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Re: [PATCH V13 6/9] target/mips: Add loongson-ext lsdc2 group of instruc

From: Philippe Mathieu-Daudé
Subject: Re: [PATCH V13 6/9] target/mips: Add loongson-ext lsdc2 group of instructions
Date: Sat, 10 Oct 2020 15:07:50 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 
On 10/7/20 10:39 AM, Huacai Chen wrote:

From: Jiaxun Yang <jiaxun.yang@flygoat.com>

LDC2/SDC2 opcodes have been rewritten as "load & store with offset"
group of instructions by loongson-ext ASE.

This patch add implementation of these instructions:
gslbx: load 1 bytes to GPR
gslhx: load 2 bytes to GPR
gslwx: load 4 bytes to GPR
gsldx: load 8 bytes to GPR
gslwxc1: load 4 bytes to FPR
gsldxc1: load 8 bytes to FPR
gssbx: store 1 bytes from GPR
gsshx: store 2 bytes from GPR
gsswx: store 4 bytes from GPR
gssdx: store 8 bytes from GPR
gsswxc1: store 4 bytes from FPR
gssdxc1: store 8 bytes from FPR

Details of Loongson-EXT is here:
https://github.com/FlyGoat/loongson-insn/blob/master/loongson-ext.md

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>


If this patch is from Jiaxun, Huacai's S-o-b should come *after*.


---
  target/mips/translate.c | 179 ++++++++++++++++++++++++++++++++++++++++++++++++
  1 file changed, 179 insertions(+)

diff --git a/target/mips/translate.c b/target/mips/translate.c
index 916b57f..4d42cfc 100644
--- a/target/mips/translate.c
+++ b/target/mips/translate.c
@@ -484,6 +484,24 @@ enum {
      OPC_GSSDRC1     = 0x7 | OPC_GSSHFS,
  };
+/* Loongson EXT LDC2/SDC2 opcodes */ 
+#define MASK_LOONGSON_LSDC2(op)           (MASK_OP_MAJOR(op) | (op & 0x7))
+
+enum {
+    OPC_GSLBX      = 0x0 | OPC_LDC2,
+    OPC_GSLHX      = 0x1 | OPC_LDC2,
+    OPC_GSLWX      = 0x2 | OPC_LDC2,
+    OPC_GSLDX      = 0x3 | OPC_LDC2,
+    OPC_GSLWXC1    = 0x6 | OPC_LDC2,
+    OPC_GSLDXC1    = 0x7 | OPC_LDC2,
+    OPC_GSSBX      = 0x0 | OPC_SDC2,
+    OPC_GSSHX      = 0x1 | OPC_SDC2,
+    OPC_GSSWX      = 0x2 | OPC_SDC2,
+    OPC_GSSDX      = 0x3 | OPC_SDC2,
+    OPC_GSSWXC1    = 0x6 | OPC_SDC2,
+    OPC_GSSDXC1    = 0x7 | OPC_SDC2,
+};
+
  /* BSHFL opcodes */
  #define MASK_BSHFL(op)              (MASK_SPECIAL3(op) | (op & (0x1F << 6)))
@@ -6172,6 +6190,165 @@ static void gen_loongson_lswc2(DisasContext *ctx, int rt, 
      tcg_temp_free(t0);
  }
+/* Loongson EXT LDC2/SDC2 */ 
+static void gen_loongson_lsdc2(DisasContext *ctx, int rt,
+                                int rs, int rd)


Alignment off (various occurences in this series).


+{
+    int offset = (int8_t)(ctx->opcode >> 3);


Please use sextract32() which is easier to read:

       int32_t offset = sextract32(ctx->opcode, 3, 8);


+    uint32_t opc = MASK_LOONGSON_LSDC2(ctx->opcode);
+    TCGv t0, t1;
+    TCGv_i32 fp0;
+
+    /* Pre-conditions */
+    switch (opc) {
+    case OPC_GSLBX:
+    case OPC_GSLHX:
+    case OPC_GSLWX:
+    case OPC_GSLDX:
+        /* prefetch, implement as NOP */
+        if (rt == 0) {
+            return;
+        }
+        break;
+    case OPC_GSSBX:
+    case OPC_GSSHX:
+    case OPC_GSSWX:
+    case OPC_GSSDX:
+        break;
+    case OPC_GSLWXC1:
+#if defined(TARGET_MIPS64)
+    case OPC_GSLDXC1:
+#endif
+        check_cp1_enabled(ctx);
+        /* prefetch, implement as NOP */
+        if (rt == 0) {
+            return;
+        }
+        break;
+    case OPC_GSSWXC1:
+#if defined(TARGET_MIPS64)
+    case OPC_GSSDXC1:
+#endif
+        check_cp1_enabled(ctx);
+        break;
+    default:
+        MIPS_INVAL("loongson_lsdc2");
+        generate_exception_end(ctx, EXCP_RI);
+        return;
+        break;
+    }
+
+    t0 = tcg_temp_new();
+
+    gen_base_offset_addr(ctx, t0, rs, offset);
+    gen_op_addr_add(ctx, t0, cpu_gpr[rd], t0);
+
+    switch (opc) {
+    case OPC_GSLBX:
+        tcg_gen_qemu_ld_tl(t0, t0, ctx->mem_idx, MO_SB);
+        gen_store_gpr(t0, rt);
+        break;
+    case OPC_GSLHX:
+        tcg_gen_qemu_ld_tl(t0, t0, ctx->mem_idx, MO_TESW |
+                            ctx->default_tcg_memop_mask);


Do Loongson EXT plan to support unaligned accesses?


