[Qemu-devel] [PATCH] ppc: Add support for 'mffscrn', 'mffscrni' instructions

[Qemu-devel] [PATCH] ppc: Add support for 'mffscrn', 'mffscrni' instructions

[Paul A. Clarke]

From: "Paul A. Clarke" <pc@us.ibm.com>

ISA 3.0B added a set of Floating-Point Status and Control Register (FPSCR)
instructions: mffsce, mffscdrn, mffscdrni, mffscrn, mffscrni, mffsl.
This patch adds support for 'mffscrn' and 'mffscrni' instructions.

'mffscrn' and 'mffscrni' are identical to 'mffsl', except they also set
the rounding mode in the FPSCR.

On CPUs without support for 'mffscrn'/'mffscrni' (below ISA 3.0), the
instructions will execute identically to 'mffs'.

Signed-off-by: Paul A. Clarke <pc@us.ibm.com>
---
 target/ppc/internal.h              |  3 ++
 target/ppc/translate/fp-impl.inc.c | 66 ++++++++++++++++++++++++++++++++++++++
 target/ppc/translate/fp-ops.inc.c  |  2 ++
 3 files changed, 71 insertions(+)

diff --git a/target/ppc/internal.h b/target/ppc/internal.h
index d3d327e..15d655b 100644
--- a/target/ppc/internal.h
+++ b/target/ppc/internal.h
@@ -157,6 +157,9 @@ EXTRACT_HELPER(FPL, 25, 1);
 EXTRACT_HELPER(FPFLM, 17, 8);
 EXTRACT_HELPER(FPW, 16, 1);
 
+/* mffscrni */
+EXTRACT_HELPER(RM, 11, 2);
+
 /* addpcis */
 EXTRACT_HELPER_SPLIT_3(DX, 10, 6, 6, 5, 16, 1, 1, 0, 0)
 #if defined(TARGET_PPC64)
diff --git a/target/ppc/translate/fp-impl.inc.c b/target/ppc/translate/fp-impl.inc.c
index 7cd9d8d..70a4788 100644
--- a/target/ppc/translate/fp-impl.inc.c
+++ b/target/ppc/translate/fp-impl.inc.c
@@ -639,6 +639,72 @@ static void gen_mffsl(DisasContext *ctx)
     tcg_temp_free_i64(t0);
 }
 
+static void gen_helper_mffscrn(DisasContext *ctx, TCGv_i64 t1)
+{
+    TCGv_i64 t0 = tcg_temp_new_i64();
+    TCGv_i32 mask = tcg_const_i32(0x0001);
+
+    gen_reset_fpstatus();
+    tcg_gen_extu_tl_i64(t0, cpu_fpscr);
+    set_fpr(rD(ctx->opcode), t0);
+
+    /* Mask FPSCR value to clear RN.  */
+    tcg_gen_andi_i64(t0, t0, ~FP_MODE);
+
+    /* Merge RN into FPSCR value.  */
+    tcg_gen_or_i64(t0, t0, t1);
+
+    gen_helper_store_fpscr(cpu_env, t0, mask);
+
+    tcg_temp_free_i32(mask);
+    tcg_temp_free_i64(t0);
+}
+
+/* mffscrn */
+static void gen_mffscrn(DisasContext *ctx)
+{
+    TCGv_i64 t1;
+
+    if (unlikely(!(ctx->insns_flags2 & PPC2_ISA300))) {
+        return gen_mffs(ctx);
+    }
+
+    if (unlikely(!ctx->fpu_enabled)) {
+        gen_exception(ctx, POWERPC_EXCP_FPU);
+        return;
+    }
+
+    t1 = tcg_temp_new_i64();
+    get_fpr(t1, rB(ctx->opcode));
+    /* Mask FRB to get just RN.  */
+    tcg_gen_andi_i64(t1, t1, FP_MODE);
+
+    gen_helper_mffscrn(ctx, t1);
+
+    tcg_temp_free_i64(t1);
+}
+
+/* mffscrni */
+static void gen_mffscrni(DisasContext *ctx)
+{
+    TCGv_i64 t1;
+
+    if (unlikely(!(ctx->insns_flags2 & PPC2_ISA300))) {
+        return gen_mffs(ctx);
+    }
+
+    if (unlikely(!ctx->fpu_enabled)) {
+        gen_exception(ctx, POWERPC_EXCP_FPU);
+        return;
+    }
+
+    t1 = tcg_const_i64((uint64_t)RM(ctx->opcode));
+
+    gen_helper_mffscrn(ctx, t1);
+
+    tcg_temp_free_i64(t1);
+}
+
 /* mtfsb0 */
 static void gen_mtfsb0(DisasContext *ctx)
 {
diff --git a/target/ppc/translate/fp-ops.inc.c b/target/ppc/translate/fp-ops.inc.c
index 88ebc25..598cd53 100644
--- a/target/ppc/translate/fp-ops.inc.c
+++ b/target/ppc/translate/fp-ops.inc.c
@@ -107,6 +107,8 @@ GEN_HANDLER(mcrfs, 0x3F, 0x00, 0x02, 0x0063F801, PPC_FLOAT),
 GEN_HANDLER_E_2(mffs, 0x3F, 0x07, 0x12, 0x00, 0x00000000, PPC_FLOAT, PPC_NONE),
 GEN_HANDLER_E_2(mffsl, 0x3F, 0x07, 0x12, 0x18, 0x00000000, PPC_FLOAT,
     PPC2_ISA300),
+GEN_HANDLER_E_2(mffscrn, 0x3F, 0x07, 0x12, 0x16, 0x00000000, PPC_FLOAT, PPC_NONE),
+GEN_HANDLER_E_2(mffscrni, 0x3F, 0x07, 0x12, 0x17, 0x00000000, PPC_FLOAT, PPC_NONE),
 GEN_HANDLER(mtfsb0, 0x3F, 0x06, 0x02, 0x001FF800, PPC_FLOAT),
 GEN_HANDLER(mtfsb1, 0x3F, 0x06, 0x01, 0x001FF800, PPC_FLOAT),
 GEN_HANDLER(mtfsf, 0x3F, 0x07, 0x16, 0x00000000, PPC_FLOAT),
-- 
1.8.3.1