Index: llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp =================================================================== --- llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp +++ llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp @@ -91,6 +91,7 @@ #include "llvm/Support/Errc.h" #include "llvm/Support/Error.h" #include "llvm/Support/FileSystem.h" +#include "llvm/Support/GlobPattern.h" #include "llvm/Support/MathExtras.h" #include "llvm/Transforms/IPO.h" #include "llvm/Transforms/IPO/FunctionAttrs.h" @@ -156,6 +157,12 @@ cl::ZeroOrMore, cl::desc("Disable whole program visibility (overrides enabling options)")); +/// Provide way to prevent certain function from being devirtualized +cl::list + SkipFunctionNames("wholeprogramdevirt-skip", + cl::desc("Prevent function(s) from being devirtualized"), + cl::ZeroOrMore, cl::CommaSeparated); + // Find the minimum offset that we may store a value of size Size bits at. If // IsAfter is set, look for an offset before the object, otherwise look for an // offset after the object. @@ -491,6 +498,7 @@ // eliminate the type check by RAUWing the associated llvm.type.test call with // true. std::map NumUnsafeUsesForTypeTest; + std::vector FunctionsToSkip; DevirtModule(Module &M, function_ref AARGetter, function_ref OREGetter, @@ -506,6 +514,9 @@ IntPtrTy(M.getDataLayout().getIntPtrType(M.getContext(), 0)), RemarksEnabled(areRemarksEnabled()), OREGetter(OREGetter) { assert(!(ExportSummary && ImportSummary)); + for (const std::string &Name : SkipFunctionNames) + if (Expected Pattern = GlobPattern::create(Name)) + FunctionsToSkip.push_back(std::move(*Pattern)); } bool areRemarksEnabled(); @@ -926,6 +937,10 @@ if (!Fn) return false; + for (auto &SkipPattern : FunctionsToSkip) + if (SkipPattern.match(Fn->getName())) + return false; + // We can disregard __cxa_pure_virtual as a possible call target, as // calls to pure virtuals are UB. if (Fn->getName() == "__cxa_pure_virtual") Index: llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll =================================================================== --- llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll +++ llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll @@ -1,4 +1,12 @@ ; RUN: opt -S -wholeprogramdevirt -whole-program-visibility -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s +; Skipping vf0i1 is identical to setting public LTO visibility. We don't devirtualize vf0i1 and all other +; virtual call targets. +; RUN: opt -S -wholeprogramdevirt -whole-program-visibility -pass-remarks=wholeprogramdevirt -wholeprogramdevirt-skip=vf0i1 %s 2>&1 | FileCheck %s --check-prefix=SKIP +; We have two set of call targets {vf0i1, vf1i1} and {vf1i32, vf2i32, vf3i32, vf4i32}. +; The command below prevents both of them from devirtualization. +; RUN: opt -S -wholeprogramdevirt -whole-program-visibility -pass-remarks=wholeprogramdevirt -wholeprogramdevirt-skip=vf0i1,vf1i32 %s 2>&1 | FileCheck %s --check-prefix=SKIP-ALL +; Check wildcard +; RUN: opt -S -wholeprogramdevirt -whole-program-visibility -pass-remarks=wholeprogramdevirt -wholeprogramdevirt-skip=vf?i1 %s 2>&1 | FileCheck %s --check-prefix=SKIP target datalayout = "e-p:64:64" target triple = "x86_64-unknown-linux-gnu" @@ -14,6 +22,14 @@ ; CHECK: remark: :0:0: devirtualized vf4i32 ; CHECK-NOT: devirtualized +; SKIP: remark: :0:0: devirtualized vf1i32 +; SKIP: remark: :0:0: devirtualized vf2i32 +; SKIP: remark: :0:0: devirtualized vf3i32 +; SKIP: remark: :0:0: devirtualized vf4i32 +; SKIP-NOT: devirtualized + +; SKIP-ALL-NOT: devirtualized + ; 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*),