target/riscv: Move gen_arith_imm() decoding into trans_* functions

gen_arith_imm() does a lot of decoding manually, which was hard to read
in case of the shift instructions and is not necessary anymore with
decodetree.

Backports commit 7a50d3e2ae7f13b24fe55990ea0b8ddcbbb43130 from qemu

qemu/target/riscv/insn32.decode

@@ -35,12 +35,13 @@
 
 # Argument sets:
 &b    imm rs2 rs1
+&i    imm rs1 rd
 &shift     shamt rs1 rd
 &atomic    aq rl rs2 rs1 rd
 
 # Formats 32:
 @r       .......   ..... ..... ... ..... .......                   %rs2 %rs1 %rd
-@i       ............    ..... ... ..... .......         imm=%imm_i     %rs1 %rd
+@i       ............    ..... ... ..... ....... &i      imm=%imm_i     %rs1 %rd
 @b       .......   ..... ..... ... ..... ....... &b      imm=%imm_b %rs2 %rs1
 @s       .......   ..... ..... ... ..... .......         imm=%imm_s %rs2 %rs1
 @u       ....................      ..... .......         imm=%imm_u          %rd

qemu/target/riscv/insn_trans/trans_rvi.inc.c

@@ -225,52 +225,101 @@ static bool trans_sd(DisasContext *ctx, arg_sd *a)
 
 static bool trans_addi(DisasContext *ctx, arg_addi *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_ADDI, a->rd, a->rs1, a->imm);
-    return true;
+    return gen_arith_imm(ctx, a, &tcg_gen_add_tl);
 }
 
 static bool trans_slti(DisasContext *ctx, arg_slti *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_SLTI, a->rd, a->rs1, a->imm);
+    TCGContext *tcg_ctx = ctx->uc->tcg_ctx;
+    TCGv source1;
+    source1 = tcg_temp_new(tcg_ctx);
+    gen_get_gpr(ctx, source1, a->rs1);
+
+    tcg_gen_setcondi_tl(tcg_ctx, TCG_COND_LT, source1, source1, a->imm);
+
+    gen_set_gpr(ctx, a->rd, source1);
+    tcg_temp_free(tcg_ctx, source1);
     return true;
 }
 
 static bool trans_sltiu(DisasContext *ctx, arg_sltiu *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_SLTIU, a->rd, a->rs1, a->imm);
+    TCGContext *tcg_ctx = ctx->uc->tcg_ctx;
+    TCGv source1;
+    source1 = tcg_temp_new(tcg_ctx);
+    gen_get_gpr(ctx, source1, a->rs1);
+
+    tcg_gen_setcondi_tl(tcg_ctx, TCG_COND_LTU, source1, source1, a->imm);
+
+    gen_set_gpr(ctx, a->rd, source1);
+    tcg_temp_free(tcg_ctx, source1);
     return true;
 }
 
 static bool trans_xori(DisasContext *ctx, arg_xori *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_XORI, a->rd, a->rs1, a->imm);
-    return true;
+    return gen_arith_imm(ctx, a, &tcg_gen_xor_tl);
 }
 static bool trans_ori(DisasContext *ctx, arg_ori *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_ORI, a->rd, a->rs1, a->imm);
-    return true;
+    return gen_arith_imm(ctx, a, &tcg_gen_or_tl);
 }
 static bool trans_andi(DisasContext *ctx, arg_andi *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_ANDI, a->rd, a->rs1, a->imm);
-    return true;
+    return gen_arith_imm(ctx, a, &tcg_gen_and_tl);
 }
 static bool trans_slli(DisasContext *ctx, arg_slli *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_SLLI, a->rd, a->rs1, a->shamt);
+    if (a->shamt >= TARGET_LONG_BITS) {
+        return false;
+    }
+
+    if (a->rd != 0) {
+        TCGContext *tcg_ctx = ctx->uc->tcg_ctx;
+        TCGv t = tcg_temp_new(tcg_ctx);
+        gen_get_gpr(ctx, t, a->rs1);
+
+        tcg_gen_shli_tl(tcg_ctx, t, t, a->shamt);
+
+        gen_set_gpr(ctx, a->rd, t);
+        tcg_temp_free(tcg_ctx, t);
+    } /* NOP otherwise */
     return true;
 }
 
