Re: [google] re-enable r185948

[Xinliang David Li <davidxl at google dot com>]

ok. Is the change in google-47 branch?

Please also submit this to trunk (there was also a previous one pending).

thanks,

David

On Thu, May 3, 2012 at 4:44 AM, Dehao Chen <dehao@google.com> wrote:
> Hi,
>
> This patch was reverted because of performance degradation. However, it
> turns out to be an innocent performance loss. Thus we want to reenable it in
> google branches.
>
> Passed bootstrap and gcc regression tests and google performance tests.
>
> OK for google branch?
>
> Thanks,
> Dehao
>
> gcc/ChangeLog.google-4_6
> 2012-05-03 ?Dehao Chen ?<dehao@google.com>
>
> * predict.c (predict_iv_comparison): Add the comparison of induction
> variable against its initial value. (Reenable r185948)
>
> gcc/testsuite/ChangeLog.google-4_6
> 2012-05-03 ?Dehao Chen ?<dehao@google.com>
>
> * gcc.dg/predict-1.c: Check if LOOP_IV_COMPARE static predict
> heuristic is working properly. Reenable r185948.
> * gcc.dg/predict-2.c: Likewise
> * gcc.dg/predict-3.c: Likewise
> * gcc.dg/predict-4.c: Likewise
> * gcc.dg/predict-5.c: Likewise
> * gcc.dg/predict-6.c: Likewise
>
> Index: testsuite/gcc.dg/predict-3.c
> ===================================================================
> --- testsuite/gcc.dg/predict-3.c (revision 187013)
> +++ testsuite/gcc.dg/predict-3.c (working copy)
> @@ -10,10 +10,16 @@
> ? ?int i, ret = 0;
> ? ?for (i = 0; i <= bound; i++)
> ? ? ?{
> + ? ? ?if (i < bound - 2)
> + global += bar (i);
> + ? ? ?if (i <= bound)
> + global += bar (i);
> + ? ? ?if (i + 1 < bound)
> + global += bar (i);
> ? ? ? ?if (i != bound)
> ? global += bar (i);
> ? ? ?}
> ?}
>
> -/* { dg-final { scan-tree-dump "loop iv compare heuristics"
> "profile_estimate"} } */
> +/* { dg-final { scan-tree-dump-times "loop iv compare heuristics: 100.0%" 4
> "profile_estimate"} } */
> ?/* { dg-final { cleanup-tree-dump "profile_estimate" } } */
> Index: testsuite/gcc.dg/predict-4.c
> ===================================================================
> --- testsuite/gcc.dg/predict-4.c (revision 187013)
> +++ testsuite/gcc.dg/predict-4.c (working copy)
> @@ -15,5 +15,5 @@
> ? ? ?}
> ?}
>
> -/* { dg-final { scan-tree-dump "loop iv compare heuristics"
> "profile_estimate"} } */
> +/* { dg-final { scan-tree-dump "loop iv compare heuristics: 50.0%"
> "profile_estimate"} } */
> ?/* { dg-final { cleanup-tree-dump "profile_estimate" } } */
> Index: testsuite/gcc.dg/predict-1.c
> ===================================================================
> --- testsuite/gcc.dg/predict-1.c (revision 187013)
> +++ testsuite/gcc.dg/predict-1.c (working copy)
> @@ -10,10 +10,18 @@
> ? ?int i, ret = 0;
> ? ?for (i = 0; i < bound; i++)
> ? ? ?{
> + ? ? ?if (i > bound)
> + global += bar (i);
> + ? ? ?if (i >= bound + 2)
> + global += bar (i);
> ? ? ? ?if (i > bound - 2)
> ? global += bar (i);
> + ? ? ?if (i + 2 > bound)
> + global += bar (i);
> + ? ? ?if (i == 10)
> + global += bar (i);
> ? ? ?}
> ?}
>
> -/* { dg-final { scan-tree-dump "loop iv compare heuristics"
> "profile_estimate"} } */
> +/* { dg-final { scan-tree-dump-times "loop iv compare heuristics: 0.0%" 5
> "profile_estimate"} } */
> ?/* { dg-final { cleanup-tree-dump "profile_estimate" } } */
> Index: testsuite/gcc.dg/predict-2.c
> ===================================================================
> --- testsuite/gcc.dg/predict-2.c (revision 187013)
> +++ testsuite/gcc.dg/predict-2.c (working copy)
> @@ -5,12 +5,20 @@
>
> ?int bar(int);
>
> -void foo (int bound)
> +void foo (int base, int bound)
> ?{
> ? ?int i, ret = 0;
> - ?for (i = 0; i < bound; i++)
> + ?for (i = base; i < bound; i++)
> ? ? ?{
> - ? ? ?if (i > bound * bound )
> + ? ? ?if (i > bound * bound)
> + global += bar (i);
> + ? ? ?if (i > bound + 10)
> + global += bar (i);
> + ? ? ?if (i <= bound + 10)
> + global += bar (i);
> + ? ? ?if (i > base + 10)
> + global += bar (i);
> + ? ? ?if (i < base - 10)
> ? global += bar (i);
> ? ? ?}
> ?}
> Index: predict.c
