[GC] Fix Array optimization issues (#3438)

Precompute still tried to precompute a reference because the check was
not in the topmost place.

Also we truncated i8/i16 values, but did not extend them properly. That
was also an issue with structs.

The new test replaces the old one by moving from -O1 to -Oz (which
runs more opts, and would have noticed this earlier), and adds array
operations too, including sign extends.

4 files changed, 179 insertions, 89 deletions

diff --git a/test/passes/O1_fuzz-exec_all-features.txt b/test/passes/O1_fuzz-exec_all-features.txt
deleted file mode 100644
index 522943d69..000000000
--- a/test/passes/O1_fuzz-exec_all-features.txt
+++ /dev/null
@@ -1,52 +0,0 @@
-[fuzz-exec] calling structs
-[LoggingExternalInterface logging 0]
-[LoggingExternalInterface logging 42]
-[LoggingExternalInterface logging 100]
-[LoggingExternalInterface logging 100]
-(module
- (type ${i32} (struct (field i32)))
- (type $none_=>_none (func))
- (type $i32_=>_none (func (param i32)))
- (import "fuzzing-support" "log-i32" (func $log (param i32)))
- (export "structs" (func $0))
- (func $0
-  (local $0 (ref null ${i32}))
-  (call $log
-   (struct.get ${i32} 0
-    (local.tee $0
-     (struct.new_default_with_rtt ${i32}
-      (rtt.canon ${i32})
-     )
-    )
-   )
-  )
-  (struct.set ${i32} 0
-   (local.get $0)
-   (i32.const 42)
-  )
-  (call $log
-   (struct.get ${i32} 0
-    (local.get $0)
-   )
-  )
-  (struct.set ${i32} 0
-   (local.get $0)
-   (i32.const 100)
-  )
-  (call $log
-   (struct.get ${i32} 0
-    (local.get $0)
-   )
-  )
-  (call $log
-   (struct.get ${i32} 0
-    (local.get $0)
-   )
-  )
- )
-)
-[fuzz-exec] calling structs
-[LoggingExternalInterface logging 0]
-[LoggingExternalInterface logging 42]
-[LoggingExternalInterface logging 100]
-[LoggingExternalInterface logging 100]
diff --git a/test/passes/O1_fuzz-exec_all-features.wast b/test/passes/O1_fuzz-exec_all-features.wast
deleted file mode 100644
index 0740e60e7..000000000
--- a/test/passes/O1_fuzz-exec_all-features.wast
+++ /dev/null
@@ -1,37 +0,0 @@
-(module
- (type $struct (struct i32))
- (import "fuzzing-support" "log-i32" (func $log (param i32)))
- (func "structs"
-  (local $x (ref null $struct))
-  (local $y (ref null $struct))
-  (local.set $x
-   (struct.new_default_with_rtt $struct
-    (rtt.canon $struct)
-   )
-  )
-  ;; The value is initialized to 0
-  (call $log
-   (struct.get $struct 0 (local.get $x))
-  )
-  ;; Assigning a value works
-  (struct.set $struct 0
-   (local.get $x)
-   (i32.const 42)
-  )
-  (call $log
-   (struct.get $struct 0 (local.get $x))
-  )
-  ;; References are references, so writing to one's value affects the other's
-  (local.set $y (local.get $x))
-  (struct.set $struct 0
-   (local.get $y)
-   (i32.const 100)
-  )
-  (call $log
-   (struct.get $struct 0 (local.get $x))
-  )
-  (call $log
-   (struct.get $struct 0 (local.get $y))
-  )
- )
-)
diff --git a/test/passes/Oz_fuzz-exec_all-features.txt b/test/passes/Oz_fuzz-exec_all-features.txt
new file mode 100644
index 000000000..0663a3351
--- /dev/null
+++ b/test/passes/Oz_fuzz-exec_all-features.txt
@@ -0,0 +1,109 @@
+[fuzz-exec] calling structs
+[LoggingExternalInterface logging 0]
+[LoggingExternalInterface logging 42]
+[LoggingExternalInterface logging 100]
+[LoggingExternalInterface logging 100]
+[fuzz-exec] calling arrays
+[LoggingExternalInterface logging 50]
+[LoggingExternalInterface logging 42]
+[LoggingExternalInterface logging 128]
+[LoggingExternalInterface logging -128]
+[LoggingExternalInterface logging 42]
+(module
+ (type ${i32} (struct (field i32)))
+ (type $none_=>_none (func))
+ (type $[mut:i8] (array (mut i8)))
+ (type $i32_=>_none (func (param i32)))
+ (import "fuzzing-support" "log-i32" (func $log (param i32)))
+ (export "structs" (func $0))
