tcg: Add TCG_TARGET_HAS_MEMORY_BSWAP

For now, defined universally as true, since we previously required
backends to implement swapped memory operations.  Future patches
may now remove that support where it is onerous.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 116 insertions, 2 deletions

diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
index d7a3066..38652db 100644
--- a/tcg/tcg-op.c
+++ b/tcg/tcg-op.c
@@ -2694,25 +2694,78 @@ static void tcg_gen_req_mo(TCGBar type)
 
 void tcg_gen_qemu_ld_i32(TCGv_i32 val, TCGv addr, TCGArg idx, TCGMemOp memop)
 {
+    TCGMemOp orig_memop;
+
     tcg_gen_req_mo(TCG_MO_LD_LD | TCG_MO_ST_LD);
     memop = tcg_canonicalize_memop(memop, 0, 0);
     trace_guest_mem_before_tcg(tcg_ctx->cpu, cpu_env,
                                addr, trace_mem_get_info(memop, 0));
+
+    orig_memop = memop;
+    if (!TCG_TARGET_HAS_MEMORY_BSWAP && (memop & MO_BSWAP)) {
+        memop &= ~MO_BSWAP;
+        /* The bswap primitive requires zero-extended input.  */
+        if ((memop & MO_SSIZE) == MO_SW) {
+            memop &= ~MO_SIGN;
+        }
+    }
+
     gen_ldst_i32(INDEX_op_qemu_ld_i32, val, addr, memop, idx);
+
+    if ((orig_memop ^ memop) & MO_BSWAP) {
+        switch (orig_memop & MO_SIZE) {
+        case MO_16:
+            tcg_gen_bswap16_i32(val, val);
+            if (orig_memop & MO_SIGN) {
+                tcg_gen_ext16s_i32(val, val);
+            }
+            break;
+        case MO_32:
+            tcg_gen_bswap32_i32(val, val);
+            break;
+        default:
+            g_assert_not_reached();
+        }
+    }
 }
 
 void tcg_gen_qemu_st_i32(TCGv_i32 val, TCGv addr, TCGArg idx, TCGMemOp memop)
 {
+    TCGv_i32 swap = NULL;
+
     tcg_gen_req_mo(TCG_MO_LD_ST | TCG_MO_ST_ST);
     memop = tcg_canonicalize_memop(memop, 0, 1);
     trace_guest_mem_before_tcg(tcg_ctx->cpu, cpu_env,
                                addr, trace_mem_get_info(memop, 1));
+
+    if (!TCG_TARGET_HAS_MEMORY_BSWAP && (memop & MO_BSWAP)) {
+        swap = tcg_temp_new_i32();
+        switch (memop & MO_SIZE) {
+        case MO_16:
+            tcg_gen_ext16u_i32(swap, val);
+            tcg_gen_bswap16_i32(swap, swap);
+            break;
+        case MO_32:
+            tcg_gen_bswap32_i32(swap, val);
+            break;
+        default:
+            g_assert_not_reached();
+        }
+        val = swap;
+        memop &= ~MO_BSWAP;
+    }
+
     gen_ldst_i32(INDEX_op_qemu_st_i32, val, addr, memop, idx);
+
+    if (swap) {
+        tcg_temp_free_i32(swap);
+    }
 }
 
 void tcg_gen_qemu_ld_i64(TCGv_i64 val, TCGv addr, TCGArg idx, TCGMemOp memop)
 {
-    tcg_gen_req_mo(TCG_MO_LD_LD | TCG_MO_ST_LD);
+    TCGMemOp orig_memop;
+
     if (TCG_TARGET_REG_BITS == 32 && (memop & MO_SIZE) < MO_64) {
         tcg_gen_qemu_ld_i32(TCGV_LOW(val), addr, idx, memop);
         if (memop & MO_SIGN) {
@@ -2723,24 +2776,85 @@ void tcg_gen_qemu_ld_i64(TCGv_i64 val, TCGv addr, TCGArg idx, TCGMemOp memop)
         return;
     }
 
+    tcg_gen_req_mo(TCG_MO_LD_LD | TCG_MO_ST_LD);
     memop = tcg_canonicalize_memop(memop, 1, 0);
     trace_guest_mem_before_tcg(tcg_ctx->cpu, cpu_env,
                                addr, trace_mem_get_info(memop, 0));
+
+    orig_memop = memop;
+    if (!TCG_TARGET_HAS_MEMORY_BSWAP && (memop & MO_BSWAP)) {
+        memop &= ~MO_BSWAP;
+        /* The bswap primitive requires zero-extended input.  */
+        if ((memop & MO_SIGN) && (memop & MO_SIZE) < MO_64) {
+            memop &= ~MO_SIGN;
+        }
+    }
+
     gen_ldst_i64(INDEX_op_qemu_ld_i64, val, addr, memop, idx);
+
+    if ((orig_memop ^ memop) & MO_BSWAP) {
+        switch (orig_memop & MO_SIZE) {
+        case MO_16:
+            tcg_gen_bswap16_i64(val, val);
+            if (orig_memop & MO_SIGN) {
+                tcg_gen_ext16s_i64(val, val);
+            }
+            break;
+        case MO_32:
+            tcg_gen_bswap32_i64(val, val);
+            if (orig_memop & MO_SIGN) {
+                tcg_gen_ext32s_i64(val, val);
+            }
+            break;
+        case MO_64:
+            tcg_gen_bswap64_i64(val, val);
+            break;
+        default:
+            g_assert_not_reached();
+        }
+    }
 }
 
 void tcg_gen_qemu_st_i64(TCGv_i64 val, TCGv addr, TCGArg idx, TCGMemOp memop)
 {
-    tcg_gen_req_mo(TCG_MO_LD_ST | TCG_MO_ST_ST);
+    TCGv_i64 swap = NULL;
+
     if (TCG_TARGET_REG_BITS == 32 && (memop & MO_SIZE) < MO_64) {
         tcg_gen_qemu_st_i32(TCGV_LOW(val), addr, idx, memop);
         return;
     }
 
+    tcg_gen_req_mo(TCG_MO_LD_ST | TCG_MO_ST_ST);
     memop = tcg_canonicalize_memop(memop, 1, 1);
     trace_guest_mem_before_tcg(tcg_ctx->cpu, cpu_env,
                                addr, trace_mem_get_info(memop, 1));
+
+    if (!TCG_TARGET_HAS_MEMORY_BSWAP && (memop & MO_BSWAP)) {
+        swap = tcg_temp_new_i64();
+        switch (memop & MO_SIZE) {
+        case MO_16:
+            tcg_gen_ext16u_i64(swap, val);
+            tcg_gen_bswap16_i64(swap, swap);
+            break;
+        case MO_32:
+            tcg_gen_ext32u_i64(swap, val);
+            tcg_gen_bswap32_i64(swap, swap);
+            break;
+        case MO_64:
+            tcg_gen_bswap64_i64(swap, val);
+            break;
+        default:
+            g_assert_not_reached();
+        }
+        val = swap;
+        memop &= ~MO_BSWAP;
+    }
+
     gen_ldst_i64(INDEX_op_qemu_st_i64, val, addr, memop, idx);
+
+    if (swap) {
+        tcg_temp_free_i64(swap);
+    }
 }
 
 static void tcg_gen_ext_i32(TCGv_i32 ret, TCGv_i32 val, TCGMemOp opc)