Print remarks from WholeProgramDevirt pass for each call site.

Summary:
It's useful to have some visibility about which call sites are devirtualized,
especially for debug purposes. Another use case is a regression test on the
application side (like, Chromium).

Reviewers: pcc

Differential Revision: http://reviews.llvm.org/D22252

llvm-svn: 275145

4 files changed, 23 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
index e6f4fa29224..53eb4e2c907 100644
--- a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -35,6 +35,7 @@
 #include "llvm/IR/CallSite.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Intrinsics.h"
@@ -215,7 +216,15 @@ struct VirtualCallSite {
   // of that field for details.
   unsigned *NumUnsafeUses;
 
+  void emitRemark() {
+    Function *F = CS.getCaller();
+    emitOptimizationRemark(F->getContext(), DEBUG_TYPE, *F,
+                           CS.getInstruction()->getDebugLoc(),
+                           "devirtualized call");
+  }
+
   void replaceAndErase(Value *New) {
+    emitRemark();
     CS->replaceAllUsesWith(New);
     if (auto II = dyn_cast<InvokeInst>(CS.getInstruction())) {
       BranchInst::Create(II->getNormalDest(), CS.getInstruction());
@@ -394,6 +403,7 @@ bool DevirtModule::trySingleImplDevirt(
 
   // If so, update each call site to call that implementation directly.
   for (auto &&VCallSite : CallSites) {
+    VCallSite.emitRemark();
     VCallSite.CS.setCalledFunction(ConstantExpr::getBitCast(
         TheFn, VCallSite.CS.getCalledValue()->getType()));
     // This use is no longer unsafe.
diff --git a/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-check.ll b/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-check.ll
index 7c52f26ebea..e5e64ab05a2 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-check.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-check.ll
@@ -1,8 +1,11 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
 
+; CHECK: remark: <unknown>:0:0: devirtualized call
+; CHECK-NOT: devirtualized call
+
 @vt1 = constant [1 x i8*] [i8* bitcast (void (i8*)* @vf to i8*)], !type !0
 @vt2 = constant [1 x i8*] [i8* bitcast (void (i8*)* @vf to i8*)], !type !0
 
diff --git a/llvm/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll b/llvm/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll
index f66409093c4..ecc8ad0e7c7 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll
@@ -1,4 +1,6 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
+
+; CHECK-NOT: devirtualized call
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll b/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll
index 4e219e238e5..d2eff163a84 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll
@@ -1,8 +1,13 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
 
+; CHECK: remark: <unknown>:0:0: devirtualized call
+; CHECK: remark: <unknown>:0:0: devirtualized call
+; CHECK: remark: <unknown>:0:0: devirtualized call
+; CHECK-NOT: devirtualized call
+
 ; CHECK: [[VT1DATA:@[^ ]*]] = private constant { [8 x i8], [3 x i8*], [0 x i8] } { [8 x i8] c"\00\00\00\01\01\00\00\00", [3 x i8*] [i8* bitcast (i1 (i8*)* @vf0i1 to i8*), i8* bitcast (i1 (i8*)* @vf1i1 to i8*), i8* bitcast (i32 (i8*)* @vf1i32 to i8*)], [0 x i8] zeroinitializer }, section "vt1sec", !type [[T8:![0-9]+]]
 @vt1 = constant [3 x i8*] [
 i8* bitcast (i1 (i8*)* @vf0i1 to i8*),