From 74c388909431debbca4a7fcd38ce68091c27cde6 Mon Sep 17 00:00:00 2001
From: Douglas Katzman <dougk@google.com>
Date: Mon, 4 Mar 2024 10:35:50 -0500
Subject: [PATCH] Enable #+salted-symbol-hash for 64-bit riscv

---
 crossbuild-runner/backends/ppc64/features  |  1 -
 crossbuild-runner/backends/x86-64/features |  1 -
 src/cold/shared.lisp                       |  6 ++++++
 src/compiler/riscv/cell.lisp               | 22 ++++++++++------------
 4 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/crossbuild-runner/backends/ppc64/features b/crossbuild-runner/backends/ppc64/features
index 5836013d5..6742c14b0 100644
--- a/crossbuild-runner/backends/ppc64/features
+++ b/crossbuild-runner/backends/ppc64/features
@@ -3,4 +3,3 @@
 :64-bit :untagged-fdefns :sb-thread :soft-card-marks
 :gencgc
 :compare-and-swap-vops :alien-callbacks
-:salted-symbol-hash
diff --git a/crossbuild-runner/backends/x86-64/features b/crossbuild-runner/backends/x86-64/features
index 5cc6ff7fb..2409d99e8 100644
--- a/crossbuild-runner/backends/x86-64/features
+++ b/crossbuild-runner/backends/x86-64/features
@@ -15,4 +15,3 @@
 :executable-funinstances
 :unbind-in-unwind
 :no-continue-unwind
-:salted-symbol-hash
diff --git a/src/cold/shared.lisp b/src/cold/shared.lisp
index 2ab1574ea..39ee46fd4 100644
--- a/src/cold/shared.lisp
+++ b/src/cold/shared.lisp
@@ -319,6 +319,12 @@
           (pushnew :immobile-code sb-xc:*features*))
         (when (target-featurep :64-bit)
           (push :compact-symbol sb-xc:*features*))
+        (when (target-featurep :64-bit)
+          ;; Considering that a single config file governs rv32 and rv64, I don't
+          ;; know how to make this properly configurable. In theory, 32-bit builds could
+          ;; have a salted hash (gaining 3 bits by making the hash slot raw), but
+          ;; they don't, so in light of things, this is a valid criterion.
+          (push :salted-symbol-hash sb-xc:*features*))
         (when (target-featurep '(:and :sb-thread (:or (:and :darwin (:not (:or :ppc :x86))) :openbsd)))
           (push :os-thread-stack sb-xc:*features*))
         (when (target-featurep '(:and :x86 :int4-breakpoints))
diff --git a/src/compiler/riscv/cell.lisp b/src/compiler/riscv/cell.lisp
index acb837ea4..91950c54e 100644
--- a/src/compiler/riscv/cell.lisp
+++ b/src/compiler/riscv/cell.lisp
@@ -198,23 +198,21 @@
   (:translate symbol-global-value))
 
 #+64-bit
+(progn
 (define-vop (symbol-hash)
   (:policy :fast-safe)
   (:translate symbol-hash)
   (:args (symbol :scs (descriptor-reg)))
-  (:temporary (:scs (non-descriptor-reg)) temp)
-  (:results (res :scs (any-reg)))
+  (:results (res :scs (unsigned-reg)))
   (:result-types positive-fixnum)
   (:generator 2
-    ;; The symbol-hash slot of NIL holds NIL because it is also the
-    ;; cdr slot, so we have to strip off the two low bits to make
-    ;; sure it is a fixnum.  The lowtag selection magic that is
-    ;; required to ensure this is explained in the comment in
-    ;; objdef.lisp
-    (loadw temp symbol symbol-hash-slot other-pointer-lowtag)
-    (inst andi res temp (lognot fixnum-tag-mask))))
-
-#+64-bit
+    (loadw res symbol symbol-hash-slot other-pointer-lowtag)
+    (inst srli res res 24))) ; shift out 3 bytes
+(define-vop (symbol-name-hash symbol-hash)
+  (:translate symbol-name-hash)
+  (:generator 1
+    (inst lwu res symbol ; little-endian
+          (- (+ 4 (ash symbol-hash-slot word-shift)) other-pointer-lowtag))))
 (define-vop ()
   (:args (symbol :scs (descriptor-reg)))
   (:results (result :scs (unsigned-reg)))
@@ -225,7 +223,6 @@
    (inst lhu result symbol (+ (ash symbol-name-slot word-shift)
                               (- other-pointer-lowtag)
                               6)))) ; little-endian
-#+64-bit
 (define-vop ()
   (:policy :fast-safe)
   (:translate symbol-name)
@@ -237,6 +234,7 @@
       (loadw result symbol symbol-name-slot other-pointer-lowtag)
       (inst slli result result sb-impl::package-id-bits)
       (inst srli result result sb-impl::package-id-bits))))
+) ; end PROGN
 
 ;;;; Fdefinition (fdefn) objects.