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[COFF] Fix assembly output of comdat sections without an attached symbol 

Since SVN r335286, the .xdata sections are produced without an attached
symbol, which requires using a different syntax when printing assembly
output.

Instead of the usual syntax of '.section <name>,"dr",discard,<symbol>',
use '.section <name>,"dr"' + '.linkonce discard' (which is what GCC
uses for all assembly output).

This fixes PR38254.

Differential Revision: https://reviews.llvm.org/D49651

llvm-svn: 337756
This commit is contained in:
Martin Storsjo 2018-07-23 22:15:19 +00:00
parent c2b701408e
commit 100fc97051
2 changed files with 96 additions and 10 deletions
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25
llvm/lib/MC/MCSectionCOFF.cpp
View File

@ -69,35 +69,40 @@ void MCSectionCOFF::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
OS << '"';
if (getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
OS << ",";
if (COMDATSymbol)
OS << ",";
else
OS << "\n\t.linkonce\t";
switch (Selection) {
case COFF::IMAGE_COMDAT_SELECT_NODUPLICATES:
OS << "one_only,";
OS << "one_only";
break;
case COFF::IMAGE_COMDAT_SELECT_ANY:
OS << "discard,";
OS << "discard";
break;
case COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
OS << "same_size,";
OS << "same_size";
break;
case COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
OS << "same_contents,";
OS << "same_contents";
break;
case COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE:
OS << "associative,";
OS << "associative";
break;
case COFF::IMAGE_COMDAT_SELECT_LARGEST:
OS << "largest,";
OS << "largest";
break;
case COFF::IMAGE_COMDAT_SELECT_NEWEST:
OS << "newest,";
OS << "newest";
break;
default:
assert(false && "unsupported COFF selection type");
break;
}
assert(COMDATSymbol);
COMDATSymbol->print(OS, &MAI);
if (COMDATSymbol) {
OS << ",";
COMDATSymbol->print(OS, &MAI);
}
}
OS << '\n';
}

81
llvm/test/CodeGen/X86/mingw-comdats-xdata.ll Normal file
View File

@ -0,0 +1,81 @@
; RUN: llc -mtriple=x86_64-w64-windows-gnu < %s | FileCheck %s --check-prefix=GNU
; RUN: llc -mtriple=x86_64-w64-windows-gnu < %s -filetype=obj | llvm-objdump - -headers | FileCheck %s --check-prefix=GNUOBJ
; When doing GCC style comdats for MinGW, the .xdata sections don't have a normal comdat
; symbol attached, which requires a bit of adjustments for the assembler output.
; Generated with this C++ source:
; int bar(int);
; __declspec(selectany) int gv = 42;
; inline int foo(int x) { try { return bar(x) + gv; } catch (...) { return 0; } }
; int main() { return foo(1); }
$_Z3fooi = comdat any
$gv = comdat any
@gv = weak_odr dso_local global i32 42, comdat, align 4
; Function Attrs: norecurse uwtable
define dso_local i32 @main() #0 {
entry:
%call = tail call i32 @_Z3fooi(i32 1)
ret i32 %call
}
; GNU: main:
; Function Attrs: inlinehint uwtable
define linkonce_odr dso_local i32 @_Z3fooi(i32 %x) #1 comdat personality i8* bitcast (i32 (...)* @__gxx_personality_seh0 to i8*) {
entry:
%call = invoke i32 @_Z3bari(i32 %x)
to label %invoke.cont unwind label %lpad
invoke.cont: ; preds = %entry
%0 = load i32, i32* @gv, align 4
%add = add nsw i32 %0, %call
br label %return
lpad: ; preds = %entry
%1 = landingpad { i8*, i32 }
catch i8* null
%2 = extractvalue { i8*, i32 } %1, 0
%3 = tail call i8* @__cxa_begin_catch(i8* %2) #3
tail call void @__cxa_end_catch()
br label %return
return: ; preds = %lpad, %invoke.cont
%retval.0 = phi i32 [ %add, %invoke.cont ], [ 0, %lpad ]
ret i32 %retval.0
}
; The .xdata section below doesn't have the usual comdat symbol attached, which requires
; a different syntax for the assembly output.
; GNU: .section .text$_Z3fooi,"xr",discard,_Z3fooi
; GNU: _Z3fooi:
; GNU: .section .xdata$_Z3fooi,"dr"
; GNU: .linkonce discard
; GNU: GCC_except_table1:
; GNU: .section .data$gv,"dw",discard,gv
; GNU: gv:
; GNU: .long 42
; Make sure the assembler puts the .xdata and .pdata in sections with the right
; names.
; GNUOBJ: .text$_Z3fooi
; GNUOBJ: .xdata$_Z3fooi
; GNUOBJ: .data$gv
; GNUOBJ: .pdata$_Z3fooi
declare dso_local i32 @_Z3bari(i32)
declare dso_local i32 @__gxx_personality_seh0(...)
declare dso_local i8* @__cxa_begin_catch(i8*) local_unnamed_addr
declare dso_local void @__cxa_end_catch() local_unnamed_addr
attributes #0 = { norecurse uwtable }
attributes #1 = { inlinehint uwtable }
attributes #3 = { nounwind }