[lld] [CGData][lld-macho] Merge CG Data by LLD (PR #112674)
via llvm-commits
llvm-commits at lists.llvm.org
Fri Nov 15 22:21:55 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lld-macho
Author: Kyungwoo Lee (kyulee-com)
<details>
<summary>Changes</summary>
LLD now processes raw CG data for stable functions, similar to how it handles raw CG data for the outliner's hash tree. This data is encoded in the custom section (`__llvm_merge`) within object files. LLD merges this information into the indexed CG data file specified by the `-codegen-data-generate-path={path}` option. For the linker that does not support this feature, we could use `llvm-cgdata` tool -- https://github.com/llvm/llvm-project/blob/main/llvm/docs/CommandGuide/llvm-cgdata.rst.
Depends on #<!-- -->115750.
This is a patch for https://discourse.llvm.org/t/rfc-global-function-merging/82608.
---
Full diff: https://github.com/llvm/llvm-project/pull/112674.diff
3 Files Affected:
- (modified) lld/MachO/Driver.cpp (+21-3)
- (modified) lld/MachO/InputSection.h (+1)
- (added) lld/test/MachO/cgdata-generate-merge.s (+85)
``````````diff
diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
index ab4abb1fa97efc..e9482f85bdc078 100644
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -1326,21 +1326,39 @@ static void codegenDataGenerate() {
TimeTraceScope timeScope("Generating codegen data");
OutlinedHashTreeRecord globalOutlineRecord;
- for (ConcatInputSection *isec : inputSections)
- if (isec->getSegName() == segment_names::data &&
- isec->getName() == section_names::outlinedHashTree) {
+ StableFunctionMapRecord globalMergeRecord;
+ for (ConcatInputSection *isec : inputSections) {
+ if (isec->getSegName() != segment_names::data)
+ continue;
+ if (isec->getName() == section_names::outlinedHashTree) {
// Read outlined hash tree from each section.
OutlinedHashTreeRecord localOutlineRecord;
+ // Use a pointer to allow modification by the function.
auto *data = isec->data.data();
localOutlineRecord.deserialize(data);
// Merge it to the global hash tree.
globalOutlineRecord.merge(localOutlineRecord);
}
+ if (isec->getName() == section_names::functionMap) {
+ // Read stable functions from each section.
+ StableFunctionMapRecord localMergeRecord;
+ // Use a pointer to allow modification by the function.
+ auto *data = isec->data.data();
+ localMergeRecord.deserialize(data);
+
+ // Merge it to the global function map.
+ globalMergeRecord.merge(localMergeRecord);
+ }
+ }
+
+ globalMergeRecord.finalize();
CodeGenDataWriter Writer;
if (!globalOutlineRecord.empty())
Writer.addRecord(globalOutlineRecord);
+ if (!globalMergeRecord.empty())
+ Writer.addRecord(globalMergeRecord);
std::error_code EC;
auto fileName = config->codegenDataGeneratePath;
diff --git a/lld/MachO/InputSection.h b/lld/MachO/InputSection.h
index 7ef0e31066f372..8e1f7ea0af01e7 100644
--- a/lld/MachO/InputSection.h
+++ b/lld/MachO/InputSection.h
@@ -339,6 +339,7 @@ constexpr const char const_[] = "__const";
constexpr const char lazySymbolPtr[] = "__la_symbol_ptr";
constexpr const char lazyBinding[] = "__lazy_binding";
constexpr const char literals[] = "__literals";
+constexpr const char functionMap[] = "__llvm_merge";
constexpr const char moduleInitFunc[] = "__mod_init_func";
constexpr const char moduleTermFunc[] = "__mod_term_func";
constexpr const char nonLazySymbolPtr[] = "__nl_symbol_ptr";
diff --git a/lld/test/MachO/cgdata-generate-merge.s b/lld/test/MachO/cgdata-generate-merge.s
new file mode 100644
index 00000000000000..3f7fb6777bc3cf
--- /dev/null
+++ b/lld/test/MachO/cgdata-generate-merge.s
@@ -0,0 +1,85 @@
+# UNSUPPORTED: system-windows
+# REQUIRES: aarch64
+
+# RUN: rm -rf %t; split-file %s %t
+
+# Synthesize raw cgdata without the header (32 byte) from the indexed cgdata.
