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-rw-r--r--gcc/flow.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/gcc/flow.c b/gcc/flow.c
index ff1d861dbe5..9eae74b4ad0 100644
--- a/gcc/flow.c
+++ b/gcc/flow.c
@@ -1692,8 +1692,12 @@ propagate_one_insn (struct propagate_block_info *pbi, rtx insn)
fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
/* Record sets. Do this even for dead instructions, since they
- would have killed the values if they hadn't been deleted. */
+ would have killed the values if they hadn't been deleted. To
+ be consistent, we also have to emit a clobber when we delete
+ an insn that clobbers a live register. */
+ pbi->flags |= PROP_DEAD_INSN;
mark_set_regs (pbi, PATTERN (insn), insn);
+ pbi->flags &= ~PROP_DEAD_INSN;
/* CC0 is now known to be dead. Either this insn used it,
in which case it doesn't anymore, or clobbered it,
@@ -2960,6 +2964,8 @@ mark_set_1 (struct propagate_block_info *pbi, enum rtx_code code, rtx reg, rtx c
}
CLEAR_REGNO_REG_SET (pbi->reg_live, i);
}
+ if (flags & PROP_DEAD_INSN)
+ emit_insn_after (gen_rtx_CLOBBER (VOIDmode, reg), insn);
}
}
else if (REG_P (reg))