Make constant expression validation stricter (#5557)

Previously we treated global.get as a constant expression and only
additionally verified that the target globals were immutable in some cases. But
global.get of a mutable global is never a constant expression, and further,
only imported globals are available in constant expressions unless GC is
enabled.

Fix constant expression validation to only allow global.get of immutable,
imported globals, and fix all the invalid tests.

1 files changed, 147 insertions, 0 deletions

diff --git a/test/passes/simplify-globals-optimizing_all-features.wast b/test/passes/simplify-globals-optimizing_all-features.wast
new file mode 100644
index 000000000..988650a74
--- /dev/null
+++ b/test/passes/simplify-globals-optimizing_all-features.wast
@@ -0,0 +1,147 @@
+(module
+  (import "env" "global-1" (global $g1 i32))
+  (global $g2 (mut i32) (global.get $g1))
+  (func $foo
+   (drop (global.get $g1))
+   (drop (global.get $g2))
+  )
+)
+(module
+  (import "env" "global-1" (global $g1 i32))
+  (global $g2 i32 (global.get $g1))
+  (global $g3 i32 (global.get $g2))
+  (global $g4 i32 (global.get $g3))
+  (func $foo
+   (drop (global.get $g1))
+   (drop (global.get $g2))
+   (drop (global.get $g3))
+   (drop (global.get $g4))
+  )
+)
+(module
+  (import "env" "global-1" (global $g1 i32))
+  (global $g2 (mut i32) (global.get $g1))
+)
+(module
+  (import "env" "global-1" (global $g1 i32))
+  (global $g2 (mut i32) (global.get $g1))
+  (func $foo
+   (global.set $g2 (unreachable))
+  )
+)
+(module
+  (import "env" "global-1" (global $g1 i32))
+  (global $g2 (mut i32) (global.get $g1))
+  (export "global-2" (global $g2))
+)
+(module
+  (global $g1 i32 (i32.const 1))
+  (global $g2 i32 (global.get $g1))
+  (global $g3 f64 (f64.const -3.4))
+  (global $g4 (mut f64) (f64.const -2.8))
+  (global $g5 i32 (i32.const 2))
+  (global $g6 (mut i32) (global.get $g5))
+  (global $g7 i32 (i32.const 3))
+  (global $g8 i32 (global.get $g7))
+  (global $g9 i32 (i32.const 4))
+  (global $ga (mut i32) (global.get $g9))
+  (global $gb i32 (i32.const 5))
+  (global $gc i32 (global.get $gb))
+  (func $foo
+   (drop (global.get $g1))
+   (drop (global.get $g2))
+   (drop (global.get $g3))
+   (drop (global.get $g4))
+   (drop (global.get $g5))
+   (drop (global.get $g6))
+   (drop (global.get $g7))
+   (drop (global.get $g8))
+   (drop (global.get $g9))
+   (drop (global.get $ga))
+   (drop (global.get $gb))
+   (drop (global.get $gc))
+   (global.set $ga (i32.const 6))
+  )
+)
+(module
+  (global $g1 (mut i32) (i32.const 1))
+  (global $g2 (mut i32) (i32.const 1))
+  (func $f (param $x i32) (result i32)
+    (global.set $g1 (i32.const 100))
+    (global.set $g2 (local.get $x))
+    (if (local.get $x) (return (i32.const 0)))
+    (local.set $x
+      (i32.add
+        (global.get $g1)
+        (global.get $g2)
+      )
+    )
+    (if (local.get $x) (return (i32.const 1)))
+    (global.set $g1 (i32.const 200))
+    (global.set $g2 (local.get $x))
+    (local.set $x
+      (i32.add
+        (global.get $g1)
+        (global.get $g2)
+      )
+    )
+    (local.get $x)
+  )
+)
+(module
+  (global $g1 (mut i32) (i32.const 1))
+  (global $g2 (mut i32) (i32.const 1))
+  (func $f (param $x i32) (result i32)
+    (global.set $g1 (i32.const 100))
+    (global.set $g2 (local.get $x))
+    (local.set $x
+      (i32.add
+        (i32.add
+          (global.get $g1)
+          (global.get $g1)
+        )
+        (global.get $g2)
+      )
+    )
+    (local.get $x)
+  )
+)
+(module
+  (global $g1 (mut i32) (i32.const 1))
+  (global $g2 (mut i32) (i32.const 1))
+  (func $no (param $x i32) (result i32)
+    (global.set $g1 (i32.const 100))
+    (drop (call $no (i32.const 200))) ;; invalidate
+    (global.get $g1)
+  )
+  (func $no2 (param $x i32) (result i32)
+    (global.set $g1 (i32.const 100))
+    (global.set $g1 (local.get $x)) ;; invalidate
+    (global.get $g1)
+  )
+  (func $yes (param $x i32) (result i32)
+    (global.set $g1 (i32.const 100))
+    (global.set $g2 (local.get $x)) ;; almost invalidate
+    (global.get $g1)
+  )
+)
+;; don't remove a value with a side effect
+(module
+ (global $global$0 (mut i32) (i32.const 0))
+ (global $global$1 (mut i32) (i32.const 0))
+ (export "func_9" (func $0))
+ (func $0 (result f64)
+  (global.set $global$0
+   (block $label$1 (result i32)
+    (if
+     (i32.eqz
+      (global.get $global$1)
+     )
+     (unreachable)
+    )
+    (i32.const 2)
+   )
+  )
+  (f64.const 1)
+ )
+)