Optimize passive segments in memory-packing (#2426)

When memory is packed and there are passive segments, bulk memory
operations that reference those segments by index need to be updated to
reflect the new indices and possibly split into multiple instructions
that reference multiple split segments. For some bulk-memory operations,
it is necessary to introduce new globals to explicitly track the drop
state of the original segments, but this PR is careful to only add
globals where necessary.

3 files changed, 1362 insertions, 38 deletions

diff --git a/test/passes/memory-packing_all-features.txt b/test/passes/memory-packing_all-features.txt
index 9b2eaad29..e74fb3c9b 100644
--- a/test/passes/memory-packing_all-features.txt
+++ b/test/passes/memory-packing_all-features.txt
@@ -1,5 +1,14 @@
 (module
  (import "env" "memory" (memory $0 2048 2048))
+ (import "env" "memoryBase" (global $memoryBase i32))
+)
+(module
+ (import "env" "memory" (memory $0 2048 2048))
+ (import "env" "memoryBase" (global $memoryBase i32))
+)
+(module
+ (type $none_=>_none (func))
+ (import "env" "memory" (memory $0 2048 2048))
  (data (global.get $memoryBase) "waka this cannot be optimized\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00we don\'t know where it will go")
  (data (i32.const 1024) "waka this CAN be optimized")
  (data (i32.const 1107) "we DO know where it will go")
@@ -9,42 +18,914 @@
  (data (i32.const 4035) "nice skip here")
  (data (i32.const 4066) "another\00but no")
  (import "env" "memoryBase" (global $memoryBase i32))
+ (func $nonzero-size-init-of-active-will-trap (; 0 ;)
+  (block
+   (drop
+    (i32.const 42)
+   )
+   (drop
+    (i32.const 0)
+   )
+   (drop
+    (i32.const 13)
+   )
+   (unreachable)
+  )
+  (nop)
+ )
+ (func $nonzero-offset-init-of-active-will-trap (; 1 ;)
+  (block
+   (drop
+    (i32.const 42)
+   )
+   (drop
+    (i32.const 13)
+   )
+   (drop
+    (i32.const 0)
+   )
+   (unreachable)
+  )
+  (nop)
+ )
+ (func $zero-offset-size-init-of-active-may-trap (; 2 ;)
+  (if
+   (i32.gt_u
+    (i32.const 42)
+    (i32.shl
+     (memory.size)
+     (i32.const 16)
+    )
+   )
+   (unreachable)
+  )
+  (nop)
+ )
 )
 (module
+ (type $none_=>_none (func))
  (import "env" "memory" (memory $0 2048 2048))
- (import "env" "memoryBase" (global $memoryBase i32))
+ (data passive "zeroes at start")
+ (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes at start")
+ (data passive "\00\00\00few zeroes at start")
+ (data passive "zeroes at end")
+ (data passive "zeroes at end\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00")
+ (data passive "few zeroes at end\00\00\00")
+ (data passive "zeroes")
+ (data passive "in middle")
+ (data passive "zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00in middle")
+ (data passive "few zeroes\00\00\00in middle")
+ (data passive "multiple")
+ (data passive "spans")
+ (data passive "of zeroes")
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (data passive "no zeroes")
+ (global $__mem_segment_drop_state_0 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_1 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_2 (mut i32) (i32.const 0))
+ (func $zeroes-at-start (; 0 ;)
+  (block
+   (if
+    (global.get $__mem_segment_drop_state_0)
+    (unreachable)
+   )
+   (memory.fill
+    (i32.const 0)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 0
+    (i32.const 30)
+    (i32.const 0)
+    (i32.const 15)
+   )
+  )
+  (block
+   (global.set $__mem_segment_drop_state_0
+    (i32.const 1)
+   )
+   (data.drop 0)
+  )
+ )
+ (func $zeroes-at-start-not-split (; 1 ;)
