[Qemu-devel] [PATCH v2 13/19] target-mips: implement unaligned loads using TCG

[Aurelien Jarno]

Load/store from helpers should be avoided as they are quite
inefficient. Rewrite unaligned loads instructions using TCG and
aligned loads. The number of actual loads operations to implement
an unaligned load instruction is reduced from up to 8 to 1.

Note: As we can't rely on shift by 32 or 64 undefined behaviour,
the code loads already shift by one constants.

Reviewed-by: Richard Henderson <address@hidden>
Signed-off-by: Aurelien Jarno <address@hidden>
---
 target-mips/helper.h    |    4 --
 target-mips/op_helper.c |  142 -----------------------------------------------
 target-mips/translate.c |   75 ++++++++++++++++++++-----
 3 files changed, 62 insertions(+), 159 deletions(-)

diff --git a/target-mips/helper.h b/target-mips/helper.h
index 210960f..0e38cdd 100644
--- a/target-mips/helper.h
+++ b/target-mips/helper.h
@@ -4,13 +4,9 @@ DEF_HELPER_3(raise_exception_err, noreturn, env, i32, int)
 DEF_HELPER_2(raise_exception, noreturn, env, i32)
 
 #ifdef TARGET_MIPS64
-DEF_HELPER_4(ldl, tl, env, tl, tl, int)
-DEF_HELPER_4(ldr, tl, env, tl, tl, int)
 DEF_HELPER_4(sdl, void, env, tl, tl, int)
 DEF_HELPER_4(sdr, void, env, tl, tl, int)
 #endif
-DEF_HELPER_4(lwl, tl, env, tl, tl, int)
-DEF_HELPER_4(lwr, tl, env, tl, tl, int)
 DEF_HELPER_4(swl, void, env, tl, tl, int)
 DEF_HELPER_4(swr, void, env, tl, tl, int)
 
diff --git a/target-mips/op_helper.c b/target-mips/op_helper.c
index 78497d9..773c710 100644
--- a/target-mips/op_helper.c
+++ b/target-mips/op_helper.c
@@ -350,56 +350,6 @@ HELPER_ST_ATOMIC(scd, ld, sd, 0x7)
 #define GET_OFFSET(addr, offset) (addr - (offset))
 #endif
 
-target_ulong helper_lwl(CPUMIPSState *env, target_ulong arg1,
-                        target_ulong arg2, int mem_idx)
-{
-    target_ulong tmp;
-
-    tmp = do_lbu(env, arg2, mem_idx);
-    arg1 = (arg1 & 0x00FFFFFF) | (tmp << 24);
-
-    if (GET_LMASK(arg2) <= 2) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, 1), mem_idx);
-        arg1 = (arg1 & 0xFF00FFFF) | (tmp << 16);
-    }
-
-    if (GET_LMASK(arg2) <= 1) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, 2), mem_idx);
-        arg1 = (arg1 & 0xFFFF00FF) | (tmp << 8);
-    }
-
-    if (GET_LMASK(arg2) == 0) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, 3), mem_idx);
-        arg1 = (arg1 & 0xFFFFFF00) | tmp;
-    }
-    return (int32_t)arg1;
-}
-
-target_ulong helper_lwr(CPUMIPSState *env, target_ulong arg1,
-                        target_ulong arg2, int mem_idx)
-{
-    target_ulong tmp;
-
-    tmp = do_lbu(env, arg2, mem_idx);
-    arg1 = (arg1 & 0xFFFFFF00) | tmp;
-
-    if (GET_LMASK(arg2) >= 1) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, -1), mem_idx);
-        arg1 = (arg1 & 0xFFFF00FF) | (tmp << 8);
-    }
-
-    if (GET_LMASK(arg2) >= 2) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, -2), mem_idx);
-        arg1 = (arg1 & 0xFF00FFFF) | (tmp << 16);
-    }
-
-    if (GET_LMASK(arg2) == 3) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, -3), mem_idx);
-        arg1 = (arg1 & 0x00FFFFFF) | (tmp << 24);
-    }
-    return (int32_t)arg1;
-}
-
 void helper_swl(CPUMIPSState *env, target_ulong arg1, target_ulong arg2,
                 int mem_idx)
 {
@@ -440,98 +390,6 @@ void helper_swr(CPUMIPSState *env, target_ulong arg1, 
target_ulong arg2,
 #define GET_LMASK64(v) (((v) & 7) ^ 7)
 #endif
 
