forked from OSchip/llvm-project
[WPD/LTT] Lower type test feeding assumes via phi correctly
This fixes https://github.com/llvm/llvm-project/issues/57616. Type test lowering in ThinLTO modules relies on having type id summaries set up for the referenced types, which provide the type test resolution. If there is no summary, the type tests are lowered to false. At the very least, a default type id summary gives the type tests a resolution of Unknown, which is handled correctly (ignored by the first invocation of LTT, and lowered to true by the second). WPD sets up the type id summaries (with a default type test resolution) as it is processing the type tests, but only does this for the patterns handled by WPD, which is a type test directly feeding an assume. In the case of type tests feeding an assume via a phi, the type id summary was not being set up, leading to the type tests being lowered to false incorrectly. Fix this by adding the default type id summary entries for all type ids used on globals during index-only WPD. This is not an issue for hybrid (split-lto-unit) LTO, as in that case the type test resolution is determined and set up during LTT, since the type definitions are in the regular LTO split module, and exported via the summary to the ThinLTO split module. Differential Revision: https://reviews.llvm.org/D134012
This commit is contained in:
Teresa Johnson
parent
47e9e58808
commit
c2cf93c1a9
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@ -2311,6 +2311,13 @@ void DevirtIndex::run() {
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DenseMap<GlobalValue::GUID, std::vector<StringRef>> NameByGUID;
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for (const auto &P : ExportSummary.typeIdCompatibleVtableMap()) {
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NameByGUID[GlobalValue::getGUID(P.first)].push_back(P.first);
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// Create the type id summary resolution regardlness of whether we can
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// devirtualize, so that lower type tests knows the type id is used on
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// a global and not Unsat. We do this here rather than in the loop over the
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// CallSlots, since that handling will only see type tests that directly
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// feed assumes, and we would miss any that aren't currently handled by WPD
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// (such as type tests that feed assumes via phis).
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ExportSummary.getOrInsertTypeIdSummary(P.first);
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}
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// Collect information from summary about which calls to try to devirtualize.
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@ -2358,12 +2365,11 @@ void DevirtIndex::run() {
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std::vector<ValueInfo> TargetsForSlot;
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auto TidSummary = ExportSummary.getTypeIdCompatibleVtableSummary(S.first.TypeID);
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assert(TidSummary);
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// Create the type id summary resolution regardlness of whether we can
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// devirtualize, so that lower type tests knows the type id is used on
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// a global and not Unsat.
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// The type id summary would have been created while building the NameByGUID
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// map earlier.
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WholeProgramDevirtResolution *Res =
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&ExportSummary.getOrInsertTypeIdSummary(S.first.TypeID)
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.WPDRes[S.first.ByteOffset];
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&ExportSummary.getTypeIdSummary(S.first.TypeID)
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->WPDRes[S.first.ByteOffset];
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if (tryFindVirtualCallTargets(TargetsForSlot, *TidSummary,
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S.first.ByteOffset)) {
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@ -0,0 +1,163 @@
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; Test to ensure that type tests feeding assumes via a phi are lowered
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; correctly after ThinLTO index-only WPD, which needs to set up the necessary
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; type id summaries.
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; RUN: rm -rf %t && split-file %s %t && cd %t
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; RUN: opt -thinlto-bc y.ll -o y.bc
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; RUN: opt -thinlto-bc z.ll -o z.bc
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; RUN: llvm-lto2 run y.bc z.bc -o out \
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; RUN: -r y.bc,main,plx \
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; RUN: -r y.bc,_Z2b1v, \
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; RUN: -r y.bc,_Z2b2v, \
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; RUN: -r z.bc,_Z2b1v,pl \
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; RUN: -r z.bc,_Znwm, \
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; RUN: -r z.bc,_Z2b2v,pl \
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; RUN: -r z.bc,_ZN2D11fEv,pl \
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; RUN: -r z.bc,_ZN1B1fEv,pl \
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; RUN: -r z.bc,_ZN2D21fEv,pl \
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; RUN: -r z.bc,_ZTV2D1,pl \
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; RUN: -r z.bc,_ZTV1B,pl \
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; RUN: -r z.bc,_ZTV2D2,pl \
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; RUN: -print-after=lowertypetests -filter-print-funcs=main 2>&1 | FileCheck %s
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; The first LTT should leave the type tests as is (instead of lowering
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; them to false incorrectly).
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; CHECK: *** IR Dump After LowerTypeTestsPass on [module] ***
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; CHECK: 4:
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; CHECK: %7 = tail call i1 @llvm.type.test(ptr %6, metadata !"_ZTS2D1")
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; CHECK: br label %12
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; CHECK: 8:
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; CHECK: %11 = tail call i1 @llvm.type.test(ptr %10, metadata !"_ZTS2D2")
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; CHECK: br label %12
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; CHECK: 12:
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; CHECK: %13 = phi i1 [ %11, %8 ], [ %7, %4 ]
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; The second LTT should lower them to true.