+  (memory.init 1
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 45)
+  )
+  (memory.init 1
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 45)
+  )
+  (memory.init 1
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 45)
+  )
+  (memory.init 1
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 45)
+  )
+  (data.drop 1)
+ )
+ (func $few-zeroes-at-start (; 2 ;)
+  (memory.init 2
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 22)
+  )
+  (data.drop 2)
+ )
+ (func $zeroes-at-end (; 3 ;)
+  (block
+   (memory.init 3
+    (i32.const 0)
+    (i32.const 0)
+    (i32.const 13)
+   )
+   (memory.fill
+    (i32.const 13)
+    (i32.const 0)
+    (i32.const 30)
+   )
+  )
+  (data.drop 3)
+ )
+ (func $zeroes-at-end-not-split (; 4 ;)
+  (memory.init 4
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 43)
+  )
+  (memory.init 4
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 43)
+  )
+  (memory.init 4
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 43)
+  )
+  (memory.init 4
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 43)
+  )
+  (data.drop 4)
+ )
+ (func $few-zeroes-at-end (; 5 ;)
+  (memory.init 5
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 20)
+  )
+  (data.drop 5)
+ )
+ (func $zeroes-in-middle (; 6 ;)
+  (block
+   (memory.init 6
+    (i32.const 0)
+    (i32.const 0)
+    (i32.const 6)
+   )
+   (memory.fill
+    (i32.const 6)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 7
+    (i32.const 36)
+    (i32.const 0)
+    (i32.const 9)
+   )
+  )
+  (block
+   (data.drop 6)
+   (data.drop 7)
+  )
+ )
+ (func $zeroes-in-middle-not-split (; 7 ;)
+  (memory.init 8
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 35)
+  )
+  (memory.init 8
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 45)
+  )
+  (data.drop 8)
+ )
+ (func $few-zeroes-in-middle (; 8 ;)
+  (memory.init 9
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 22)
+  )
+  (data.drop 9)
+ )
+ (func $multiple-spans-of-zeroes (; 9 ;)
+  (block
+   (memory.init 10
+    (i32.const 0)
+    (i32.const 0)
+    (i32.const 8)
+   )
+   (memory.fill
+    (i32.const 8)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 11
+    (i32.const 38)
+    (i32.const 0)
+    (i32.const 5)
+   )
+   (memory.fill
+    (i32.const 43)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 12
+    (i32.const 73)
+    (i32.const 0)
+    (i32.const 9)
+   )
+  )
+  (block
+   (data.drop 10)
+   (data.drop 11)
+   (data.drop 12)
+  )
+ )
+ (func $even-more-zeroes (; 10 ;)
+  (block
+   (if
+    (global.get $__mem_segment_drop_state_1)
+    (unreachable)
+   )
+   (memory.fill
+    (i32.const 0)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 13
+    (i32.const 30)
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.const 34)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 14
+    (i32.const 64)
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.const 68)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 15
+    (i32.const 98)
+    (i32.const 0)
+    (i32.const 6)
+   )
+   (memory.fill
+    (i32.const 104)
+    (i32.const 0)
+    (i32.const 30)
+   )
+  )
+  (block
+   (global.set $__mem_segment_drop_state_1
+    (i32.const 1)
+   )
+   (data.drop 13)
+   (data.drop 14)
+   (data.drop 15)
+  )
+ )
+ (func $only-zeroes (; 11 ;)
+  (block
+   (if
+    (global.get $__mem_segment_drop_state_2)
+    (unreachable)
+   )
+   (memory.fill
+    (i32.const 0)
+    (i32.const 0)
+    (i32.const 30)
+   )
+  )
+  (global.set $__mem_segment_drop_state_2
+   (i32.const 1)
+  )
+ )
+ (func $no-zeroes (; 12 ;)
