diff options
Diffstat (limited to 'gcc/cse.c')
| -rw-r--r-- | gcc/cse.c | 16 |
1 files changed, 11 insertions, 5 deletions
@@ -4212,7 +4212,7 @@ fold_rtx (x, insn) from_plus: case SMIN: case SMAX: case UMIN: case UMAX: case IOR: case AND: case XOR: - case MULT: case DIV: case UDIV: + case MULT: case ASHIFT: case LSHIFTRT: case ASHIFTRT: /* If we have (<op> <reg> <const_int>) for an associative OP and REG is known to be of similar form, we may be able to replace the @@ -4260,11 +4260,9 @@ fold_rtx (x, insn) break; /* Compute the code used to compose the constants. For example, - A/C1/C2 is A/(C1 * C2), so if CODE == DIV, we want MULT. */ + A-C1-C2 is A-(C1 + C2), so if CODE == MINUS, we want PLUS. */ - associate_code - = (code == MULT || code == DIV || code == UDIV ? MULT - : is_shift || code == PLUS || code == MINUS ? PLUS : code); + associate_code = (is_shift || code == MINUS ? PLUS : code); new_const = simplify_binary_operation (associate_code, mode, const_arg1, inner_const); @@ -4302,6 +4300,14 @@ fold_rtx (x, insn) } break; + case DIV: case UDIV: + /* ??? The associative optimization performed immediately above is + also possible for DIV and UDIV using associate_code of MULT. + However, we would need extra code to verify that the + multiplication does not overflow, that is, there is no overflow + in the calculation of new_const. */ + break; + default: break; } |