[llvm] WholeProgramDevirt: Fix importing in llvm.type.checked.load case. (PR #144019)
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Thu Jun 12 22:06:55 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lto
Author: Peter Collingbourne (pcc)
<details>
<summary>Changes</summary>
We were clearing SummaryTypeCheckedLoadUsers to prevent devirtualized
llvm.type.checked.load calls from being converted to llvm.type.test,
which meant that AddCalls would not see them in the list of
callsites and they would not get imported. Fix that by not clearing
SummaryTypeCheckedLoadUsers so that the list survives to AddCalls and
using AllCallSitesDevirted to control whether to convert them instead.
---
Full diff: https://github.com/llvm/llvm-project/pull/144019.diff
3 Files Affected:
- (modified) llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp (+17-18)
- (added) llvm/test/ThinLTO/X86/Inputs/devirt_single_hybrid_foo_tcl.ll (+31)
- (modified) llvm/test/ThinLTO/X86/devirt_single_hybrid.ll (+21-1)
``````````diff
diff --git a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
index a7d9f3ba24b24..d01907df0c7de 100644
--- a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -494,28 +494,28 @@ struct CallSiteInfo {
/// Whether all call sites represented by this CallSiteInfo, including those
/// in summaries, have been devirtualized. This starts off as true because a
/// default constructed CallSiteInfo represents no call sites.
+ ///
+ /// If at the end of the pass there are still undevirtualized calls, we will
+ /// need to add a use of llvm.type.test to each of the function summaries in
+ /// the vector.
bool AllCallSitesDevirted = true;
// These fields are used during the export phase of ThinLTO and reflect
// information collected from function summaries.
- /// Whether any function summary contains an llvm.assume(llvm.type.test) for
- /// this slot.
- bool SummaryHasTypeTestAssumeUsers = false;
-
/// CFI-specific: a vector containing the list of function summaries that use
/// the llvm.type.checked.load intrinsic and therefore will require
/// resolutions for llvm.type.test in order to implement CFI checks if
- /// devirtualization was unsuccessful. If devirtualization was successful, the
- /// pass will clear this vector by calling markDevirt(). If at the end of the
- /// pass the vector is non-empty, we will need to add a use of llvm.type.test
- /// to each of the function summaries in the vector.
+ /// devirtualization was unsuccessful.
std::vector<FunctionSummary *> SummaryTypeCheckedLoadUsers;
+
+ /// A vector containing the list of function summaries that use
+ /// assume(llvm.type.test).
std::vector<FunctionSummary *> SummaryTypeTestAssumeUsers;
bool isExported() const {
- return SummaryHasTypeTestAssumeUsers ||
- !SummaryTypeCheckedLoadUsers.empty();
+ return !SummaryTypeCheckedLoadUsers.empty() ||
+ !SummaryTypeTestAssumeUsers.empty();
}
void addSummaryTypeCheckedLoadUser(FunctionSummary *FS) {
@@ -525,15 +525,11 @@ struct CallSiteInfo {
void addSummaryTypeTestAssumeUser(FunctionSummary *FS) {
SummaryTypeTestAssumeUsers.push_back(FS);
- SummaryHasTypeTestAssumeUsers = true;
AllCallSitesDevirted = false;
}
void markDevirt() {
AllCallSitesDevirted = true;
-
- // As explained in the comment for SummaryTypeCheckedLoadUsers.