+  (memory.init 16
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 9)
+  )
+  (data.drop 16)
+ )
+ (func $empty (; 13 ;)
+  (if
+   (i32.gt_u
+    (i32.const 13)
+    (i32.shl
+     (memory.size)
+     (i32.const 16)
+    )
+   )
+   (unreachable)
+  )
+  (nop)
+ )
+ (func $only-dropped (; 14 ;)
+  (nop)
+  (nop)
+ )
+ (func $only-dropped-zeroes (; 15 ;)
+  (nop)
+  (nop)
+ )
 )
 (module
+ (type $none_=>_none (func))
  (import "env" "memory" (memory $0 2048 2048))
- (import "env" "memoryBase" (global $memoryBase i32))
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00")
+ (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00")
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (data passive "even")
+ (data passive "more")
+ (data passive "zeroes")
+ (import "env" "param" (global $param i32))
+ (global $__mem_segment_drop_state_0 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_1 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_2 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_3 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_4 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_5 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_6 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_7 (mut i32) (i32.const 0))
+ (func $nonconst-dest (; 0 ;)
+  (local $0 i32)
+  (block
+   (local.set $0
+    (global.get $param)
+   )
+   (if
+    (global.get $__mem_segment_drop_state_0)
+    (unreachable)
+   )
+   (memory.fill
+    (local.get $0)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 0
+    (i32.add
+     (local.get $0)
+     (i32.const 30)
+    )
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.add
+     (local.get $0)
+     (i32.const 34)
+    )
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 1
+    (i32.add
+     (local.get $0)
+     (i32.const 64)
+    )
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.add
+     (local.get $0)
+     (i32.const 68)
+    )
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 2
+    (i32.add
+     (local.get $0)
+     (i32.const 98)
+    )
+    (i32.const 0)
+    (i32.const 6)
+   )
+   (memory.fill
+    (i32.add
+     (local.get $0)
+     (i32.const 104)
+    )
+    (i32.const 0)
+    (i32.const 30)
+   )
+  )
+  (block
+   (global.set $__mem_segment_drop_state_0
+    (i32.const 1)
+   )
+   (data.drop 0)
+   (data.drop 1)
+   (data.drop 2)
+  )
+ )
+ (func $nonconst-offset (; 1 ;)
+  (memory.init 3
+   (i32.const 0)
+   (global.get $param)
+   (i32.const 134)
+  )
+  (data.drop 3)
+ )
+ (func $nonconst-size (; 2 ;)
+  (memory.init 4
+   (i32.const 0)
+   (i32.const 0)
+   (global.get $param)
+  )
+  (data.drop 4)
+ )
+ (func $partial-skip-start (; 3 ;)
+  (block
+   (if
+    (global.get $__mem_segment_drop_state_1)
+    (unreachable)
+   )
+   (memory.fill
+    (i32.const 0)
+    (i32.const 0)
+    (i32.const 20)
+   )
+   (memory.init 5
+    (i32.const 20)
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.const 24)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 6
+    (i32.const 54)
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.const 58)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 7
+    (i32.const 88)
+    (i32.const 0)
+    (i32.const 6)
+   )
+   (memory.fill
+    (i32.const 94)
+    (i32.const 0)
+    (i32.const 30)
+   )
+  )
+  (block
+   (global.set $__mem_segment_drop_state_1
+    (i32.const 1)
+   )
+   (data.drop 5)
+   (data.drop 6)
+   (data.drop 7)
+  )
+ )
+ (func $full-skip-start (; 4 ;)
+  (block
+   (memory.init 8
+    (i32.const 0)
+    (i32.const 2)
+    (i32.const 2)
+   )
