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Re: [GOOGLE] Workaround a bug in AutoFDO which may leads to infinite loop for inlined assembly
- From: Teresa Johnson <tejohnson at google dot com>
- To: Dehao Chen <dehao at google dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, David Li <davidxl at google dot com>
- Date: Sun, 21 Apr 2013 17:00:57 -0700
- Subject: Re: [GOOGLE] Workaround a bug in AutoFDO which may leads to infinite loop for inlined assembly
- References: <CAO2gOZW5JiuDkZZxYAjtFNoN6uUsyr=uEtWdQBeqa0NvREiNNw at mail dot gmail dot com>
On Sun, Apr 21, 2013 at 4:51 PM, Dehao Chen <email@example.com> wrote:
> This patch fixed a bug in getting inline stacks: if there is no
> location info attached to a block, we should *not* try to get its
> function name because it could result in infinite loop.
Is the infinite loop within get_function_decl_from_block itself? If
so, for extra safety perhaps that routine should check if the location
is unknown and return early if it is. One other minor comment below,
otherwise it looks ok to me.
> Bootstrapped and passed all regression tests.
> Ok for gcc-4_7 branch?
> Index: gcc/auto-profile.c
> --- gcc/auto-profile.c (revision 198117)
> +++ gcc/auto-profile.c (working copy)
> @@ -662,9 +662,10 @@ get_inline_stack_by_stmt (gimple stmt, tree decl,
> block && (TREE_CODE (block) == BLOCK);
> block = BLOCK_SUPERCONTEXT (block))
> - tree decl = get_function_decl_from_block (block);
> + tree decl;
> if (LOCATION_LOCUS (BLOCK_SOURCE_LOCATION (block)) == UNKNOWN_LOCATION)
> + decl = get_function_decl_from_block (block);
> loc = BLOCK_SOURCE_LOCATION (block);
Do you want to move up the assignment to loc and use loc in the new if
> pos_stack[idx].file = expand_location (loc).file;
> pos_stack[idx].line = expand_location (loc).line;
Teresa Johnson | Software Engineer | firstname.lastname@example.org | 408-460-2413