From 3f718330636cc3d8b05670ea29253c3c70d1b297 Mon Sep 17 00:00:00 2001
From: Stas Boukarev <stassats@gmail.com>
Date: Sat, 20 Feb 2016 23:16:43 +0300
Subject: [PATCH] Micro-optimize verify-arg-count on x86oids and ARM64.

When MIN is 1 it only needs to be checked for zero, using TEST instead
of CMP on x86 saves one byte. Using CBZ on ARM64 saves one instruction.
---
 src/compiler/arm64/call.lisp  | 27 ++++++++++++++-------------
 src/compiler/x86-64/call.lisp | 35 ++++++++++++++++++++---------------
 src/compiler/x86/call.lisp    | 34 +++++++++++++++++++---------------
 3 files changed, 53 insertions(+), 43 deletions(-)

diff --git a/src/compiler/arm64/call.lisp b/src/compiler/arm64/call.lisp
index d69b3f0b4..b1d6148eb 100644
--- a/src/compiler/arm64/call.lisp
+++ b/src/compiler/arm64/call.lisp
@@ -541,24 +541,25 @@
   (:generator 3
     (let ((err-lab
            (generate-error-code vop 'invalid-arg-count-error)))
-      (flet ((load-immediate (x)
-               (add-sub-immediate (fixnumize x))))
+      (labels ((load-immediate (x)
+                 (add-sub-immediate (fixnumize x)))
+               (check-min ()
+                 (cond ((= min 1)
+                        (inst cbz nargs err-lab))
+                       ((plusp min)
+                        (inst cmp nargs (load-immediate min))
+                        (inst b :lo err-lab)))))
         (cond ((eql max 0)
                (inst cbnz nargs err-lab))
               ((not min)
                (inst cmp nargs (load-immediate max))
                (inst b :ne err-lab))
-             (max
-              (when (plusp min)
-                (inst cmp nargs (load-immediate min))
-                (inst b :lo err-lab))
-              (inst cmp nargs (load-immediate max))
-              (inst b :hi err-lab))
-             ((eql min 1)
-              (inst cbz nargs err-lab))
-             ((plusp min)
-              (inst cmp nargs (load-immediate min))
-              (inst b :lo err-lab)))))))
+              (max
+               (check-min)
+               (inst cmp nargs (load-immediate max))
+               (inst b :hi err-lab))
+              (t
+               (check-min)))))))
 
 ;;;; Local call with unknown values convention return:
 
diff --git a/src/compiler/x86-64/call.lisp b/src/compiler/x86-64/call.lisp
index 30b2dab3f..60f4b6946 100644
--- a/src/compiler/x86-64/call.lisp
+++ b/src/compiler/x86-64/call.lisp
@@ -1311,21 +1311,26 @@
   (:vop-var vop)
   (:save-p :compute-only)
   (:generator 3
-    (let ((err-lab (generate-error-code vop 'invalid-arg-count-error)))
-      (cond ((not min)
-             (if (zerop max)
-                 (inst test nargs nargs)
-                 (inst cmp nargs (fixnumize max)))
-             (inst jmp :ne err-lab))
-            (max
-             (when (plusp min)
-               (inst cmp nargs (fixnumize min))
-               (inst jmp :b err-lab))
-             (inst cmp nargs (fixnumize max))
-             (inst jmp :a err-lab))
-            ((plusp min)
-             (inst cmp nargs (fixnumize min))
-             (inst jmp :b err-lab))))))
+    (let ((err-lab
+            (generate-error-code vop 'invalid-arg-count-error nargs)))
+      (flet ((check-min ()
+               (cond ((= min 1)
+                      (inst test nargs nargs)
+                      (inst jmp :e err-lab))
+                     ((plusp min)
+                      (inst cmp nargs (fixnumize min))
+                      (inst jmp :b err-lab)))))
+        (cond ((not min)
+               (if (zerop max)
+                   (inst test nargs nargs)
+                   (inst cmp nargs (fixnumize max)))
+               (inst jmp :ne err-lab))
+              (max
+               (check-min)
+               (inst cmp nargs (fixnumize max))
+               (inst jmp :a err-lab))
+              (t
+               (check-min)))))))
 
 ;; Signal an error about an untagged number.
 ;; These are pretty much boilerplate and could be generic except:
diff --git a/src/compiler/x86/call.lisp b/src/compiler/x86/call.lisp
index e3d396eb4..bc341bf9a 100644
--- a/src/compiler/x86/call.lisp
+++ b/src/compiler/x86/call.lisp
@@ -1394,21 +1394,25 @@
   (:save-p :compute-only)
   (:generator 3
     (let ((err-lab
-           (generate-error-code vop 'invalid-arg-count-error nargs)))
-      (cond ((not min)
-             (if (zerop max)
-                 (inst test nargs nargs)
-                 (inst cmp nargs (fixnumize max)))
-             (inst jmp :ne err-lab))
-            (max
-             (when (plusp min)
-               (inst cmp nargs (fixnumize min))
-               (inst jmp :b err-lab))
-             (inst cmp nargs (fixnumize max))
-             (inst jmp :a err-lab))
-            ((plusp min)
-             (inst cmp nargs (fixnumize min))
-             (inst jmp :b err-lab))))))
+            (generate-error-code vop 'invalid-arg-count-error nargs)))
+      (flet ((check-min ()
+               (cond ((= min 1)
+                      (inst test nargs nargs)
+                      (inst jmp :e err-lab))
+                     ((plusp min)
+                      (inst cmp nargs (fixnumize min))
+                      (inst jmp :b err-lab)))))
+        (cond ((not min)
+               (if (zerop max)
+                   (inst test nargs nargs)
+                   (inst cmp nargs (fixnumize max)))
+               (inst jmp :ne err-lab))
+              (max
+               (check-min)
+               (inst cmp nargs (fixnumize max))
+               (inst jmp :a err-lab))
+              (t
+               (check-min)))))))
 
 ;;; Single-stepping
 (defun emit-single-step-test ()
-- 
2.11.4.GIT