[llvm] d5b701b - [ThinLTO] Import globals recursively

[Evgeny Leviant via llvm-commits]

Author: Evgeny Leviant
Date: 2020-08-20T12:13:43+03:00
New Revision: d5b701b9727d6c4bb919369d668f2d07a4a30e22

URL: https://github.com/llvm/llvm-project/commit/d5b701b9727d6c4bb919369d668f2d07a4a30e22
DIFF: https://github.com/llvm/llvm-project/commit/d5b701b9727d6c4bb919369d668f2d07a4a30e22.diff

LOG: [ThinLTO] Import globals recursively

Differential revision: https://reviews.llvm.org/D73698

Added: 
    

Modified: 
    llvm/lib/Transforms/IPO/FunctionImport.cpp
    llvm/test/ThinLTO/X86/import-constant.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index e02f8d62da7a..e71c85bbfbf0 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -261,8 +261,8 @@ selectCallee(const ModuleSummaryIndex &Index,
 
 namespace {
 
-using EdgeInfo = std::tuple<const FunctionSummary *, unsigned /* Threshold */,
-                            GlobalValue::GUID>;
+using EdgeInfo =
+    std::tuple<const GlobalValueSummary *, unsigned /* Threshold */>;
 
 } // anonymous namespace
 
@@ -282,8 +282,9 @@ updateValueInfoForIndirectCalls(const ModuleSummaryIndex &Index, ValueInfo VI) {
 }
 
 static void computeImportForReferencedGlobals(
-    const FunctionSummary &Summary, const ModuleSummaryIndex &Index,
+    const GlobalValueSummary &Summary, const ModuleSummaryIndex &Index,
     const GVSummaryMapTy &DefinedGVSummaries,
+    SmallVectorImpl<EdgeInfo> &Worklist,
     FunctionImporter::ImportMapTy &ImportList,
     StringMap<FunctionImporter::ExportSetTy> *ExportLists) {
   for (auto &VI : Summary.refs()) {
@@ -321,6 +322,11 @@ static void computeImportForReferencedGlobals(
         // which is more efficient than adding them here.
         if (ExportLists)
           (*ExportLists)[RefSummary->modulePath()].insert(VI);
+
+        // If variable is not writeonly we attempt to recursively analyze
+        // its references in order to import referenced constants.
+        if (!Index.isWriteOnly(cast<GlobalVarSummary>(RefSummary.get())))
+          Worklist.emplace_back(RefSummary.get(), 0);
         break;
       }
   }
@@ -360,7 +366,7 @@ static void computeImportForFunction(
     StringMap<FunctionImporter::ExportSetTy> *ExportLists,
     FunctionImporter::ImportThresholdsTy &ImportThresholds) {
   computeImportForReferencedGlobals(Summary, Index, DefinedGVSummaries,
-                                    ImportList, ExportLists);
+                                    Worklist, ImportList, ExportLists);
   static int ImportCount = 0;
   for (auto &Edge : Summary.calls()) {
     ValueInfo VI = Edge.first;
@@ -508,7 +514,7 @@ static void computeImportForFunction(
     ImportCount++;
 
     // Insert the newly imported function to the worklist.
-    Worklist.emplace_back(ResolvedCalleeSummary, AdjThreshold, VI.getGUID());
+    Worklist.emplace_back(ResolvedCalleeSummary, AdjThreshold);
   }
 }
 
@@ -549,13 +555,17 @@ static void ComputeImportForModule(
 
   // Process the newly imported functions and add callees to the worklist.
   while (!Worklist.empty()) {
-    auto FuncInfo = Worklist.pop_back_val();
-    auto *Summary = std::get<0>(FuncInfo);
-    auto Threshold = std::get<1>(FuncInfo);
-
-    computeImportForFunction(*Summary, Index, Threshold, DefinedGVSummaries,
-                             Worklist, ImportList, ExportLists,
-                             ImportThresholds);
+    auto GVInfo = Worklist.pop_back_val();
+    auto *Summary = std::get<0>(GVInfo);
+    auto Threshold = std::get<1>(GVInfo);
+
+    if (auto *FS = dyn_cast<FunctionSummary>(Summary))
+      computeImportForFunction(*FS, Index, Threshold, DefinedGVSummaries,
+                               Worklist, ImportList, ExportLists,
+                               ImportThresholds);
+    else
+      computeImportForReferencedGlobals(*Summary, Index, DefinedGVSummaries,
+                                        Worklist, ImportList, ExportLists);
   }
 
   // Print stats about functions considered but rejected for importing

diff  --git a/llvm/test/ThinLTO/X86/import-constant.ll b/llvm/test/ThinLTO/X86/import-constant.ll
index 162bc3d28b7e..1bc2a1c2f7a4 100644
--- a/llvm/test/ThinLTO/X86/import-constant.ll
+++ b/llvm/test/ThinLTO/X86/import-constant.ll
@@ -14,13 +14,23 @@
 ; RUN: llvm-dis %t-out.1.3.import.bc -o - | FileCheck %s --check-prefix=IMPORT
 ; RUN: llvm-dis %t-out.1.4.opt.bc -o - | FileCheck %s --check-prefix=OPT
 
+; Check when importing references is prohibited
+; RUN: llvm-lto2 run -save-temps %t1.bc %t2.bc -o %t-out-norefs \
+; RUN:    -import-constants-with-refs=false \
+; RUN:    -r=%t1.bc,main,plx \
+; RUN:    -r=%t1.bc,_Z6getObjv,l \
+; RUN:    -r=%t2.bc,_Z6getObjv,pl \
+; RUN:    -r=%t2.bc,val,pl \
+; RUN:    -r=%t2.bc,outer,pl
+; RUN: llvm-dis %t-out-norefs.1.3.import.bc -o - | FileCheck %s --check-prefix=NOREFS
+
 ; Check that variable has been promoted in the source module
 ; PROMOTE: @_ZL3Obj.llvm.{{.*}} = hidden constant %struct.S { i32 4, i32 8, i32* @val }
 
 ; @outer is a write-only variable, so it's been converted to zeroinitializer.
 ; IMPORT:      @outer = internal local_unnamed_addr global %struct.Q zeroinitializer
-; IMPORT-NEXT: @_ZL3Obj.llvm.{{.*}} =  available_externally hidden constant %struct.S { i32 4, i32 8, i32* @val }
-; IMPORT-NEXT: @val = external dso_local global i32
+; IMPORT-NEXT: @_ZL3Obj.llvm.{{.*}} = available_externally hidden constant %struct.S { i32 4, i32 8, i32* @val }
+; IMPORT-NEXT: @val = available_externally global i32 42
 
 ; OPT: @outer = internal unnamed_addr global %struct.Q zeroinitializer
 
@@ -29,6 +39,9 @@
 ; OPT-NEXT:   store %struct.S* null, %struct.S** getelementptr inbounds (%struct.Q, %struct.Q* @outer, i64 0, i32 0)
 ; OPT-NEXT:   ret i32 12
 
+; NOREFS:      @outer = internal local_unnamed_addr global %struct.Q zeroinitializer
+; NOREFS-NEXT: @_ZL3Obj.llvm.{{.*}} = external hidden constant %struct.S
+
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"