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| author | Xavier Leroy <xavier.leroy@college-de-france.fr> | 2019-07-11 10:56:23 +0200 |
|---|---|---|
| committer | Xavier Leroy <xavierleroy@users.noreply.github.com> | 2019-07-12 09:55:12 +0200 |
| commit | 83deaa4b3a164423254008d8594de99edc491c3b (patch) | |
| tree | 6f532296f067acd5a0b528950d10eb8733c13de3 /x86_32 | |
| parent | a8c84a5270b7620c6555e58d0338afd9405bc2b2 (diff) | |
| download | compcert-kvx-83deaa4b3a164423254008d8594de99edc491c3b.tar.gz compcert-kvx-83deaa4b3a164423254008d8594de99edc491c3b.zip | |
Revised specification of NaN payload behavior
When an FP arithmetic instruction produces a NaN result, the payload
of this NaN depends on the architecture.
Before, the payload behavior was specified by 3 architecture-dependent
parameters: `Archi.choose_binop_pl_64` and `Archi.choose_binop_pl_32`
and `Archi.fpu_results_default_qNaN`. This was adequate for
two-argument operations, but doesn't extend to FMA.
In preparation for FMA support, this commit generalizes the `Archi.choose`
functions from two arguments to any number of arguments. In passing,
`Archi.fpu_results_default_qNaN` is no longer needed.
Diffstat (limited to 'x86_32')
| -rw-r--r-- | x86_32/Archi.v | 30 |
1 files changed, 17 insertions, 13 deletions
diff --git a/x86_32/Archi.v b/x86_32/Archi.v index f10570e2..c6d66e09 100644 --- a/x86_32/Archi.v +++ b/x86_32/Archi.v @@ -16,7 +16,7 @@ (** Architecture-dependent parameters for x86 in 32-bit mode *) -Require Import ZArith. +Require Import ZArith List. (*From Flocq*) Require Import Binary Bits. @@ -34,24 +34,28 @@ Proof. unfold splitlong. destruct ptr64; simpl; congruence. Qed. -Definition default_nan_64 : { x : binary64 | is_nan _ _ x = true } := - exist _ (B754_nan 53 1024 true (iter_nat 51 _ xO xH) (eq_refl true)) (eq_refl true). +Definition default_nan_64 := (true, iter_nat 51 _ xO xH). +Definition default_nan_32 := (true, iter_nat 22 _ xO xH). -Definition choose_binop_pl_64 (pl1 pl2 : positive) := - false. (**r always choose first NaN *) +(* Always choose the first NaN argument, if any *) -Definition default_nan_32 : { x : binary32 | is_nan _ _ x = true } := - exist _ (B754_nan 24 128 true (iter_nat 22 _ xO xH) (eq_refl true)) (eq_refl true). +Definition choose_nan_64 (l: list (bool * positive)) : bool * positive := + match l with nil => default_nan_64 | n :: _ => n end. -Definition choose_binop_pl_32 (pl1 pl2 : positive) := - false. (**r always choose first NaN *) +Definition choose_nan_32 (l: list (bool * positive)) : bool * positive := + match l with nil => default_nan_32 | n :: _ => n end. -Definition fpu_returns_default_qNaN := false. +Lemma choose_nan_64_idem: forall n, + choose_nan_64 (n :: n :: nil) = choose_nan_64 (n :: nil). +Proof. auto. Qed. + +Lemma choose_nan_32_idem: forall n, + choose_nan_32 (n :: n :: nil) = choose_nan_32 (n :: nil). +Proof. auto. Qed. Definition float_of_single_preserves_sNaN := false. Global Opaque ptr64 big_endian splitlong - default_nan_64 choose_binop_pl_64 - default_nan_32 choose_binop_pl_32 - fpu_returns_default_qNaN + default_nan_64 choose_nan_64 + default_nan_32 choose_nan_32 float_of_single_preserves_sNaN. |