[Qemu-devel] [PATCH v8 21/35] RISC-V: Add mcycle/minstret support for -icount auto

[Michael Clark]

Previously the mycycle/minstret CSRs and rdcycle/rdinstret
psuedo instructions would return the time as a proxy for an
increasing instruction counter in the absence of having a
precise instruction count. If QEMU is invoked with -icount,
the mcycle/minstret CSRs and rdcycle/rdinstret psuedo
instructions will return the instruction count.

Cc: Sagar Karandikar <address@hidden>
Cc: Bastian Koppelmann <address@hidden>
Cc: Palmer Dabbelt <address@hidden>
Cc: Alistair Francis <address@hidden>
Signed-off-by: Michael Clark <address@hidden>
---
 target/riscv/op_helper.c | 24 ++++++++++++++++++++----
 target/riscv/translate.c |  2 ++
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c
index 2daf07c..7d3f1ee 100644
--- a/target/riscv/op_helper.c
+++ b/target/riscv/op_helper.c
@@ -433,25 +433,41 @@ target_ulong csr_read_helper(CPURISCVState *env, 
target_ulong csrno)
     case CSR_INSTRET:
     case CSR_CYCLE:
         if (ctr_ok) {
-            return cpu_get_host_ticks();
+            if (use_icount) {
+                return cpu_get_icount();
+            } else {
+                return cpu_get_host_ticks();
+            }
         }
         break;
 #if defined(TARGET_RISCV32)
     case CSR_INSTRETH:
     case CSR_CYCLEH:
         if (ctr_ok) {
-            return cpu_get_host_ticks() >> 32;
+            if (use_icount) {
+                return cpu_get_icount() >> 32;
+            } else {
+                return cpu_get_host_ticks() >> 32;
+            }
         }
         break;
 #endif
 #ifndef CONFIG_USER_ONLY
     case CSR_MINSTRET:
     case CSR_MCYCLE:
-        return cpu_get_host_ticks();
+        if (use_icount) {
+            return cpu_get_icount();
+        } else {
+            return cpu_get_host_ticks();
+        }
     case CSR_MINSTRETH:
     case CSR_MCYCLEH:
 #if defined(TARGET_RISCV32)
-        return cpu_get_host_ticks() >> 32;
+        if (use_icount) {
+            return cpu_get_icount() >> 32;
+        } else {
+            return cpu_get_host_ticks() >> 32;
+        }
 #endif
         break;
     case CSR_MUCOUNTEREN:
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index c3a029a..c0e6a04 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -1390,6 +1390,7 @@ static void gen_system(CPURISCVState *env, DisasContext 
*ctx, uint32_t opc,
         break;
     default:
         tcg_gen_movi_tl(imm_rs1, rs1);
+        gen_io_start();
         switch (opc) {
         case OPC_RISC_CSRRW:
             gen_helper_csrrw(dest, cpu_env, source1, csr_store);
@@ -1413,6 +1414,7 @@ static void gen_system(CPURISCVState *env, DisasContext 
*ctx, uint32_t opc,
             gen_exception_illegal(ctx);
             return;
         }
+        gen_io_end();
         gen_set_gpr(rd, dest);
         /* end tb since we may be changing priv modes, to get mmu_index right 
*/
         tcg_gen_movi_tl(cpu_pc, ctx->next_pc);
-- 
2.7.0