, !"second level alias metadata"}
+; CHECK: !12 = distinct !{!12, !0, !"second level alias metadata"}
+; CHECK: !13 = !{!3, !4, !5, !6, !11}
 ; CHECK: !14 = distinct !{!14, !0, !"second level alias metadata"}
-; CHECK: !15 = !{!3, !4, !5, !6, !7, !8, !13}
+; CHECK: !15 = !{!3, !4, !5, !6, !11, !12}
 ; CHECK: !16 = distinct !{!16, !0, !"second level alias metadata"}
-; CHECK: !17 = !{!3, !4, !5, !6, !7, !8, !13, !14}
-; CHECK: !18 = distinct !{!18, !0, !"second level alias metadata"}
-; CHECK: !19 = !{!3, !4, !5, !6, !7, !8, !13, !14, !16}
+; CHECK: !17 = !{!3, !4, !5, !6, !11, !12, !14}
 ;
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-unknown"
Index: test/Isl/CodeGen/MemAccess/create_arrays.ll
===================================================================
--- test/Isl/CodeGen/MemAccess/create_arrays.ll
+++ test/Isl/CodeGen/MemAccess/create_arrays.ll
@@ -32,15 +32,14 @@
 ; CODEGEN:  {{%.*}} = load double, double* %polly.access.E, align 8, !alias.scope [[TAG0:![0-9]+]], !noalias [[TAG2:![0-9]+]]
 ; CODEGEN:  store double {{%.*}}, double* %scevgep36, align 8, !alias.scope [[TAG5:![0-9]+]], !noalias [[TAG8:![0-9]+]]
 ;
-; CODEGEN-DAG: [[TAG0]] = distinct !{[[TAG0]], [[TAG1:![0-9]+]], !"polly.alias.scope.E"}
-; CODEGEN-DAG: [[TAG1]] = distinct !{[[TAG1]], !"polly.alias.scope.domain"}
-; CODEGEN-DAG: [[TAG2]] = !{[[TAG3:![0-9]+]], [[TAG4:![0-9]+]], [[TAG5:![0-9]+]], [[TAG6:![0-9]+]], [[TAG7:![0-9]+]]}
-; CODEGEN-DAG: [[TAG3]] = distinct !{[[TAG3]], [[TAG1]], !"polly.alias.scope.MemRef_B"}
-; CODEGEN-DAG: [[TAG4]] = distinct !{[[TAG4]], [[TAG1]], !"polly.alias.scope.MemRef_beta"}
-; CODEGEN-DAG: [[TAG5]] = distinct !{[[TAG5]], [[TAG1]], !"polly.alias.scope.MemRef_A"}
-; CODEGEN-DAG: [[TAG6]] = distinct !{[[TAG6]], [[TAG1]], !"polly.alias.scope.D"}
-; CODEGEN-DAG: [[TAG7]] = distinct !{[[TAG7]], [[TAG1]], !"polly.alias.scope.F"}
-; CODEGEN-DAG: [[TAG8]] = !{[[TAG3]], [[TAG4]], [[TAG6]], [[TAG0]], [[TAG7]]}
+; CODEGEN: [[TAG0]] = distinct !{[[TAG0]], [[TAG1:![0-9]+]], !"polly.alias.scope.E"}
+; CODEGEN: [[TAG1]] = distinct !{[[TAG1]], !"polly.alias.scope.domain"}
+; CODEGEN: [[TAG2]] = !{[[TAG3:![0-9]+]], [[TAG4:![0-9]+]], [[TAG5:![0-9]+]], [[TAG6:![0-9]+]]}
+; CODEGEN: [[TAG3]] = distinct !{[[TAG3]], [[TAG1]], !"polly.alias.scope.MemRef_B"}
+; CODEGEN: [[TAG4]] = distinct !{[[TAG4]], [[TAG1]], !"polly.alias.scope.MemRef_A"}
+; CODEGEN: [[TAG5]] = distinct !{[[TAG5]], [[TAG1]], !"polly.alias.scope.D"}
+; CODEGEN: [[TAG6]] = distinct !{[[TAG6]], [[TAG1]], !"polly.alias.scope.F"}
+; CODEGEN: [[TAG7:![0-9]+]] = !{[[TAG3]], [[TAG5]], [[TAG0]], [[TAG6]]}
 ;
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-unknown"
Index: lib/CodeGen/IRBuilder.cpp
===================================================================
--- lib/CodeGen/IRBuilder.cpp
+++ lib/CodeGen/IRBuilder.cpp
@@ -60,21 +60,28 @@
   AliasScopeMap.clear();
   OtherAliasScopeListMap.clear();
 
+  // We are only interested in arrays, but no scalar references. Scalars should
+  // be handled easily by basicaa.
+  std::vector<ScopArrayInfo *> Arrays;
+  for (ScopArrayInfo *Array : S.arrays())
+    if (Array->isArrayKind())
+      Arrays.push_back(Array);
+
   // The construction of alias scopes is quadratic in the number of arrays
   // involved. In case of too many arrays, skip the construction of alias
   // information to avoid quadratic increases in compile time and code size.
-  if (std::distance(S.array_begin(), S.array_end()) > MaxArraysInAliasScops)
+  if (Arrays.size() > MaxArraysInAliasScops)
     return;
 
   std::string AliasScopeStr = "polly.alias.scope.";
-  for (const ScopArrayInfo *Array : S.arrays()) {
+  for (const ScopArrayInfo *Array : Arrays) {
     assert(Array->getBasePtr() && "Base pointer must be present");
     AliasScopeMap[Array->getBasePtr()] =
         getID(Ctx, AliasScopeDomain,
               MDString::get(Ctx, (AliasScopeStr + Array->getName()).c_str()));
   }
 
-  for (const ScopArrayInfo *Array : S.arrays()) {
+  for (const ScopArrayInfo *Array : Arrays) {
     MDNode *AliasScopeList = MDNode::get(Ctx, {});
     for (const auto &AliasScopePair : AliasScopeMap) {
       if (Array->getBasePtr() == AliasScopePair.first)


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