- if (target_read_memory (pc, buf, sizeof buf)
- || (memcmp (buf, insns_ecx, sizeof buf) != 0
- && memcmp (buf, insns_edx, sizeof buf) != 0
- && memcmp (buf, insns_eax, sizeof buf) != 0))
+ if (target_read_memory (pc, buf, sizeof buf))
+ return pc;
+
+ /* Check caller-saved saved register. The first instruction has
+ to be "leal 4(%esp), %reg". */
+ if (buf[0] == 0x8d && buf[2] == 0x24 && buf[3] == 0x4)
+ {
+ /* MOD must be binary 10 and R/M must be binary 100. */
+ if ((buf[1] & 0xc7) != 0x44)
+ return pc;
+
+ /* REG has register number. */
+ reg = (buf[1] >> 3) & 7;
+ offset = 4;
+ }
+ else
+ {
+ /* Check callee-saved saved register. The first instruction
+ has to be "pushl %reg". */
+ if ((buf[0] & 0xf8) != 0x50)
+ return pc;
+
+ /* Get register. */
+ reg = buf[0] & 0x7;
+
+ /* The next instruction has to be "leal 8(%esp), %reg". */
+ if (buf[1] != 0x8d || buf[3] != 0x24 || buf[4] != 0x8)
+ return pc;
+
+ /* MOD must be binary 10 and R/M must be binary 100. */
+ if ((buf[2] & 0xc7) != 0x44)
+ return pc;
+
+ /* REG has register number. Registers in pushl and leal have to
+ be the same. */
+ if (reg != ((buf[2] >> 3) & 7))
+ return pc;
+
+ offset = 5;
+ }
+
+ /* Rigister can't be %esp nor %ebp. */
+ if (reg == 4 || reg == 5)
+ return pc;
+
+ /* The next instruction has to be "andl $-XXX, %esp". */
+ if (buf[offset + 1] != 0xe4
+ || (buf[offset] != 0x81 && buf[offset] != 0x83))
+ return pc;
+
+ offset_and = offset;
+ offset += buf[offset] == 0x81 ? 6 : 3;
+
+ /* The next instruction has to be "pushl -4(%reg)". 8bit -4 is
+ 0xfc. REG must be binary 110 and MOD must be binary 01. */
+ if (buf[offset] != 0xff
+ || buf[offset + 2] != 0xfc
+ || (buf[offset + 1] & 0xf8) != 0x70)
+ return pc;
+
+ /* R/M has register. Registers in leal and pushl have to be the
+ same. */
+ if (reg != (buf[offset + 1] & 7))