[Mesa-dev] [PATCH] radeon/llvm: Dynamically allocate branch/loop stack arrays

[Marek Olšák]

Reviewed-by: Marek Olšák <marek.olsak at amd.com>

Marek

On Wed, Oct 29, 2014 at 8:58 AM, Michel Dänzer <michel at daenzer.net> wrote:
> From: Michel Dänzer <michel.daenzer at amd.com>
>
> This prevents us from silently overflowing the stack arrays, and allows
> arbitrary stack depths.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85454
>
> Reported-and-Tested-by: Nick Sarnie <commendsarnex at gmail.com>
> Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
> ---
>  src/gallium/drivers/radeon/radeon_llvm.h           | 10 ++++---
>  .../drivers/radeon/radeon_setup_tgsi_llvm.c        | 33 ++++++++++++++++++++--
>  2 files changed, 37 insertions(+), 6 deletions(-)
>
> diff --git a/src/gallium/drivers/radeon/radeon_llvm.h b/src/gallium/drivers/radeon/radeon_llvm.h
> index 00714fb..8612ef8 100644
> --- a/src/gallium/drivers/radeon/radeon_llvm.h
> +++ b/src/gallium/drivers/radeon/radeon_llvm.h
> @@ -33,10 +33,10 @@
>
>  #define RADEON_LLVM_MAX_INPUTS 32 * 4
>  #define RADEON_LLVM_MAX_OUTPUTS 32 * 4
> -#define RADEON_LLVM_MAX_BRANCH_DEPTH 16
> -#define RADEON_LLVM_MAX_LOOP_DEPTH 16
>  #define RADEON_LLVM_MAX_ARRAYS 16
>
> +#define RADEON_LLVM_INITIAL_CF_DEPTH 4
> +
>  #define RADEON_LLVM_MAX_SYSTEM_VALUES 4
>
>  struct radeon_llvm_branch {
> @@ -122,11 +122,13 @@ struct radeon_llvm_context {
>
>         /*=== Private Members ===*/
>
> -       struct radeon_llvm_branch branch[RADEON_LLVM_MAX_BRANCH_DEPTH];
> -       struct radeon_llvm_loop loop[RADEON_LLVM_MAX_LOOP_DEPTH];
> +       struct radeon_llvm_branch *branch;
> +       struct radeon_llvm_loop *loop;
>
>         unsigned branch_depth;
> +       unsigned branch_depth_max;
>         unsigned loop_depth;
> +       unsigned loop_depth_max;
>
>         struct tgsi_declaration_range arrays[RADEON_LLVM_MAX_ARRAYS];
>         unsigned num_arrays;
> diff --git a/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c b/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
> index 2fa23ed..c30a9d0 100644
> --- a/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
> +++ b/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
> @@ -446,7 +446,19 @@ static void bgnloop_emit(
>                                                 endloop_block, "LOOP");
>         LLVMBuildBr(gallivm->builder, loop_block);
>         LLVMPositionBuilderAtEnd(gallivm->builder, loop_block);
> -       ctx->loop_depth++;
> +
> +       if (++ctx->loop_depth > ctx->loop_depth_max) {
> +               unsigned new_max = ctx->loop_depth_max << 1;
> +
> +               if (!new_max)
> +                       new_max = RADEON_LLVM_INITIAL_CF_DEPTH;
> +
> +               ctx->loop = REALLOC(ctx->loop, ctx->loop_depth_max *
> +                                   sizeof(ctx->loop[0]),
> +                                   new_max * sizeof(ctx->loop[0]));
> +               ctx->loop_depth_max = new_max;
> +       }
> +
>         ctx->loop[ctx->loop_depth - 1].loop_block = loop_block;
>         ctx->loop[ctx->loop_depth - 1].endloop_block = endloop_block;
>  }
> @@ -577,7 +589,18 @@ static void if_cond_emit(
>         LLVMBuildCondBr(gallivm->builder, cond, if_block, else_block);
>         LLVMPositionBuilderAtEnd(gallivm->builder, if_block);
>
> -       ctx->branch_depth++;
> +       if (++ctx->branch_depth > ctx->branch_depth_max) {
> +               unsigned new_max = ctx->branch_depth_max << 1;
> +
> +               if (!new_max)
> +                       new_max = RADEON_LLVM_INITIAL_CF_DEPTH;
> +
> +               ctx->branch = REALLOC(ctx->branch, ctx->branch_depth_max *
> +                                     sizeof(ctx->branch[0]),
> +                                     new_max * sizeof(ctx->branch[0]));
> +               ctx->branch_depth_max = new_max;
> +       }
> +
>         ctx->branch[ctx->branch_depth - 1].endif_block = endif_block;
>         ctx->branch[ctx->branch_depth - 1].if_block = if_block;
>         ctx->branch[ctx->branch_depth - 1].else_block = else_block;
> @@ -1440,4 +1463,10 @@ void radeon_llvm_dispose(struct radeon_llvm_context * ctx)
>         LLVMContextDispose(ctx->soa.bld_base.base.gallivm->context);
>         FREE(ctx->temps);
>         ctx->temps = NULL;
> +       FREE(ctx->loop);
> +       ctx->loop = NULL;
> +       ctx->loop_depth_max = 0;
> +       FREE(ctx->branch);
> +       ctx->branch = NULL;
> +       ctx->branch_depth_max = 0;
>  }
> --
> 2.1.1
>
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