From 1a66537fe667a6d3d9b0281b093e407d41c50573 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Tue, 21 May 2019 10:41:25 +0000 Subject: [PATCH] [PPC64] Update LocalEntry from assigned symbols On PowerPC64 ELFv2 ABI, functions may have 2 entry points: global and local. The local entry point location of a function is stored in the st_other field of the symbol, as an offset relative to the global entry point. In order to make symbol assignments (e.g. .equ/.set) work properly with this, PPCTargetELFStreamer already copies the local entry bits from the source symbol to the destination one, on emitAssignment(). The problem is that this copy is performed only at the assignment location, where the source symbol may not yet have processed the .localentry directive, that sets the local entry. This may cause the destination symbol to end up with wrong local entry information. Other symbol info is not affected by this because, in this case, the destination symbol value is actually a symbol reference. This change keeps track of these assignments, and update all needed st_other fields when finish() is called. Patch by Leandro Lupori! Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D56586 llvm-svn: 361237 --- .../PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp | 30 +++++++++++++++---- ...ry-symver.s => ppc64-localentry-symbols.s} | 17 +++++++++++ 2 files changed, 41 insertions(+), 6 deletions(-) rename llvm/test/MC/PowerPC/{ppc64-localentry-symver.s => ppc64-localentry-symbols.s} (58%) diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp index 831cf2b1913fb..395b4236fa835 100644 --- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp +++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp @@ -15,6 +15,7 @@ #include "MCTargetDesc/PPCMCAsmInfo.h" #include "PPCTargetStreamer.h" #include "TargetInfo/PowerPCTargetInfo.h" +#include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/StringRef.h" #include "llvm/ADT/Triple.h" #include "llvm/BinaryFormat/ELF.h" @@ -182,16 +183,33 @@ class PPCTargetELFStreamer : public PPCTargetStreamer { void emitAssignment(MCSymbol *S, const MCExpr *Value) override { auto *Symbol = cast(S); + // When encoding an assignment to set symbol A to symbol B, also copy // the st_other bits encoding the local entry point offset. - if (Value->getKind() != MCExpr::SymbolRef) - return; - const auto &RhsSym = cast( - static_cast(Value)->getSymbol()); - unsigned Other = Symbol->getOther(); + if (copyLocalEntry(Symbol, Value)) + UpdateOther.insert(Symbol); + else + UpdateOther.erase(Symbol); + } + + void finish() override { + for (auto *Sym : UpdateOther) + copyLocalEntry(Sym, Sym->getVariableValue()); + } + +private: + SmallPtrSet UpdateOther; + + bool copyLocalEntry(MCSymbolELF *D, const MCExpr *S) { + auto *Ref = dyn_cast(S); + if (!Ref) + return false; + const auto &RhsSym = cast(Ref->getSymbol()); + unsigned Other = D->getOther(); Other &= ~ELF::STO_PPC64_LOCAL_MASK; Other |= RhsSym.getOther() & ELF::STO_PPC64_LOCAL_MASK; - Symbol->setOther(Other); + D->setOther(Other); + return true; } }; diff --git a/llvm/test/MC/PowerPC/ppc64-localentry-symver.s b/llvm/test/MC/PowerPC/ppc64-localentry-symbols.s similarity index 58% rename from llvm/test/MC/PowerPC/ppc64-localentry-symver.s rename to llvm/test/MC/PowerPC/ppc64-localentry-symbols.s index 4c7490646db03..f1d5c5d0ab1ac 100644 --- a/llvm/test/MC/PowerPC/ppc64-localentry-symver.s +++ b/llvm/test/MC/PowerPC/ppc64-localentry-symbols.s @@ -4,6 +4,11 @@ # CHECK: 0000000000000000 gw F .text 00000000 0x60 __impl_foo # CHECK: 0000000000000000 g F .text 00000000 0x60 foo # CHECK: 0000000000000000 gw F .text 00000000 0x60 foo@FBSD_1.1 +# CHECK: 0000000000000008 g F .text 00000000 0x60 func +# CHECK: 0000000000000008 gw F .text 00000000 0x60 weak_func + +.text +.abiversion 2 .globl foo .type foo,@function @@ -15,3 +20,15 @@ foo: .symver __impl_foo, foo@FBSD_1.1 .weak __impl_foo .set __impl_foo, foo + +.globl func +# Mimick FreeBSD weak function/reference +.weak weak_func +.equ weak_func, func + +.p2align 2 +.type func,@function +func: + nop + nop + .localentry func, 8