From 66055230bf6673b76e7330fef76d752a1ea8638e Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Thu, 7 May 2020 14:00:24 -0700 Subject: [TargetLoweringObjectFileImpl] Produce .text.hot. instead of .text.hot for -fno-unique-section-names GNU ld's internal linker script uses (https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=add44f8d5c5c05e08b11e033127a744d61c26aee) .text : { *(.text.unlikely .text.*_unlikely .text.unlikely.*) *(.text.exit .text.exit.*) *(.text.startup .text.startup.*) *(.text.hot .text.hot.*) *(SORT(.text.sorted.*)) *(.text .stub .text.* .gnu.linkonce.t.*) /* .gnu.warning sections are handled specially by elf.em. */ *(.gnu.warning) } Because `*(.text.exit .text.exit.*)` is ordered before `*(.text .text.*)`, in a -ffunction-sections build, the C library function `exit` will be placed before other functions. gold's `-z keep-text-section-prefix` has the same problem. In lld, `-z keep-text-section-prefix` recognizes `.text.{exit,hot,startup,unlikely,unknown}.*`, but not `.text.{exit,hot,startup,unlikely,unknown}`, to avoid the strange placement problem. In -fno-function-sections or -fno-unique-section-names mode, a function whose `function_section_prefix` is set to `.exit"` will go to the output section `.text` instead of `.text.exit` when linked by lld. To address the problem, append a dot to become `.text.exit.` Reviewed By: grimar Differential Revision: https://reviews.llvm.org/D79600 --- llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp') diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp index a9b1455d13ab..a3bfd650d4b3 100644 --- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp +++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp @@ -611,15 +611,19 @@ getELFSectionNameForGlobal(const GlobalObject *GO, SectionKind Kind, Name = getSectionPrefixForGlobal(Kind); } + bool HasPrefix = false; if (const auto *F = dyn_cast(GO)) { - if (Optional Prefix = F->getSectionPrefix()) + if (Optional Prefix = F->getSectionPrefix()) { Name += *Prefix; + HasPrefix = true; + } } if (UniqueSectionName) { Name.push_back('.'); TM.getNameWithPrefix(Name, GO, Mang, /*MayAlwaysUsePrivate*/true); - } + } else if (HasPrefix) + Name.push_back('.'); return Name; } -- cgit v1.2.3