On Wed, 5 Dec 2001, John Baldwin wrote:
Review of what I can see and quote easily.
> The patch is at http://www.FreeBSD.org/~jhb/patches/i386_asm.patch. Mostly it
> does the following:
This URL appears to be well formed ;-).
> - Add missing "cc" clobbers in constraints
Does this have any effect (for i386's) except to create a lot of clutter
Even i386.md doesn't use it. gcc.info says:
! If your assembler instruction can alter the condition code register,
! add `cc' to the list of clobbered registers. GNU CC on some machines
! represents the condition codes as a specific hardware register; `cc'
! serves to name this register. On other machines, the condition code is
! handled differently, and specifying `cc' has no effect. But it is
! valid no matter what the machine.
! Here we will concern ourselves with determining the effect of an
! insn on the condition code and will limit ourselves to the following
! possible effects: The condition code can be set unpredictably
! (clobbered), not be changed, be set to agree with the results of the
! operation, or only changed if the item previously set into the
! condition code has been modified.
! Here is part of a sample `md' file for such a machine:
! (define_attr "type" "load,store,arith,fp,branch" (const_string "arith"))
! (define_attr "cc" "clobber,unchanged,set,change0"
None of i386.md, alpha.md or sparc.md do this. i386's and alphas have a
cc0 register, but it is only mentioned for instructsions whose main (only?)
effect is to to set the condition codes.
> - Use the "+" modifier for output operands rather than using "0", "1", etc.
> to list operands in both input and output sections.
> - Fix the atomic operations to accept the contraints type on v so we can use
> "iq" rather than "ir" for char operations (this last came from Peter Jeremy
> and bde).
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