From bdf976b26069349d9f07b7327efc859aaa71e848 Mon Sep 17 00:00:00 2001
From: Ian <i.r.butterworth@gmail.com>
Date: Sat, 7 Jan 2023 12:36:12 -0500
Subject: [PATCH 1/2] make cache mismatch log more informative

---
 base/loading.jl        | 30 +++++++++++++++++++++++++++++-
 src/staticdata_utils.c |  1 +
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/base/loading.jl b/base/loading.jl
index f7ff11f1ae165..3f25b627460cc 100644
--- a/base/loading.jl
+++ b/base/loading.jl
@@ -2505,6 +2505,30 @@ function check_clone_targets(clone_targets)
     end
 end
 
+struct CacheFlags
+    # ??OOCDDP - see jl_cache_flags
+    use_pkgimages::Bool
+    debug_level::Int
+    check_bounds::Bool
+    opt_level::Int
+
+    CacheFlags(f::Int) = CacheFlags(UInt8(f))
+    function CacheFlags(f::UInt8)
+        s = bitstring(f)
+        use_pkgimages = parse(Bool, s[end])
+        debug_level = parse(Int, s[end-2:end-1], base=2)
+        check_bounds = parse(Bool, s[end-3])
+        opt_level = parse(Int, s[end-5:end-4], base=2)
+        new(use_pkgimages, debug_level, check_bounds, opt_level)
+    end
+end
+function show(io::IO, cf::CacheFlags)
+    print(io, "use_pkgimages = ", cf.use_pkgimages)
+    print(io, ", debug_level = ", cf.debug_level)
+    print(io, ", check_bounds = ", cf.check_bounds)
+    print(io, ", opt_level = ", cf.opt_level)
+end
+
 # returns true if it "cachefile.ji" is stale relative to "modpath.jl" and build_id for modkey
 # otherwise returns the list of dependencies to also check
 @constprop :none function stale_cachefile(modpath::String, cachefile::String; ignore_loaded::Bool = false)
@@ -2523,7 +2547,11 @@ end
             return true # ignore empty file
         end
         if ccall(:jl_match_cache_flags, UInt8, (UInt8,), flags) == 0
-            @debug "Rejecting cache file $cachefile for $modkey since the flags are mismatched" cachefile_flags=flags current_flags=ccall(:jl_cache_flags, UInt8, ())
+            @debug """
+            Rejecting cache file $cachefile for $modkey since the flags are mismatched
+              current session: $(CacheFlags(ccall(:jl_cache_flags, UInt8, ())))
+              cache file:      $(CacheFlags(flags))
+            """
             return true
         end
         pkgimage = !isempty(clone_targets)
diff --git a/src/staticdata_utils.c b/src/staticdata_utils.c
index 220a354847dfe..cb107b06a9585 100644
--- a/src/staticdata_utils.c
+++ b/src/staticdata_utils.c
@@ -621,6 +621,7 @@ JL_DLLEXPORT uint8_t jl_cache_flags(void)
     flags |= (jl_options.opt_level & 3) << 4;
     // NOTES:
     // In contrast to check-bounds, inline has no "observable effect"
+    // CacheFlags in loading.jl should be kept in-sync with this
     return flags;
 }
 

From 6d08729858f41fdf3e9c3a0a8b1aaf236999fef8 Mon Sep 17 00:00:00 2001
From: Ian Butterworth <i.r.butterworth@gmail.com>
Date: Sat, 7 Jan 2023 22:28:40 -0500
Subject: [PATCH 2/2] use bitmasking instead

---
 base/loading.jl | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/base/loading.jl b/base/loading.jl
index 3f25b627460cc..9137651007c30 100644
--- a/base/loading.jl
+++ b/base/loading.jl
@@ -2514,11 +2514,10 @@ struct CacheFlags
 
     CacheFlags(f::Int) = CacheFlags(UInt8(f))
     function CacheFlags(f::UInt8)
-        s = bitstring(f)
-        use_pkgimages = parse(Bool, s[end])
-        debug_level = parse(Int, s[end-2:end-1], base=2)
-        check_bounds = parse(Bool, s[end-3])
-        opt_level = parse(Int, s[end-5:end-4], base=2)
+        use_pkgimages = Bool(f & 1)
+        debug_level = Int((f >> 1) & 3)
+        check_bounds = Bool((f >> 2) & 1)
+        opt_level = Int((f >> 4) & 3)
         new(use_pkgimages, debug_level, check_bounds, opt_level)
     end
 end