+        gen_store_gpr(t0, rt);
+        break;
+    case OPC_GSLWX:
+        gen_base_offset_addr(ctx, t0, rs, offset);
+        if (rd) {
+            gen_op_addr_add(ctx, t0, cpu_gpr[rd], t0);
+        }
+        tcg_gen_qemu_ld_tl(t0, t0, ctx->mem_idx, MO_TESL |
+                            ctx->default_tcg_memop_mask);
+        gen_store_gpr(t0, rt);
+        break;
+#if defined(TARGET_MIPS64)
+    case OPC_GSLDX:
+        gen_base_offset_addr(ctx, t0, rs, offset);
+        if (rd) {
+            gen_op_addr_add(ctx, t0, cpu_gpr[rd], t0);
+        }
+        tcg_gen_qemu_ld_tl(t0, t0, ctx->mem_idx, MO_TEQ |
+                            ctx->default_tcg_memop_mask);
+        gen_store_gpr(t0, rt);
+        break;
+#endif
+    case OPC_GSLWXC1:
+        check_cp1_enabled(ctx);
+        gen_base_offset_addr(ctx, t0, rs, offset);
+        if (rd) {
+            gen_op_addr_add(ctx, t0, cpu_gpr[rd], t0);
+        }
+        fp0 = tcg_temp_new_i32();
+        tcg_gen_qemu_ld_i32(fp0, t0, ctx->mem_idx, MO_TESL |
+                            ctx->default_tcg_memop_mask);
+        gen_store_fpr32(ctx, fp0, rt);
+        tcg_temp_free_i32(fp0);
+        break;
+#if defined(TARGET_MIPS64)
+    case OPC_GSLDXC1:
+        check_cp1_enabled(ctx);
+        gen_base_offset_addr(ctx, t0, rs, offset);
+        if (rd) {
+            gen_op_addr_add(ctx, t0, cpu_gpr[rd], t0);
+        }
+        tcg_gen_qemu_ld_tl(t0, t0, ctx->mem_idx, MO_TEQ |
+                            ctx->default_tcg_memop_mask);
+        gen_store_fpr64(ctx, t0, rt);
+        break;
+#endif
+    case OPC_GSSBX:
+        t1 = tcg_temp_new();
+        gen_load_gpr(t1, rt);
+        tcg_gen_qemu_st_tl(t1, t0, ctx->mem_idx, MO_SB);
+        tcg_temp_free(t1);
+        break;
+    case OPC_GSSHX:
+        t1 = tcg_temp_new();
+        gen_load_gpr(t1, rt);
+        tcg_gen_qemu_st_tl(t1, t0, ctx->mem_idx, MO_TEUW |
+                            ctx->default_tcg_memop_mask);
+        tcg_temp_free(t1);
+        break;
+    case OPC_GSSWX:
+        t1 = tcg_temp_new();
+        gen_load_gpr(t1, rt);
+        tcg_gen_qemu_st_tl(t1, t0, ctx->mem_idx, MO_TEUL |
+                            ctx->default_tcg_memop_mask);
+        tcg_temp_free(t1);
+        break;
+#if defined(TARGET_MIPS64)
+    case OPC_GSSDX:
+        t1 = tcg_temp_new();
+        gen_load_gpr(t1, rt);
+        tcg_gen_qemu_st_tl(t1, t0, ctx->mem_idx, MO_TEQ |
+                            ctx->default_tcg_memop_mask);
+        tcg_temp_free(t1);
+        break;
+#endif
+    case OPC_GSSWXC1:
+        fp0 = tcg_temp_new_i32();
+        gen_load_fpr32(ctx, fp0, rt);
+        tcg_gen_qemu_st_i32(fp0, t0, ctx->mem_idx, MO_TEUL |
+                            ctx->default_tcg_memop_mask);
+        tcg_temp_free_i32(fp0);
+        break;
+#if defined(TARGET_MIPS64)
+    case OPC_GSSDXC1:
+        t1 = tcg_temp_new();
+        gen_load_fpr64(ctx, t1, rt);
+        tcg_gen_qemu_st_i64(t1, t0, ctx->mem_idx, MO_TEQ |
+                            ctx->default_tcg_memop_mask);
+        tcg_temp_free(t1);
+        break;
+#endif
+    default:
+        break;
+    }
+
+    tcg_temp_free(t0);
+}
+
  /* Traps */
  static void gen_trap(DisasContext *ctx, uint32_t opc,
                       int rs, int rt, int16_t imm)
@@ -31055,6 +31232,8 @@ static void decode_opc(CPUMIPSState *env, DisasContext 
*ctx)
                  /* OPC_JIC, OPC_JIALC */
                  gen_compute_compact_branch(ctx, op, 0, rt, imm);
              }
+        } else if (ctx->insn_flags & ASE_LEXT) {
+            gen_loongson_lsdc2(ctx, rt, rs, rd);
          } else {
              /* OPC_LWC2, OPC_SWC2 */
              /* COP2: Not implemented. */
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