[ThinLTO] Skip opt pipeline and summary wrapper pass on empty modules #120143
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Follow up to PR118508, to avoid unnecessary compile time for an empty combind regular LTO module if all modules end up being ThinLTO only.
llvmbot
added
lld
lld:ELF
LTO
|
@llvm/pr-subscribers-lto @llvm/pr-subscribers-lld-elf Author: Teresa Johnson (teresajohnson) ChangesFollow up to PR118508, to avoid unnecessary compile time for an empty Full diff: https://github.com/llvm/llvm-project/pull/120143.diff 4 Files Affected:
diff --git a/lld/test/ELF/lto/new-pass-manager.ll b/lld/test/ELF/lto/new-pass-manager.ll
index cc6ff34cd91ae3..77a1d4ed3d27d2 100644
--- a/lld/test/ELF/lto/new-pass-manager.ll
+++ b/lld/test/ELF/lto/new-pass-manager.ll
@@ -9,3 +9,7 @@
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"
+
+define void @foo() {
+ ret void
+}
diff --git a/llvm/lib/LTO/LTOBackend.cpp b/llvm/lib/LTO/LTOBackend.cpp
index bdf4ff8960bc82..51bd7cc29c7699 100644
--- a/llvm/lib/LTO/LTOBackend.cpp
+++ b/llvm/lib/LTO/LTOBackend.cpp
@@ -351,6 +351,13 @@ static void runNewPMPasses(const Config &Conf, Module &Mod, TargetMachine *TM,
MPM.run(Mod, MAM);
}
+static bool isEmptyModule(const Module &Mod) {
+ // Module is empty if it has no functions, no globals, no inline asm and no
+ // named metadata (aliases and ifuncs require functions or globals so we
+ // don't need to check those explicitly).
+ return Mod.empty() && Mod.global_empty() && Mod.named_metadata_empty() && Mod.getModuleInlineAsm().empty();
+}
+
bool lto::opt(const Config &Conf, TargetMachine *TM, unsigned Task, Module &Mod,
bool IsThinLTO, ModuleSummaryIndex *ExportSummary,
const ModuleSummaryIndex *ImportSummary,
@@ -372,9 +379,16 @@ bool lto::opt(const Config &Conf, TargetMachine *TM, unsigned Task, Module &Mod,
/*EmbedBitcode*/ true, /*EmbedCmdline*/ true,
/*Cmdline*/ CmdArgs);
}
- // FIXME: Plumb the combined index into the new pass manager.
- runNewPMPasses(Conf, Mod, TM, Conf.OptLevel, IsThinLTO, ExportSummary,
- ImportSummary);
+ // No need to run any opt passes if the module is empty.
+ // In theory these passes should take almost no time for an empty
+ // module, however, this guards against doing any unnecessary summary-based
+ // analysis in the case of a ThinLTO build where this might be an empty
+ // regular LTO combined module, with a large combined index from ThinLTO.
+ if (!isEmptyModule(Mod)) {
+ // FIXME: Plumb the combined index into the new pass manager.
+ runNewPMPasses(Conf, Mod, TM, Conf.OptLevel, IsThinLTO, ExportSummary,
+ ImportSummary);
+ }
return !Conf.PostOptModuleHook || Conf.PostOptModuleHook(Task, Mod);
}
@@ -422,8 +436,14 @@ static void codegen(const Config &Conf, TargetMachine *TM,
legacy::PassManager CodeGenPasses;
TargetLibraryInfoImpl TLII(Triple(Mod.getTargetTriple()));
CodeGenPasses.add(new TargetLibraryInfoWrapperPass(TLII));
- CodeGenPasses.add(
- createImmutableModuleSummaryIndexWrapperPass(&CombinedIndex));
+ // No need to make index available if the module is empty.
+ // In theory these passes should not use the index for an empty
+ // module, however, this guards against doing any unnecessary summary-based
+ // analysis in the case of a ThinLTO build where this might be an empty
+ // regular LTO combined module, with a large combined index from ThinLTO.
+ if (!isEmptyModule(Mod))
+ CodeGenPasses.add(
+ createImmutableModuleSummaryIndexWrapperPass(&CombinedIndex));
if (Conf.PreCodeGenPassesHook)
Conf.PreCodeGenPassesHook(CodeGenPasses);
if (TM->addPassesToEmitFile(CodeGenPasses, *Stream->OS,
diff --git a/llvm/test/Feature/load_plugin_error.ll b/llvm/test/Feature/load_plugin_error.ll
index a112bfbb1cd193..b40dddff1205fc 100644
--- a/llvm/test/Feature/load_plugin_error.ll
+++ b/llvm/test/Feature/load_plugin_error.ll
@@ -5,7 +5,7 @@
; RUN: opt %s -o %t.o
; RUN: not llvm-lto2 run -load-pass-plugin=%t/nonexistent.so %t.o -o %t \
-; RUN: -r %t.o,test 2>&1 | \
+; RUN: -r %t.o,test,plx 2>&1 | \
; RUN: FileCheck %s
; CHECK: Could not load library {{.*}}nonexistent.so
diff --git a/llvm/test/Other/X86/lto-hot-cold-split.ll b/llvm/test/Other/X86/lto-hot-cold-split.ll
index 22c79c7e06bba6..24903f34ed074b 100644
--- a/llvm/test/Other/X86/lto-hot-cold-split.ll
+++ b/llvm/test/Other/X86/lto-hot-cold-split.ll
@@ -10,3 +10,7 @@ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
; OLDPM-ANYLTO-POSTLINK-Os: HotColdSplittingPass
+
+define void @foo() {
+ ret void
+}
|
|
@llvm/pr-subscribers-lld Author: Teresa Johnson (teresajohnson) ChangesFollow up to PR118508, to avoid unnecessary compile time for an empty Full diff: https://github.com/llvm/llvm-project/pull/120143.diff 4 Files Affected:
diff --git a/lld/test/ELF/lto/new-pass-manager.ll b/lld/test/ELF/lto/new-pass-manager.ll
index cc6ff34cd91ae3..77a1d4ed3d27d2 100644
--- a/lld/test/ELF/lto/new-pass-manager.ll
+++ b/lld/test/ELF/lto/new-pass-manager.ll
@@ -9,3 +9,7 @@
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"
+
+define void @foo() {
+ ret void
+}
diff --git a/llvm/lib/LTO/LTOBackend.cpp b/llvm/lib/LTO/LTOBackend.cpp
index bdf4ff8960bc82..51bd7cc29c7699 100644
--- a/llvm/lib/LTO/LTOBackend.cpp
+++ b/llvm/lib/LTO/LTOBackend.cpp
@@ -351,6 +351,13 @@ static void runNewPMPasses(const Config &Conf, Module &Mod, TargetMachine *TM,
MPM.run(Mod, MAM);
}
+static bool isEmptyModule(const Module &Mod) {
+ // Module is empty if it has no functions, no globals, no inline asm and no
+ // named metadata (aliases and ifuncs require functions or globals so we
+ // don't need to check those explicitly).