 static bool trans_srli(DisasContext *ctx, arg_srli *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_SHIFT_RIGHT_I, a->rd, a->rs1, a->shamt);
+    if (a->shamt >= TARGET_LONG_BITS) {
+        return false;
+    }
+
+    if (a->rd != 0) {
+        TCGContext *tcg_ctx = ctx->uc->tcg_ctx;
+        TCGv t = tcg_temp_new(tcg_ctx);
+        gen_get_gpr(ctx, t, a->rs1);
+
+        tcg_gen_shri_tl(tcg_ctx, t, t, a->shamt);
+        gen_set_gpr(ctx, a->rd, t);
+        tcg_temp_free(tcg_ctx, t);
+    } /* NOP otherwise */
     return true;
 }
 
 static bool trans_srai(DisasContext *ctx, arg_srai *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_SHIFT_RIGHT_I, a->rd, a->rs1, a->shamt | 0x400);
+    if (a->shamt >= TARGET_LONG_BITS) {
+        return false;
+    }
+
+    if (a->rd != 0) {
+        TCGContext *tcg_ctx = ctx->uc->tcg_ctx;
+        TCGv t = tcg_temp_new(tcg_ctx);
+        gen_get_gpr(ctx, t, a->rs1);
+
+        tcg_gen_sari_tl(tcg_ctx, t, t, a->shamt);
+        gen_set_gpr(ctx, a->rd, t);
+        tcg_temp_free(tcg_ctx, t);
+    } /* NOP otherwise */
     return true;
 }
 
@@ -337,26 +386,45 @@ static bool trans_and(DisasContext *ctx, arg_and *a)
 #ifdef TARGET_RISCV64
 static bool trans_addiw(DisasContext *ctx, arg_addiw *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_ADDIW, a->rd, a->rs1, a->imm);
-    return true;
+    return gen_arith_imm(ctx, a, &gen_addw);
 }
 
 static bool trans_slliw(DisasContext *ctx, arg_slliw *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_SLLIW, a->rd, a->rs1, a->shamt);
+    TCGContext *tcg_ctx = ctx->uc->tcg_ctx;
+    TCGv source1;
+    source1 = tcg_temp_new(tcg_ctx);
+    gen_get_gpr(ctx, source1, a->rs1);
+
+    tcg_gen_shli_tl(tcg_ctx, source1, source1, a->shamt);
+    tcg_gen_ext32s_tl(tcg_ctx, source1, source1);
+    gen_set_gpr(ctx, a->rd, source1);
+
+    tcg_temp_free(tcg_ctx, source1);
     return true;
 }
 
 static bool trans_srliw(DisasContext *ctx, arg_srliw *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_SHIFT_RIGHT_IW, a->rd, a->rs1, a->shamt);
+    TCGContext *tcg_ctx = ctx->uc->tcg_ctx;
+    TCGv t = tcg_temp_new(tcg_ctx);
+    gen_get_gpr(ctx, t, a->rs1);
+    tcg_gen_extract_tl(tcg_ctx, t, t, a->shamt, 32 - a->shamt);
+    /* sign-extend for W instructions */
+    tcg_gen_ext32s_tl(tcg_ctx, t, t);
+    gen_set_gpr(ctx, a->rd, t);
+    tcg_temp_free(tcg_ctx, t);
     return true;
 }
 
 static bool trans_sraiw(DisasContext *ctx, arg_sraiw *a)
 {
-    gen_arith_imm(ctx, OPC_RISC_SHIFT_RIGHT_IW , a->rd, a->rs1,
-                  a->shamt | 0x400);
+    TCGContext *tcg_ctx = ctx->uc->tcg_ctx;
+    TCGv t = tcg_temp_new(tcg_ctx);
+    gen_get_gpr(ctx, t, a->rs1);
+    tcg_gen_sextract_tl(tcg_ctx, t, t, a->shamt, 32 - a->shamt);
+    gen_set_gpr(ctx, a->rd, t);
+    tcg_temp_free(tcg_ctx, t);
     return true;
 }
 

qemu/target/riscv/translate.c

@@ -447,87 +447,6 @@ static void gen_arith(DisasContext *ctx, uint32_t opc, int rd, int rs1,
     tcg_temp_free(tcg_ctx, source2);
 }
 
