Merge pull request #456 from riscv-boom/ifu3

[WIP]

CHIPYARD.hash

@@ -1 +1,2 @@
-7b6a45a6a8aaa88faf08f4f8e18ad9bbd7743d7f
+0f34a22c5383284d62fdd594e882e321c4ef9cfa
+

docs/sections/debugging.rst

@@ -17,75 +17,3 @@ pipeline clears. This effectively turns BOOM into a unpipelined in-order
 core. The chicken bit is controlled by the third bit of the CSR at ``0x7c1``.
 Writing this CSR with `csrwi 0x7c1, 0x8` will turn off all out-of-orderiness
 in the core. High-performance can be re-enabled with `csrwi 0x7c1, 0x0`.
-
-Pipeline Visualization
-----------------------
-
-"Pipeview" is a useful diagnostic and visualization tool for seeing how
-instructions are scheduled on an out-of-order pipeline.
-
-Pipeview displays every fetched instruction and shows when it is
-fetched, decoded, renamed, dispatched, issued, completed, and committed
-("retired"). It shows both committed and misspeculated instructions. It
-also shows when stores were successfully acknowledged by the memory
-system ("store-completion"). It is useful for programmers who wish to
-see how their code is performing and for architects to see which
-bottlenecks are constricting machine performance.
-
-.. _pipeview-text:
-.. code-block:: none
-    :caption: Pipeview Text Output (uncolored)
-
-    -(       33320000) 0x00000018a0.0 sw a0, 220(gp)
-    [......f.d...i...c.........r.............]-(       33320000) 0x00000018a4.0 blt s1, a2, pc + 52
-    [.......f.d..i.c............r............]-(       33320000) 0x00000018a8.0 slliw a5, a2, 2
-    [.......f.d...i...c.........r............]-(       33320000) 0x00000018ac.0 addw a5, a5, a2
-    [........f.d...i...c.........r...........]-(       33320000) 0x00000018b0.0 addiw a5, a5, -3
-    [........f.d..i.c............r...........]-(       33320000) 0x00000018b4.0 mv a0, a2
-    [.........f.d..i.c............r..........]-(       33320000) 0x00000018b8.0 li a1, 3
-    [.........f.d...i...c.........r..........]-(       33320000) 0x00000018bc.0 addi a2, s0, -184
-    [..........f.di...c............r..s......]-(       33320000) 0x00000018c0.0 sw a5, -184(s0)
-    [..........f.d...i...c.........r.........]-(       33320000) 0x00000018c4.0 jal pc - 0x1284
-    [...........f.d.i.c.............r........]-(       33320000) 0x0000000640.0 addiw a0, a0, 2
-    [...........f.d..i.c............r........]-(       33320000) 0x0000000644.0 addw a1, a0, a1
-    [............f.d.i..c............r...s...]-(       33320000) 0x0000000648.0 sw a1, 0(a2)
-    [............f.d......i...c......r.......]-(       33320000) 0x000000064c.0 ret
-    [.............f.d..i..c...........r......]-(       33320000) 0x00000018c8.0 lw a2, -188(s0)
-    [.............f.d......i...c......r......]-(       33320000) 0x00000018cc.0 addiw a2, a2, 1
-    [..............f.d..i.....c........r..s..]-(       33320000) 0x00000018d0.0 sw a2, -188(s0)
-    [..............f.d......i...c......r.....]-(       33320000) 0x00000018d4.0 bge s1, a2, pc - 44
-    [...............f.d..i..c...........r....]-(       33320000) 0x00000018d8.0 lw a3, -184(s0)
-    [...............f.d...i..c..........r....]-(       33320000) 0x00000018dc.0 ld a0, -200(s0)
-    [................f.di...c............r...]-(       33320000) 0x00000018e0.0 addi a1, gp, 256
-    [................f.d.i...c...........r...]-(       33320000) 0x00000018e4.0 jal pc - 0x1294
-    [.................f.d...i.c...........r..]-(       33320000) 0x0000000650.0 addiw a6, a2, 5
-    [.................f.d....i...c........r..]-(       33320000) 0x0000000654.0 mv a5, a6
-
-To display the text-based pipeline visualizations, BOOM generates traces
-compatible with the O3 Pipeline Viewer included in the gem5 simulator
-suite.
-
-To enable pipeline visualization, first set ``O3PIPEVIEW_PRINTF`` in
-``src/main/scala/common/consts.scala`` to ``true``:
-
-.. code-block:: bash
-
-    val O3PIPEVIEW_PRINTF = true // dump trace for O3PipeView from gem5
-
-Rebuild and rerun BOOM. You should find the traces (``*.out``) in
-the ``verilator/output/`` or ``vcs/output/`` directories if you are using ``chipyard`` to
-run the core. To generate the visualization, first download and install gem5, and then run:
-
-.. code-block:: bash
-
-    boom/util/pipeview-helper.py -f <TRACE_FILE> > clean_trace.out
-    gem5/util/o3-pipeview.py --color --store_completions -o pipeview.out clean_trace.out
-
-You can view the visualization by running:
-
-.. code-block:: bash
-
-    less -r pipeview.out
-
-To learn more about ``o3-pipeview.py`` and to download gem5 visit
-http://www.m5sim.org/Visualization.

src/main/resources/csrc/btb_sw.cc

@@ -0,0 +1,56 @@
+#define BTB_SIZE 32
+
+#include <stdint.h>
+#include <stdio.h>
+
+uint64_t btb_addrs[BTB_SIZE];
+uint64_t btb_targs[BTB_SIZE];
+uint8_t btb_is_br[BTB_SIZE];
+uint8_t btb_is_jal[BTB_SIZE];
+uint32_t entry_point;
+
+extern "C" void initialize_btb()
+{
+  for (int i = 0; i < BTB_SIZE; i++)
+    btb_addrs[i] = 0;
+  entry_point = 0;
+}
+
+extern "C" void predict_target(unsigned long long ip, unsigned long long hist, unsigned char *valid, unsigned long long *target,
+                               unsigned char *is_br, unsigned char *is_jal)
+{
+  for (int i = 0; i < BTB_SIZE; i++) {
+    if (btb_addrs[i] == ip) {
+      *target = btb_targs[i];
+      *is_br = btb_is_br[i];
+      *is_jal = btb_is_jal[i];
+      *valid = 1;
+      return;
+    }
+  }
+  *valid = 0;
+}
+
+extern "C" void update_btb(unsigned long long ip, unsigned long long hist, unsigned long long target,
+                           unsigned char is_br, unsigned char is_jal)
+{
+  if (!is_br && !is_jal)
+    return;
+
+  for (int i = 0; i < BTB_SIZE; i++) {
+    if (btb_addrs[i] == ip) {
+      btb_targs[i] = target;
+      btb_is_br[i] = is_br;
+      btb_is_jal[i] = is_jal;
+      return;
+    }
+  }
+  btb_addrs[entry_point] = ip;
+  btb_targs[entry_point] = target;
+  btb_is_br[entry_point] = is_br;
+  btb_is_jal[entry_point] = is_jal;
+  entry_point++;
+  if (entry_point == BTB_SIZE) {
+    entry_point = 0;
+  }
+}