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| author | Xavier Leroy <xavier.leroy@college-de-france.fr> | 2019-07-10 15:43:03 +0200 |
|---|---|---|
| committer | Xavier Leroy <xavierleroy@users.noreply.github.com> | 2019-07-17 09:26:44 +0200 |
| commit | 822a6a12316aa043eea7f6aed4d730bc10a73d7b (patch) | |
| tree | bfeee08920725b1e871cc5902c4d71e862318292 /x86/SelectOp.vp | |
| parent | 7cd0af8ba5d737fa9c45bb9fa454b38e9704097a (diff) | |
| download | compcert-822a6a12316aa043eea7f6aed4d730bc10a73d7b.tar.gz compcert-822a6a12316aa043eea7f6aed4d730bc10a73d7b.zip | |
x86_64: branchless implementation of floatofintu and intuoffloat
The implementation uses float <-> signed 64-bit integer conversion
instructions, and is both efficient and branchless.
Based on a suggestion by Rémi Hutin.
Diffstat (limited to 'x86/SelectOp.vp')
| -rw-r--r-- | x86/SelectOp.vp | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/x86/SelectOp.vp b/x86/SelectOp.vp index 378590ce..31be8c32 100644 --- a/x86/SelectOp.vp +++ b/x86/SelectOp.vp @@ -40,6 +40,7 @@ Require Import Coqlib. Require Import Compopts. Require Import AST Integers Floats Builtins. Require Import Op CminorSel. +Require Archi. Local Open Scope cminorsel_scope. @@ -498,21 +499,27 @@ Nondetfunction floatofint (e: expr) := end. Definition intuoffloat (e: expr) := - Elet e - (Elet (Eop (Ofloatconst (Float.of_intu Float.ox8000_0000)) Enil) - (Econdition (CEcond (Ccompf Clt) (Eletvar 1 ::: Eletvar 0 ::: Enil)) - (intoffloat (Eletvar 1)) - (addimm Float.ox8000_0000 (intoffloat (subf (Eletvar 1) (Eletvar 0))))))%nat. + if Archi.splitlong then + Elet e + (Elet (Eop (Ofloatconst (Float.of_intu Float.ox8000_0000)) Enil) + (Econdition (CEcond (Ccompf Clt) (Eletvar 1 ::: Eletvar 0 ::: Enil)) + (intoffloat (Eletvar 1)) + (addimm Float.ox8000_0000 (intoffloat (subf (Eletvar 1) (Eletvar 0))))))%nat + else + Eop Olowlong (Eop Olongoffloat (e ::: Enil) ::: Enil). Nondetfunction floatofintu (e: expr) := match e with | Eop (Ointconst n) Enil => Eop (Ofloatconst (Float.of_intu n)) Enil | _ => - let f := Eop (Ofloatconst (Float.of_intu Float.ox8000_0000)) Enil in - Elet e - (Econdition (CEcond (Ccompuimm Clt Float.ox8000_0000) (Eletvar O ::: Enil)) - (floatofint (Eletvar O)) - (addf (floatofint (addimm (Int.neg Float.ox8000_0000) (Eletvar O))) f)) + if Archi.splitlong then + let f := Eop (Ofloatconst (Float.of_intu Float.ox8000_0000)) Enil in + Elet e + (Econdition (CEcond (Ccompuimm Clt Float.ox8000_0000) (Eletvar O ::: Enil)) + (floatofint (Eletvar O)) + (addf (floatofint (addimm (Int.neg Float.ox8000_0000) (Eletvar O))) f)) + else + Eop Ofloatoflong (Eop Ocast32unsigned (e ::: Enil) ::: Enil) end. Definition intofsingle (e: expr) := Eop Ointofsingle (e ::: Enil). |