+   (memory.fill
+    (i32.const 2)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 9
+    (i32.const 32)
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.const 36)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 10
+    (i32.const 66)
+    (i32.const 0)
+    (i32.const 6)
+   )
+   (memory.fill
+    (i32.const 72)
+    (i32.const 0)
+    (i32.const 30)
+   )
+  )
+  (block
+   (data.drop 8)
+   (data.drop 9)
+   (data.drop 10)
+  )
+ )
+ (func $partial-skip-end (; 5 ;)
+  (block
+   (if
+    (global.get $__mem_segment_drop_state_2)
+    (unreachable)
+   )
+   (memory.fill
+    (i32.const 0)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 11
+    (i32.const 30)
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.const 34)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 12
+    (i32.const 64)
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.const 68)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 13
+    (i32.const 98)
+    (i32.const 0)
+    (i32.const 6)
+   )
+   (memory.fill
+    (i32.const 104)
+    (i32.const 0)
+    (i32.const 20)
+   )
+  )
+  (block
+   (global.set $__mem_segment_drop_state_2
+    (i32.const 1)
+   )
+   (data.drop 11)
+   (data.drop 12)
+   (data.drop 13)
+  )
+ )
+ (func $full-skip-end (; 6 ;)
+  (block
+   (if
+    (global.get $__mem_segment_drop_state_3)
+    (unreachable)
+   )
+   (memory.fill
+    (i32.const 0)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 14
+    (i32.const 30)
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.const 34)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 15
+    (i32.const 64)
+    (i32.const 0)
+    (i32.const 4)
+   )
+   (memory.fill
+    (i32.const 68)
+    (i32.const 0)
+    (i32.const 30)
+   )
+   (memory.init 16
+    (i32.const 98)
+    (i32.const 0)
+    (i32.const 4)
+   )
+  )
+  (block
+   (global.set $__mem_segment_drop_state_3
+    (i32.const 1)
+   )
+   (data.drop 14)
+   (data.drop 15)
+   (data.drop 16)
+  )
+ )
+ (func $slice-zeroes (; 7 ;)
+  (block
+   (if
+    (global.get $__mem_segment_drop_state_4)
+    (unreachable)
+   )
+   (memory.fill
+    (i32.const 0)
+    (i32.const 0)
+    (i32.const 10)
+   )
+  )
+  (block
+   (global.set $__mem_segment_drop_state_4
+    (i32.const 1)
+   )
+   (data.drop 17)
+   (data.drop 18)
+   (data.drop 19)
+  )
+ )
+ (func $slice-nonzeroes (; 8 ;)
+  (memory.init 20
+   (i32.const 0)
+   (i32.const 1)
+   (i32.const 2)
+  )
+  (block
+   (data.drop 20)
+   (data.drop 21)
+   (data.drop 22)
+  )
+ )
+ (func $zero-size (; 9 ;)
+  (if
+   (i32.or
+    (i32.gt_u
+     (i32.const 13)
+     (i32.shl
+      (memory.size)
+      (i32.const 16)
+     )
+    )
+    (global.get $__mem_segment_drop_state_5)
+   )
+   (unreachable)
+  )
+  (block
+   (global.set $__mem_segment_drop_state_5
+    (i32.const 1)
+   )
+   (data.drop 23)
+   (data.drop 24)
+   (data.drop 25)
+  )
+ )
+ (func $zero-size-undropped (; 10 ;)
+  (if
+   (i32.or
+    (i32.gt_u
+     (i32.const 13)
+     (i32.shl
+      (memory.size)
+      (i32.const 16)
+     )
+    )
+    (global.get $__mem_segment_drop_state_6)
+   )
+   (unreachable)
+  )
+ )
+ (func $out-of-bounds-offset (; 11 ;)
+  (block
+   (drop
+    (i32.const 0)
+   )
+   (drop
+    (i32.const 135)
+   )
+   (drop
+    (i32.const 1)
+   )
+   (unreachable)
+  )
+  (nop)
+ )
+ (func $zero-size-out-of-bounds-offset (; 12 ;)
+  (block
+   (drop
+    (i32.const 0)
+   )
+   (drop
+    (i32.const 135)
+   )
+   (drop
+    (i32.const 0)
+   )
+   (unreachable)
+  )
+  (nop)
+ )
+ (func $out-of-bounds-size (; 13 ;)
+  (block
