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-rw-r--r--src/passes/RemoveUnusedBrs.cpp10
-rw-r--r--test/lit/passes/remove-unused-brs.wast66
2 files changed, 57 insertions, 19 deletions
diff --git a/src/passes/RemoveUnusedBrs.cpp b/src/passes/RemoveUnusedBrs.cpp
index 32f7bd48a..47a1f1c65 100644
--- a/src/passes/RemoveUnusedBrs.cpp
+++ b/src/passes/RemoveUnusedBrs.cpp
@@ -621,9 +621,13 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
block->finalize();
return true;
}
- } else {
- // this is already an if-else. if one side is a dead end, we can
- // append to the other, if there is no returned value to concern us
+ } else if (iff->condition->type != Type::unreachable) {
+ // This is already an if-else. If one side is a dead end, we can
+ // append to the other, if there is no returned value to concern us.
+ // Note that we skip ifs with unreachable conditions, as they are dead
+ // code that DCE can remove, and modifying them can lead to errors
+ // (one of the arms may still be concrete, in which case appending to
+ // it would be invalid).
// can't be, since in the middle of a block
assert(!iff->type.isConcrete());
diff --git a/test/lit/passes/remove-unused-brs.wast b/test/lit/passes/remove-unused-brs.wast
index 2019d37a4..c61320602 100644
--- a/test/lit/passes/remove-unused-brs.wast
+++ b/test/lit/passes/remove-unused-brs.wast
@@ -30,7 +30,7 @@
)
)
- ;; CHECK: (func $selectify-simple (type $0) (param $0 i32) (result i32)
+ ;; CHECK: (func $selectify-simple (type $1) (param $0 i32) (result i32)
;; CHECK-NEXT: (select
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: (i32.lt_u
@@ -73,7 +73,7 @@
)
)
- ;; CHECK: (func $restructure-br_if (type $0) (param $x i32) (result i32)
+ ;; CHECK: (func $restructure-br_if (type $1) (param $x i32) (result i32)
;; CHECK-NEXT: (if (result i32)
;; CHECK-NEXT: (local.get $x)
;; CHECK-NEXT: (then
@@ -104,12 +104,12 @@
)
)
- ;; CHECK: (func $nothing (type $1)
+ ;; CHECK: (func $nothing (type $0)
;; CHECK-NEXT: )
(func $nothing)
- ;; CHECK: (func $restructure-br_if-condition-reorderable (type $0) (param $x i32) (result i32)
+ ;; CHECK: (func $restructure-br_if-condition-reorderable (type $1) (param $x i32) (result i32)
;; CHECK-NEXT: (if (result i32)
;; CHECK-NEXT: (block (result i32)
;; CHECK-NEXT: (call $nothing)
@@ -146,7 +146,7 @@
)
)
- ;; CHECK: (func $restructure-br_if-value-effectful (type $0) (param $x i32) (result i32)
+ ;; CHECK: (func $restructure-br_if-value-effectful (type $1) (param $x i32) (result i32)
;; CHECK-NEXT: (select
;; CHECK-NEXT: (block (result i32)
;; CHECK-NEXT: (call $nothing)
@@ -188,7 +188,7 @@
)
)
- ;; CHECK: (func $restructure-br_if-value-effectful-corner-case-1 (type $0) (param $x i32) (result i32)
+ ;; CHECK: (func $restructure-br_if-value-effectful-corner-case-1 (type $1) (param $x i32) (result i32)
;; CHECK-NEXT: (block $x (result i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (br_if $x
@@ -233,7 +233,7 @@
(i32.const 400)
)
- ;; CHECK: (func $restructure-br_if-value-effectful-corner-case-2 (type $0) (param $x i32) (result i32)
+ ;; CHECK: (func $restructure-br_if-value-effectful-corner-case-2 (type $1) (param $x i32) (result i32)