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; CHECK: *** IR Dump After LowerTypeTestsPass on [module] ***
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; CHECK-NOT: @llvm.type.test
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; CHECK: 10:
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; CHECK: %11 = phi i1 [ true, %7 ], [ true, %4 ]
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;--- y.ll
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; ModuleID = 'y.cc'
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source_filename = "y.cc"
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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define i32 @main(i32 %argc, ptr %argv) {
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entry:
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%tobool.not = icmp eq i32 %argc, 0
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br i1 %tobool.not, label %if.else, label %if.then
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if.then:
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%call = tail call ptr @_Z2b1v()
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%vtable = load ptr, ptr %call, align 8
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%0 = tail call i1 @llvm.type.test(ptr %vtable, metadata !"_ZTS2D1")
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br label %if.end
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if.else:
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%call1 = tail call ptr @_Z2b2v()
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%vtable2 = load ptr, ptr %call1, align 8
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%1 = tail call i1 @llvm.type.test(ptr %vtable2, metadata !"_ZTS2D2")
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br label %if.end
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if.end:
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%.sink = phi i1 [ %1, %if.else ], [ %0, %if.then ]
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%vtable2.sink = phi ptr [ %vtable2, %if.else ], [ %vtable, %if.then ]
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%call1.sink = phi ptr [ %call1, %if.else ], [ %call, %if.then ]
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tail call void @llvm.assume(i1 %.sink)
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%2 = load ptr, ptr %vtable2.sink, align 8
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tail call void %2(ptr align 8 %call1.sink)
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ret i32 0
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}
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declare ptr @_Z2b1v()
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declare i1 @llvm.type.test(ptr, metadata)
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declare void @llvm.assume(i1)
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declare ptr @_Z2b2v()
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!llvm.module.flags = !{!0, !1, !2, !3, !4}
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!llvm.ident = !{!5}
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!0 = !{i32 1, !"wchar_size", i32 4}
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!1 = !{i32 1, !"Virtual Function Elim", i32 0}
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!2 = !{i32 7, !"PIC Level", i32 2}
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!3 = !{i32 7, !"PIE Level", i32 2}
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!4 = !{i32 7, !"uwtable", i32 2}
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!5 = !{!"clang version 15.0.0 (git@github.com:llvm/llvm-project.git e6f39e3f31ba88f2084a5d987f9a827aff4e17b1)"}
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;--- z.ll
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; ModuleID = 'z.cc'
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source_filename = "z.cc"
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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$_ZN2D11fEv = comdat any
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$_ZN1B1fEv = comdat any
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$_ZN2D21fEv = comdat any
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$_ZTV2D1 = comdat any
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$_ZTV1B = comdat any
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$_ZTV2D2 = comdat any
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@_ZTV2D1 = linkonce_odr constant { [3 x ptr] } { [3 x ptr] [ptr null, ptr null, ptr @_ZN2D11fEv] }, comdat, align 8, !type !0, !type !1, !type !2, !type !3, !vcall_visibility !4
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@_ZTV1B = linkonce_odr constant { [3 x ptr] } { [3 x ptr] [ptr null, ptr null, ptr @_ZN1B1fEv] }, comdat, align 8, !type !0, !type !1, !vcall_visibility !4
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@_ZTV2D2 = linkonce_odr constant { [3 x ptr] } { [3 x ptr] [ptr null, ptr null, ptr @_ZN2D21fEv] }, comdat, align 8, !type !0, !type !1, !type !5, !type !6, !vcall_visibility !4
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define ptr @_Z2b1v() {
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entry:
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%call = tail call ptr @_Znwm(i64 8)
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store ptr getelementptr inbounds ({ [3 x ptr] }, ptr @_ZTV2D1, i64 0, inrange i32 0, i64 2), ptr %call, align 8
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ret ptr %call
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}
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declare ptr @_Znwm(i64)
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define ptr @_Z2b2v() {
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entry:
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%call = tail call ptr @_Znwm(i64 8)
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store ptr getelementptr inbounds ({ [3 x ptr] }, ptr @_ZTV2D2, i64 0, inrange i32 0, i64 2), ptr %call, align 8
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ret ptr %call
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}
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define linkonce_odr void @_ZN2D11fEv(ptr %this) comdat align 2 {
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entry:
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ret void
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}
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define linkonce_odr void @_ZN1B1fEv(ptr %this) comdat align 2 {
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entry:
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ret void
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}
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define linkonce_odr void @_ZN2D21fEv(ptr %this) comdat align 2 {
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entry:
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ret void
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}
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!llvm.module.flags = !{!7, !8, !9, !10, !11}
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!llvm.ident = !{!12}
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!0 = !{i64 16, !"_ZTS1B"}
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!1 = !{i64 16, !"_ZTSM1BFvvE.virtual"}
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!2 = !{i64 16, !"_ZTS2D1"}
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!3 = !{i64 16, !"_ZTSM2D1FvvE.virtual"}
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!4 = !{i64 1}
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!5 = !{i64 16, !"_ZTS2D2"}
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!6 = !{i64 16, !"_ZTSM2D2FvvE.virtual"}
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!7 = !{i32 1, !"wchar_size", i32 4}
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!8 = !{i32 1, !"Virtual Function Elim", i32 0}
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!9 = !{i32 7, !"PIC Level", i32 2}
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!10 = !{i32 7, !"PIE Level", i32 2}
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!11 = !{i32 7, !"uwtable", i32 2}
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!12 = !{!"clang version 15.0.0 (git@github.com:llvm/llvm-project.git e6f39e3f31ba88f2084a5d987f9a827aff4e17b1)"}
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