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  1. Apr 16, 2012
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  7. Apr 05, 2012
    • Bill Wendling's avatar
      The internalize pass can be dangerous for LTO. · 4f60125d
      Bill Wendling authored 
      Consider the following program:

$ cat main.c
void foo(void) { }

int main(int argc, char *argv[]) {
    foo();
    return 0;
}
$ cat bundle.c 
extern void foo(void);

void bar(void) {
     foo();
}
$ clang -o main main.c
$ clang -o bundle.so bundle.c -bundle -bundle_loader ./main
$ nm -m bundle.so
0000000000000f40 (__TEXT,__text) external _bar
                 (undefined) external _foo (from executable)
                 (undefined) external dyld_stub_binder (from libSystem)
$ clang -o main main.c -O4
$ clang -o bundle.so bundle.c -bundle -bundle_loader ./main
Undefined symbols for architecture x86_64:
  "_foo", referenced from:
      _bar in bundle-elQN6d.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

The linker was told that the 'foo' in 'main' was 'internal' and had no uses, so
it was dead stripped.

Another situation is something like:

define void @foo() {
  ret void
}

define void @bar() {
  call asm volatile "call _foo" ...
  ret void
}

The only use of 'foo' is inside of an inline ASM call. Since we don't look
inside those for uses of functions, we don't specify this as a "use."

Get around this by not invoking the 'internalize' pass by default. This is an
admitted hack for LTO correctness.
<rdar://problem/11185386>

llvm-svn: 154124
      4f60125d
  9. Apr 03, 2012
  11. Mar 31, 2012
  13. Jan 20, 2012
  15. Dec 02, 2011
    • Nick Lewycky's avatar
      Move global variables in TargetMachine into new TargetOptions class. As an API · 50f02cb2
      Nick Lewycky authored 
      change, now you need a TargetOptions object to create a TargetMachine. Clang
patch to follow.

One small functionality change in PTX. PTX had commented out the machine
verifier parts in their copy of printAndVerify. That now calls the version in
LLVMTargetMachine. Users of PTX who need verification disabled should rely on
not passing the command-line flag to enable it.

llvm-svn: 145714
      50f02cb2
  17. Nov 05, 2011
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  51. Mar 02, 2011
    • Rafael Espindola's avatar
      Add a special streamer to libLTO that just records symbols definitions and · 1e49a6d9
      Rafael Espindola authored 
      uses.

The result produced by the streamer is used to give the linker more accurate
information and to add to llvm.compiler.used. The second improvement removes
the need for the user to add __attribute__((used)) to functions only used in
inline asm. The first one lets us build firefox with LTO on Darwin :-)

llvm-svn: 126830
      1e49a6d9
  53. Feb 24, 2011
  55. Feb 20, 2011
  57. Feb 12, 2011