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tcg: Mask shift quantities while folding 

The TCG result would be undefined, but we can at least produce one
plausible result and avoid triggering the wrath of analysis tools.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2014-03-18 07:45:39 -07:00
parent 20022fa15f
commit 50c5c4d125
1 changed files with 20 additions and 15 deletions
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35
tcg/optimize.c
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@ -220,34 +220,34 @@ static TCGArg do_constant_folding_2(TCGOpcode op, TCGArg x, TCGArg y)
return x ^ y;
case INDEX_op_shl_i32:
return (uint32_t)x << (uint32_t)y;
return (uint32_t)x << (y & 31);
case INDEX_op_shl_i64:
return (uint64_t)x << (uint64_t)y;
return (uint64_t)x << (y & 63);
case INDEX_op_shr_i32:
return (uint32_t)x >> (uint32_t)y;
return (uint32_t)x >> (y & 31);
case INDEX_op_shr_i64:
return (uint64_t)x >> (uint64_t)y;
return (uint64_t)x >> (y & 63);
case INDEX_op_sar_i32:
return (int32_t)x >> (int32_t)y;
return (int32_t)x >> (y & 31);
case INDEX_op_sar_i64:
return (int64_t)x >> (int64_t)y;
return (int64_t)x >> (y & 63);
case INDEX_op_rotr_i32:
return ror32(x, y);
return ror32(x, y & 31);
case INDEX_op_rotr_i64:
return ror64(x, y);
return ror64(x, y & 63);
case INDEX_op_rotl_i32:
return rol32(x, y);
return rol32(x, y & 31);
case INDEX_op_rotl_i64:
return rol64(x, y);
return rol64(x, y & 63);
CASE_OP_32_64(not):
return ~x;
@ -806,29 +806,34 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
case INDEX_op_sar_i32:
if (temps[args[2]].state == TCG_TEMP_CONST) {
mask = (int32_t)temps[args[1]].mask >> temps[args[2]].val;
tmp = temps[args[2]].val & 31;
mask = (int32_t)temps[args[1]].mask >> tmp;
}
break;
case INDEX_op_sar_i64:
if (temps[args[2]].state == TCG_TEMP_CONST) {
mask = (int64_t)temps[args[1]].mask >> temps[args[2]].val;
tmp = temps[args[2]].val & 63;
mask = (int64_t)temps[args[1]].mask >> tmp;
}
break;
case INDEX_op_shr_i32:
if (temps[args[2]].state == TCG_TEMP_CONST) {
mask = (uint32_t)temps[args[1]].mask >> temps[args[2]].val;
tmp = temps[args[2]].val & 31;
mask = (uint32_t)temps[args[1]].mask >> tmp;
}
break;
case INDEX_op_shr_i64:
if (temps[args[2]].state == TCG_TEMP_CONST) {
mask = (uint64_t)temps[args[1]].mask >> temps[args[2]].val;
tmp = temps[args[2]].val & 63;
mask = (uint64_t)temps[args[1]].mask >> tmp;
}
break;
CASE_OP_32_64(shl):
if (temps[args[2]].state == TCG_TEMP_CONST) {
mask = temps[args[1]].mask << temps[args[2]].val;
tmp = temps[args[2]].val & (TCG_TARGET_REG_BITS - 1);
mask = temps[args[1]].mask << tmp;
}
break;