From 594d93848abbc5aed0f49bedd5cd1163dc424272 Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev@redking.me.uk>
Date: Fri, 17 Aug 2018 15:54:07 +0000
Subject: [PATCH] [TableGen] TypeInfer - Cache the legal types as
 TypeSetByHwMode

We were just caching the MVT set of legal types, then every call creating a new TypeSetByHwMode with it and passing it back on the stack. There's no need to do this - we can create and cache the whole TypeSetByHwMode once and return a const reference to it each time.

Additionally, TypeInfer::expandOverloads wasn't making use of the fact that the cache just contains a default mode containing all the types.

Saves up to 30secs in debug builds of x86 -gen-dag-isel.

Differential Revision: https://reviews.llvm.org/D50903

llvm-svn: 340042
---
 utils/TableGen/CodeGenDAGPatterns.cpp | 25 ++++++++++---------------
 utils/TableGen/CodeGenDAGPatterns.h   |  6 +++---
 2 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/utils/TableGen/CodeGenDAGPatterns.cpp b/utils/TableGen/CodeGenDAGPatterns.cpp
index c9dc8a96c8c..dc88da220e8 100644
--- a/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -740,17 +740,12 @@ bool TypeInfer::EnforceSameSize(TypeSetByHwMode &A, TypeSetByHwMode &B) {
 
 void TypeInfer::expandOverloads(TypeSetByHwMode &VTS) {
   ValidateOnExit _1(VTS, *this);
-  TypeSetByHwMode Legal = getLegalTypes();
-  bool HaveLegalDef = Legal.hasDefault();
+  const TypeSetByHwMode &Legal = getLegalTypes();
+  assert(Legal.isDefaultOnly() && "Default-mode only expected");
+  const TypeSetByHwMode::SetType &LegalTypes = Legal.get(DefaultMode);
 
-  for (auto &I : VTS) {
-    unsigned M = I.first;
-    if (!Legal.hasMode(M) && !HaveLegalDef) {
-      TP.error("Invalid mode " + Twine(M));
-      return;
-    }
-    expandOverloads(I.second, Legal.get(M));
-  }
+  for (auto &I : VTS)
+    expandOverloads(I.second, LegalTypes);
 }
 
 void TypeInfer::expandOverloads(TypeSetByHwMode::SetType &Out,
@@ -802,17 +797,17 @@ void TypeInfer::expandOverloads(TypeSetByHwMode::SetType &Out,
   }
 }
 
-TypeSetByHwMode TypeInfer::getLegalTypes() {
+const TypeSetByHwMode &TypeInfer::getLegalTypes() {
   if (!LegalTypesCached) {
+    TypeSetByHwMode::SetType &LegalTypes = LegalCache.getOrCreate(DefaultMode);
     // Stuff all types from all modes into the default mode.
     const TypeSetByHwMode &LTS = TP.getDAGPatterns().getLegalTypes();
     for (const auto &I : LTS)
-      LegalCache.insert(I.second);
+      LegalTypes.insert(I.second);
     LegalTypesCached = true;
   }
-  TypeSetByHwMode VTS;
-  VTS.getOrCreate(DefaultMode) = LegalCache;
-  return VTS;
+  assert(LegalCache.isDefaultOnly() && "Default-mode only expected");
+  return LegalCache;
 }
 
 #ifndef NDEBUG
diff --git a/utils/TableGen/CodeGenDAGPatterns.h b/utils/TableGen/CodeGenDAGPatterns.h
index 9be3816cc7f..104feb90792 100644
--- a/utils/TableGen/CodeGenDAGPatterns.h
+++ b/utils/TableGen/CodeGenDAGPatterns.h
@@ -350,11 +350,11 @@ struct TypeInfer {
   bool Validate = true;   // Indicate whether to validate types.
 
 private:
-  TypeSetByHwMode getLegalTypes();
+  const TypeSetByHwMode &getLegalTypes();
 
-  /// Cached legal types.
+  /// Cached legal types (in default mode).
   bool LegalTypesCached = false;
-  TypeSetByHwMode::SetType LegalCache = {};
+  TypeSetByHwMode LegalCache;
 };
 
 /// Set type used to track multiply used variables in patterns