MC-COFF: GlobalAlias is not emitted

[llvmbot]

Bugzilla Link	8251
Resolution	FIXED
Resolved on	Oct 07, 2010 01:30
Version	trunk
OS	All
Reporter	LLVM Bugzilla Contributor
CC	@Bigcheese

Extended Description

clang++ emits aliases for dtors.
(eg. __ZN4llvm5RegexD1Ev and __ZN4llvm5RegexD2Ev)
and compilation fails with -integrated-as.

define void @​foo() {
entry:
ret void
}

@​bar =global i32 zeroinitializer

@​qux = alias void ()* @​foo
@​quux = alias i32* @​bar

$ llc -mtriple=i686-mingw32 -filetype=obj (incorrect)

SYMBOL TABLE:
[ 0](sec 1)(fl 0x00)(ty 0)(scl 3) (nx 1) 0x00000000 .text
AUX scnlen 0x4 nreloc 0 nlnno 0 checksum 0x0 assoc 1 comdat 0
[ 2](sec 2)(fl 0x00)(ty 0)(scl 3) (nx 1) 0x00000000 .data
AUX scnlen 0x4 nreloc 0 nlnno 0 checksum 0x0 assoc 2 comdat 0
[ 4](sec 1)(fl 0x00)(ty 200)(scl 2) (nx 0) 0x00000000 _foo
[ 5](sec 2)(fl 0x00)(ty 0)(scl 2) (nx 0) 0x00000000 _bar

$ llc -mtriple=i686-mingw32

    .globl  _qux

_qux = _foo
.globl _quux
_quux = _bar

$ as (mingw's GNU as; correct)

SYMBOL TABLE:
[ 0](sec -2)(fl 0x00)(ty 0)(scl 103) (nx 1) 0x00000000 fake
File
[ 2](sec 1)(fl 0x00)(ty 0)(scl 3) (nx 1) 0x00000000 .text
AUX scnlen 0x1 nreloc 0 nlnno 0
[ 4](sec 2)(fl 0x00)(ty 0)(scl 3) (nx 1) 0x00000000 .data
AUX scnlen 0x4 nreloc 0 nlnno 0
[ 6](sec 3)(fl 0x00)(ty 0)(scl 3) (nx 1) 0x00000000 .bss
AUX scnlen 0x0 nreloc 0 nlnno 0
[ 8](sec 1)(fl 0x00)(ty 200)(scl 2) (nx 0) 0x00000000 _foo
[ 9](sec 2)(fl 0x00)(ty 0)(scl 2) (nx 0) 0x00000000 _bar
[ 10](sec 1)(fl 0x00)(ty 0)(scl 2) (nx 0) 0x00000000 _qux
[ 11](sec 2)(fl 0x00)(ty 0)(scl 2) (nx 0) 0x00000000 _quux

[llvmbot]

assigned to @Bigcheese

[llvmbot]

Workaround: disable -mconstructor-aliases in clang/lib/Driver/Tools.cpp

[Bigcheese]

Simple fix for the problem.
This seems to fix the problem, however, there may be subtle bugs due to the "real" symbol data being changed later in the object writer.

[llvmbot]

Simple fix for the problem.

It seems to work for me. Linking passes.

Although I could close this now, I saw some problems around MC-COFF,
and I cannot confirm it would be really right.

I am trying bootstrapping clang/cygming.
It goes good without -integrated-as.

This seems to fix the problem, however, there may be subtle bugs due to the
"real" symbol data being changed later in the object writer.

I have not met it yet, indeed.

[Bigcheese]

Fixed in r115909.