diff options
Diffstat (limited to 'test')
| -rw-r--r-- | test/lit/passes/simplify-locals_rse_fallthrough.wast | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/test/lit/passes/simplify-locals_rse_fallthrough.wast b/test/lit/passes/simplify-locals_rse_fallthrough.wast new file mode 100644 index 000000000..a9161a853 --- /dev/null +++ b/test/lit/passes/simplify-locals_rse_fallthrough.wast @@ -0,0 +1,47 @@ +;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited. +;; RUN: wasm-opt %s --simplify-locals --rse -S -o - \ +;; RUN: | filecheck %s + +(module + ;; CHECK: (func $no (param $x i32) (result i32) + ;; CHECK-NEXT: (i32.add + ;; CHECK-NEXT: (block $block (result i32) + ;; CHECK-NEXT: (local.tee $x + ;; CHECK-NEXT: (br_if $block + ;; CHECK-NEXT: (local.get $x) + ;; CHECK-NEXT: (local.tee $x + ;; CHECK-NEXT: (i32.const 42) + ;; CHECK-NEXT: ) + ;; CHECK-NEXT: ) + ;; CHECK-NEXT: ) + ;; CHECK-NEXT: ) + ;; CHECK-NEXT: (local.get $x) + ;; CHECK-NEXT: ) + ;; CHECK-NEXT: ) + (func $no (param $x i32) (result i32) + (i32.add + (block $block (result i32) + ;; This local.tee is necessary. It might seem that the br_if flows out + ;; $x, so we don't need to write that same value to $x once more. + ;; SimplifyLocals and RedundantSetElimination try to find such sets and + ;; remove them. But this set is necessary, since a tee of $x executes + ;; after that local.get. That is, the br_if flows out the *old* value of + ;; $x. What happens in practice is that we branch (since the condition + ;; is 42), and flow out the old $x, which gets tee'd into $x once more. + ;; As a result, the block flows out the original value of $x, and the + ;; local.get reads that same value, so the final add returns 2 times the + ;; original value of $x. For all that to happen, we need those + ;; optimization passes to *not* remove the outer local.tee. + (local.tee $x + (br_if $block + (local.get $x) + (local.tee $x + (i32.const 42) + ) + ) + ) + ) + (local.get $x) + ) + ) +) |