From adac407ed9eec0d5515823bd82f7fdc0aef0da1d Mon Sep 17 00:00:00 2001 From: Peter Collingbourne Date: Wed, 10 Apr 2013 16:52:15 +0000 Subject: [PATCH] Use a scheme closer to that of GNU as when deciding the type of a symbol with multiple .type declarations. Differential Revision: http://llvm-reviews.chandlerc.com/D607 llvm-svn: 179184 --- llvm/lib/MC/MCELFStreamer.cpp | 40 ++++++++++++++++++++++---- llvm/test/MC/ELF/type.s | 53 +++++++++++++++++++++++++++++------ 2 files changed, 78 insertions(+), 15 deletions(-) diff --git a/llvm/lib/MC/MCELFStreamer.cpp b/llvm/lib/MC/MCELFStreamer.cpp index 7f5f1b63e5fe..7faa6f411b38 100644 --- a/llvm/lib/MC/MCELFStreamer.cpp +++ b/llvm/lib/MC/MCELFStreamer.cpp @@ -13,6 +13,7 @@ #include "llvm/MC/MCELFStreamer.h" #include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/STLExtras.h" #include "llvm/MC/MCAssembler.h" #include "llvm/MC/MCCodeEmitter.h" #include "llvm/MC/MCContext.h" @@ -126,6 +127,26 @@ void MCELFStreamer::EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) { Alias->setVariableValue(Value); } +// When GNU as encounters more than one .type declaration for an object it seems +// to use a mechanism similar to the one below to decide which type is actually +// used in the object file. The greater of T1 and T2 is selected based on the +// following ordering: +// STT_NOTYPE < STT_OBJECT < STT_FUNC < STT_GNU_IFUNC < STT_TLS < anything else +// If neither T1 < T2 nor T2 < T1 according to this ordering, use T2 (the user +// provided type). +static unsigned CombineSymbolTypes(unsigned T1, unsigned T2) { + unsigned TypeOrdering[] = {ELF::STT_NOTYPE, ELF::STT_OBJECT, ELF::STT_FUNC, + ELF::STT_GNU_IFUNC, ELF::STT_TLS}; + for (unsigned i = 0; i != array_lengthof(TypeOrdering); ++i) { + if (T1 == TypeOrdering[i]) + return T2; + if (T2 == TypeOrdering[i]) + return T1; + } + + return T2; +} + void MCELFStreamer::EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) { // Indirect symbols are handled differently, to match how 'as' handles @@ -187,27 +208,34 @@ void MCELFStreamer::EmitSymbolAttribute(MCSymbol *Symbol, break; case MCSA_ELF_TypeFunction: - MCELF::SetType(SD, ELF::STT_FUNC); + MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD), + ELF::STT_FUNC)); break; case MCSA_ELF_TypeIndFunction: - MCELF::SetType(SD, ELF::STT_GNU_IFUNC); + MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD), + ELF::STT_GNU_IFUNC)); break; case MCSA_ELF_TypeObject: - MCELF::SetType(SD, ELF::STT_OBJECT); + MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD), + ELF::STT_OBJECT)); break; case MCSA_ELF_TypeTLS: - MCELF::SetType(SD, ELF::STT_TLS); + MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD), + ELF::STT_TLS)); break; case MCSA_ELF_TypeCommon: - MCELF::SetType(SD, ELF::STT_COMMON); + // TODO: Emit these as a common symbol. + MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD), + ELF::STT_OBJECT)); break; case MCSA_ELF_TypeNoType: - MCELF::SetType(SD, ELF::STT_NOTYPE); + MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD), + ELF::STT_NOTYPE)); break; case MCSA_Protected: diff --git a/llvm/test/MC/ELF/type.s b/llvm/test/MC/ELF/type.s index ec53e4ffa524..00277ce9c469 100644 --- a/llvm/test/MC/ELF/type.s +++ b/llvm/test/MC/ELF/type.s @@ -12,35 +12,70 @@ bar: // Test that gnu_unique_object is accepted. .type zed,@gnu_unique_object +obj: + .global obj + .type obj,@object + .type obj,@notype + +func: + .global func + .type func,@function + .type func,@object + ifunc: .global ifunc .type ifunc,@gnu_indirect_function + .type ifunc,@function -// CHECK: # Symbol 4 -// CHECK-NEXT: (('st_name', 0x00000005) # 'bar' +tls: + .global tls + .type tls,@tls_object + .type tls,@gnu_indirect_function + +// CHECK: (('st_name', {{.*}}) # 'bar' // CHECK-NEXT: ('st_bind', 0x1) // CHECK-NEXT: ('st_type', 0x1) // CHECK-NEXT: ('st_other', 0x00) // CHECK-NEXT: ('st_shndx', 0x0001) // CHECK-NEXT: ('st_value', 0x0000000000000000) // CHECK-NEXT: ('st_size', 0x0000000000000000) -// CHECK-NEXT: ), -// CHECK-NEXT: # Symbol 5 -// CHECK-NEXT: (('st_name', 0x00000001) # 'foo' + +// CHECK: (('st_name', {{.*}}) # 'foo' // CHECK-NEXT: ('st_bind', 0x1) // CHECK-NEXT: ('st_type', 0x2) // CHECK-NEXT: ('st_other', 0x00) // CHECK-NEXT: ('st_shndx', 0x0001) // CHECK-NEXT: ('st_value', 0x0000000000000000) // CHECK-NEXT: ('st_size', 0x0000000000000000) -// CHECK-NEXT: ), -// CHECK-NEXT: # Symbol 6 -// CHECK-NEXT: (('st_name', 0x00000009) # 'ifunc' + +// CHECK: (('st_name', {{.*}}) # 'func' +// CHECK-NEXT: ('st_bind', 0x1) +// CHECK-NEXT: ('st_type', 0x2) +// CHECK-NEXT: ('st_other', 0x00) +// CHECK-NEXT: ('st_shndx', 0x0001) +// CHECK-NEXT: ('st_value', 0x0000000000000000) +// CHECK-NEXT: ('st_size', 0x0000000000000000) + +// CHECK: (('st_name', {{.*}}) # 'ifunc' // CHECK-NEXT: ('st_bind', 0x1) // CHECK-NEXT: ('st_type', 0xa) // CHECK-NEXT: ('st_other', 0x00) // CHECK-NEXT: ('st_shndx', 0x0001) // CHECK-NEXT: ('st_value', 0x0000000000000000) // CHECK-NEXT: ('st_size', 0x0000000000000000) -// CHECK-NEXT: ), +// CHECK: (('st_name', {{.*}}) # 'obj' +// CHECK-NEXT: ('st_bind', 0x1) +// CHECK-NEXT: ('st_type', 0x1) +// CHECK-NEXT: ('st_other', 0x00) +// CHECK-NEXT: ('st_shndx', 0x0001) +// CHECK-NEXT: ('st_value', 0x0000000000000000) +// CHECK-NEXT: ('st_size', 0x0000000000000000) + +// CHECK: (('st_name', {{.*}}) # 'tls' +// CHECK-NEXT: ('st_bind', 0x1) +// CHECK-NEXT: ('st_type', 0x6) +// CHECK-NEXT: ('st_other', 0x00) +// CHECK-NEXT: ('st_shndx', 0x0001) +// CHECK-NEXT: ('st_value', 0x0000000000000000) +// CHECK-NEXT: ('st_size', 0x0000000000000000)