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tcg/riscv: Add the relocation functions

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Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <6ac4f4b0d5ea93cb0ee9a3b8b47ee9f7b3711494.1545246859.git.alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Alistair Francis 2018-12-19 19:18:06 +00:00 committed by Richard Henderson
parent bedf14e335
commit dfa8e74f94
1 changed files with 88 additions and 0 deletions
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88
tcg/riscv/tcg-target.inc.c
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@ -422,3 +422,91 @@ static void tcg_out_nop_fill(tcg_insn_unit *p, int count)
p[i] = encode_i(OPC_ADDI, TCG_REG_ZERO, TCG_REG_ZERO, 0);
}
}
/*
* Relocations
*/
static bool reloc_sbimm12(tcg_insn_unit *code_ptr, tcg_insn_unit *target)
{
intptr_t offset = (intptr_t)target - (intptr_t)code_ptr;
if (offset == sextreg(offset, 1, 12) << 1) {
code_ptr[0] |= encode_sbimm12(offset);
return true;
}
return false;
}
static bool reloc_jimm20(tcg_insn_unit *code_ptr, tcg_insn_unit *target)
{
intptr_t offset = (intptr_t)target - (intptr_t)code_ptr;
if (offset == sextreg(offset, 1, 20) << 1) {
code_ptr[0] |= encode_ujimm20(offset);
return true;
}
return false;
}
static bool reloc_call(tcg_insn_unit *code_ptr, tcg_insn_unit *target)
{
intptr_t offset = (intptr_t)target - (intptr_t)code_ptr;
int32_t lo = sextreg(offset, 0, 12);
int32_t hi = offset - lo;
if (offset == hi + lo) {
code_ptr[0] |= encode_uimm20(hi);
code_ptr[1] |= encode_imm12(lo);
return true;
}
return false;
}
static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
intptr_t value, intptr_t addend)
{
uint32_t insn = *code_ptr;
intptr_t diff;
bool short_jmp;
tcg_debug_assert(addend == 0);
switch (type) {
case R_RISCV_BRANCH:
diff = value - (uintptr_t)code_ptr;
short_jmp = diff == sextreg(diff, 0, 12);
if (short_jmp) {
return reloc_sbimm12(code_ptr, (tcg_insn_unit *)value);
} else {
/* Invert the condition */
insn = insn ^ (1 << 12);
/* Clear the offset */
insn &= 0x01fff07f;
/* Set the offset to the PC + 8 */
insn |= encode_sbimm12(8);
/* Move forward */
code_ptr[0] = insn;
/* Overwrite the NOP with jal x0,value */
diff = value - (uintptr_t)(code_ptr + 1);
insn = encode_uj(OPC_JAL, TCG_REG_ZERO, diff);
code_ptr[1] = insn;
return true;
}
break;
case R_RISCV_JAL:
return reloc_jimm20(code_ptr, (tcg_insn_unit *)value);
break;
case R_RISCV_CALL:
return reloc_call(code_ptr, (tcg_insn_unit *)value);
break;
default:
tcg_abort();
}
}