+   (drop
+    (i32.const 0)
+   )
+   (drop
+    (i32.const 0)
+   )
+   (drop
+    (i32.const 135)
+   )
+   (unreachable)
+  )
+  (nop)
+ )
+ (func $zero-size-at-bounds-offset (; 14 ;)
+  (if
+   (i32.or
+    (i32.gt_u
+     (i32.const 0)
+     (i32.shl
+      (memory.size)
+      (i32.const 16)
+     )
+    )
+    (global.get $__mem_segment_drop_state_7)
+   )
+   (unreachable)
+  )
+  (block
+   (global.set $__mem_segment_drop_state_7
+    (i32.const 1)
+   )
+   (data.drop 29)
+   (data.drop 30)
+   (data.drop 31)
+  )
+ )
 )
 (module
  (type $none_=>_none (func))
- (memory $0 1 1)
- (func $foo (; 0 ;)
+ (import "env" "memory" (memory $0 2048 2048))
+ (data passive "hi")
+ (data passive "even")
+ (data passive "hi")
+ (data passive "hi")
+ (data passive "even")
+ (data passive "hi")
+ (data passive "even")
+ (data passive "hi")
+ (data passive "even")
+ (data passive "hi")
+ (global $__mem_segment_drop_state_0 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_1 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_2 (mut i32) (i32.const 0))
+ (global $__mem_segment_drop_state_3 (mut i32) (i32.const 0))
+ (func $zero-length-init-zeroes (; 0 ;)
   (if
    (i32.or
     (i32.gt_u
-     (i32.const 0)
-     (i32.mul
-      (i32.const 65536)
+     (i32.const 13)
+     (i32.shl
       (memory.size)
+      (i32.const 16)
      )
     )
-    (i32.or
-     (i32.const 0)
-     (i32.const 0)
+    (global.get $__mem_segment_drop_state_0)
+   )
+   (unreachable)
+  )
+  (block
+   (global.set $__mem_segment_drop_state_0
+    (i32.const 1)
+   )
+   (data.drop 0)
+   (data.drop 1)
+   (data.drop 2)
+  )
+ )
+ (func $zero-length-init-nonzeroes (; 1 ;)
+  (if
+   (i32.or
+    (i32.gt_u
+     (i32.const 13)
+     (i32.shl
+      (memory.size)
+      (i32.const 16)
+     )
     )
+    (global.get $__mem_segment_drop_state_1)
    )
    (unreachable)
   )
+  (block
+   (global.set $__mem_segment_drop_state_1
+    (i32.const 1)
+   )
+   (data.drop 3)
+   (data.drop 4)
+   (data.drop 5)
+  )
  )
- (func $bar (; 1 ;)
-  (drop
-   (loop $loop-in (result i32)
-    (nop)
-    (i32.const 42)
+ (func $zero-length-init-zeroes-2 (; 2 ;)
+  (if
+   (i32.or
+    (i32.gt_u
+     (i32.const 13)
+     (i32.shl
+      (memory.size)
+      (i32.const 16)
+     )
+    )
+    (global.get $__mem_segment_drop_state_2)
+   )
+   (unreachable)
+  )
+  (block
+   (global.set $__mem_segment_drop_state_2
+    (i32.const 1)
+   )
+   (data.drop 6)
+   (data.drop 7)
+  )
+ )
+ (func $zero-length-init-nonzeroes-2 (; 3 ;)
+  (if
+   (i32.or
+    (i32.gt_u
+     (i32.const 13)
+     (i32.shl
+      (memory.size)
+      (i32.const 16)
+     )
+    )
+    (global.get $__mem_segment_drop_state_3)
+   )
+   (unreachable)
+  )
+  (block
+   (global.set $__mem_segment_drop_state_3
+    (i32.const 1)
    )
+   (data.drop 8)
+   (data.drop 9)
   )
  )
 )
diff --git a/test/passes/memory-packing_all-features.wast b/test/passes/memory-packing_all-features.wast
index edaba9f11..ea1ea19f7 100644
--- a/test/passes/memory-packing_all-features.wast
+++ b/test/passes/memory-packing_all-features.wast
@@ -1,38 +1,483 @@
 (module
   (import "env" "memory" (memory $0 2048 2048))
   (import "env" "memoryBase" (global $memoryBase i32))
+  ;; nothing
+)
+
+(module
+  (import "env" "memory" (memory $0 2048 2048))
+  (import "env" "memoryBase" (global $memoryBase i32))
+  (data (i32.const 4066) "") ;; empty
+)
+
+(module
+  (import "env" "memory" (memory $0 2048 2048))
+  (import "env" "memoryBase" (global $memoryBase i32))
+
