tcg/loongarch64: Fix tcg_out_movi vs some pcrel pointers

Simplify the logic for two-part, 32-bit pc-relative addresses.
Rather than assume all such fit in int32_t, do some arithmetic
and assert a result, do some arithmetic first and then check
to see if the pieces are in range.

Cc: [email protected]
Fixes: dacc517 ("tcg/loongarch64: Implement tcg_out_mov and tcg_out_movi")
Reviewed-by: Song Gao <[email protected]>
Reported-by: Song Gao <[email protected]>
Signed-off-by: Richard Henderson <[email protected]>
(cherry picked from commit 521d7fb)
Signed-off-by: Michael Tokarev <[email protected]>

Author: rth7680

tcg/loongarch64/tcg-target.c.inc

@@ -366,8 +366,7 @@ static void tcg_out_movi(TCGContext *s, TCGType type, TCGReg rd,
      * back to the slow path.
      */
 
-    intptr_t pc_offset;
-    tcg_target_long val_lo, val_hi, pc_hi, offset_hi;
+    intptr_t src_rx, pc_offset;
     tcg_target_long hi12, hi32, hi52;
 
     /* Value fits in signed i32.  */
@@ -377,24 +376,23 @@ static void tcg_out_movi(TCGContext *s, TCGType type, TCGReg rd,
     }
 
     /* PC-relative cases.  */
-    pc_offset = tcg_pcrel_diff(s, (void *)val);
-    if (pc_offset == sextreg(pc_offset, 0, 22) && (pc_offset & 3) == 0) {
-        /* Single pcaddu2i.  */
-        tcg_out_opc_pcaddu2i(s, rd, pc_offset >> 2);
-        return;
+    src_rx = (intptr_t)tcg_splitwx_to_rx(s->code_ptr);
+    if ((val & 3) == 0) {
+        pc_offset = val - src_rx;
+        if (pc_offset == sextreg(pc_offset, 0, 22)) {
+            /* Single pcaddu2i.  */
+            tcg_out_opc_pcaddu2i(s, rd, pc_offset >> 2);
+            return;
+        }
     }
 
-    if (pc_offset == (int32_t)pc_offset) {
-        /* Offset within 32 bits; load with pcalau12i + ori.  */
-        val_lo = sextreg(val, 0, 12);
-        val_hi = val >> 12;
-        pc_hi = (val - pc_offset) >> 12;
-        offset_hi = val_hi - pc_hi;
-
-        tcg_debug_assert(offset_hi == sextreg(offset_hi, 0, 20));
-        tcg_out_opc_pcalau12i(s, rd, offset_hi);
+    pc_offset = (val >> 12) - (src_rx >> 12);
+    if (pc_offset == sextreg(pc_offset, 0, 20)) {
+        /* Load with pcalau12i + ori.  */
+        tcg_target_long val_lo = val & 0xfff;
+        tcg_out_opc_pcalau12i(s, rd, pc_offset);
         if (val_lo != 0) {
-            tcg_out_opc_ori(s, rd, rd, val_lo & 0xfff);
+            tcg_out_opc_ori(s, rd, rd, val_lo);
         }
         return;
     }