> ===================================================================
> --- predict.c (revision 187013)
> +++ predict.c (working copy)
> @@ -1070,6 +1070,10 @@
> ? ? ?bound = get_base_value (bound);
> ? ?if (!bound)
> ? ? ?return false;
> + ?if (TREE_CODE (base) != INTEGER_CST)
> + ? ?base = get_base_value (base);
> + ?if (!base)
> + ? ?return false;
>
> ? ?*loop_invariant = bound;
> ? ?*compare_code = code;
> @@ -1185,8 +1189,7 @@
> ? ? ? ?return;
> ? ? ?}
>
> - ?if (!expr_coherent_p (loop_bound_var, compare_var)
> - ? ? ?|| loop_iv_base_var != compare_base)
> + ?if (!expr_coherent_p(loop_iv_base_var, compare_base))
> ? ? ?return;
>
> ? ?/* If loop bound, base and compare bound are all constents, we can
> @@ -1230,34 +1233,52 @@
> ? ? ? ?return;
> ? ? ?}
>
> - ?if ((loop_bound_code == LT_EXPR || loop_bound_code == LE_EXPR)
> - ? ? ?&& (compare_code == LT_EXPR || compare_code == LE_EXPR))
> - ? ?predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, TAKEN);
> - ?else if ((loop_bound_code == GT_EXPR || loop_bound_code == GE_EXPR)
> - ? && (compare_code == GT_EXPR || compare_code == GE_EXPR))
> - ? ?predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, TAKEN);
> - ?else if (loop_bound_code == NE_EXPR)
> - ? ?{
> - ? ? ?/* If the loop backedge condition is "(i != bound)", we do
> - the comparison based on the step of IV:
> - ? * step < 0 : backedge condition is like (i > bound)
> - ? * step > 0 : backedge condition is like (i < bound) ?*/
> - ? ? ?gcc_assert (loop_bound_step != 0);
> + ?if (expr_coherent_p (loop_bound_var, compare_var))
> + ? ?{
> + ? ? ?if ((loop_bound_code == LT_EXPR || loop_bound_code == LE_EXPR)
> + ?&& (compare_code == LT_EXPR || compare_code == LE_EXPR))
> + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, TAKEN);
> + ? ? ?else if ((loop_bound_code == GT_EXPR || loop_bound_code == GE_EXPR)
> + ? ? ? && (compare_code == GT_EXPR || compare_code == GE_EXPR))
> + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, TAKEN);
> + ? ? ?else if (loop_bound_code == NE_EXPR)
> + {
> + ?/* If the loop backedge condition is "(i != bound)", we do
> + ? ? the comparison based on the step of IV:
> + ? ? * step < 0 : backedge condition is like (i > bound)
> + ? ? * step > 0 : backedge condition is like (i < bound) ?*/
> + ?gcc_assert (loop_bound_step != 0);
> + ?if (loop_bound_step > 0
> + ? ? ?&& (compare_code == LT_EXPR
> + ?|| compare_code == LE_EXPR))
> + ? ?predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, TAKEN);
> + ?else if (loop_bound_step < 0
> + ? && (compare_code == GT_EXPR
> + ? ? ? || compare_code == GE_EXPR))
> + ? ?predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, TAKEN);
> + ?else
> + ? ?predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, NOT_TAKEN);
> + }
> + ? ? ?else
> + /* The branch is predicted not-taken if loop_bound_code is
> + ? opposite with compare_code. ?*/
> + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, NOT_TAKEN);
> + ? ?}
> + ?else if (expr_coherent_p (loop_iv_base_var, compare_var))
> + ? ?{
> + ? ? ?/* For cases like:
> + ? for (i = s; i < h; i++)
> + ? ? if (i > s + 2) ....
> + The branch should be predicted taken. ?*/
> ? ? ? ?if (loop_bound_step > 0
> - ?&& (compare_code == LT_EXPR
> - ? ? ?|| compare_code == LE_EXPR))
> + ?&& (compare_code == GT_EXPR || compare_code == GE_EXPR))
> ? predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, TAKEN);
> ? ? ? ?else if (loop_bound_step < 0
> - ? ? ? && (compare_code == GT_EXPR
> - ? || compare_code == GE_EXPR))
> + ? ? ? && (compare_code == LT_EXPR || compare_code == LE_EXPR))
> ? predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, TAKEN);
> ? ? ? ?else
> ? predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, NOT_TAKEN);
> ? ? ?}
> - ?else
> - ? ?/* The branch is predicted not-taken if loop_bound_code is
> - ? ? ? opposite with compare_code. ?*/
> - ? ?predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE, NOT_TAKEN);
> ?}
>
> ?/* Predict edge probabilities by exploiting loop structure. ?*/
>