Re: [PATCH] or1k: Fix issue with set_got clobbering r9

[Stafford Horne <shorne@gmail.com>]

On Fri, Aug 30, 2019 at 08:21:56AM -0700, Richard Henderson wrote:
> LGTM.

Thank you.
 
> On 8/30/19 2:31 AM, Stafford Horne wrote:
> > Hello, any comments on this?
> > 
> > If nothing I will commit in a few days.
> > 
> > On Thu, Aug 22, 2019 at 08:44:04PM +0900, Stafford Horne wrote:
> >> When compiling glibc we found that the GOT register was being allocated
> >> r9 when the instruction was still set_got_tmp.  That caused set_got to
> >> clobber r9.  We cannot simply say set_got_tmp clobbers r9 as this is the
> >> reason for having the temporary set_got_tmp.
> >>
> >> Fix by using a register class constraint that does not allow r9 during
> >> register allocation.
> >>
> >> gcc/ChangeLog:
> >>
> >> 	* config/or1k/constraints.md (t): New constraint.
> >> 	* config/or1k/or1k.h (GOT_REGS): New register class.
> >> 	* config/or1k/or1k.md (set_got_tmp, set_got): Use t contraint.
> >> ---
> >>  gcc/config/or1k/constraints.md | 4 ++++
> >>  gcc/config/or1k/or1k.h         | 3 +++
> >>  gcc/config/or1k/or1k.md        | 4 ++--
> >>  3 files changed, 9 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/gcc/config/or1k/constraints.md b/gcc/config/or1k/constraints.md
> >> index 8cac7eb5329..ba330c6b8c2 100644
> >> --- a/gcc/config/or1k/constraints.md
> >> +++ b/gcc/config/or1k/constraints.md
> >> @@ -25,6 +25,7 @@
> >>  ; We use:
> >>  ;  c - sibcall registers
> >>  ;  d - double pair base registers (excludes r0, r30 and r31 which overflow)
> >> +;  t - got address registers (excludes r9 is clobbered by set_got)
> > 
> > I will changee this to (... r9 which is clobbered ...)
> > 
> >>  ;  I - constant signed 16-bit
> >>  ;  K - constant unsigned 16-bit
> >>  ;  M - constant signed 16-bit shifted left 16-bits (l.movhi)
> >> @@ -36,6 +37,9 @@
> >>  (define_register_constraint "d" "DOUBLE_REGS"
> >>    "Registers which can be used for double reg pairs.")
> >>  
> >> +(define_register_constraint "t" "GOT_REGS"
> >> +  "Registers which can be used to store the Global Offset Table (GOT) address.")
> >> +
> >>  ;; Immediates
> >>  (define_constraint "I"
> >>    "A signed 16-bit immediate in the range -32768 to 32767."
> >> diff --git a/gcc/config/or1k/or1k.h b/gcc/config/or1k/or1k.h
> >> index 2b29e62fdd3..4c32607bac1 100644
> >> --- a/gcc/config/or1k/or1k.h
> >> +++ b/gcc/config/or1k/or1k.h
> >> @@ -190,6 +190,7 @@ enum reg_class
> >>    NO_REGS,
> >>    SIBCALL_REGS,
> >>    DOUBLE_REGS,
> >> +  GOT_REGS,
> >>    GENERAL_REGS,
> >>    FLAG_REGS,
> >>    ALL_REGS,
> >> @@ -202,6 +203,7 @@ enum reg_class
> >>    "NO_REGS", 			\
> >>    "SIBCALL_REGS",		\
> >>    "DOUBLE_REGS",		\
> >> +  "GOT_REGS",			\
> >>    "GENERAL_REGS",		\
> >>    "FLAG_REGS",			\
> >>    "ALL_REGS" }
> >> @@ -215,6 +217,7 @@ enum reg_class
> >>  { { 0x00000000, 0x00000000 },	\
> >>    { SIBCALL_REGS_MASK,   0 },	\
> >>    { 0x7f7ffffe, 0x00000000 },	\
> >> +  { 0xfffffdff, 0x00000000 },	\
> >>    { 0xffffffff, 0x00000003 },	\
> >>    { 0x00000000, 0x00000004 },	\
> >>    { 0xffffffff, 0x00000007 }	\
> >> diff --git a/gcc/config/or1k/or1k.md b/gcc/config/or1k/or1k.md
> >> index cee11d078cc..36bcee336ab 100644
> >> --- a/gcc/config/or1k/or1k.md
> >> +++ b/gcc/config/or1k/or1k.md
> >> @@ -706,7 +706,7 @@
> >>  ;; set_got pattern below.  This works because the set_got_tmp insn is the
> >>  ;; first insn in the stream and that it isn't moved during RA.
> >>  (define_insn "set_got_tmp"
> >> -  [(set (match_operand:SI 0 "register_operand" "=r")
> >> +  [(set (match_operand:SI 0 "register_operand" "=t")
> >>  	(unspec_volatile:SI [(const_int 0)] UNSPECV_SET_GOT))]
> >>    ""
> >>  {
> >> @@ -715,7 +715,7 @@
> >>  
> >>  ;; The insn to initialize the GOT.
> >>  (define_insn "set_got"
> >> -  [(set (match_operand:SI 0 "register_operand" "=r")
> >> +  [(set (match_operand:SI 0 "register_operand" "=t")
> >>  	(unspec:SI [(const_int 0)] UNSPEC_SET_GOT))
> >>     (clobber (reg:SI LR_REGNUM))]
> >>    ""
> >> -- 
> >> 2.21.0
> >>
>