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Re: Using and clobbering hard regs in parallel
- To: rth at redhat dot com (Richard Henderson)
- Subject: Re: Using and clobbering hard regs in parallel
- From: Joern Rennecke <amylaar at redhat dot com>
- Date: Fri, 20 Jul 2001 23:53:04 +0100 (BST)
- Cc: amylaar at redhat dot com (Joern Rennecke),Stephen dot Clarke at st dot com (Stephen Clarke), gcc at gcc dot gnu dot org,geoffk at geoffk dot org
> ! This does not necessarily mean that the register @var{op} has no useful
> ! value after this insn since it may also be an output of the insn. In
> ! such a case, however, a @code{REG_DEAD} note would be redundant and is
> ! usually not present until after the reload pass, but no code relies on
> ! this fact.
>
> @findex REG_INC
> @item REG_INC
> --- 2798,2814 ----
> value immediately after this insn would not affect the future behavior
> of the program.
>
> ! It does not follow that the register @var{op} has no useful value after
> ! this insn since @var{op} is not necessarily modified by this insn.
The first half of this sentence is true, but the reason stated is wrong.
It is because @var{op} might be modified that it might contain a useful
value. The original version had this right.