-target_ulong helper_ldl(CPUMIPSState *env, target_ulong arg1,
-                        target_ulong arg2, int mem_idx)
-{
-    uint64_t tmp;
-
-    tmp = do_lbu(env, arg2, mem_idx);
-    arg1 = (arg1 & 0x00FFFFFFFFFFFFFFULL) | (tmp << 56);
-
-    if (GET_LMASK64(arg2) <= 6) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, 1), mem_idx);
-        arg1 = (arg1 & 0xFF00FFFFFFFFFFFFULL) | (tmp << 48);
-    }
-
-    if (GET_LMASK64(arg2) <= 5) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, 2), mem_idx);
-        arg1 = (arg1 & 0xFFFF00FFFFFFFFFFULL) | (tmp << 40);
-    }
-
-    if (GET_LMASK64(arg2) <= 4) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, 3), mem_idx);
-        arg1 = (arg1 & 0xFFFFFF00FFFFFFFFULL) | (tmp << 32);
-    }
-
-    if (GET_LMASK64(arg2) <= 3) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, 4), mem_idx);
-        arg1 = (arg1 & 0xFFFFFFFF00FFFFFFULL) | (tmp << 24);
-    }
-
-    if (GET_LMASK64(arg2) <= 2) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, 5), mem_idx);
-        arg1 = (arg1 & 0xFFFFFFFFFF00FFFFULL) | (tmp << 16);
-    }
-
-    if (GET_LMASK64(arg2) <= 1) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, 6), mem_idx);
-        arg1 = (arg1 & 0xFFFFFFFFFFFF00FFULL) | (tmp << 8);
-    }
-
-    if (GET_LMASK64(arg2) == 0) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, 7), mem_idx);
-        arg1 = (arg1 & 0xFFFFFFFFFFFFFF00ULL) | tmp;
-    }
-
-    return arg1;
-}
-
-target_ulong helper_ldr(CPUMIPSState *env, target_ulong arg1,
-                        target_ulong arg2, int mem_idx)
-{
-    uint64_t tmp;
-
-    tmp = do_lbu(env, arg2, mem_idx);
-    arg1 = (arg1 & 0xFFFFFFFFFFFFFF00ULL) | tmp;
-
-    if (GET_LMASK64(arg2) >= 1) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, -1), mem_idx);
-        arg1 = (arg1 & 0xFFFFFFFFFFFF00FFULL) | (tmp  << 8);
-    }
-
-    if (GET_LMASK64(arg2) >= 2) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, -2), mem_idx);
-        arg1 = (arg1 & 0xFFFFFFFFFF00FFFFULL) | (tmp << 16);
-    }
-
-    if (GET_LMASK64(arg2) >= 3) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, -3), mem_idx);
-        arg1 = (arg1 & 0xFFFFFFFF00FFFFFFULL) | (tmp << 24);
-    }
-
-    if (GET_LMASK64(arg2) >= 4) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, -4), mem_idx);
-        arg1 = (arg1 & 0xFFFFFF00FFFFFFFFULL) | (tmp << 32);
-    }
-
-    if (GET_LMASK64(arg2) >= 5) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, -5), mem_idx);
-        arg1 = (arg1 & 0xFFFF00FFFFFFFFFFULL) | (tmp << 40);
-    }
-
-    if (GET_LMASK64(arg2) >= 6) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, -6), mem_idx);
-        arg1 = (arg1 & 0xFF00FFFFFFFFFFFFULL) | (tmp << 48);
-    }
-
-    if (GET_LMASK64(arg2) == 7) {
-        tmp = do_lbu(env, GET_OFFSET(arg2, -7), mem_idx);
-        arg1 = (arg1 & 0x00FFFFFFFFFFFFFFULL) | (tmp << 56);
-    }
-
-    return arg1;
-}
-
 void helper_sdl(CPUMIPSState *env, target_ulong arg1, target_ulong arg2,
                 int mem_idx)
 {
diff --git a/target-mips/translate.c b/target-mips/translate.c
index c46129d..b385923 100644
--- a/target-mips/translate.c
+++ b/target-mips/translate.c
@@ -1125,7 +1125,7 @@ static void gen_ld (CPUMIPSState *env, DisasContext *ctx, 
uint32_t opc,
                     int rt, int base, int16_t offset)
 {
     const char *opn = "ld";
-    TCGv t0, t1;
+    TCGv t0, t1, t2;
 
