From f9172d3c7b2af5e5712ea330a06e33e9c1ced051 Mon Sep 17 00:00:00 2001
From: Nikita Popov <nikita.ppv@gmail.com>
Date: Sun, 18 Oct 2020 16:41:44 +0200
Subject: [PATCH] [AA] Add helper to update result (NFC)

This pattern was repeated a few times, and for some reason always
using insert or try_emplace, even though we know in advance that
we're looking for an existing entry and not trying to create a
new one.
---
 llvm/include/llvm/Analysis/AliasAnalysis.h |  6 +++++
 llvm/lib/Analysis/BasicAliasAnalysis.cpp   | 41 ++++++++----------------------
 2 files changed, 17 insertions(+), 30 deletions(-)

diff --git a/llvm/include/llvm/Analysis/AliasAnalysis.h b/llvm/include/llvm/Analysis/AliasAnalysis.h
index 1e60dd6..35ee7f4 100644
--- a/llvm/include/llvm/Analysis/AliasAnalysis.h
+++ b/llvm/include/llvm/Analysis/AliasAnalysis.h
@@ -349,6 +349,12 @@ public:
   IsCapturedCacheT IsCapturedCache;
 
   AAQueryInfo() : AliasCache(), IsCapturedCache() {}
+
+  AliasResult updateResult(const LocPair &Locs, AliasResult Result) {
+    auto It = AliasCache.find(Locs);
+    assert(It != AliasCache.end() && "Entry must have existed");
+    return It->second = Result;
+  }
 };
 
 class BatchAAResults;
diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index aac36f3..5baf31e 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1577,12 +1577,8 @@ AliasResult BasicAAResult::aliasPHI(const PHINode *PN, LocationSize PNSize,
       }
 
       // Reset if speculation failed.
-      if (Alias != NoAlias) {
-        auto Pair =
-            AAQI.AliasCache.insert(std::make_pair(Locs, OrigAliasResult));
-        assert(!Pair.second && "Entry must have existed");
-        Pair.first->second = OrigAliasResult;
-      }
+      if (Alias != NoAlias)
+        AAQI.updateResult(Locs, OrigAliasResult);
       return Alias;
     }
 
@@ -1801,12 +1797,8 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
   if (const GEPOperator *GV1 = dyn_cast<GEPOperator>(V1)) {
     AliasResult Result =
         aliasGEP(GV1, V1Size, V1AAInfo, V2, V2Size, V2AAInfo, O1, O2, AAQI);
-    if (Result != MayAlias) {
-      auto ItInsPair = AAQI.AliasCache.insert(std::make_pair(Locs, Result));
-      assert(!ItInsPair.second && "Entry must have existed");
-      ItInsPair.first->second = Result;
-      return Result;
-    }
+    if (Result != MayAlias)
+      return AAQI.updateResult(Locs, Result);
   }
 
   if (isa<PHINode>(V2) && !isa<PHINode>(V1)) {
@@ -1818,11 +1810,8 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
   if (const PHINode *PN = dyn_cast<PHINode>(V1)) {
     AliasResult Result =
         aliasPHI(PN, V1Size, V1AAInfo, V2, V2Size, V2AAInfo, O2, AAQI);
-    if (Result != MayAlias) {
-      Pair = AAQI.AliasCache.try_emplace(Locs, Result);
-      assert(!Pair.second && "Entry must have existed");
-      return Pair.first->second = Result;
-    }
+    if (Result != MayAlias)
+      return AAQI.updateResult(Locs, Result);
   }
 
   if (isa<SelectInst>(V2) && !isa<SelectInst>(V1)) {
@@ -1834,11 +1823,8 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
   if (const SelectInst *S1 = dyn_cast<SelectInst>(V1)) {
     AliasResult Result =
         aliasSelect(S1, V1Size, V1AAInfo, V2, V2Size, V2AAInfo, O2, AAQI);
-    if (Result != MayAlias) {
-      Pair = AAQI.AliasCache.try_emplace(Locs, Result);
-      assert(!Pair.second && "Entry must have existed");
-      return Pair.first->second = Result;
-    }
+    if (Result != MayAlias)
+      return AAQI.updateResult(Locs, Result);
   }
 
   // If both pointers are pointing into the same object and one of them
@@ -1846,19 +1832,14 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
   if (O1 == O2)
     if (V1Size.isPrecise() && V2Size.isPrecise() &&
         (isObjectSize(O1, V1Size.getValue(), DL, TLI, NullIsValidLocation) ||
-         isObjectSize(O2, V2Size.getValue(), DL, TLI, NullIsValidLocation))) {
-      Pair = AAQI.AliasCache.try_emplace(Locs, PartialAlias);
-      assert(!Pair.second && "Entry must have existed");
-      return Pair.first->second = PartialAlias;
-    }
+         isObjectSize(O2, V2Size.getValue(), DL, TLI, NullIsValidLocation)))
+      return AAQI.updateResult(Locs, PartialAlias);
 
   // Recurse back into the best AA results we have, potentially with refined
   // memory locations. We have already ensured that BasicAA has a MayAlias
   // cache result for these, so any recursion back into BasicAA won't loop.
   AliasResult Result = getBestAAResults().alias(Locs.first, Locs.second, AAQI);
-  Pair = AAQI.AliasCache.try_emplace(Locs, Result);
-  assert(!Pair.second && "Entry must have existed");
-  return Pair.first->second = Result;
+  return AAQI.updateResult(Locs, Result);
 }
 
 /// Check whether two Values can be considered equivalent.
-- 
2.7.4