From da72590c1961d05f6ce678deecf115372b2930e5 Mon Sep 17 00:00:00 2001
From: Hoa Nguyen <hn@hnpl.org>
Date: Sun, 1 Oct 2023 22:52:07 -0700
Subject: [PATCH] arch-riscv: FS bits -> DIRTY for more floating point loads

The affected instructions are,
- c.flw
- c.flwsp
- flh
- flw

This change is related to [1] [2], which also aim to change the
FS bits to DIRTY when the state of any floating point register
might change.

[1] https://gem5-review.googlesource.com/c/public/gem5/+/65272
[2] https://github.com/gem5/gem5/pull/370

Change-Id: I098e1b1812fb352bd5d3614ff5d3547e58903b65
Signed-off-by: Hoa Nguyen <hn@hnpl.org>
---
 src/arch/riscv/isa/decoder.isa | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/arch/riscv/isa/decoder.isa b/src/arch/riscv/isa/decoder.isa
index 0ad7283fcd..2f110fca35 100644
--- a/src/arch/riscv/isa/decoder.isa
+++ b/src/arch/riscv/isa/decoder.isa
@@ -90,6 +90,9 @@ decode QUADRANT default Unknown::unknown() {
                         return std::make_shared<IllegalInstFault>("FPU is off",
                                                                    machInst);
 
+                    status.fs = FPUStatus::DIRTY;
+                    xc->setMiscReg(MISCREG_STATUS, status);
+
                     freg_t fd = freg(f32(Mem_uw));
                     Fp2_bits = fd.v;
                 }}, {{
@@ -317,8 +320,6 @@ decode QUADRANT default Unknown::unknown() {
                     return std::make_shared<IllegalInstFault>("FPU is off",
                                                                machInst);
 
-                // Mutating any floating point register changes the FS bit
-                // of the STATUS CSR.
                 status.fs = FPUStatus::DIRTY;
                 xc->setMiscReg(MISCREG_STATUS, status);
 
@@ -350,6 +351,9 @@ decode QUADRANT default Unknown::unknown() {
                         return std::make_shared<IllegalInstFault>("FPU is off",
                                                                    machInst);
 
+                    status.fs = FPUStatus::DIRTY;
+                    xc->setMiscReg(MISCREG_STATUS, status);
+
                     freg_t fd;
                     fd = freg(f32(Mem_uw));
                     Fd_bits = fd.v;
@@ -487,6 +491,10 @@ decode QUADRANT default Unknown::unknown() {
                     if (status.fs == FPUStatus::OFF)
                         return std::make_shared<IllegalInstFault>(
                                     "FPU is off", machInst);
+
+                    status.fs = FPUStatus::DIRTY;
+                    xc->setMiscReg(MISCREG_STATUS, status);
+
                     freg_t fd;
                     fd = freg(f16(Mem_uh));
                     Fd_bits = fd.v;
@@ -496,6 +504,10 @@ decode QUADRANT default Unknown::unknown() {
                     if (status.fs == FPUStatus::OFF)
                         return std::make_shared<IllegalInstFault>(
                                     "FPU is off", machInst);
+
+                    status.fs = FPUStatus::DIRTY;
+                    xc->setMiscReg(MISCREG_STATUS, status);
+
                     freg_t fd;
                     fd = freg(f32(Mem_uw));
                     Fd_bits = fd.v;
@@ -506,8 +518,6 @@ decode QUADRANT default Unknown::unknown() {
                         return std::make_shared<IllegalInstFault>(
                                     "FPU is off", machInst);
 
-                    // Mutating any floating point register changes the FS bit
-                    // of the STATUS CSR.
                     status.fs = FPUStatus::DIRTY;
                     xc->setMiscReg(MISCREG_STATUS, status);