Arm constant pool generation

diff -u -p -r1.38 dyngen.c
@@ -1211,90 +1211,137 @@ int arm_emit_ldr_info(const char *name, 
 {
     uint8_t *p;
     uint32_t insn;
-    int offset, min_offset, pc_offset, data_size;
+    int offset, min_offset, pc_offset, data_size, spare, max_pool;
     uint8_t data_allocated[1024];
     unsigned int data_index;
+    int type;
     
     memset(data_allocated, 0, sizeof(data_allocated));
     
     p = p_start;
     min_offset = p_end - p_start;
+    spare = 0x7fffffff;
     while (p < p_start + min_offset) {
         insn = get32((uint32_t *)p);
+        /* TODO: Armv5e ldrd.  */
+        /* TODO: VFP load.  */
         if ((insn & 0x0d5f0000) == 0x051f0000) {
             /* ldr reg, [pc, #im] */
             offset = insn & 0xfff;
             if (!(insn & 0x00800000))
-                        offset = -offset;
+                offset = -offset;
+            max_pool = 4096;
+            type = 0;
+        } else if ((insn & 0x0e5f0f00) == 0x0c1f0100) {
+            /* FPA ldf.  */
+            offset = (insn & 0xff) << 2;
+            if (!(insn & 0x00800000))
+                offset = -offset;
+            max_pool = 1024;
+            type = 1;
+        } else if ((insn & 0x0fff0000) == 0x028f0000) {
+            /* Some gcc load a doubleword immediate with
+               add regN, pc, #imm
+               ldmia regN, {regN, regM}
+               Hope and pray the compiler never generates somethin like
+               add reg, pc, #imm1; ldr reg, [reg, #-imm2]; */
+            int r;
+
+            r = (insn & 0xf00) >> 7;
+            offset = ((insn & 0xff) >> r) | ((insn & 0xff) << (32 - r));
+            max_pool = 1024;
+            type = 2;
+        } else {
+            max_pool = 0;
+            type = -1;
+        }
+        if (type >= 0) {
+            /* PC-relative load needs fixing up.  */
+            if (spare > max_pool - offset)
+                spare = max_pool - offset;
             if ((offset & 3) !=0)
-                error("%s:%04x: ldr pc offset must be 32 bit aligned", 
+                error("%s:%04x: pc offset must be 32 bit aligned", 
+                      name, start_offset + p - p_start);
+            if (offset < 0)
+                error("%s:%04x: Embedded literal value",
                       name, start_offset + p - p_start);
             pc_offset = p - p_start + offset + 8;
             if (pc_offset <= (p - p_start) || 
                 pc_offset >= (p_end - p_start))
-                error("%s:%04x: ldr pc offset must point inside the function code", 
+                error("%s:%04x: pc offset must point inside the function code", 
                       name, start_offset + p - p_start);
             if (pc_offset < min_offset)
                 min_offset = pc_offset;
             if (outfile) {
-                /* ldr position */
+                /* The intruction position */
                 fprintf(outfile, "    arm_ldr_ptr->ptr = gen_code_ptr + %d;\n", 
                         p - p_start);
-                /* ldr data index */
-                data_index = ((p_end - p_start) - pc_offset - 4) >> 2;
-                fprintf(outfile, "    arm_ldr_ptr->data_ptr = arm_data_ptr + %d;\n", 
+                /* The position of the constant pool data.  */
+                data_index = ((p_end - p_start) - pc_offset) >> 2;
+                fprintf(outfile, "    arm_ldr_ptr->data_ptr = arm_data_ptr - %d;\n", 
                         data_index);
+                fprintf(outfile, "    arm_ldr_ptr->type = %d;\n", type);
                 fprintf(outfile, "    arm_ldr_ptr++;\n");
-                if (data_index >= sizeof(data_allocated))
-                    error("%s: too many data", name);
-                if (!data_allocated[data_index]) {
-                    ELF_RELOC *rel;
-                    int i, addend, type;
-                    const char *sym_name, *p;
-                    char relname[1024];
-
-                    data_allocated[data_index] = 1;
-
-                    /* data value */
-                    addend = get32((uint32_t *)(p_start + pc_offset));
-                    relname[0] = '\0';
-                    for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) {
-                        if (rel->r_offset == (pc_offset + start_offset)) {
-                            sym_name = get_rel_sym_name(rel);
-                            /* the compiler leave some unnecessary references to the code */
-                            get_reloc_expr(relname, sizeof(relname), sym_name);
-                            type = ELF32_R_TYPE(rel->r_info);
-                            if (type != R_ARM_ABS32)
-                                error("%s: unsupported data relocation", name);
-                            break;
-                        }
-                    }
-                    fprintf(outfile, "    arm_data_ptr[%d] = 0x%x",
-                            data_index, addend);
-                    if (relname[0] != '\0')
-                        fprintf(outfile, " + %s", relname);
-                    fprintf(outfile, ";\n");
-                }
             }
         }
         p += 4;
     }
+
+    /* Copy and relocate the constant pool data.  */
     data_size = (p_end - p_start) - min_offset;
     if (data_size > 0 && outfile) {
-        fprintf(outfile, "    arm_data_ptr += %d;\n", data_size >> 2);
+        spare += min_offset;
+        fprintf(outfile, "    arm_data_ptr -= %d;\n", data_size >> 2);
+        fprintf(outfile, "    arm_pool_ptr -= %d;\n", data_size);
+        fprintf(outfile, "    if (arm_pool_ptr > gen_code_ptr + %d)\n"
+                         "        arm_pool_ptr = gen_code_ptr + %d;\n",
+                         spare, spare);
+
+        data_index = 0;
+        for (pc_offset = min_offset;
+             pc_offset < p_end - p_start;
+             pc_offset += 4) {
+
+            ELF_RELOC *rel;
+            int i, addend, type;
+            const char *sym_name;
+            char relname[1024];
+
+            /* data value */
+            addend = get32((uint32_t *)(p_start + pc_offset));
+            relname[0] = '\0';
+            for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) {
+                if (rel->r_offset == (pc_offset + start_offset)) {
+                    sym_name = get_rel_sym_name(rel);
+                    /* the compiler leave some unnecessary references to the code */
+                    get_reloc_expr(relname, sizeof(relname), sym_name);
+                    type = ELF32_R_TYPE(rel->r_info);
+                    if (type != R_ARM_ABS32)
+                        error("%s: unsupported data relocation", name);
+                    break;
+                }
+            }
+            fprintf(outfile, "    arm_data_ptr[%d] = 0x%x",
+                    data_index, addend);
+            if (relname[0] != '\0')
+                fprintf(outfile, " + %s", relname);
+            fprintf(outfile, ";\n");
+
+            data_index++;
+        }
     }
 
