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Re: [PATCH, rs6000] PR71800, use correct constraint for stxsiwx
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Pat Haugen <pthaugen at linux dot vnet dot ibm dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, David Edelsohn <dje dot gcc at gmail dot com>
- Date: Fri, 8 Jul 2016 00:43:35 -0500
- Subject: Re: [PATCH, rs6000] PR71800, use correct constraint for stxsiwx
- Authentication-results: sourceware.org; auth=none
- References: <577EBECF.email@example.com>
On Thu, Jul 07, 2016 at 03:42:55PM -0500, Pat Haugen wrote:
> The following patch corrects the constraint so that we only generate 'stxsiwx' on Power8 or later hardware. Ok for trunk after successful bootstrap/regtest?
I don't really understand this. Before, it required UPPER_REGS_DF (which
seems correct), and now it requires UPPER_REGS_SF, which seems wrong.
Could you explain a bit more please?
> 2016-07-07 Pat Haugen <firstname.lastname@example.org>
> PR target/71800
> * config/rs6000/rs6000.md (stfiwx): Change constraint to 'wu' to
> prevent generation of 'stxsiwx' on pre Power8 hardware.
> Index: config/rs6000/rs6000.md
> --- config/rs6000/rs6000.md (revision 238117)
> +++ config/rs6000/rs6000.md (working copy)
> @@ -5748,7 +5748,7 @@ (define_expand "lround<mode>di2"
> ; An UNSPEC is used so we don't have to support SImode in FP registers.
> (define_insn "stfiwx"
> [(set (match_operand:SI 0 "memory_operand" "=Z,Z")
> - (unspec:SI [(match_operand:DI 1 "gpc_reg_operand" "d,wv")]
> + (unspec:SI [(match_operand:DI 1 "gpc_reg_operand" "d,wu")]