[llvm] r312698 - ModuleSummaryAnalysis: Correctly handle all function operand references.

[Peter Collingbourne via llvm-commits]

Author: pcc
Date: Wed Sep  6 22:35:35 2017
New Revision: 312698

URL: http://llvm.org/viewvc/llvm-project?rev=312698&view=rev
Log:
ModuleSummaryAnalysis: Correctly handle all function operand references.

The current code that handles personality functions when creating a
module summary does not correctly handle the case where a function's
personality function operand refers to the function indirectly
(e.g. via a bitcast). This patch handles such cases by treating
personality function references like any other reference, i.e. by
adding them to the function's reference list. This has the minor side
benefit of allowing personality functions to participate in early
dead stripping.

We do this by calling findRefEdges on the function itself. This way
we also end up handling other function operands (specifically prefix
data and prologue data) for free.

Differential Revision: https://reviews.llvm.org/D37553

Modified:
    llvm/trunk/lib/Analysis/ModuleSummaryAnalysis.cpp
    llvm/trunk/test/ThinLTO/X86/Inputs/personality.ll
    llvm/trunk/test/ThinLTO/X86/personality.ll

Modified: llvm/trunk/lib/Analysis/ModuleSummaryAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ModuleSummaryAnalysis.cpp?rev=312698&r1=312697&r2=312698&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ModuleSummaryAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/ModuleSummaryAnalysis.cpp Wed Sep  6 22:35:35 2017
@@ -215,9 +215,13 @@ computeFunctionSummary(ModuleSummaryInde
   SetVector<FunctionSummary::ConstVCall> TypeTestAssumeConstVCalls,
       TypeCheckedLoadConstVCalls;
   ICallPromotionAnalysis ICallAnalysis;
+  SmallPtrSet<const User *, 8> Visited;
+
+  // Add personality function, prefix data and prologue data to function's ref
+  // list.
+  findRefEdges(Index, &F, RefEdges, Visited);
 
   bool HasInlineAsmMaybeReferencingInternal = false;
-  SmallPtrSet<const User *, 8> Visited;
   for (const BasicBlock &BB : F)
     for (const Instruction &I : BB) {
       if (isa<DbgInfoIntrinsic>(I))
@@ -456,12 +460,6 @@ ModuleSummaryIndex llvm::buildModuleSumm
                            CantBePromoted);
   }
 
-  // Set live flag for all personality functions. That allows to
-  // preserve them during DCE.
-  for (const llvm::Function &F : M)
-    if (!F.isDeclaration() && F.hasPersonalityFn())
-      setLiveRoot(Index, F.getPersonalityFn()->getName());
-
   // Compute summaries for all variables defined in module, and save in the
   // index.
   for (const GlobalVariable &G : M.globals()) {

Modified: llvm/trunk/test/ThinLTO/X86/Inputs/personality.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/ThinLTO/X86/Inputs/personality.ll?rev=312698&r1=312697&r2=312698&view=diff
==============================================================================
--- llvm/trunk/test/ThinLTO/X86/Inputs/personality.ll (original)
+++ llvm/trunk/test/ThinLTO/X86/Inputs/personality.ll Wed Sep  6 22:35:35 2017
@@ -8,3 +8,11 @@ define void @bar() personality i32 (i32,
 define protected i32 @personality_routine(i32, i32, i64, i8*, i8*) {
   ret i32 0
 }
+
+define protected i32 @personality_routine2(i32, i32, i64, i8*, i8*) {
+  ret i32 0
+}
+
+define protected i32 @personality_routine3(i32, i32, i64, i8*, i8*) {
+  ret i32 0
+}

Modified: llvm/trunk/test/ThinLTO/X86/personality.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/ThinLTO/X86/personality.ll?rev=312698&r1=312697&r2=312698&view=diff
==============================================================================
--- llvm/trunk/test/ThinLTO/X86/personality.ll (original)
+++ llvm/trunk/test/ThinLTO/X86/personality.ll Wed Sep  6 22:35:35 2017
@@ -4,8 +4,14 @@
 ; RUN: llvm-lto2 run -o %t.o %t1.bc %t2.bc -save-temps \
 ; RUN:   -r %t2.bc,bar,p \
 ; RUN:   -r %t2.bc,personality_routine,p \
+; RUN:   -r %t2.bc,personality_routine2,p \
+; RUN:   -r %t2.bc,personality_routine3,p \
 ; RUN:   -r %t1.bc,foo,p \
+; RUN:   -r %t1.bc,foo2,p \
+; RUN:   -r %t1.bc,foo3,p \
 ; RUN:   -r %t1.bc,personality_routine,l \
+; RUN:   -r %t1.bc,personality_routine2,l \
+; RUN:   -r %t1.bc,personality_routine3,l \
 ; RUN:   -r %t1.bc,main,xp \
 ; RUN:   -r %t1.bc,bar,l
 ; RUN: llvm-readobj -t %t.o.1 | FileCheck %s --check-prefix=BINDING
@@ -22,18 +28,51 @@
 ; BINDING-NEXT:  Section: .text
 ; BINDING-NEXT: }
 
+; BINDING-NEXT: Symbol {
+; BINDING-NEXT:  Name: personality_routine2
+; BINDING-NEXT:  Value:
+; BINDING-NEXT:  Size:
+; BINDING-NEXT:  Binding: Global
+; BINDING-NEXT:  Type: Function
+; BINDING-NEXT:  Other [
+; BINDING-NEXT:    STV_PROTECTED
+; BINDING-NEXT:  ]
+; BINDING-NEXT:  Section: .text
+; BINDING-NEXT: }
+
+; BINDING-NOT:  Name: personality_routine3
+
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-pc-linux-gnu"
 
 declare protected i32 @personality_routine(i32, i32, i64, i8*, i8*)
+declare protected i32 @personality_routine2(i32, i32, i64, i8*, i8*)
+declare protected i32 @personality_routine3(i32, i32, i64, i8*, i8*)
 declare void @bar()
 
 define void @foo() personality i32 (i32, i32, i64, i8*, i8*)* @personality_routine {
   ret void
 }
 
+define internal void @foo2b() personality i8* bitcast (i32 (i32, i32, i64, i8*, i8*)* @personality_routine2 to i8*) {
+  ret void
+}
+
+define internal void @foo2a() prologue void ()* @foo2b {
+  ret void
+}
+
+define void @foo2() prefix void ()* @foo2a {
+  ret void
+}
+
+define void @foo3() personality i8* bitcast (i32 (i32, i32, i64, i8*, i8*)* @personality_routine3 to i8*) {
+  ret void
+}
+
 define i32 @main() {
   call void @foo()
+  call void @foo2()
   call void @bar()
   ret i32 0
 }