- SummaryTypeCheckedLoadUsers.clear();
}
};
@@ -2465,11 +2461,14 @@ bool DevirtModule::run() {
if (ExportSummary && isa<MDString>(S.first.TypeID)) {
auto GUID = GlobalValue::getGUIDAssumingExternalLinkage(
cast<MDString>(S.first.TypeID)->getString());
- for (auto *FS : S.second.CSInfo.SummaryTypeCheckedLoadUsers)
- FS->addTypeTest(GUID);
+ auto AddTypeTestsForTypeCheckedLoads = [&](CallSiteInfo &CSI) {
+ if (!CSI.AllCallSitesDevirted)
+ for (auto *FS : CSI.SummaryTypeCheckedLoadUsers)
+ FS->addTypeTest(GUID);
+ };
+ AddTypeTestsForTypeCheckedLoads(S.second.CSInfo);
for (auto &CCS : S.second.ConstCSInfo)
- for (auto *FS : CCS.second.SummaryTypeCheckedLoadUsers)
- FS->addTypeTest(GUID);
+ AddTypeTestsForTypeCheckedLoads(CCS.second);
}
}
diff --git a/llvm/test/ThinLTO/X86/Inputs/devirt_single_hybrid_foo_tcl.ll b/llvm/test/ThinLTO/X86/Inputs/devirt_single_hybrid_foo_tcl.ll
new file mode 100644
index 0000000000000..4a696837bc8e9
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/Inputs/devirt_single_hybrid_foo_tcl.ll
@@ -0,0 +1,31 @@
+; ModuleID = 'foo.cpp'
+source_filename = "foo.cpp"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.A = type { ptr }
+
+; Function Attrs: uwtable
+define hidden i32 @_Z3fooP1A(ptr %pA) local_unnamed_addr {
+entry:
+ %vtable = load ptr, ptr %pA, align 8, !tbaa !2
+ %0 = call { ptr, i1 } @llvm.type.checked.load(ptr %vtable, i32 0, metadata !"_ZTS1A")
+ %1 = extractvalue { ptr, i1 } %0, 0
+ %call = tail call i32 %1(ptr %pA)
+ %add = add nsw i32 %call, 10
+ ret i32 %add
+}
+
+declare { ptr, i1 } @llvm.type.checked.load(ptr, i32, metadata)
+
+; Function Attrs: nounwind willreturn
+declare void @llvm.assume(i1)
+
+!llvm.module.flags = !{!0}
+!llvm.ident = !{!1}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{!"clang version 10.0.0 (trunk 373596)"}
+!2 = !{!3, !3, i64 0}
+!3 = !{!"vtable pointer", !4, i64 0}
+!4 = !{!"Simple C++ TBAA"}
diff --git a/llvm/test/ThinLTO/X86/devirt_single_hybrid.ll b/llvm/test/ThinLTO/X86/devirt_single_hybrid.ll
index 90fdf0d7dfa09..fe3242e93159a 100644
--- a/llvm/test/ThinLTO/X86/devirt_single_hybrid.ll
+++ b/llvm/test/ThinLTO/X86/devirt_single_hybrid.ll
@@ -2,8 +2,28 @@
; when we're running hybrid LTO.
;
; RUN: opt -thinlto-bc -thinlto-split-lto-unit %s -o %t-main.bc
-; RUN: opt -thinlto-bc -thinlto-split-lto-unit %p/Inputs/devirt_single_hybrid_foo.ll -o %t-foo.bc
; RUN: opt -thinlto-bc -thinlto-split-lto-unit %p/Inputs/devirt_single_hybrid_bar.ll -o %t-bar.bc
+;
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit %p/Inputs/devirt_single_hybrid_foo.ll -o %t-foo.bc
+; RUN: llvm-lto2 run -save-temps %t-main.bc %t-foo.bc %t-bar.bc -pass-remarks=. -o %t \
+; RUN: -whole-program-visibility \
+; RUN: -r=%t-foo.bc,_Z3fooP1A,pl \
+; RUN: -r=%t-main.bc,main,plx \
+; RUN: -r=%t-main.bc,_Z3barv,l \
+; RUN: -r=%t-bar.bc,_Z3barv,pl \
+; RUN: -r=%t-bar.bc,_Z3fooP1A, \
+; RUN: -r=%t-bar.bc,_ZNK1A1fEv,pl \
+; RUN: -r=%t-bar.bc,_ZTV1A,l \
+; RUN: -r=%t-bar.bc,_ZTVN10__cxxabiv117__class_type_infoE, \
+; RUN: -r=%t-bar.bc,_ZTS1A,pl \
+; RUN: -r=%t-bar.bc,_ZTI1A,pl \
+; RUN: -r=%t-bar.bc,_ZNK1A1fEv, \
+; RUN: -r=%t-bar.bc,_ZTV1A,pl \
+; RUN: -r=%t-bar.bc,_ZTI1A, 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t.1.3.import.bc -o - | FileCheck %s --check-prefix=IMPORT
+; RUN: llvm-dis %t.1.5.precodegen.bc -o - | FileCheck %s --check-prefix=CODEGEN
+
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit %p/Inputs/devirt_single_hybrid_foo_tcl.ll -o %t-foo.bc
; RUN: llvm-lto2 run -save-temps %t-main.bc %t-foo.bc %t-bar.bc -pass-remarks=. -o %t \
; RUN: -whole-program-visibility \
; RUN: -r=%t-foo.bc,_Z3fooP1A,pl \
``````````
</details>
https://github.com/llvm/llvm-project/pull/144019
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