Integrate MinGW build with DWARF2 exception handling.

Only works with DWARF2-enabled GCC 4.x (not the default MinGW GCC).
Fix fastcall symbol names for COFF assembler output.
Add DWARF2 unwind info to COFF assembler output.
Use COFF assembler mode for MinGW builds.
Always enable the DWARF2 handler if compiled with GCC.

1 files changed, 45 insertions, 0 deletions

diff --git a/src/buildvm_x86.dasc b/src/buildvm_x86.dasc
index 1878613e..4e4ccc49 100644
--- a/src/buildvm_x86.dasc
+++ b/src/buildvm_x86.dasc
@@ -4920,6 +4920,51 @@ static void emit_asm_debug(BuildCtx *ctx)
         "\t.align " SZPTR "\n"
         ".LEFDE1:\n\n", (int)ctx->codesz, CFRAME_SIZE);
     break;
+  case BUILD_coffasm:
+    fprintf(ctx->fp, "\t.section .eh_frame,\"dr\"\n");
+    fprintf(ctx->fp,
+      "\t.def %slj_err_unwind_dwarf; .scl 2; .type 32; .endef\n",
+      LJ_32 ? "_" : "");
+    fprintf(ctx->fp,
+        "Lframe1:\n"
+        "\t.long LECIE1-LSCIE1\n"
+        "LSCIE1:\n"
+        "\t.long 0\n"
+        "\t.byte 0x1\n"
+        "\t.string \"zP\"\n"
+        "\t.uleb128 0x1\n"
+        "\t.sleb128 -" SZPTR "\n"
+        "\t.byte " REG_RA "\n"
+        "\t.uleb128 5\n"                        /* augmentation length */
+        "\t.byte 0x00\n"                        /* absptr */
+        "\t.long %slj_err_unwind_dwarf\n"
+        "\t.byte 0xc\n\t.uleb128 " REG_SP "\n\t.uleb128 " SZPTR "\n"
+        "\t.byte 0x80+" REG_RA "\n\t.uleb128 0x1\n"
+        "\t.align " SZPTR "\n"
+        "LECIE1:\n\n", LJ_32 ? "_" : "");
+    fprintf(ctx->fp,
+        "LSFDE1:\n"
+        "\t.long LEFDE1-LASFDE1\n"
+        "LASFDE1:\n"
+        "\t.long LASFDE1-Lframe1\n"
+        "\t.long %slj_vm_asm_begin\n"
+        "\t.long %d\n"
+        "\t.uleb128 0\n"                        /* augmentation length */
+        "\t.byte 0xe\n\t.uleb128 %d\n"          /* def_cfa_offset */
+#if LJ_64
+        "\t.byte 0x86\n\t.uleb128 0x2\n"        /* offset rbp */
+        "\t.byte 0x83\n\t.uleb128 0x3\n"        /* offset rbx */
+        "\t.byte 0x8f\n\t.uleb128 0x4\n"        /* offset r15 */
+        "\t.byte 0x8e\n\t.uleb128 0x5\n"        /* offset r14 */
+#else
+        "\t.byte 0x85\n\t.uleb128 0x2\n"        /* offset ebp */
+        "\t.byte 0x87\n\t.uleb128 0x3\n"        /* offset edi */
+        "\t.byte 0x86\n\t.uleb128 0x4\n"        /* offset esi */
+        "\t.byte 0x83\n\t.uleb128 0x5\n"        /* offset ebx */
+#endif
+        "\t.align " SZPTR "\n"
+        "LEFDE1:\n\n", LJ_32 ? "_" : "", (int)ctx->codesz, CFRAME_SIZE);
+    break;
   case BUILD_machasm:
     fprintf(ctx->fp, "\t.section __TEXT,__eh_frame,coalesced,no_toc+strip_static_syms+live_support\n");
     fprintf(ctx->fp,