+ (export "arrays" (func $1))
+ (func $0 (; has Stack IR ;)
+  (local $0 (ref null ${i32}))
+  (call $log
+   (struct.get ${i32} 0
+    (local.tee $0
+     (struct.new_default_with_rtt ${i32}
+      (rtt.canon ${i32})
+     )
+    )
+   )
+  )
+  (struct.set ${i32} 0
+   (local.get $0)
+   (i32.const 42)
+  )
+  (call $log
+   (struct.get ${i32} 0
+    (local.get $0)
+   )
+  )
+  (struct.set ${i32} 0
+   (local.get $0)
+   (i32.const 100)
+  )
+  (call $log
+   (struct.get ${i32} 0
+    (local.get $0)
+   )
+  )
+  (call $log
+   (struct.get ${i32} 0
+    (local.get $0)
+   )
+  )
+ )
+ (func $1 (; has Stack IR ;)
+  (local $0 (ref null $[mut:i8]))
+  (call $log
+   (array.len $[mut:i8]
+    (local.tee $0
+     (array.new_with_rtt $[mut:i8]
+      (rtt.canon $[mut:i8])
+      (i32.const 50)
+      (i32.const 42)
+     )
+    )
+   )
+  )
+  (call $log
+   (array.get_u $[mut:i8]
+    (local.get $0)
+    (i32.const 10)
+   )
+  )
+  (array.set $[mut:i8]
+   (local.get $0)
+   (i32.const 10)
+   (i32.const 65408)
+  )
+  (call $log
+   (array.get_u $[mut:i8]
+    (local.get $0)
+    (i32.const 10)
+   )
+  )
+  (call $log
+   (array.get_s $[mut:i8]
+    (local.get $0)
+    (i32.const 10)
+   )
+  )
+  (call $log
+   (array.get_s $[mut:i8]
+    (local.get $0)
+    (i32.const 20)
+   )
+  )
+ )
+)
+[fuzz-exec] calling structs
+[LoggingExternalInterface logging 0]
+[LoggingExternalInterface logging 42]
+[LoggingExternalInterface logging 100]
+[LoggingExternalInterface logging 100]
+[fuzz-exec] calling arrays
+[LoggingExternalInterface logging 50]
+[LoggingExternalInterface logging 42]
+[LoggingExternalInterface logging 128]
+[LoggingExternalInterface logging -128]
+[LoggingExternalInterface logging 42]
diff --git a/test/passes/Oz_fuzz-exec_all-features.wast b/test/passes/Oz_fuzz-exec_all-features.wast
new file mode 100644
index 000000000..d32ee0c19
--- /dev/null
+++ b/test/passes/Oz_fuzz-exec_all-features.wast
@@ -0,0 +1,70 @@
+(module
+ (type $struct (struct i32))
+ (type $bytes (array (mut i8)))
+ (import "fuzzing-support" "log-i32" (func $log (param i32)))
+ (func "structs"
+  (local $x (ref null $struct))
+  (local $y (ref null $struct))
+  (local.set $x
+   (struct.new_default_with_rtt $struct
+    (rtt.canon $struct)
+   )
+  )
+  ;; The value is initialized to 0
+  ;; Note: -Oz will optimize all these to constants thanks to Precompute
+  (call $log
+   (struct.get $struct 0 (local.get $x))
+  )
+  ;; Assigning a value works
+  (struct.set $struct 0
+   (local.get $x)
+   (i32.const 42)
+  )
+  (call $log
+   (struct.get $struct 0 (local.get $x))
+  )
+  ;; References are references, so writing to one's value affects the other's
+  (local.set $y (local.get $x))
+  (struct.set $struct 0
+   (local.get $y)
+   (i32.const 100)
+  )
+  (call $log
+   (struct.get $struct 0 (local.get $x))
+  )
+  (call $log
+   (struct.get $struct 0 (local.get $y))
+  )
+ )
+ (func "arrays"
+  (local $x (ref null $bytes))
+  (local.set $x
+   (array.new_with_rtt $bytes
+    (rtt.canon $bytes)
+    (i32.const 50) ;; size
+    (i32.const 42) ;; value to splat into the array
+   )
+  )
+  ;; The length should be 50
+  (call $log
+   (array.len $bytes (local.get $x))
+  )
+  ;; The value should be 42
+  (call $log
+   (array.get_u $bytes (local.get $x) (i32.const 10))
+  )
+  ;; Write a value that will be truncated into an i8
+  (array.set $bytes (local.get $x) (i32.const 10) (i32.const 0xff80))
+  ;; The value should be 0x80 (-128 or 128 depending on signed/unsigned)
+  (call $log
+   (array.get_u $bytes (local.get $x) (i32.const 10))
+  )
+  (call $log
+   (array.get_s $bytes (local.get $x) (i32.const 10))
+  )
+  ;; Other items than the one at index 10 are unaffected.
+  (call $log
+   (array.get_s $bytes (local.get $x) (i32.const 20))
+  )
+ )
+)