-    /* the last instruction must be a mov pc, lr */
+    /* the last instruction must be ldmfd fp, {..., pc}  */
     if (p == p_start)
         goto arm_ret_error;
     p -= 4;
     insn = get32((uint32_t *)p);
-    if ((insn & 0xffff0000) != 0xe91b0000) {
+    if ((insn & 0xffff8000) != 0xe91b8000) {
     arm_ret_error:
         if (!outfile)
             printf("%s: invalid epilog\n", name);
     }
-    return p - p_start;	    
+    return p - p_start;
 }
 #endif
 

@@ -2221,6 +2268,28 @@ int gen_file(FILE *outfile, int out_type
         
     } else {
         /* generate big code generation switch */
+
+#ifdef HOST_ARM
+        /* We need to know the size of all the ops so we can figure out when
+           to emit constant pools.  This must be consistent with opc.h.  */
+fprintf(outfile,
+"static const uint32_t arm_opc_size[] = {\n"
+"  0,\n" /* end */
+"  0,\n" /* nop */
+"  0,\n" /* nop1 */
+"  0,\n" /* nop2 */
+"  0,\n"); /* nop3 */
+        for(i = 0, sym = symtab; i < nb_syms; i++, sym++) {
+            const char *name;
+            name = get_sym_name(sym);
+            if (strstart(name, OP_PREFIX, NULL)) {
+                fprintf(outfile, "  %d,\n", sym->st_size);
+            }
+	}
+fprintf(outfile,
+"};\n");
+#endif
+
 fprintf(outfile,
 "int dyngen_code(uint8_t *gen_code_buf,\n"
 "                uint16_t *label_offsets, uint16_t *jmp_offsets,\n"

@@ -2231,10 +2300,36 @@ fprintf(outfile,
 "    const uint32_t *opparam_ptr;\n");
 
