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


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
> 


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