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tcg/ppc: Allow the constant pool to overflow at 32k 

There is no point in coding for a 2GB offset when the max TB size
is already limited to 64k.  If we further restrict to 32k then we
can eliminate the extra ADDIS instruction.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2019-04-22 17:12:33 +00:00
parent aeee05f53a
commit a7cdaf710f
1 changed files with 10 additions and 18 deletions
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28
tcg/ppc/tcg-target.inc.c
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@ -529,7 +529,6 @@ static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
intptr_t value, intptr_t addend)
{
tcg_insn_unit *target;
tcg_insn_unit old;
value += addend;
target = (tcg_insn_unit *)value;
@ -540,22 +539,16 @@ static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
case R_PPC_REL24:
return reloc_pc24(code_ptr, target);
case R_PPC_ADDR16:
/* We are abusing this relocation type. This points to a pair
of insns, addis + load. If the displacement is small, we
can nop out the addis. */
if (value == (int16_t)value) {
code_ptr[0] = NOP;
old = deposit32(code_ptr[1], 0, 16, value);
code_ptr[1] = deposit32(old, 16, 5, TCG_REG_TB);
} else {
int16_t lo = value;
int hi = value - lo;
if (hi + lo != value) {
return false;
}
code_ptr[0] = deposit32(code_ptr[0], 0, 16, hi >> 16);
code_ptr[1] = deposit32(code_ptr[1], 0, 16, lo);
/*
* We are (slightly) abusing this relocation type. In particular,
* assert that the low 2 bits are zero, and do not modify them.
* That way we can use this with LD et al that have opcode bits
* in the low 2 bits of the insn.
*/
if ((value & 3) || value != (int16_t)value) {
return false;
}
*code_ptr = (*code_ptr & ~0xfffc) | (value & 0xfffc);
break;
default:
g_assert_not_reached();
@ -701,8 +694,7 @@ static void tcg_out_movi_int(TCGContext *s, TCGType type, TCGReg ret,
if (!in_prologue && USE_REG_TB) {
new_pool_label(s, arg, R_PPC_ADDR16, s->code_ptr,
-(intptr_t)s->code_gen_ptr);
tcg_out32(s, ADDIS | TAI(ret, TCG_REG_TB, 0));
tcg_out32(s, LD | TAI(ret, ret, 0));
tcg_out32(s, LD | TAI(ret, TCG_REG_TB, 0));
return;
}