Brad Bishop | 316dfdd | 2018-06-25 12:45:53 -0400 | [diff] [blame] | 1 | From 25738bb9c75f94b451201acfd6bcab13bdeee512 Mon Sep 17 00:00:00 2001 |
| 2 | From: Roy Li <rongqing.li@windriver.com> |
| 3 | Date: Thu, 5 May 2016 09:52:01 +0800 |
| 4 | Subject: [PATCH] [PATCH] avoid gcc optimize-away the loops |
Patrick Williams | b48b7b4 | 2016-08-17 15:04:38 -0500 | [diff] [blame] | 5 | |
Andrew Geissler | 6aa7eec | 2023-03-03 12:41:14 -0600 | [diff] [blame^] | 6 | Upstream-Status: Pending |
Patrick Williams | b48b7b4 | 2016-08-17 15:04:38 -0500 | [diff] [blame] | 7 | |
| 8 | Change expression used in do_integer_mul and do_uint64_mul |
| 9 | benchmarks so GCC doesn't optimize-away the loops, other |
| 10 | things are same: |
| 11 | - TEN(r *= s;); r -= t; |
| 12 | + i = 0; |
| 13 | + while ( i++ < 10) |
| 14 | + r *= s; |
| 15 | + r -= t; |
| 16 | |
| 17 | and TEN is macro: |
| 18 | #define TEN(a) a a a a a a a a a a |
| 19 | |
| 20 | Signed-off-by: Roy Li <rongqing.li@windriver.com> |
Brad Bishop | 316dfdd | 2018-06-25 12:45:53 -0400 | [diff] [blame] | 21 | |
Patrick Williams | b48b7b4 | 2016-08-17 15:04:38 -0500 | [diff] [blame] | 22 | --- |
| 23 | src/lat_ops.c | 30 +++++++++++++++++++++++++----- |
| 24 | 1 file changed, 25 insertions(+), 5 deletions(-) |
| 25 | |
| 26 | diff --git a/src/lat_ops.c b/src/lat_ops.c |
| 27 | index d343ff3..457072b 100644 |
| 28 | --- a/src/lat_ops.c |
| 29 | +++ b/src/lat_ops.c |
| 30 | @@ -126,11 +126,23 @@ do_integer_mul(iter_t iterations, void* cookie) |
| 31 | struct _state *pState = (struct _state*)cookie; |
| 32 | register int r = pState->N + 37431; |
| 33 | register int s = pState->N + 4; |
| 34 | - register int t = r * s * s * s * s * s * s * s * s * s * s - r; |
| 35 | + register int t = r; |
| 36 | + int i = 0; |
| 37 | + |
| 38 | + while ( i++ < 10) |
| 39 | + t *= s; |
| 40 | + t -= r; |
| 41 | |
| 42 | while (iterations-- > 0) { |
| 43 | - TEN(r *= s;); r -= t; |
| 44 | - TEN(r *= s;); r -= t; |
| 45 | + i = 0; |
| 46 | + while ( i++ < 10) |
| 47 | + r *= s; |
| 48 | + r -= t; |
| 49 | + |
| 50 | + i = 0; |
| 51 | + while ( i++ < 10) |
| 52 | + r *= s; |
| 53 | + r -= t; |
| 54 | } |
| 55 | use_int(r); |
| 56 | } |
| 57 | @@ -207,13 +219,21 @@ do_int64_mul(iter_t iterations, void* cookie) |
| 58 | register int64 r = (int64)pState->N + 37420; |
| 59 | register int64 s = (int64)pState->N + 4; |
| 60 | register int64 t; |
| 61 | + int i = 0; |
| 62 | |
| 63 | r += (int64)(pState->N + 6)<<32; |
| 64 | t = r * s * s * s * s * s * s * s * s * s * s - r; |
| 65 | |
| 66 | while (iterations-- > 0) { |
| 67 | - TEN(r *= s;); r -= t; |
| 68 | - TEN(r *= s;); r -= t; |
| 69 | + i = 0; |
| 70 | + while ( i++ < 10) |
| 71 | + r *= s; |
| 72 | + r -= t; |
| 73 | + |
| 74 | + i = 0; |
| 75 | + while ( i++ < 10) |
| 76 | + r *= s; |
| 77 | + r -= t; |
| 78 | } |
| 79 | use_int((int)r); |
| 80 | } |