+ return Mod.empty() && Mod.global_empty() && Mod.named_metadata_empty() && Mod.getModuleInlineAsm().empty();
+}
+
bool lto::opt(const Config &Conf, TargetMachine *TM, unsigned Task, Module &Mod,
bool IsThinLTO, ModuleSummaryIndex *ExportSummary,
const ModuleSummaryIndex *ImportSummary,
@@ -372,9 +379,16 @@ bool lto::opt(const Config &Conf, TargetMachine *TM, unsigned Task, Module &Mod,
/*EmbedBitcode*/ true, /*EmbedCmdline*/ true,
/*Cmdline*/ CmdArgs);
}
- // FIXME: Plumb the combined index into the new pass manager.
- runNewPMPasses(Conf, Mod, TM, Conf.OptLevel, IsThinLTO, ExportSummary,
- ImportSummary);
+ // No need to run any opt passes if the module is empty.
+ // In theory these passes should take almost no time for an empty
+ // module, however, this guards against doing any unnecessary summary-based
+ // analysis in the case of a ThinLTO build where this might be an empty
+ // regular LTO combined module, with a large combined index from ThinLTO.
+ if (!isEmptyModule(Mod)) {
+ // FIXME: Plumb the combined index into the new pass manager.
+ runNewPMPasses(Conf, Mod, TM, Conf.OptLevel, IsThinLTO, ExportSummary,
+ ImportSummary);
+ }
return !Conf.PostOptModuleHook || Conf.PostOptModuleHook(Task, Mod);
}
@@ -422,8 +436,14 @@ static void codegen(const Config &Conf, TargetMachine *TM,
legacy::PassManager CodeGenPasses;
TargetLibraryInfoImpl TLII(Triple(Mod.getTargetTriple()));
CodeGenPasses.add(new TargetLibraryInfoWrapperPass(TLII));
- CodeGenPasses.add(
- createImmutableModuleSummaryIndexWrapperPass(&CombinedIndex));
+ // No need to make index available if the module is empty.
+ // In theory these passes should not use the index for an empty
+ // module, however, this guards against doing any unnecessary summary-based
+ // analysis in the case of a ThinLTO build where this might be an empty
+ // regular LTO combined module, with a large combined index from ThinLTO.
+ if (!isEmptyModule(Mod))
+ CodeGenPasses.add(
+ createImmutableModuleSummaryIndexWrapperPass(&CombinedIndex));
if (Conf.PreCodeGenPassesHook)
Conf.PreCodeGenPassesHook(CodeGenPasses);
if (TM->addPassesToEmitFile(CodeGenPasses, *Stream->OS,
diff --git a/llvm/test/Feature/load_plugin_error.ll b/llvm/test/Feature/load_plugin_error.ll
index a112bfbb1cd193..b40dddff1205fc 100644
--- a/llvm/test/Feature/load_plugin_error.ll
+++ b/llvm/test/Feature/load_plugin_error.ll
@@ -5,7 +5,7 @@
; RUN: opt %s -o %t.o
; RUN: not llvm-lto2 run -load-pass-plugin=%t/nonexistent.so %t.o -o %t \
-; RUN: -r %t.o,test 2>&1 | \
+; RUN: -r %t.o,test,plx 2>&1 | \
; RUN: FileCheck %s
; CHECK: Could not load library {{.*}}nonexistent.so
diff --git a/llvm/test/Other/X86/lto-hot-cold-split.ll b/llvm/test/Other/X86/lto-hot-cold-split.ll
index 22c79c7e06bba6..24903f34ed074b 100644
--- a/llvm/test/Other/X86/lto-hot-cold-split.ll
+++ b/llvm/test/Other/X86/lto-hot-cold-split.ll
@@ -10,3 +10,7 @@ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
; OLDPM-ANYLTO-POSTLINK-Os: HotColdSplittingPass
+
+define void @foo() {
+ ret void
+}
|
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/16/builds/11812 Here is the relevant piece of the build log for the reference |
BaiXilin
pushed a commit
to BaiXilin/llvm-fix-vnni-instr-types
that referenced
this pull request
Jan 12, 2025
…llvm#120143) Follow up to PR118508, to avoid unnecessary compile time for an empty combind regular LTO module if all modules end up being ThinLTO only. This required minor changes to a few tests to ensure they weren't empty.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Follow up to PR118508, to avoid unnecessary compile time for an empty
combind regular LTO module if all modules end up being ThinLTO only.
This required minor changes to a few tests to ensure they weren't empty.