10a7946072
The underlying issue in the LLVM gold plugin now has a proposed fix that we can use to remove the hack. Differential Revision: https://phabricator.services.mozilla.com/D145539
88 lines
3.1 KiB
Diff
88 lines
3.1 KiB
Diff
[gold] Ignore bitcode from sections inside object files
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-fembed-bitcode will put bitcode into special sections within object
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files, but this is not meant to be used by LTO, so the gold plugin
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should ignore it.
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https://github.com/llvm/llvm-project/issues/47216
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diff --git a/llvm/test/tools/gold/X86/Inputs/bcsection-lib.ll b/llvm/test/tools/gold/X86/Inputs/bcsection-lib.ll
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new file mode 100644
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--- /dev/null
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+++ b/llvm/test/tools/gold/X86/Inputs/bcsection-lib.ll
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@@ -0,0 +1,6 @@
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+declare void @elf_func()
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+
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+define i32 @lib_func() {
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+ call void @elf_func()
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+ ret i32 0
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+}
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diff --git a/llvm/test/tools/gold/X86/Inputs/bcsection.s b/llvm/test/tools/gold/X86/Inputs/bcsection.s
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--- a/llvm/test/tools/gold/X86/Inputs/bcsection.s
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+++ b/llvm/test/tools/gold/X86/Inputs/bcsection.s
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@@ -1,2 +1,7 @@
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+.global elf_func
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+
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+elf_func:
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+ ret
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+
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.section .llvmbc
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.incbin "bcsection.bc"
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diff --git a/llvm/test/tools/gold/X86/bcsection.ll b/llvm/test/tools/gold/X86/bcsection.ll
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--- a/llvm/test/tools/gold/X86/bcsection.ll
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+++ b/llvm/test/tools/gold/X86/bcsection.ll
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@@ -2,16 +2,29 @@
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; RUN: llvm-as -o %t/bcsection.bc %s
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; RUN: llvm-mc -I=%t -filetype=obj -triple=x86_64-unknown-unknown -o %t/bcsection.bco %p/Inputs/bcsection.s
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-; RUN: llvm-nm --no-llvm-bc %t/bcsection.bco 2>&1 | FileCheck %s -check-prefix=NO-SYMBOLS
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-; NO-SYMBOLS: no symbols
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+; RUN: llc -filetype=obj -mtriple=x86_64-unknown-unknown -o %t/bcsection-lib.o %p/Inputs/bcsection-lib.ll
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-; RUN: %gold -r -o %t/bcsection.o -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext %t/bcsection.bco
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-; RUN: llvm-nm --no-llvm-bc %t/bcsection.o | FileCheck %s
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+; RUN: %gold -shared --no-undefined -o %t/bcsection.so -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext %t/bcsection.bco %t/bcsection-lib.o
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+
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+; This test checks that the gold plugin does not attempt to use the bitcode
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+; in the .llvmbc section for LTO. bcsection-lib.o calls a function that is
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+; present the symbol table of bcsection.bco, but not included in the embedded
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+; bitcode. If the linker were to use the bitcode, then the symbols in the
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+; symbol table of bcsection.bco will be ignored and the link will fail.
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+;
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+; bcsection.bco:
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+; .text:
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+; elf_func
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+; .llvmbc:
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+; bitcode_func
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+;
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+; bcsection-lib.o:
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+; calls elf_func()
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-unknown"
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; CHECK: main
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-define i32 @main() {
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+define i32 @bitcode_func() {
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ret i32 0
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}
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diff --git a/llvm/tools/gold/gold-plugin.cpp b/llvm/tools/gold/gold-plugin.cpp
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--- a/llvm/tools/gold/gold-plugin.cpp
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+++ b/llvm/tools/gold/gold-plugin.cpp
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@@ -540,6 +540,14 @@
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BufferRef = Buffer->getMemBufferRef();
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}
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+ // Only use bitcode files for LTO. InputFile::create() will load bitcode
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+ // from special sections within a binary object, this bitcode is typically
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+ // generated by -fembed-bitcode and is not meant for LTO use.
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+ if (identify_magic(BufferRef.getBuffer()) != file_magic::bitcode) {
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+ *claimed = 0;
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+ return LDPS_OK;
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+ }
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+
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*claimed = 1;
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Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
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