   (data (global.get $memoryBase) "waka this cannot be optimized\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00we don't know where it will go")
+
   (data (i32.const 1024) "waka this CAN be optimized\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00we DO know where it will go")
+
   (data (i32.const 2000) "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeros before")
+
   (data (i32.const 3000) "zeros after\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00")
+
   (data (i32.const 4000) "zeros\00in\00the\00middle\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00nice skip here\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00another\00but no")
+
+  (func $nonzero-size-init-of-active-will-trap
+    (memory.init 0
+      (i32.const 42)
+      (i32.const 0)
+      (i32.const 13)
+    )
+    (data.drop 0)
+  )
+
+  (func $nonzero-offset-init-of-active-will-trap
+    (memory.init 0
+      (i32.const 42)
+      (i32.const 13)
+      (i32.const 0)
+    )
+    (data.drop 0)
+  )
+
+  (func $zero-offset-size-init-of-active-may-trap
+    (memory.init 0
+      (i32.const 42)
+      (i32.const 0)
+      (i32.const 0)
+    )
+    (data.drop 0)
+  )
 )
+
 (module
   (import "env" "memory" (memory $0 2048 2048))
-  (import "env" "memoryBase" (global $memoryBase i32))
-  ;; nothing
+
+  (data passive "not referenced, delete me") ;; 0
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes at start") ;; 1
+
+  (func $zeroes-at-start
+    (memory.init 1
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 45)
+    )
+    (data.drop 1)
+  )
+
+  ;; the not-split tests have too many memory.init and data.drop instructions for splitting to be worth it
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes at start") ;; 2
+
+  (func $zeroes-at-start-not-split
+    (memory.init 2
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 45)
+    )
+    (memory.init 2
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 45)
+    )
+    (memory.init 2
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 45)
+    )
+    (memory.init 2
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 45)
+    )
+    (data.drop 2)
+  )
+
+  (data passive "\00\00\00few zeroes at start") ;; 3
+
+  (func $few-zeroes-at-start
+    (memory.init 3
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 22)
+    )
+    (data.drop 3)
+  )
+
+  (data passive "zeroes at end\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 4
+
+  (func $zeroes-at-end
+    (memory.init 4
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 43)
+    )
+    (data.drop 4)
+  )
+
+  (data passive "zeroes at end\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 5
+
+  (func $zeroes-at-end-not-split
+    (memory.init 5
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 43)
+    )
+    (memory.init 5
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 43)
+    )
+    (memory.init 5
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 43)
+    )
+    (memory.init 5
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 43)
+    )
+    (data.drop 5)
+  )
+
+  (data passive "few zeroes at end\00\00\00") ;; 6
+
+  (func $few-zeroes-at-end
+    (memory.init 6
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 20)
+    )
+    (data.drop 6)
+  )
+
+  (data passive "zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00in middle") ;; 7
+
+  (func $zeroes-in-middle
+    (memory.init 7
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 45)
+    )
+    (data.drop 7)
+  )
+
+  (data passive "zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00in middle") ;; 8
+
+  (func $zeroes-in-middle-not-split
