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Optimize reading a single byte/short/word. (#390) 

gdb has developed a nasty habit of very often reading 30-some
half-words. This change speeds that up significantly.

Change-Id: Iab1b7575bec5c57051c6e630ae292dddf8fe6350
debug-log-reg-failure
Tim Newsome 2019-07-15 10:34:40 -07:00 committed by GitHub
parent 9b34f8ca3c
commit 09016bcb6e
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 61 additions and 4 deletions
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65
src/target/riscv/riscv-013.c
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@ -2456,6 +2456,59 @@ error:
return result;
}
/* Only need to save/restore one GPR to read a single word, and the progbuf
* program doesn't need to increment. */
static int read_memory_progbuf_one(struct target *target, target_addr_t address,
uint32_t size, uint8_t *buffer)
{
uint64_t s0;
if (register_read(target, &s0, GDB_REGNO_S0) != ERROR_OK)
return ERROR_FAIL;
/* Write the program (load, increment) */
struct riscv_program program;
riscv_program_init(&program, target);
switch (size) {
case 1:
riscv_program_lbr(&program, GDB_REGNO_S0, GDB_REGNO_S0, 0);
break;
case 2:
riscv_program_lhr(&program, GDB_REGNO_S0, GDB_REGNO_S0, 0);
break;
case 4:
riscv_program_lwr(&program, GDB_REGNO_S0, GDB_REGNO_S0, 0);
break;
default:
LOG_ERROR("Unsupported size: %d", size);
return ERROR_FAIL;
}
if (riscv_program_ebreak(&program) != ERROR_OK)
return ERROR_FAIL;
if (riscv_program_write(&program) != ERROR_OK)
return ERROR_FAIL;
/* Write address to S0, and execute buffer. */
if (write_abstract_arg(target, 0, address, riscv_xlen(target)) != ERROR_OK)
return ERROR_FAIL;
uint32_t command = access_register_command(target, GDB_REGNO_S0,
riscv_xlen(target), AC_ACCESS_REGISTER_WRITE |
AC_ACCESS_REGISTER_TRANSFER | AC_ACCESS_REGISTER_POSTEXEC);
if (execute_abstract_command(target, command) != ERROR_OK)
return ERROR_FAIL;
uint64_t value;
if (register_read(target, &value, GDB_REGNO_S0) != ERROR_OK)
return ERROR_FAIL;
write_to_buf(buffer, value, size);
if (riscv_set_register(target, GDB_REGNO_S0, s0) != ERROR_OK)
return ERROR_FAIL;
return ERROR_OK;
}
/**
* Read the requested memory, silently handling memory access errors.
*/
@ -2471,6 +2524,12 @@ static int read_memory_progbuf(struct target *target, target_addr_t address,
memset(buffer, 0, count*size);
if (execute_fence(target) != ERROR_OK)
return ERROR_FAIL;
if (count == 1)
return read_memory_progbuf_one(target, address, size, buffer);
/* s0 holds the next address to write to
* s1 holds the next data value to write
*/
@ -2480,9 +2539,6 @@ static int read_memory_progbuf(struct target *target, target_addr_t address,
if (register_read(target, &s1, GDB_REGNO_S1) != ERROR_OK)
return ERROR_FAIL;
if (execute_fence(target) != ERROR_OK)
return ERROR_FAIL;
/* Write the program (load, increment) */
struct riscv_program program;
riscv_program_init(&program, target);
@ -2504,7 +2560,8 @@ static int read_memory_progbuf(struct target *target, target_addr_t address,
if (riscv_program_ebreak(&program) != ERROR_OK)
return ERROR_FAIL;
riscv_program_write(&program);
if (riscv_program_write(&program) != ERROR_OK)
return ERROR_FAIL;
result = read_memory_progbuf_inner(target, address, size, count, buffer);