tcg/ppc: Return false on failure from patch_reloc

The reloc_pc{14,24}_val routines retain their asserts.
Use these directly within the slow paths.
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: NRichard Henderson <richard.henderson@linaro.org>

tcg/ppc/tcg-target.inc.c

@@ -193,9 +193,14 @@ static uint32_t reloc_pc24_val(tcg_insn_unit *pc, tcg_insn_unit *target)
     return disp & 0x3fffffc;
 }
 
-static void reloc_pc24(tcg_insn_unit *pc, tcg_insn_unit *target)
+static bool reloc_pc24(tcg_insn_unit *pc, tcg_insn_unit *target)
 {
-    *pc = (*pc & ~0x3fffffc) | reloc_pc24_val(pc, target);
+    ptrdiff_t disp = tcg_ptr_byte_diff(target, pc);
+    if (in_range_b(disp)) {
+        *pc = (*pc & ~0x3fffffc) | (disp & 0x3fffffc);
+        return true;
+    }
+    return false;
 }
 
 static uint16_t reloc_pc14_val(tcg_insn_unit *pc, tcg_insn_unit *target)
@@ -205,9 +210,14 @@ static uint16_t reloc_pc14_val(tcg_insn_unit *pc, tcg_insn_unit *target)
     return disp & 0xfffc;
 }
 
-static void reloc_pc14(tcg_insn_unit *pc, tcg_insn_unit *target)
+static bool reloc_pc14(tcg_insn_unit *pc, tcg_insn_unit *target)
 {
-    *pc = (*pc & ~0xfffc) | reloc_pc14_val(pc, target);
+    ptrdiff_t disp = tcg_ptr_byte_diff(target, pc);
+    if (disp == (int16_t) disp) {
+        *pc = (*pc & ~0xfffc) | (disp & 0xfffc);
+        return true;
+    }
+    return false;
 }
 
 /* parse target specific constraints */
@@ -524,11 +534,9 @@ static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
 
     switch (type) {
     case R_PPC_REL14:
-        reloc_pc14(code_ptr, target);
-        break;
+        return reloc_pc14(code_ptr, target);
     case R_PPC_REL24:
-        reloc_pc24(code_ptr, target);
-        break;
+        return reloc_pc24(code_ptr, target);
     case R_PPC_ADDR16:
         /* We are abusing this relocation type.  This points to a pair
            of insns, addis + load.  If the displacement is small, we
@@ -540,7 +548,9 @@ static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
         } else {
             int16_t lo = value;
             int hi = value - lo;
-            assert(hi + lo == value);
+            if (hi + lo != value) {
+                return false;
+            }
             code_ptr[0] = deposit32(code_ptr[0], 0, 16, hi >> 16);
             code_ptr[1] = deposit32(code_ptr[1], 0, 16, lo);
         }
@@ -1638,7 +1648,7 @@ static void tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *lb)
     TCGMemOp opc = get_memop(oi);
     TCGReg hi, lo, arg = TCG_REG_R3;
 
-    reloc_pc14(lb->label_ptr[0], s->code_ptr);
+    **lb->label_ptr |= reloc_pc14_val(*lb->label_ptr, s->code_ptr);
 
     tcg_out_mov(s, TCG_TYPE_PTR, arg++, TCG_AREG0);
 
@@ -1683,7 +1693,7 @@ static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *lb)
     TCGMemOp s_bits = opc & MO_SIZE;
     TCGReg hi, lo, arg = TCG_REG_R3;
 
-    reloc_pc14(lb->label_ptr[0], s->code_ptr);
+    **lb->label_ptr |= reloc_pc14_val(*lb->label_ptr, s->code_ptr);
 
     tcg_out_mov(s, TCG_TYPE_PTR, arg++, TCG_AREG0);