[Qemu-devel] [PATCH] Handle .LCn symbols in dyngen

[Gwenole Beauchesne <gbeauchesne@mandriva.com>]

Hi,

sparc-user build fails on x86_64 with gcc4 because op_fnegs() uses a local
constant (0.0) and dyngen can't emit it. Before I realized Paul fixed this
in his former gcc4 patch with a helper call (which is not in the final
gcc4 patch), I merged the following from the SheepShaver dyngen.

Note: I probably should have simply used the extern char __dot_sym 
__asm__(".sym") trick from the HOST_SPARC case, which this patch clobbers. 
What dot symbols were emitted on sparc host?

2005-06-02  Gwenole Beauchesne  <gbeauchesne@mandriva.com>

	* dyngen.c: handle .LCn symbols.

--- qemu-0.7.0/dyngen.c.gcc4-dot-syms	2005-06-02 17:02:27.000000000 -0400
+++ qemu-0.7.0/dyngen.c	2005-06-02 17:07:59.000000000 -0400
@@ -29,6 +29,7 @@
 #include <inttypes.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <assert.h>
 
 #include "config-host.h"
 
@@ -323,11 +324,46 @@ void put32(uint32_t *p, uint32_t val)
     *p = val;
 }
 
+/* Helper functions to pretty print data */
+static void print_data(FILE *outfile, const char *name, const uint8_t *data, int data_size)
+{
+    int i;
+    fprintf(outfile, "static const uint8_t %s[] = {", name);
+    for (i = 0; i < data_size; i++) {
+        if ((i % 12) == 0) {
+            if (i != 0)
+                fprintf(outfile, ",");
+            fprintf(outfile, "\n    ");
+        }
+        else
+            fprintf(outfile, ", ");
+        fprintf(outfile, "0x%02x", data[i]);
+    }
+    fprintf(outfile, "\n};\n");
+}
+
+static char *gen_dot_prefix(const char *sym_name)
+{
+  static char name[256];
+  assert(sym_name[0] == '.');
+  snprintf(name, sizeof(name), "dg_dot_%s", sym_name + 1);
+  return name;
+}
+
 /* executable information */
 EXE_SYM *symtab;
 int nb_syms;
 int text_shndx;
 uint8_t *text;
+static struct elf_shdr *rodata_cst4_sec;
+static uint8_t *rodata_cst4 = NULL;
+static int rodata_cst4_shndx;
+static struct elf_shdr *rodata_cst8_sec;
+static uint8_t *rodata_cst8 = NULL;
+static int rodata_cst8_shndx;
+static struct elf_shdr *rodata_cst16_sec;
+static uint8_t *rodata_cst16 = NULL;
+static int rodata_cst16_shndx;
 EXE_RELOC *relocs;
 int nb_relocs;
 
@@ -520,8 +556,25 @@ int load_object(const char *filename)
             }
         }
     }
-    /* text section */
 
+    /* rodata sections */
+    rodata_cst4_sec = find_elf_section(shdr, ehdr.e_shnum, shstr, ".rodata.cst4");
+    if (rodata_cst4_sec) {
+      rodata_cst4_shndx = rodata_cst4_sec - shdr;
+      rodata_cst4 = sdata[rodata_cst4_shndx];
+    }
+    rodata_cst8_sec = find_elf_section(shdr, ehdr.e_shnum, shstr, ".rodata.cst8");
+    if (rodata_cst8_sec) {
+      rodata_cst8_shndx = rodata_cst8_sec - shdr;
+      rodata_cst8 = sdata[rodata_cst8_shndx];
+    }
+    rodata_cst16_sec = find_elf_section(shdr, ehdr.e_shnum, shstr, ".rodata.cst16");
+    if (rodata_cst16_sec) {
+      rodata_cst16_shndx = rodata_cst16_sec - shdr;
+      rodata_cst16 = sdata[rodata_cst16_shndx];
+    }
+
+    /* text section */
     text_sec = find_elf_section(shdr, ehdr.e_shnum, shstr, ".text");
     if (!text_sec)
         error("could not find .text section");
@@ -1193,6 +1246,8 @@ void get_reloc_expr(char *name, int name
 
     if (strstart(sym_name, "__op_param", &p)) {
         snprintf(name, name_size, "param%s", p);
+    } else if (strstart(sym_name, ".LC", NULL)) {
+        snprintf(name, name_size, "(long)(%s)", gen_dot_prefix(sym_name));
     } else if (strstart(sym_name, "__op_gen_label", &p)) {
         snprintf(name, name_size, "gen_labels[param%s]", p);
     } else {
@@ -2220,7 +2275,8 @@ void gen_code(const char *name, host_ulo
                 if (*sym_name && 
                     !strstart(sym_name, "__op_param", NULL) &&
                     !strstart(sym_name, "__op_jmp", NULL) &&
-                    !strstart(sym_name, "__op_gen_label", NULL)) {
+                    !strstart(sym_name, "__op_gen_label", NULL) &&
+                    !strstart(sym_name, ".LC", NULL)) {
 #if defined(HOST_SPARC)
 		    if (sym_name[0] == '.') {
 			fprintf(outfile,
@@ -3035,6 +3091,23 @@ int gen_file(FILE *outfile, int out_type
         }
         
     } else {
+#if defined(CONFIG_FORMAT_ELF)
+        /* emit local symbols */
+        for(i = 0, sym = symtab; i < nb_syms; i++, sym++) {
+            const char *name;
+            name = get_sym_name(sym);
+            if (strstart(name, ".LC", NULL)) {
+                if (sym->st_shndx == (rodata_cst16_sec - shdr))
+                    print_data(outfile, gen_dot_prefix(name), rodata_cst16 + sym->st_value, 16);
+                else if (sym->st_shndx == (rodata_cst8_sec - shdr))
+                    print_data(outfile, gen_dot_prefix(name), rodata_cst8 + sym->st_value, 8);
+                else if (sym->st_shndx == (rodata_cst4_sec - shdr))
+                    print_data(outfile, gen_dot_prefix(name), rodata_cst4 + sym->st_value, 4);
+                else
+                    error("invalid section for local data %s (%x)\n", name, sym->st_shndx);
+            }
+        }
+#endif
         /* generate big code generation switch */
 fprintf(outfile,
 "int dyngen_code(uint8_t *gen_code_buf,\n"