-static void gen_arith_imm(DisasContext *ctx, uint32_t opc, int rd,
-        int rs1, target_long imm)
-{
-    TCGContext *tcg_ctx = ctx->uc->tcg_ctx;
-    TCGv source1 = tcg_temp_new(tcg_ctx);
-    int shift_len = TARGET_LONG_BITS;
-    int shift_a;
-
-    gen_get_gpr(ctx, source1, rs1);
-
-    switch (opc) {
-    case OPC_RISC_ADDI:
-#if defined(TARGET_RISCV64)
-    case OPC_RISC_ADDIW:
-#endif
-        tcg_gen_addi_tl(tcg_ctx, source1, source1, imm);
-        break;
-    case OPC_RISC_SLTI:
-        tcg_gen_setcondi_tl(tcg_ctx, TCG_COND_LT, source1, source1, imm);
-        break;
-    case OPC_RISC_SLTIU:
-        tcg_gen_setcondi_tl(tcg_ctx, TCG_COND_LTU, source1, source1, imm);
-        break;
-    case OPC_RISC_XORI:
-        tcg_gen_xori_tl(tcg_ctx, source1, source1, imm);
-        break;
-    case OPC_RISC_ORI:
-        tcg_gen_ori_tl(tcg_ctx, source1, source1, imm);
-        break;
-    case OPC_RISC_ANDI:
-        tcg_gen_andi_tl(tcg_ctx, source1, source1, imm);
-        break;
-#if defined(TARGET_RISCV64)
-    case OPC_RISC_SLLIW:
-        shift_len = 32;
-        /* FALLTHRU */
-#endif
-    case OPC_RISC_SLLI:
-        if (imm >= shift_len) {
-            goto do_illegal;
-        }
-        tcg_gen_shli_tl(tcg_ctx, source1, source1, imm);
-        break;
-#if defined(TARGET_RISCV64)
-    case OPC_RISC_SHIFT_RIGHT_IW:
-        shift_len = 32;
-        /* FALLTHRU */
-#endif
-    case OPC_RISC_SHIFT_RIGHT_I:
-        /* differentiate on IMM */
-        shift_a = imm & 0x400;
-        imm &= 0x3ff;
-        if (imm >= shift_len) {
-            goto do_illegal;
-        }
-        if (imm != 0) {
-            if (shift_a) {
-                /* SRAI[W] */
-                tcg_gen_sextract_tl(tcg_ctx, source1, source1, imm, shift_len - imm);
-            } else {
-                /* SRLI[W] */
-                tcg_gen_extract_tl(tcg_ctx, source1, source1, imm, shift_len - imm);
-            }
-            /* No further sign-extension needed for W instructions.  */
-            opc &= ~0x8;
-        }
-        break;
-    default:
-    do_illegal:
-        gen_exception_illegal(ctx);
-        return;
-    }
-
-    if (opc & 0x8) { /* sign-extend for W instructions */
-        tcg_gen_ext32s_tl(tcg_ctx, source1, source1);
-    }
-
-    gen_set_gpr(ctx, rd, source1);
-    tcg_temp_free(tcg_ctx, source1);
-}
-
 static void gen_jal(DisasContext *ctx, int rd, target_ulong imm)
 {
     target_ulong next_pc;
@@ -809,6 +728,34 @@ static int ex_rvc_register(int reg)
 bool decode_insn32(DisasContext *ctx, uint32_t insn);
 /* Include the auto-generated decoder for 32 bit insn */
 #include "decode_insn32.inc.c"
+
+static bool gen_arith_imm(DisasContext *ctx, arg_i *a,
+                          void(*func)(TCGContext *, TCGv, TCGv, TCGv))
+{
+    TCGContext *tcg_ctx = ctx->uc->tcg_ctx;
+    TCGv source1, source2;
+    source1 = tcg_temp_new(tcg_ctx);
+    source2 = tcg_temp_new(tcg_ctx);
+
+    gen_get_gpr(ctx, source1, a->rs1);
+    tcg_gen_movi_tl(tcg_ctx, source2, a->imm);
+
+    (*func)(tcg_ctx, source1, source1, source2);
+
+    gen_set_gpr(ctx, a->rd, source1);
+    tcg_temp_free(tcg_ctx, source1);
+    tcg_temp_free(tcg_ctx, source2);
+    return true;
+}
+
+#ifdef TARGET_RISCV64
+static void gen_addw(TCGContext *tcg_ctx, TCGv ret, TCGv arg1, TCGv arg2)
+{
+    tcg_gen_add_tl(tcg_ctx, ret, arg1, arg2);
+    tcg_gen_ext32s_tl(tcg_ctx, ret, ret);
+}
+#endif
+
 /* Include insn module translation function */
 #include "insn_trans/trans_rvi.inc.c"
 #include "insn_trans/trans_rvm.inc.c"