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tccgen.c: Avoid undefined behaviour in constant propagation.

master
Edmund Grimley Evans 2015-11-17 19:34:31 +00:00
parent 569fba6db9
commit 5d496b1695
1 changed files with 38 additions and 31 deletions
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69
tccgen.c
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@ -1394,33 +1394,38 @@ static void gen_opl(int op)
}
#endif
static uint64_t gen_opic_sdiv(uint64_t a, uint64_t b)
{
uint64_t x = (a >> 63 ? -a : a) / (b >> 63 ? -b : b);
return (a ^ b) >> 63 ? -x : x;
}
static int gen_opic_lt(uint64_t a, uint64_t b)
{
return (a ^ (uint64_t)1 << 63) < (b ^ (uint64_t)1 << 63);
}
/* handle integer constant optimizations and various machine
independent opt */
static void gen_opic(int op)
{
int c1, c2, t1, t2, n;
SValue *v1, *v2;
long long l1, l2;
typedef unsigned long long U;
SValue *v1 = vtop - 1;
SValue *v2 = vtop;
int t1 = v1->type.t & VT_BTYPE;
int t2 = v2->type.t & VT_BTYPE;
int c1 = (v1->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST;
int c2 = (v2->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST;
uint64_t l1 = c1 ? v1->c.i : 0;
uint64_t l2 = c2 ? v2->c.i : 0;
int shm = (t1 == VT_LLONG) ? 63 : 31;
v1 = vtop - 1;
v2 = vtop;
t1 = v1->type.t & VT_BTYPE;
t2 = v2->type.t & VT_BTYPE;
l1 = v1->c.i;
if (t1 != VT_LLONG)
l1 = ((uint32_t)l1 |
(v1->type.t & VT_UNSIGNED ? 0 : -(l1 & 0x80000000)));
l2 = v2->c.i;
if (t2 != VT_LLONG)
l2 = ((uint32_t)l2 |
(v2->type.t & VT_UNSIGNED ? 0 : -(l2 & 0x80000000)));
/* currently, we cannot do computations with forward symbols */
c1 = (v1->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST;
c2 = (v2->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST;
if (c1 && c2) {
switch(op) {
case '+': l1 += l2; break;
@ -1442,26 +1447,28 @@ static void gen_opic(int op)
goto general_case;
}
switch(op) {
default: l1 /= l2; break;
case '%': l1 %= l2; break;
case TOK_UDIV: l1 = (U)l1 / l2; break;
case TOK_UMOD: l1 = (U)l1 % l2; break;
default: l1 = gen_opic_sdiv(l1, l2); break;
case '%': l1 = l1 - l2 * gen_opic_sdiv(l1, l2); break;
case TOK_UDIV: l1 = l1 / l2; break;
case TOK_UMOD: l1 = l1 % l2; break;
}
break;
case TOK_SHL: l1 <<= l2; break;
case TOK_SHR: l1 = (U)l1 >> l2; break;
case TOK_SAR: l1 >>= l2; break;
case TOK_SHL: l1 <<= (l2 & shm); break;
case TOK_SHR: l1 >>= (l2 & shm); break;
case TOK_SAR:
l1 = (l1 >> 63) ? ~(~l1 >> (l2 & shm)) : l1 >> (l2 & shm);
break;
/* tests */
case TOK_ULT: l1 = (U)l1 < (U)l2; break;
case TOK_UGE: l1 = (U)l1 >= (U)l2; break;
case TOK_ULT: l1 = l1 < l2; break;
case TOK_UGE: l1 = l1 >= l2; break;
case TOK_EQ: l1 = l1 == l2; break;
case TOK_NE: l1 = l1 != l2; break;
case TOK_ULE: l1 = (U)l1 <= (U)l2; break;
case TOK_UGT: l1 = (U)l1 > (U)l2; break;
case TOK_LT: l1 = l1 < l2; break;
case TOK_GE: l1 = l1 >= l2; break;
case TOK_LE: l1 = l1 <= l2; break;
case TOK_GT: l1 = l1 > l2; break;
case TOK_ULE: l1 = l1 <= l2; break;
case TOK_UGT: l1 = l1 > l2; break;
case TOK_LT: l1 = gen_opic_lt(l1, l2); break;
case TOK_GE: l1 = !gen_opic_lt(l1, l2); break;
case TOK_LE: l1 = !gen_opic_lt(l2, l1); break;
case TOK_GT: l1 = gen_opic_lt(l2, l1); break;
/* logical */
case TOK_LAND: l1 = l1 && l2; break;
case TOK_LOR: l1 = l1 || l2; break;
@ -1507,7 +1514,7 @@ static void gen_opic(int op)
} else if (c2 && (op == '*' || op == TOK_PDIV || op == TOK_UDIV)) {
/* try to use shifts instead of muls or divs */
if (l2 > 0 && (l2 & (l2 - 1)) == 0) {
n = -1;
int n = -1;
while (l2) {
l2 >>= 1;
n++;