;; CHECK-NEXT: (block $x (result i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (br_if $x
@@ -272,7 +272,7 @@
(call $get-i32)
)
)
- ;; CHECK: (func $restructure-br_if-value-effectful-corner-case-3 (type $0) (param $x i32) (result i32)
+ ;; CHECK: (func $restructure-br_if-value-effectful-corner-case-3 (type $1) (param $x i32) (result i32)
;; CHECK-NEXT: (block $x (result i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (br_if $x
@@ -305,7 +305,7 @@
)
)
- ;; CHECK: (func $restructure-br_if-value-effectful-corner-case-4 (type $0) (param $x i32) (result i32)
+ ;; CHECK: (func $restructure-br_if-value-effectful-corner-case-4 (type $1) (param $x i32) (result i32)
;; CHECK-NEXT: (block $x (result i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (br_if $x
@@ -340,7 +340,7 @@
)
)
- ;; CHECK: (func $restructure-select-no-multivalue (type $1)
+ ;; CHECK: (func $restructure-select-no-multivalue (type $0)
;; CHECK-NEXT: (tuple.drop 2
;; CHECK-NEXT: (block $block (type $2) (result i32 i32)
;; CHECK-NEXT: (tuple.drop 2
@@ -387,7 +387,7 @@
)
)
- ;; CHECK: (func $if-of-if (type $1)
+ ;; CHECK: (func $if-of-if (type $0)
;; CHECK-NEXT: (local $x i32)
;; CHECK-NEXT: (if
;; CHECK-NEXT: (select
@@ -421,7 +421,7 @@
)
)
- ;; CHECK: (func $if-of-if-but-side-effects (type $1)
+ ;; CHECK: (func $if-of-if-but-side-effects (type $0)
;; CHECK-NEXT: (local $x i32)
;; CHECK-NEXT: (if
;; CHECK-NEXT: (local.tee $x
@@ -460,7 +460,7 @@
)
)
- ;; CHECK: (func $if-of-if-but-too-costly (type $1)
+ ;; CHECK: (func $if-of-if-but-too-costly (type $0)
;; CHECK-NEXT: (local $x i32)
;; CHECK-NEXT: (if
;; CHECK-NEXT: (local.tee $x
@@ -515,7 +515,7 @@
)
)
- ;; CHECK: (func $if-of-if-but-inner-else (type $1)
+ ;; CHECK: (func $if-of-if-but-inner-else (type $0)
;; CHECK-NEXT: (local $x i32)
;; CHECK-NEXT: (if
;; CHECK-NEXT: (local.tee $x
@@ -555,7 +555,7 @@
)
)
- ;; CHECK: (func $if-of-if-but-outer-else (type $1)
+ ;; CHECK: (func $if-of-if-but-outer-else (type $0)
;; CHECK-NEXT: (local $x i32)
;; CHECK-NEXT: (if
;; CHECK-NEXT: (local.tee $x
@@ -595,7 +595,7 @@
)
)
- ;; CHECK: (func $unreachable-if (type $1)
+ ;; CHECK: (func $unreachable-if (type $0)
;; CHECK-NEXT: (block $block
;; CHECK-NEXT: (if (result i32)
;; CHECK-NEXT: (unreachable)
@@ -624,4 +624,38 @@
)
)
)
+
+ ;; CHECK: (func $loop-with-unreachable-if (type $0)
+ ;; CHECK-NEXT: (loop $label
+ ;; CHECK-NEXT: (if (result i32)
+ ;; CHECK-NEXT: (unreachable)
+ ;; CHECK-NEXT: (then
+ ;; CHECK-NEXT: (unreachable)
+ ;; CHECK-NEXT: )
+ ;; CHECK-NEXT: (else
+ ;; CHECK-NEXT: (i32.const 0)
+ ;; CHECK-NEXT: )
+ ;; CHECK-NEXT: )
+ ;; CHECK-NEXT: (br $label)
+ ;; CHECK-NEXT: )
+ ;; CHECK-NEXT: )
+ (func $loop-with-unreachable-if
+ ;; We normally move brs right after an if into one of the if arms, when
+ ;; possible. That is almost possible here, but the if condition is
+ ;; unreachable, which allows one of the arms to have a concrete type. It is
+ ;; invalid to append to such an arm, so we should do nothing (leaving this
+ ;; for DCE).
+ (loop $label
+ (if (result i32)
+ (unreachable)
+ (then
+ (unreachable)
+ )
+ (else
+ (i32.const 0)
+ )
+ )
+ (br $label)
+ )
+ )
)
generated by cgit v1.2.3 (git 2.39.1) at 2025-08-05 15:46:20 +0000