[IRA]: Fix implicit preference calculation.

When searching prefered hard regs from too strict constraints we can ignore
some alternatives for subsequent operands.  This can result in worse code
generation.  The patch fixes this.

gcc/ChangeLog:

	* ira-lives.cc (ira_implicitly_set_insn_hard_regs): Use the same
	start prefered for all operand.

diff --git a/gcc/ira-lives.cc b/gcc/ira-lives.cc
index 04e586343c82220685d8b5b80a29f926ac9d659f..a6b3eff1ab86681abc0f158eb8a14a2d6b710b50 100644 (file)
--- a/gcc/ira-lives.cc
+++ b/gcc/ira-lives.cc
@@ -956,12 +956,14 @@ ira_implicitly_set_insn_hard_regs (HARD_REG_SET *set,
          mode = (GET_CODE (op) == SCRATCH
                  ? GET_MODE (op) : PSEUDO_REGNO_MODE (regno));
          cl = NO_REGS;
-         for (; (c = *p); p += CONSTRAINT_LEN (c, p))
+         for (alternative_mask curr_preferred = preferred;
+              (c = *p);
+              p += CONSTRAINT_LEN (c, p))
            if (c == '#')
-             preferred &= ~ALTERNATIVE_BIT (0);
+             curr_preferred &= ~ALTERNATIVE_BIT (0);
            else if (c == ',')
-             preferred >>= 1;
-           else if (preferred & 1)
+             curr_preferred >>= 1;
+           else if (curr_preferred & 1)
              {
                cl = reg_class_for_constraint (lookup_constraint (p));
                if (cl != NO_REGS)