[PATCH v2 16/20] disas/nanomips: Replace exception handling

[Milica Lazarevic]

Since there's no support for exception handling in C, the try-catch
blocks have been deleted, and throw clauses are replaced. When a runtime
error happens, we're printing out the error message. Disassembling of
the current instruction interrupts. This behavior is achieved by adding
sigsetjmp() to discard further disassembling after the error message
prints and by adding the siglongjmp() function to imitate throwing an
error. The goal was to maintain the same output as it was.

Signed-off-by: Milica Lazarevic <milica.lazarevic@syrmia.com>
---
 disas/nanomips.cpp | 126 ++++++++++++++++++++++-----------------------
 1 file changed, 61 insertions(+), 65 deletions(-)

diff --git a/disas/nanomips.cpp b/disas/nanomips.cpp
index 5142f307fc..a8295ebfa8 100644
--- a/disas/nanomips.cpp
+++ b/disas/nanomips.cpp
@@ -31,7 +31,6 @@
 #include "disas/dis-asm.h"
 
 #include <string.h>
-#include <stdexcept>
 #include <stdio.h>
 #include <stdarg.h>
 
@@ -134,10 +133,12 @@ static uint64 renumber_registers(uint64 index, uint64 
*register_list,
         return register_list[index];
     }
 
-    throw std::runtime_error(img_format(
-                   "Invalid register mapping index %" PRIu64
-                   ", size of list = %zu",
-                   index, register_list_size));
+    g_autofree char *err = img_format(
+                      "Invalid register mapping index %" PRIu64
+                      ", size of list = %zu",
+                      index, register_list_size);
+    info->fprintf_func(info->stream, "%s", err);
+    siglongjmp(info->buf, 1);
 }
 
 
@@ -514,8 +515,10 @@ static const char *GPR(uint64 reg, struct Dis_info *info)
         return gpr_reg[reg];
     }
 
-    throw std::runtime_error(img_format("Invalid GPR register index %" PRIu64,
-                                         reg));
+    g_autofree char *err = img_format("Invalid GPR register index %" PRIu64,
+                                 reg);
+    info->fprintf_func(info->stream, "%s", err);
+    siglongjmp(info->buf, 1);
 }
 
 
@@ -553,8 +556,10 @@ static const char *FPR(uint64 reg, struct Dis_info *info)
         return fpr_reg[reg];
     }
 
-    throw std::runtime_error(img_format("Invalid FPR register index %" PRIu64,
-                                         reg));
+    g_autofree const char *err = img_format(
+        "Invalid FPR register index %" PRIu64, reg);
+    info->fprintf_func(info->stream, "%s", err);
+    siglongjmp(info->buf, 1);
 }
 
 
@@ -568,8 +573,10 @@ static const char *AC(uint64 reg, struct Dis_info *info)
         return ac_reg[reg];
     }
 
-    throw std::runtime_error(img_format("Invalid AC register index %" PRIu64,
-                                         reg));
+    const char *err = img_format("Invalid AC register index %" PRIu64,
+                                 reg);
+    info->fprintf_func(info->stream, "%s", err);
+    siglongjmp(info->buf, 1);
 }
 
 
@@ -631,65 +638,48 @@ static int Disassemble(const uint16 *data, char *dis,
                        TABLE_ENTRY_TYPE & type, const Pool *table,
                        int table_size, struct Dis_info *info)
 {
-    try
-    {
-        for (int i = 0; i < table_size; i++) {
-            uint64 op_code = extract_op_code_value(data,
-                                 table[i].instructions_size);
-            if ((op_code & table[i].mask) == table[i].value) {
-                /* possible match */
-                conditional_function cond = table[i].condition;
-                if ((cond == NULL) || cond(op_code)) {
-                    try
-                    {
-                        if (table[i].type == pool) {
-                            return Disassemble(data, dis, type,
-                                               table[i].next_table,
-                                               table[i].next_table_size, info);
-                        } else if ((table[i].type == instruction) ||
-                                   (table[i].type == call_instruction) ||
-                                   (table[i].type == branch_instruction) ||
-                                   (table[i].type == return_instruction)) {
-                            if ((table[i].attributes != 0) &&
-                                (ALL_ATTRIBUTES & table[i].attributes) == 0) {
-                                /*
-                                 * failed due to instruction having
-                                 * an ASE attribute and the requested version
-                                 * not having that attribute
-                                 */
-                                strcpy(dis, "ASE attribute mismatch");
-                                return -5;
-                            }
-                            disassembly_function dis_fn = table[i].disassembly;
-                            if (dis_fn == 0) {
-                                strcpy(dis,
-                                "disassembler failure - bad table entry");
-                                return -6;
-                            }
-                            type = table[i].type;
-                            g_autofree char *dis_str = dis_fn(op_code, info);
-                            strcpy(dis, dis_str);
-                            return table[i].instructions_size;
-                        } else {
-                            strcpy(dis, "reserved instruction");
-                            return -2;
+    for (int i = 0; i < table_size; i++) {
+        uint64 op_code = extract_op_code_value(data,
+                             table[i].instructions_size);
+        if ((op_code & table[i].mask) == table[i].value) {
+            /* possible match */
+            conditional_function cond = table[i].condition;
+            if ((cond == NULL) || cond(op_code)) {
+                if (table[i].type == pool) {
+                    return Disassemble(data, dis, type,
+                                       table[i].next_table,
+                                       table[i].next_table_size, info);
+                } else if ((table[i].type == instruction) ||
+                           (table[i].type == call_instruction) ||
+                           (table[i].type == branch_instruction) ||
+                           (table[i].type == return_instruction)) {
+                        if ((table[i].attributes != 0) &&
+                            (ALL_ATTRIBUTES & table[i].attributes) == 0) {
+                            /*
+                             * failed due to instruction having
+                             * an ASE attribute and the requested version
+                             * not having that attribute
+                             */
+                            strcpy(dis, "ASE attribute mismatch");
+                            return -5;
                         }
-                    }
-                    catch (std::runtime_error & e)
-                    {
-                        strcpy(dis, e.what());
-                        return -3;          /* runtime error */
+                        disassembly_function dis_fn = table[i].disassembly;
+                        if (dis_fn == 0) {
+                            strcpy(dis,
+                            "disassembler failure - bad table entry");
+                            return -6;
+                        }
+                        type = table[i].type;
+                        g_autofree char *dis_str = dis_fn(op_code, info);
+                        strcpy(dis, dis_str);
+                        return table[i].instructions_size;
+                    } else {
+                        strcpy(dis, "reserved instruction");
+                        return -2;
                     }
                 }
             }
         }
-    }
-    catch (std::exception & e)
-    {
-        strcpy(dis, e.what());
-        return -4;          /* runtime error */
-    }
-
     strcpy(dis, "failed to disassemble");
     return -1;      /* failed to disassemble        */
 }
@@ -22333,6 +22323,12 @@ int print_insn_nanomips(bfd_vma memaddr, struct 
disassemble_info *info)
         (*info->fprintf_func)(info->stream, "     ");
     }
 
+    /* Handle runtime errors. */
+    if (sigsetjmp(disassm_info.buf, 0) != 0) {
+        info->insn_type = dis_noninsn;
+        return insn3 ? 6 : insn2 ? 4 : 2;
+    }
+
     int length = nanomips_dis(buf, &disassm_info, insn1, insn2, insn3);
 
     /* FIXME: Should probably use a hash table on the major opcode here.  */
-- 
2.25.1