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Fix absolute memory references

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This properly fixes what 870271ea tried to fix.  Absolute memory
references can't use %rip relative addressing, and additionally,
if the address doesn't fit 32bit (signed) it must be loaded via
movabs.  No good testcase added, it would require catching signals
and still be unreliable.
This commit is contained in:
Michael Matz 2017-11-15 13:39:28 +01:00
parent 74463eb954
commit 348dd9f4a6
1 changed files with 25 additions and 6 deletions
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31
x86_64-gen.c
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@ -288,12 +288,18 @@ static void gen_modrm_impl(int op_reg, int r, Sym *sym, int c, int is_got)
op_reg = REG_VALUE(op_reg) << 3; op_reg = REG_VALUE(op_reg) << 3;
if ((r & VT_VALMASK) == VT_CONST) { if ((r & VT_VALMASK) == VT_CONST) {
/* constant memory reference */ /* constant memory reference */
o(0x05 | op_reg); if (!(r & VT_SYM)) {
if (is_got) { /* Absolute memory reference */
gen_gotpcrel(r, sym, c); o(0x04 | op_reg); /* [sib] | destreg */
} else { oad(0x25, c); /* disp32 */
gen_addrpc32(r, sym, c); } else {
} o(0x05 | op_reg); /* (%rip)+disp32 | destreg */
if (is_got) {
gen_gotpcrel(r, sym, c);
} else {
gen_addrpc32(r, sym, c);
}
}
} else if ((r & VT_VALMASK) == VT_LOCAL) { } else if ((r & VT_VALMASK) == VT_LOCAL) {
/* currently, we use only ebp as base */ /* currently, we use only ebp as base */
if (c == (char)c) { if (c == (char)c) {
@ -381,6 +387,19 @@ void load(int r, SValue *sv)
fr = get_reg(RC_INT); fr = get_reg(RC_INT);
load(fr, &v1); load(fr, &v1);
} }
if (fc != sv->c.i) {
/* If the addends doesn't fit into a 32bit signed
we must use a 64bit move. We've checked above
that this doesn't have a sym associated. */
v1.type.t = VT_LLONG;
v1.r = VT_CONST;
v1.c.i = sv->c.i;
fr = r;
if (!(reg_classes[fr] & (RC_INT|RC_R11)))
fr = get_reg(RC_INT);
load(fr, &v1);
fc = 0;
}
ll = 0; ll = 0;
/* Like GCC we can load from small enough properly sized /* Like GCC we can load from small enough properly sized
structs and unions as well. structs and unions as well.