Added potential test. btbthrash forces jump and divide instructions to occupy the same location in the btb. Instruction class prediction mispredicts ever time. This is useful incase someone changes the hazard code or fpu.

2025-02-11 06:05:49 +00:00 · 2024-10-29 09:58:53 -05:00 · 2024-10-29 09:58:53 -05:00 · 896bb21f7c
commit 896bb21f7c
parent a4cda877ef
1 changed files with 145 additions and 0 deletions
--- a/tests/coverage/btbthrash.S
+++ b/tests/coverage/btbthrash.S
@ -0,0 +1,145 @@
+///////////////////////////////////////////
+// btbtrash.S
+//
+// Written: Rose Thompson rose@rosethompson.net 23 October 2024
+//
+// Purpose: Test the branch target buffer alias with divide and cache pipeline stalls
+//
+// A component of the CORE-V-WALLY configurable RISC-V project.
+// https://github.com/openhwgroup/cvw
+// 
+// Copyright (C) 2021-23 Harvey Mudd College & Oklahoma State University
+//
+// SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
+//
+// Licensed under the Solderpad Hardware License v 2.1 (the “License”); you may not use this file 
+// except in compliance with the License, or, at your option, the Apache License version 2.0. You 
+// may obtain a copy of the License at
+//
+// https://solderpad.org/licenses/SHL-2.1/
+//
+// Unless required by applicable law or agreed to in writing, any work distributed under the 
+// License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, 
+// either express or implied. See the License for the specific language governing permissions 
+// and limitations under the License.
+////////////////////////////////////////////////////////////////////////////////////////////////
+
+// load code to initalize stack, handle interrupts, terminate
+#include "WALLY-init-lib.h"
+
+main:
+
+    # Division test (having trouble with buildroot)
+        li x1, 1938759018
+        li x2, 3745029
+        li x3, 458
+        li x4, 29587209347
+        li x5, 28957
+        li x6, 298
+        li x7, 238562
+        li x8, 198674
+        li x9, 134
+        li x10, 906732
+        li x11, 29
+        li x12, 50912
+        li x13, 59
+        li x14, 6902385
+        li x15, 1923857
+        li x16, 3985
+        li x17, 3947
+        li x18, 15984
+        li x19, 5
+        li x20, 9684658489
+        li x21, 6548
+        li x22, 3564
+        li x23, 94
+        li x24, 689464
+        li x25, 42567
+        li x26, 98453
+        li x27, 648
+        li x28, 984
+        li x29, 6984
+        li x30, 864
+
+        # x31 will be our loop counter
+        li x31, 4
+
+.align 12
+jump1:  
+        divuw x0, x1, x2
+        j jump3
+jump4:
+        divuw x0, x5, x6
+        j jump5
+jump6:
+        divuw x0, x10, x9
+        j jump7
+jump8:
+        divuw x0, x14, x3
+        j jump9
+jump10:
+        divuw x0, x18, x17
+        j jump11
+jump12:
+        divuw x0, x21, x22
+        j jump13
+jump14:
+        divuw x0, x24, x25
+        j jump15
+jump16:
+        divuw x0, x29, x28
+        j jump17
+jump18:
+        divuw x0, x1, x30
+        j jump19
+jump20:
+        divuw x0, x3, x19
+        j jump21
+jump22:
+        divuw x0, x12, x13
+        j jump23
+
+.align 12 # size of the 1024 btb apart
+jump2:
+        j jump1
+jump3:  
+        divuw x0, x4, x3
+        j jump4
+jump5:  
+        divuw x0, x7, x8
+        j jump6
+jump7:  
+        divuw x0, x12, x11
+        j jump8
+jump9:  
+        divuw x0, x15, x16
+        j jump10
+jump11:  
+        divuw x0, x20, x19
+        j jump12
+jump13:  
+        divuw x0, x24, x23
+        j jump14
+jump15:  
+        divuw x0, x26, x27
+        j jump16
+jump17:  
+        divuw x0, x29, x30
+        j jump18
+jump19:  
+        divuw x0, x2, x3
+        j jump20
+jump21:  
+        divuw x0, x4, x5
+        j jump22
+jump23:  
+        divuw x0, x20, x21
+        #j jump22
+
+        fence.i
+
+        addi x31, x31, -1
+        bne x31, x0, jump1
+finsihed:       
+    j done
+