     if (rt == 0 && env->insn_flags & (INSN_LOONGSON2E | INSN_LOONGSON2F)) {
         /* Loongson CPU uses a load to zero register for prefetch.
@@ -1157,21 +1157,45 @@ static void gen_ld (CPUMIPSState *env, DisasContext 
*ctx, uint32_t opc,
         opn = "lld";
         break;
     case OPC_LDL:
-        save_cpu_state(ctx, 1);
         t1 = tcg_temp_new();
+        tcg_gen_andi_tl(t1, t0, 7);
+#ifndef TARGET_WORDS_BIGENDIAN
+        tcg_gen_xori_tl(t1, t1, 7);
+#endif
+        tcg_gen_shli_tl(t1, t1, 3);
+        tcg_gen_andi_tl(t0, t0, ~7);
+        tcg_gen_qemu_ld64(t0, t0, ctx->mem_idx);
+        tcg_gen_shl_tl(t0, t0, t1);
+        tcg_gen_xori_tl(t1, t1, 63);
+        t2 = tcg_const_tl(0x7fffffffffffffffull);
+        tcg_gen_shr_tl(t2, t2, t1);
         gen_load_gpr(t1, rt);
-        gen_helper_1e2i(ldl, t1, t1, t0, ctx->mem_idx);
-        gen_store_gpr(t1, rt);
+        tcg_gen_and_tl(t1, t1, t2);
+        tcg_temp_free(t2);
+        tcg_gen_or_tl(t0, t0, t1);
         tcg_temp_free(t1);
+        gen_store_gpr(t0, rt);
         opn = "ldl";
         break;
     case OPC_LDR:
-        save_cpu_state(ctx, 1);
         t1 = tcg_temp_new();
+        tcg_gen_andi_tl(t1, t0, 7);
+#ifdef TARGET_WORDS_BIGENDIAN
+        tcg_gen_xori_tl(t1, t1, 7);
+#endif
+        tcg_gen_shli_tl(t1, t1, 3);
+        tcg_gen_andi_tl(t0, t0, ~7);
+        tcg_gen_qemu_ld64(t0, t0, ctx->mem_idx);
+        tcg_gen_shr_tl(t0, t0, t1);
+        tcg_gen_xori_tl(t1, t1, 63);
+        t2 = tcg_const_tl(0xfffffffffffffffeull);
+        tcg_gen_shl_tl(t2, t2, t1);
         gen_load_gpr(t1, rt);
-        gen_helper_1e2i(ldr, t1, t1, t0, ctx->mem_idx);
-        gen_store_gpr(t1, rt);
+        tcg_gen_and_tl(t1, t1, t2);
+        tcg_temp_free(t2);
+        tcg_gen_or_tl(t0, t0, t1);
         tcg_temp_free(t1);
+        gen_store_gpr(t0, rt);
         opn = "ldr";
         break;
     case OPC_LDPC:
@@ -1217,21 +1241,46 @@ static void gen_ld (CPUMIPSState *env, DisasContext 
*ctx, uint32_t opc,
         opn = "lbu";
         break;
     case OPC_LWL:
-        save_cpu_state(ctx, 1);
         t1 = tcg_temp_new();
+        tcg_gen_andi_tl(t1, t0, 3);
+#ifndef TARGET_WORDS_BIGENDIAN
+        tcg_gen_xori_tl(t1, t1, 3);
+#endif
+        tcg_gen_shli_tl(t1, t1, 3);
+        tcg_gen_andi_tl(t0, t0, ~3);
+        tcg_gen_qemu_ld32u(t0, t0, ctx->mem_idx);
+        tcg_gen_shl_tl(t0, t0, t1);
+        tcg_gen_xori_tl(t1, t1, 31);
+        t2 = tcg_const_tl(0x7fffffffull);
+        tcg_gen_shr_tl(t2, t2, t1);
         gen_load_gpr(t1, rt);
-        gen_helper_1e2i(lwl, t1, t1, t0, ctx->mem_idx);
-        gen_store_gpr(t1, rt);
+        tcg_gen_and_tl(t1, t1, t2);
+        tcg_temp_free(t2);
+        tcg_gen_or_tl(t0, t0, t1);
         tcg_temp_free(t1);
+        tcg_gen_ext32s_tl(t0, t0);
+        gen_store_gpr(t0, rt);
         opn = "lwl";
         break;
     case OPC_LWR:
-        save_cpu_state(ctx, 1);
         t1 = tcg_temp_new();
+        tcg_gen_andi_tl(t1, t0, 3);
+#ifdef TARGET_WORDS_BIGENDIAN
+        tcg_gen_xori_tl(t1, t1, 3);
+#endif
+        tcg_gen_shli_tl(t1, t1, 3);
+        tcg_gen_andi_tl(t0, t0, ~3);
+        tcg_gen_qemu_ld32u(t0, t0, ctx->mem_idx);
+        tcg_gen_shr_tl(t0, t0, t1);
+        tcg_gen_xori_tl(t1, t1, 31);
+        t2 = tcg_const_tl(0xfffffffeull);
+        tcg_gen_shl_tl(t2, t2, t1);
         gen_load_gpr(t1, rt);
-        gen_helper_1e2i(lwr, t1, t1, t0, ctx->mem_idx);
-        gen_store_gpr(t1, rt);
+        tcg_gen_and_tl(t1, t1, t2);
+        tcg_temp_free(t2);
+        tcg_gen_or_tl(t0, t0, t1);
         tcg_temp_free(t1);
+        gen_store_gpr(t0, rt);
         opn = "lwr";
         break;
     case OPC_LL:
-- 
1.7.10.4