From 8d63c9fc0640f6e946d51a347fb2ee5f331b9cea Mon Sep 17 00:00:00 2001
From: Matthew Poremba <matthew.poremba@amd.com>
Date: Wed, 2 Nov 2022 14:58:29 -0700
Subject: [PATCH] gpu-compute: Add granulated SGPR computation for gfx9

The granulated SGPR size is used when the number of SGPRs is unknown.
The computation for this has changed since gfx8 and is commented as a
TODO in a comment.

This changeset implements the change and also checks for an invalid SGPR
count. According to LLVM code this could happen "due to a compiler bug
or when using inline asm.":
https://github.com/llvm/llvm-project/blob/main/llvm/lib/Target/AMDGPU/
    AMDGPUAsmPrinter.cpp#L723

Change-Id: Ie487a53940b323a0002341075e0f81af4147a7d8
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/65252
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
---
 src/gpu-compute/hsa_queue_entry.hh | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/gpu-compute/hsa_queue_entry.hh b/src/gpu-compute/hsa_queue_entry.hh
index 4261f2c631..fbe0efef21 100644
--- a/src/gpu-compute/hsa_queue_entry.hh
+++ b/src/gpu-compute/hsa_queue_entry.hh
@@ -96,9 +96,22 @@ class HSAQueueEntry
         if (!numVgprs)
             numVgprs = (akc->granulated_workitem_vgpr_count + 1) * 4;
 
-        // TODO: Granularity changes for GFX9!
-        if (!numSgprs)
-            numSgprs = (akc->granulated_wavefront_sgpr_count + 1) * 8;
+        if (!numSgprs || numSgprs ==
+            std::numeric_limits<decltype(akc->wavefront_sgpr_count)>::max()) {
+            // Supported major generation numbers: 0 (BLIT kernels), 8, and 9
+            uint16_t version = akc->amd_machine_version_major;
+            assert((version == 0) || (version == 8) || (version == 9));
+            // SGPR allocation granularies:
+            // - GFX8: 8
+            // - GFX9: 16
+            // Source: https://llvm.org/docs/AMDGPUUsage.html
+            if ((version == 0) || (version == 8)) {
+                // We assume that BLIT kernels use the same granularity as GFX8
+                numSgprs = (akc->granulated_wavefront_sgpr_count + 1) * 8;
+            } else if (version == 9) {
+                numSgprs = ((akc->granulated_wavefront_sgpr_count + 1) * 16)/2;
+            }
+        }
 
         initialVgprState.reset();
         initialSgprState.reset();