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Use fallthrough in optimizeInstructions to further optimize (unsigned)x >= 0 ==> i32(0) #7557

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Use fallthrough in optimizeInstructions to further optimize (unsigned)x >= 0 ==> i32(0) #7557

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e406be6
opt for #7556
xuruiyang2002 Apr 26, 2025
1cacdf3
test
xuruiyang2002 Apr 26, 2025
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11 changes: 6 additions & 5 deletions src/passes/OptimizeInstructions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -562,12 +562,13 @@ struct OptimizeInstructions
{
// unsigned(x) >= 0 => i32(1)
Const* c;
Expression* x;
if (matches(curr, binary(GeU, any(&x), ival(&c))) &&
if (curr->op == Abstract::getBinary(curr->left->type, Abstract::GeU) &&
(c = getFallthrough(curr->right)->dynCast<Const>()) &&
c->value.isZero()) {
c->value = Literal::makeOne(Type::i32);
c->type = Type::i32;
return replaceCurrent(getDroppedChildrenAndAppend(curr, c));
// We could reuse c here, if we checked it had no more uses
auto one =
Builder(*getModule()).makeConst(Literal::makeOne(Type::i32));
return replaceCurrent(getDroppedChildrenAndAppend(curr, one));
}
// unsigned(x) < 0 => i32(0)
if (curr->op == Abstract::getBinary(curr->left->type, Abstract::LtU) &&
Expand Down
64 changes: 64 additions & 0 deletions test/lit/passes/optimize-instructions-mvp.wast
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Original file line number Diff line number Diff line change
Expand Up @@ -11550,6 +11550,44 @@
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (i32.load
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result i32)
;; CHECK-NEXT: (i32.store
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (i64.load
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result i64)
;; CHECK-NEXT: (i64.store
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: (i64.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: (i64.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
Expand Down Expand Up @@ -11884,6 +11922,32 @@
)
(i64.const 0)
))
(drop (i32.ge_u
(i32.load
(i32.const 0)
)
(block (result i32)
(i32.store
(i32.const 0)
(i32.const 0)
)
(i32.const 0)
)
)
)
(drop (i64.ge_u
(i64.load
(i32.const 0)
)
(block (result i64)
(i64.store
(i32.const 0)
(i64.const 0)
)
(i64.const 0)
)
)
)

;; (unsigned)x < 0 => i32(0)
(drop (i32.lt_u
Expand Down
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