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Re: [PATCH 22/67] target/arm: Convert FCMP, FCMPE, FCCMP, FCCMPE to deco


From: Richard Henderson
Subject: Re: [PATCH 22/67] target/arm: Convert FCMP, FCMPE, FCCMP, FCCMPE to decodetree
Date: Thu, 5 Dec 2024 19:31:16 -0600
User-agent: Mozilla Thunderbird

On 12/5/24 15:27, Peter Maydell wrote:
On Thu, 5 Dec 2024 at 21:21, Peter Maydell <peter.maydell@linaro.org> wrote:

On Sun, 1 Dec 2024 at 15:17, Richard Henderson
<richard.henderson@linaro.org> wrote:

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
  target/arm/tcg/translate-a64.c | 287 +++++++++++++--------------------
  target/arm/tcg/a64.decode      |   8 +
  2 files changed, 116 insertions(+), 179 deletions(-)


+/* FCMP, FCMPE */
+static bool trans_FCMP(DisasContext *s, arg_FCMP *a)
+{
+    int check;
+
+    if (a->z && a->rm != 0) {
+        return false;

We did not check this case before, and the pseudocode in the
Arm ARM doesn't check it either (there's a comment for the rm
field that says "ignored when opc<0> == '1'").

...this probably falls under the "RES0 UNPREDICTABLE" handling,
but "ignore the field" is permitted for that. If we really want
to change our choice of UNPREDICTABLE here I think we should do
it separately from this refactoring.

Fair.  I've removed it for now.

r~



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