+# RUN: llvm-cgdata --convert --format binary %t/raw-1.cgtext -o %t/raw-1.cgdata
+# RUN: od -t x1 -j 32 -An %t/raw-1.cgdata | tr -d '\n\r\t' | sed 's/[ ][ ]*/ /g; s/^[ ]*//; s/[ ]*$//; s/[ ]/,0x/g; s/^/0x/' > %t/raw-1-bytes.txt
+# RUN: sed "s/<RAW_BYTES>/$(cat %t/raw-1-bytes.txt)/g" %t/merge-template.s > %t/merge-1.s
+# RUN: llvm-cgdata --convert --format binary %t/raw-2.cgtext -o %t/raw-2.cgdata
+# RUN: od -t x1 -j 32 -An %t/raw-2.cgdata | tr -d '\n\r\t' | sed 's/[ ][ ]*/ /g; s/^[ ]*//; s/[ ]*$//; s/[ ]/,0x/g; s/^/0x/' > %t/raw-2-bytes.txt
+# RUN: sed "s/<RAW_BYTES>/$(cat %t/raw-2-bytes.txt)/g" %t/merge-template.s > %t/merge-2.s
+
+# RUN: llvm-mc -filetype obj -triple arm64-apple-darwin %t/merge-1.s -o %t/merge-1.o
+# RUN: llvm-mc -filetype obj -triple arm64-apple-darwin %t/merge-2.s -o %t/merge-2.o
+# RUN: llvm-mc -filetype obj -triple arm64-apple-darwin %t/main.s -o %t/main.o
+
+# This checks if the codegen data from the linker is identical to the merged codegen data
+# from each object file, which is obtained using the llvm-cgdata tool.
+# RUN: %no-arg-lld -dylib -arch arm64 -platform_version ios 14.0 15.0 -o %t/out \
+# RUN: %t/merge-1.o %t/merge-2.o %t/main.o --codegen-data-generate-path=%t/out-cgdata
+# RUN: llvm-cgdata --merge %t/merge-1.o %t/merge-2.o %t/main.o -o %t/merge-cgdata
+# RUN: diff %t/out-cgdata %t/merge-cgdata
+
+# Merge order doesn't matter in the yaml format. `main.o` is dropped due to missing __llvm_merge.
+# RUN: llvm-cgdata --merge %t/merge-2.o %t/merge-1.o -o %t/merge-cgdata-shuffle
+# RUN: llvm-cgdata --convert %t/out-cgdata -o %t/out-cgdata.yaml
+# RUN: llvm-cgdata --convert %t/merge-cgdata-shuffle -o %t/merge-cgdata-shuffle.yaml
+# RUN: diff %t/out-cgdata.yaml %t/merge-cgdata-shuffle.yaml
+
+# We can also generate the merged codegen data from the executable that is not dead-stripped.
+# RUN: llvm-objdump -h %t/out| FileCheck %s
+# CHECK: __llvm_merge
+# RUN: llvm-cgdata --merge %t/out -o %t/merge-cgdata-exe
+# RUN: diff %t/merge-cgdata-exe %t/merge-cgdata
+
+# Dead-strip will remove __llvm_merge sections from the final executable.
+# But the codeden data is still correctly produced from the linker.
+# RUN: %no-arg-lld -dylib -arch arm64 -platform_version ios 14.0 15.0 -o %t/out-strip \
+# RUN: %t/merge-1.o %t/merge-2.o %t/main.o -dead_strip --codegen-data-generate-path=%t/out-cgdata-strip
+# RUN: llvm-cgdata --merge %t/merge-1.o %t/merge-2.o %t/main.o -o %t/merge-cgdata-strip
+# RUN: diff %t/out-cgdata-strip %t/merge-cgdata-strip
+# RUN: diff %t/out-cgdata-strip %t/merge-cgdata
+
+# Ensure no __llvm_merge section remains in the executable.
+# RUN: llvm-objdump -h %t/out-strip | FileCheck %s --check-prefix=STRIP
+# STRIP-NOT: __llvm_merge
+
+#--- raw-1.cgtext
+:stable_function_map
+---
+- Hash: 123
+ FunctionName: f1
+ ModuleName: 'foo.bc'
+ InstCount: 7
+ IndexOperandHashes:
+ - InstIndex: 3
+ OpndIndex: 0
+ OpndHash: 456
+...
+
+#--- raw-2.cgtext
+:stable_function_map
+---
+- Hash: 123
+ FunctionName: f2
+ ModuleName: 'goo.bc'
+ InstCount: 7
+ IndexOperandHashes:
+ - InstIndex: 3
+ OpndIndex: 0
+ OpndHash: 789
+...
+
+#--- merge-template.s
+.section __DATA,__llvm_merge
+_data:
+.byte <RAW_BYTES>
+
+#--- main.s
+.globl _main
+
+.text
+_main:
+ ret
``````````
</details>
https://github.com/llvm/llvm-project/pull/112674
More information about the llvm-commits
mailing list