[ThinLTO] Look through aliases when computing hash keys

Without this, we don't consider types used by aliasees in our cache key.
This caused issues when using the same cache for thin-linking the same
TU with different sets of virtual call candidates for a virtual call
inside of a constructor. That's sort of a mouthful. :)

Differential Revision: https://reviews.llvm.org/D55060

llvm-svn: 348216

2 files changed, 16 insertions, 8 deletions

diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index f4840db9fe0..c1d3cadfaf9 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -221,8 +221,14 @@ void llvm::computeLTOCacheKey(
   // Imported functions may introduce new uses of type identifier resolutions,
   // so we need to collect their used resolutions as well.
   for (auto &ImpM : ImportList)
-    for (auto &ImpF : ImpM.second)
-      AddUsedThings(Index.findSummaryInModule(ImpF, ImpM.first()));
+    for (auto &ImpF : ImpM.second) {
+      GlobalValueSummary *S = Index.findSummaryInModule(ImpF, ImpM.first());
+      AddUsedThings(S);
+      // If this is an alias, we also care about any types/etc. that the aliasee
+      // may reference.
+      if (auto *AS = dyn_cast_or_null<AliasSummary>(S))
+        AddUsedThings(AS->getBaseObject());
+    }
 
   auto AddTypeIdSummary = [&](StringRef TId, const TypeIdSummary &S) {
     AddString(TId);
diff --git a/llvm/test/ThinLTO/X86/cache-typeid-resolutions.ll b/llvm/test/ThinLTO/X86/cache-typeid-resolutions.ll
index 1609e90b0ae..e5092dd63ec 100644
--- a/llvm/test/ThinLTO/X86/cache-typeid-resolutions.ll
+++ b/llvm/test/ThinLTO/X86/cache-typeid-resolutions.ll
@@ -9,23 +9,25 @@
 ; where both t and t-import are sensitive to typeid1's resolution
 ; so 4 distinct objects in total.
 ; RUN: rm -rf %t.cache
-; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
-; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t1.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx -r=%t1.bc,vt1,plx
+; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f1_actual,plx -r=%t.bc,f2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
+; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t1.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f1_actual,plx -r=%t.bc,f2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx -r=%t1.bc,vt1,plx
 ; RUN: ls %t.cache | count 4
 
 ; Three resolutions for typeid2: Indir, SingleImpl, UniqueRetVal
 ; where both t and t-import are sensitive to typeid2's resolution
 ; so 6 distinct objects in total.
 ; RUN: rm -rf %t.cache
-; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
-; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t2.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t2.bc,vt2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
-; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t3.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t3.bc,vt2a,plx -r=%t3.bc,vt2b,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
+; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t.bc,f1_actual,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
+; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t2.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t.bc,f1_actual,plx -r=%t2.bc,vt2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
+; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t3.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t.bc,f1_actual,plx -r=%t3.bc,vt2a,plx -r=%t3.bc,vt2b,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
 ; RUN: ls %t.cache | count 6
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
-define i1 @f1(i8* %p) {
+@f1 = alias i1(i8*), i1 (i8*)* @f1_actual
+
+define i1 @f1_actual(i8* %p) {
   %x = call i1 @llvm.type.test(i8* %p, metadata !"typeid1")
   ret i1 %x
 }