 #ifdef HOST_ARM
+/* Arm is tricky because it uses constant pools for loading immediate values.
+   We assume (and require) each function is code followed by a constant pool.
+   All the ops are small so this should be ok.  For each op we figure
+   out how much "spare" range we have in the load instructions.  This allows
+   us to insert subsequent ops in between the op and the constant pool,
+   eliminating the neeed to jump around the pool.
+
+   We currently generate:
+   
+   [ For this example we assume merging would move op1_pool out of range.
+     In practive we should be able to combine many ops before the offset
+     limits are reached. ]
+   op1_code;
+   op2_code;
+   goto op3;
+   op2_pool;
+   op1_pool;
+op3:
+   op3_code;
+   ret;
+   op3_pool;
+
+   Ideally we'd put op1_pool before op2_pool, but that requires two passes.
+ */
 fprintf(outfile,
 "    uint8_t *last_gen_code_ptr = gen_code_buf;\n"
 "    LDREntry *arm_ldr_ptr = arm_ldr_table;\n"
-"    uint32_t *arm_data_ptr = arm_data_table;\n");
+"    uint32_t *arm_data_ptr = arm_data_table + ARM_LDR_TABLE_SIZE;\n"
+/* Initialise the parmissible pool offset to an arbitary large value.  */
+"    uint8_t *arm_pool_ptr = gen_code_buf + 0x1000000;\n");
 #endif
 
 fprintf(outfile,

@@ -2246,9 +2341,23 @@ fprintf(outfile,
 	/* Generate prologue, if needed. */ 
 
 fprintf(outfile,
-"    for(;;) {\n"
-"        switch(*opc_ptr++) {\n"
-);
+"    for(;;) {\n");
+
+#ifdef HOST_ARM
+/* Generate constant pool if needed */
+fprintf(outfile,
+"            if (gen_code_ptr + arm_opc_size[*opc_ptr] >= arm_pool_ptr) {\n"
+"                gen_code_ptr = arm_flush_ldr(gen_code_ptr, arm_ldr_table, "
+"arm_ldr_ptr, arm_data_ptr, arm_data_table + ARM_LDR_TABLE_SIZE, 1);\n"
+"                last_gen_code_ptr = gen_code_ptr;\n"
+"                arm_ldr_ptr = arm_ldr_table;\n"
+"                arm_data_ptr = arm_data_table + ARM_LDR_TABLE_SIZE;\n"
+"                arm_pool_ptr = gen_code_ptr + 0x1000000;\n"
+"            }\n");
+#endif
+
+fprintf(outfile,
+"        switch(*opc_ptr++) {\n");
 
         for(i = 0, sym = symtab; i < nb_syms; i++, sym++) {
             const char *name;

@@ -2282,17 +2391,6 @@ fprintf(outfile,
 "            goto the_end;\n"
 "        }\n");
 
-#ifdef HOST_ARM
-/* generate constant table if needed */
-fprintf(outfile,
-"        if ((gen_code_ptr - last_gen_code_ptr) >= (MAX_FRAG_SIZE - MAX_OP_SIZE)) {\n"
-"            gen_code_ptr = arm_flush_ldr(gen_code_ptr, arm_ldr_table, arm_ldr_ptr, arm_data_table, arm_data_ptr, 1);\n"
-"            last_gen_code_ptr = gen_code_ptr;\n"
-"            arm_ldr_ptr = arm_ldr_table;\n"
-"            arm_data_ptr = arm_data_table;\n"
-"        }\n");         
-#endif
-
 
 fprintf(outfile,
 "    }\n"

@@ -2301,7 +2399,10 @@ fprintf(outfile,
 
 /* generate some code patching */ 
 #ifdef HOST_ARM
-fprintf(outfile, "gen_code_ptr = arm_flush_ldr(gen_code_ptr, arm_ldr_table, arm_ldr_ptr, arm_data_table, arm_data_ptr, 0);\n");
+fprintf(outfile,
+"if (arm_data_ptr != arm_data_table + ARM_LDR_TABLE_SIZE)\n"
+"    gen_code_ptr = arm_flush_ldr(gen_code_ptr, arm_ldr_table, "
+"arm_ldr_ptr, arm_data_ptr, arm_data_table + ARM_LDR_TABLE_SIZE, 0);\n");
 #endif
     /* flush instruction cache */
     fprintf(outfile, "flush_icache_range((unsigned long)gen_code_buf, (unsigned long)gen_code_ptr);\n");

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