+    (memory.init 8
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 35)
+    )
+    (memory.init 8
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 45)
+    )
+    (data.drop 8)
+  )
+
+  (data passive "few zeroes\00\00\00in middle") ;; 9
+
+  (func $few-zeroes-in-middle
+    (memory.init 9
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 22)
+    )
+    (data.drop 9)
+  )
+
+  (data passive "multiple\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00spans\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00of zeroes") ;; 10
+
+  (func $multiple-spans-of-zeroes
+    (memory.init 10
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 82)
+    )
+    (data.drop 10)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 11
+
+  (func $even-more-zeroes
+    (memory.init 11
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 134)
+    )
+    (data.drop 11)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 12
+
+  (func $only-zeroes
+    (memory.init 12
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 30)
+    )
+    (data.drop 12)
+  )
+
+  (data passive "no zeroes") ;; 13
+
+  (func $no-zeroes
+    (memory.init 13
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 9)
+    )
+    (data.drop 13)
+  )
+
+  (data passive "") ;; 14
+
+  (func $empty
+    (memory.init 14
+      (i32.const 13)
+      (i32.const 0)
+      (i32.const 0)
+    )
+    (data.drop 14)
+  )
+
+  (data passive "only dropped") ;; 15
+
+  (func $only-dropped
+    (data.drop 15)
+    (data.drop 15)
+  )
+
+  (data passive "\00\00\00\00\00") ;; 16
+
+  (func $only-dropped-zeroes
+    (data.drop 16)
+    (data.drop 16)
+  )
+
+  (data passive "") ;; not referenced
+
+  (data passive "\00\00\00\00\00") ;; not referenced
 )
+
 (module
   (import "env" "memory" (memory $0 2048 2048))
-  (import "env" "memoryBase" (global $memoryBase i32))
-  (data (i32.const 4066) "") ;; empty
+  (import "env" "param" (global $param i32))
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 0
+
+  (func $nonconst-dest
+    (memory.init 0
+      (global.get $param)
+      (i32.const 0)
+      (i32.const 134)
+    )
+    (data.drop 0)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 1
+
+  (func $nonconst-offset
+    (memory.init 1
+      (i32.const 0)
+      (global.get $param)
+      (i32.const 134)
+    )
+    (data.drop 1)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 2
+
+  (func $nonconst-size
+    (memory.init 2
+      (i32.const 0)
+      (i32.const 0)
+      (global.get $param)
+    )
+    (data.drop 2)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 3
+
+  (func $partial-skip-start
+    (memory.init 3
+      (i32.const 0)
+      (i32.const 10)
+      (i32.const 124)
+    )
+    (data.drop 3)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 4
+
+  (func $full-skip-start
+    (memory.init 4
+      (i32.const 0)
+      (i32.const 32)
+      (i32.const 102)
+    )
+    (data.drop 4)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 5
+
+  (func $partial-skip-end
+    (memory.init 5
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 124)
+    )
+    (data.drop 5)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 6
+
+  (func $full-skip-end
+    (memory.init 6
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 102)
+    )
+    (data.drop 6)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 7
+
+  (func $slice-zeroes
+    (memory.init 7
+      (i32.const 0)
+      (i32.const 35)
+      (i32.const 10)
+    )
+    (data.drop 7)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 8
+
+  (func $slice-nonzeroes
+    (memory.init 8
+      (i32.const 0)
+      (i32.const 31)
+      (i32.const 2)
+    )
+    (data.drop 8)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 9
+
+  (func $zero-size
+    (memory.init 9
+      (i32.const 13)
+      (i32.const 40)
+      (i32.const 0)
+    )
+    (data.drop 9)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 10
+
+  (func $zero-size-undropped
+    (memory.init 10
+      (i32.const 13)
+      (i32.const 40)
+      (i32.const 0)
+    )
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 11
+
+  (func $out-of-bounds-offset
+    (memory.init 11
+      (i32.const 0)
+      (i32.const 135)
+      (i32.const 1)
+    )
+    (data.drop 11)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 12
+
+  (func $zero-size-out-of-bounds-offset
+    (memory.init 12
+      (i32.const 0)
+      (i32.const 135)
+      (i32.const 0)
+    )
+    (data.drop 12)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 13
+
+  (func $out-of-bounds-size
+    (memory.init 13
+      (i32.const 0)
+      (i32.const 0)
+      (i32.const 135)
+    )
+    (data.drop 13)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00more\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00zeroes\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00") ;; 14
+
+  (func $zero-size-at-bounds-offset
+    (memory.init 14
+      (i32.const 0)
+      (i32.const 134)
+      (i32.const 0)
+    )
+    (data.drop 14)
+  )
 )
+
 (module
- (memory $0 1 1)
- (data (i32.const 0) "")
- (func $foo
-  (memory.init 0
-   (i32.const 0)
-   (i32.const 0)
-   (i32.const 0)
-  )
- )
- (func $bar
-  (drop
-   (loop (result i32)
+  (import "env" "memory" (memory $0 2048 2048))
+  (data passive "hi\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00hi") ;; 0
+
+  (func $zero-length-init-zeroes
+    (memory.init 0
+      (i32.const 13)
+      (i32.const 10)
+      (i32.const 0)
+    )
     (data.drop 0)
-    (i32.const 42)
-   )
   )
- )
+
+  (data passive "hi\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00hi") ;; 1
+
+  (func $zero-length-init-nonzeroes
+    (memory.init 1
+      (i32.const 13)
+      (i32.const 33)
+      (i32.const 0)
+    )
+    (data.drop 1)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00hi") ;; 2
+
+  (func $zero-length-init-zeroes-2
+    (memory.init 2
+      (i32.const 13)
+      (i32.const 10)
+      (i32.const 0)
+    )
+    (data.drop 2)
+  )
+
+  (data passive "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00even\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00hi") ;; 3
+
+  (func $zero-length-init-nonzeroes-2
+    (memory.init 3
+      (i32.const 13)
+      (i32.const 31)
+      (i32.const 0)
+    )
+    (data.drop 3)
+  )
 )
diff --git a/test/wasm2js/emscripten.2asm.js.opt b/test/wasm2js/emscripten.2asm.js.opt
index 5dcef5bce..84e33bb6f 100644
--- a/test/wasm2js/emscripten.2asm.js.opt
+++ b/test/wasm2js/emscripten.2asm.js.opt
@@ -201,10 +201,8 @@ var writeSegment = (
     }
   )(wasmMemory.buffer);
 writeSegment(1024, "aGVsbG8sIHdvcmxkIQoAAJwMAAAtKyAgIDBYMHgAKG51bGwp");
-writeSegment(1072, "EQAKABEREQAAAAAFAAAAAAAACQAAAAAL");
-writeSegment(1104, "EQAPChEREQMKBwABEwkLCwAACQYLAAALAAYRAAAAERER");
-writeSegment(1153, "Cw==");
-writeSegment(1162, "EQAKChEREQAKAAACAAkLAAAACQALAAAL");
+writeSegment(1072, "EQAKABEREQAAAAAFAAAAAAAACQAAAAALAAAAAAAAAAARAA8KERERAwoHAAETCQsLAAAJBgsAAAsABhEAAAARERE=");
+writeSegment(1153, "CwAAAAAAAAAAEQAKChEREQAKAAACAAkLAAAACQALAAAL");
 writeSegment(1211, "DA==");
 writeSegment(1223, "DAAAAAAMAAAAAAkMAAAAAAAMAAAM");
 writeSegment(1269, "Dg==");