diff options
Diffstat (limited to 'gcc/gcse.c')
| -rw-r--r-- | gcc/gcse.c | 35 |
1 files changed, 34 insertions, 1 deletions
@@ -150,6 +150,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA #include "toplev.h" #include "rtl.h" +#include "tree.h" #include "tm_p.h" #include "regs.h" #include "hard-reg-set.h" @@ -4559,6 +4560,38 @@ fis_get_condition (rtx jump) return tmp; } +/* Check the comparison COND to see if we can safely form an implicit set from + it. COND is either an EQ or NE comparison. */ + +static bool +implicit_set_cond_p (rtx cond) +{ + enum machine_mode mode = GET_MODE (XEXP (cond, 0)); + rtx cst = XEXP (cond, 1); + + /* We can't perform this optimization if either operand might be or might + contain a signed zero. */ + if (HONOR_SIGNED_ZEROS (mode)) + { + /* It is sufficient to check if CST is or contains a zero. We must + handle float, complex, and vector. If any subpart is a zero, then + the optimization can't be performed. */ + /* ??? The complex and vector checks are not implemented yet. We just + always return zero for them. */ + if (GET_CODE (cst) == CONST_DOUBLE) + { + REAL_VALUE_TYPE d; + REAL_VALUE_FROM_CONST_DOUBLE (d, cst); + if (REAL_VALUES_EQUAL (d, dconst0)) + return 0; + } + else + return 0; + } + + return gcse_constant_p (cst); +} + /* Find the implicit sets of a function. An "implicit set" is a constraint on the value of a variable, implied by a conditional jump. For example, following "if (x == 2)", the then branch may be optimized as though the @@ -4584,7 +4617,7 @@ find_implicit_sets (void) && (GET_CODE (cond) == EQ || GET_CODE (cond) == NE) && GET_CODE (XEXP (cond, 0)) == REG && REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER - && gcse_constant_p (XEXP (cond, 1))) + && implicit_set_cond_p (cond)) { dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest : FALLTHRU_EDGE (bb)->dest; |