[PATCH] D91812: [ThinLTO/WPD] Enable -wholeprogramdevirt-skip in ThinLTO backends

[Teresa Johnson via Phabricator via llvm-commits]

tejohnson created this revision.
tejohnson added reviewers: pcc, evgeny777.
Herald added subscribers: cfe-commits, steven_wu, hiraditya, inglorion, Prazek.
Herald added projects: clang, LLVM.
tejohnson requested review of this revision.

Previously this option could be used to skip devirtualizations of the
given functions in regular LTO and in the ThinLTO indexing step. This
change allows them to be skipped in the backend as well, which is useful
when debugging WPD in a distributed ThinLTO backend.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D91812

Files:
  clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll
  llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp


Index: llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
===================================================================
--- llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -1030,6 +1030,10 @@
 
 void DevirtModule::applySingleImplDevirt(VTableSlotInfo &SlotInfo,
                                          Constant *TheFn, bool &IsExported) {
+  // Don't devirtualize function if we're told to skip it
+  // in -wholeprogramdevirt-skip.
+  if (FunctionsToSkip.match(TheFn->stripPointerCasts()->getName()))
+    return;
   auto Apply = [&](CallSiteInfo &CSInfo) {
     for (auto &&VCallSite : CSInfo.CallSites) {
       if (RemarksEnabled)
Index: clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll
===================================================================
--- clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll
+++ clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll
@@ -40,8 +40,16 @@
 ; CHECK-DIS: ^2 = typeid: (name: "_ZTS1A", summary: (typeTestRes: (kind: allOnes, sizeM1BitWidth: 7), wpdResolutions: ((offset: 0, wpdRes: (kind: branchFunnel)), (offset: 8, wpdRes: (kind: singleImpl, singleImplName: "_ZN1A1nEi"))))) ; guid = 7004155349499253778
 
 ; RUN: %clang_cc1 -triple x86_64-grtev4-linux-gnu \
-; RUN:   -emit-obj -fthinlto-index=%t.o.thinlto.bc -O2 \
-; RUN:   -emit-llvm -o - -x ir %t.o | FileCheck %s --check-prefixes=CHECK-IR
+; RUN:   -emit-obj -fthinlto-index=%t.o.thinlto.bc -O2 -Rpass=wholeprogramdevirt \
+; RUN:   -emit-llvm -o - -x ir %t.o 2>&1 | FileCheck %s --check-prefixes=CHECK-IR --check-prefixes=REMARKS
+
+; Check that the devirtualization is suppressed via -wholeprogramdevirt-skip
+; RUN: %clang_cc1 -triple x86_64-grtev4-linux-gnu -mllvm -wholeprogramdevirt-skip=_ZN1A1nEi \
+; RUN:   -emit-obj -fthinlto-index=%t.o.thinlto.bc -O2 -Rpass=wholeprogramdevirt \
+; RUN:   -emit-llvm -o - -x ir %t.o 2>&1 | FileCheck %s --check-prefixes=SKIP-IR --check-prefixes=SKIP-REMARKS
+
+; REMARKS: single-impl: devirtualized a call to _ZN1A1nEi
+; SKIP-REMARKS-NOT: single-impl
 
 ; Check that backend does not fail generating native code.
 ; RUN: %clang_cc1 -triple x86_64-grtev4-linux-gnu \
@@ -78,6 +86,7 @@
 
   ; Check that the call was devirtualized.
   ; CHECK-IR: %call = tail call i32 @_ZN1A1nEi
+  ; SKIP-IR-NOT: %call = tail call i32 @_ZN1A1nEi
   %call = tail call i32 %4(%struct.A* nonnull %obj, i32 %a)
   %vtable16 = load i8*, i8** %0
   %5 = tail call { i8*, i1 } @llvm.type.checked.load(i8* %vtable16, i32 0, metadata !"_ZTS1A")


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