diff mbox series

[v3,21/24] disas/nanomips: Replace exception handling

Message ID 20220912122635.74032-22-milica.lazarevic@syrmia.com
State New
Headers show
Series Convert nanoMIPS disassembler from C++ to C | expand

Commit Message

Milica Lazarevic Sept. 12, 2022, 12:26 p.m. UTC 
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 | 100 ++++++++++++++++++++-------------------------
 1 file changed, 45 insertions(+), 55 deletions(-)

Comments

Richard Henderson Sept. 13, 2022, 8:12 a.m. UTC | #1 
On 9/12/22 13:26, Milica Lazarevic wrote:
> 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 | 100 ++++++++++++++++++++-------------------------
>   1 file changed, 45 insertions(+), 55 deletions(-)

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

r~
diff mbox series

Patch

diff --git a/disas/nanomips.cpp b/disas/nanomips.cpp
index 077dfe0dea..0121d5da61 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>
 
@@ -133,10 +132,9 @@  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));
+    info->fprintf_func(info->stream, "Invalid register mapping index %" PRIu64
+                       ", size of list = %zu", index, register_list_size);
+    siglongjmp(info->buf, 1);
 }
 
 
@@ -466,8 +464,9 @@  static const char *GPR(uint64 reg, Dis_info *info)
         return gpr_reg[reg];
     }
 
-    throw std::runtime_error(img_format("Invalid GPR register index %" PRIu64,
-                                         reg));
+    info->fprintf_func(info->stream, "Invalid GPR register index %" PRIu64,
+                       reg);
+    siglongjmp(info->buf, 1);
 }
 
 
@@ -503,8 +502,9 @@  static const char *FPR(uint64 reg, Dis_info *info)
         return fpr_reg[reg];
     }
 
-    throw std::runtime_error(img_format("Invalid FPR register index %" PRIu64,
-                                         reg));
+    info->fprintf_func(info->stream, "Invalid FPR register index %" PRIu64,
+                       reg);
+    siglongjmp(info->buf, 1);
 }
 
 
@@ -518,8 +518,9 @@  static const char *AC(uint64 reg, Dis_info *info)
         return ac_reg[reg];
     }
 
-    throw std::runtime_error(img_format("Invalid AC register index %" PRIu64,
-                                         reg));
+    info->fprintf_func(info->stream, "Invalid AC register index %" PRIu64,
+                       reg);
+    siglongjmp(info->buf, 1);
 }
 
 
@@ -562,55 +563,38 @@  static int Disassemble(const uint16 *data, char **dis,
                      TABLE_ENTRY_TYPE & type, const Pool *table,
                      int table_size, 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)) {
-                            disassembly_function dis_fn = table[i].disassembly;
-                            if (dis_fn == 0) {
-                                *dis = g_strdup(
-                                    "disassembler failure - bad table entry");
-                                return -6;
-                            }
-                            type = table[i].type;
-                            *dis = dis_fn(op_code, info);
-                            return table[i].instructions_size;
-                        } else {
-                            *dis = g_strdup("reserved instruction");
-                            return -2;
-                        }
-                    }
-                    catch (std::runtime_error & e)
-                    {
-                        *dis = g_strdup(e.what());
-                        return -3;          /* runtime error */
+    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)) {
+                    disassembly_function dis_fn = table[i].disassembly;
+                    if (dis_fn == 0) {
+                        *dis = g_strdup(
+                            "disassembler failure - bad table entry");
+                        return -6;
                     }
+                    type = table[i].type;
+                    *dis = dis_fn(op_code, info);
+                    return table[i].instructions_size;
+                } else {
+                    *dis = g_strdup("reserved instruction");
+                    return -2;
                 }
             }
         }
     }
-    catch (std::exception & e)
-    {
-        *dis = g_strdup(e.what());
-        return -4;          /* runtime error */
-    }
-
     *dis = g_strdup("failed to disassemble");
     return -1;      /* failed to disassemble        */
 }
@@ -22004,6 +21988,12 @@  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.  */