[llvm-commits] [llvm-gcc-4.2] r99629 - /llvm-gcc-4.2/trunk/gcc/gimplify.c

[Devang Patel]

Chris,

	This patch causes regressions in gdb test suite.
-
Devang
On Mar 26, 2010, at 11:41 AM, Chris Lattner wrote:

> Author: lattner
> Date: Fri Mar 26 13:41:06 2010
> New Revision: 99629
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=99629&view=rev
> Log:
> disable a minor optimization on darwin.  For code like this:
> 
> extern int a, b, c, d;
> void foo() {
>  int *Arr[] = {&a, &b, &c, &d, &a, &b, &c, &d, &a, &b, &c, &d, &a, &b, &c, &d,
>    &a, &b, &c, &d, &a, &b, &c, &d, &a, &b, &c, &d, &a, &b, &c, &d };
>  bar(Arr);
> }
> 
> the compiler synthesizes a global variable for the temporary array and then
> memcpy's from it to Arr.  This is all great, but emitting the temporary global
> with an L label on darwin fouls up atomization and can thus break dead code
> stripping.
> 
> The right answer is to use an 'l' label without .globl, but this will require
> introducing a yet-another new linkage type to llvm, which I'll do later.
> 
> This fixes rdar://7233622
> 
> 
> Modified:
>    llvm-gcc-4.2/trunk/gcc/gimplify.c
> 
> Modified: llvm-gcc-4.2/trunk/gcc/gimplify.c
> URL: http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/gimplify.c?rev=99629&r1=99628&r2=99629&view=diff
> ==============================================================================
> --- llvm-gcc-4.2/trunk/gcc/gimplify.c (original)
> +++ llvm-gcc-4.2/trunk/gcc/gimplify.c Fri Mar 26 13:41:06 2010
> @@ -3097,9 +3097,16 @@
> 		TREE_STATIC (new) = 1;
> 		TREE_READONLY (new) = 1;
>                 /* LLVM LOCAL begin */
> +                /* On Darwin, we can't emit temporaries like this with private
> +                 * linkage, because it breaks 'atomization' of stuff in the
> +                 * object file by the linker.  We need to emit this as a l label
> +                 * without .globl.
> +                 */
> +#ifndef CONFIG_DARWIN_H
> #ifdef ENABLE_LLVM
> 		DECL_LLVM_PRIVATE (new) = 1;
> #endif
> +#endif
>                 /* LLVM LOCAL end */
> 		DECL_INITIAL (new) = ctor;
> 		if (align > DECL_ALIGN (new))
> 
> 
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