target-mips: implement unaligned loads using TCG

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 <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

1 files changed, 62 insertions, 13 deletions

diff --git a/target-mips/translate.c b/target-mips/translate.c
index a48a475..05d88c4 100644
--- a/target-mips/translate.c
+++ b/target-mips/translate.c
@@ -1580,7 +1580,7 @@ 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.
@@ -1612,21 +1612,45 @@ 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:
@@ -1672,21 +1696,46 @@ 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: