Skip to content

Fix Vacuuming of code leading up to an infinite loop #6632

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 4 commits into from
May 29, 2024
Merged

Fix Vacuuming of code leading up to an infinite loop #6632

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
be5ad79
show problem
kripken May 29, 2024
429fbd2
fix
kripken May 29, 2024
d38961c
Merge remote-tracking branch 'origin/main' into vacuum.iloop
kripken May 29, 2024
1442250
comment
kripken May 29, 2024
File filter

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 5 additions & 4 deletions src/passes/Vacuum.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -158,15 +158,16 @@ struct Vacuum : public WalkerPass<ExpressionStackWalker<Vacuum>> {
continue;
}

// Check if we may no longer be heading to a trap. Two situations count
// here: Control flow might branch, or we might call (since a call might
// reach an import; see notes on that in pass.h:trapsNeverHappen).
// Check if we may no longer be heading to a trap. We can only optimize
// if the trap will actually be reached. Two situations can prevent that
// here: Control flow might branch away, or we might hang (which can
// happen in a call or a loop).
//
// We also cannot remove a pop as it is necessary for structural
// reasons.
EffectAnalyzer effects(getPassOptions(), *getModule(), list[i]);
if (effects.transfersControlFlow() || effects.calls ||
effects.danglingPop) {
effects.mayNotReturn || effects.danglingPop) {
headingToTrap = false;
continue;
}
Expand Down
63 changes: 41 additions & 22 deletions test/lit/passes/vacuum-tnh.wast
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -117,10 +117,10 @@
)

;; A helper function for the above, that returns nothing.
;; YESTNH: (func $return-nothing (type $1)
;; YESTNH: (func $return-nothing (type $0)
;; YESTNH-NEXT: (nop)
;; YESTNH-NEXT: )
;; NO_TNH: (func $return-nothing (type $1)
;; NO_TNH: (func $return-nothing (type $0)
;; NO_TNH-NEXT: (nop)
;; NO_TNH-NEXT: )
(func $return-nothing)
Expand Down Expand Up @@ -179,10 +179,10 @@
(local.get $y)
)

;; YESTNH: (func $toplevel (type $1)
;; YESTNH: (func $toplevel (type $0)
;; YESTNH-NEXT: (nop)
;; YESTNH-NEXT: )
;; NO_TNH: (func $toplevel (type $1)
;; NO_TNH: (func $toplevel (type $0)
;; NO_TNH-NEXT: (unreachable)
;; NO_TNH-NEXT: )
(func $toplevel
Expand All @@ -191,7 +191,7 @@
(unreachable)
)

;; YESTNH: (func $drop-loop (type $1)
;; YESTNH: (func $drop-loop (type $0)
;; YESTNH-NEXT: (drop
;; YESTNH-NEXT: (loop $loop (result i32)
;; YESTNH-NEXT: (br_if $loop
Expand All @@ -201,7 +201,7 @@
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; NO_TNH: (func $drop-loop (type $1)
;; NO_TNH: (func $drop-loop (type $0)
;; NO_TNH-NEXT: (drop
;; NO_TNH-NEXT: (loop $loop (result i32)
;; NO_TNH-NEXT: (br_if $loop
Expand All @@ -224,7 +224,7 @@
)
)

;; YESTNH: (func $loop-effects (type $1)
;; YESTNH: (func $loop-effects (type $0)
;; YESTNH-NEXT: (drop
;; YESTNH-NEXT: (loop $loop (result i32)
;; YESTNH-NEXT: (drop
Expand All @@ -239,7 +239,7 @@
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; NO_TNH: (func $loop-effects (type $1)
;; NO_TNH: (func $loop-effects (type $0)
;; NO_TNH-NEXT: (drop
;; NO_TNH-NEXT: (loop $loop (result i32)
;; NO_TNH-NEXT: (drop
Expand Down Expand Up @@ -272,7 +272,7 @@
)
)

;; YESTNH: (func $if-unreachable (type $0) (param $p i32)
;; YESTNH: (func $if-unreachable (type $1) (param $p i32)
;; YESTNH-NEXT: (drop
;; YESTNH-NEXT: (local.get $p)
;; YESTNH-NEXT: )
Expand All @@ -294,7 +294,7 @@
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; NO_TNH: (func $if-unreachable (type $0) (param $p i32)
;; NO_TNH: (func $if-unreachable (type $1) (param $p i32)
;; NO_TNH-NEXT: (if
;; NO_TNH-NEXT: (local.get $p)
;; NO_TNH-NEXT: (then
Expand Down Expand Up @@ -415,7 +415,7 @@
)
)

;; YESTNH: (func $block-unreachable (type $0) (param $p i32)
;; YESTNH: (func $block-unreachable (type $1) (param $p i32)
;; YESTNH-NEXT: (if
;; YESTNH-NEXT: (local.get $p)
;; YESTNH-NEXT: (then
Expand All @@ -433,7 +433,7 @@
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; NO_TNH: (func $block-unreachable (type $0) (param $p i32)
;; NO_TNH: (func $block-unreachable (type $1) (param $p i32)
;; NO_TNH-NEXT: (if
;; NO_TNH-NEXT: (local.get $p)
;; NO_TNH-NEXT: (then
Expand Down Expand Up @@ -482,7 +482,7 @@
)
)

;; YESTNH: (func $block-unreachable-named (type $0) (param $p i32)
;; YESTNH: (func $block-unreachable-named (type $1) (param $p i32)
;; YESTNH-NEXT: (if
;; YESTNH-NEXT: (local.get $p)
;; YESTNH-NEXT: (then
Expand All @@ -499,7 +499,7 @@
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; NO_TNH: (func $block-unreachable-named (type $0) (param $p i32)
;; NO_TNH: (func $block-unreachable-named (type $1) (param $p i32)
;; NO_TNH-NEXT: (if
;; NO_TNH-NEXT: (local.get $p)
;; NO_TNH-NEXT: (then
Expand Down Expand Up @@ -544,10 +544,10 @@
)
)

;; YESTNH: (func $block-unreachable-all (type $0) (param $p i32)
;; YESTNH: (func $block-unreachable-all (type $1) (param $p i32)
;; YESTNH-NEXT: (nop)
;; YESTNH-NEXT: )
;; NO_TNH: (func $block-unreachable-all (type $0) (param $p i32)
;; NO_TNH: (func $block-unreachable-all (type $1) (param $p i32)
;; NO_TNH-NEXT: (if
;; NO_TNH-NEXT: (local.get $p)
;; NO_TNH-NEXT: (then
Expand Down Expand Up @@ -584,15 +584,15 @@
)
)

;; YESTNH: (func $block-unreachable-but-call (type $1)
;; YESTNH: (func $block-unreachable-but-call (type $0)
;; YESTNH-NEXT: (i32.store
;; YESTNH-NEXT: (i32.const 0)
;; YESTNH-NEXT: (i32.const 1)
;; YESTNH-NEXT: )
;; YESTNH-NEXT: (call $block-unreachable-but-call)
;; YESTNH-NEXT: (unreachable)
;; YESTNH-NEXT: )
;; NO_TNH: (func $block-unreachable-but-call (type $1)
;; NO_TNH: (func $block-unreachable-but-call (type $0)
;; NO_TNH-NEXT: (i32.store
;; NO_TNH-NEXT: (i32.const 0)
;; NO_TNH-NEXT: (i32.const 1)
Expand Down Expand Up @@ -620,7 +620,7 @@
(unreachable)
)

;; YESTNH: (func $catch-pop (type $1)
;; YESTNH: (func $catch-pop (type $0)
;; YESTNH-NEXT: (try $try
;; YESTNH-NEXT: (do
;; YESTNH-NEXT: (call $catch-pop)
Expand All @@ -633,7 +633,7 @@
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; NO_TNH: (func $catch-pop (type $1)
;; NO_TNH: (func $catch-pop (type $0)
;; NO_TNH-NEXT: (try $try
;; NO_TNH-NEXT: (do
;; NO_TNH-NEXT: (call $catch-pop)
Expand Down Expand Up @@ -673,7 +673,7 @@
)
)

;; YESTNH: (func $loop-unreachable (type $0) (param $p i32)
;; YESTNH: (func $loop-unreachable (type $1) (param $p i32)
;; YESTNH-NEXT: (loop $loop
;; YESTNH-NEXT: (i32.store
;; YESTNH-NEXT: (i32.const 0)
Expand All @@ -688,7 +688,7 @@
;; YESTNH-NEXT: (unreachable)
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; NO_TNH: (func $loop-unreachable (type $0) (param $p i32)
;; NO_TNH: (func $loop-unreachable (type $1) (param $p i32)
;; NO_TNH-NEXT: (loop $loop
;; NO_TNH-NEXT: (i32.store
;; NO_TNH-NEXT: (i32.const 0)
Expand Down Expand Up @@ -728,4 +728,23 @@
(unreachable)
)
)

;; YESTNH: (func $unreached-infinite-loop (type $0)
;; YESTNH-NEXT: (loop $label$1
;; YESTNH-NEXT: (br $label$1)
;; YESTNH-NEXT: )
;; YESTNH-NEXT: )
;; NO_TNH: (func $unreached-infinite-loop (type $0)
;; NO_TNH-NEXT: (loop $label$1
;; NO_TNH-NEXT: (br $label$1)
;; NO_TNH-NEXT: )
;; NO_TNH-NEXT: )
(func $unreached-infinite-loop
;; Code that reaches an unreachable can be removed in TNH mode, but an
;; infinite loop may not reach it, so nothing can be removed here.
(loop $label$1
(br $label$1)
)
(unreachable)
)
)