ab65d8f10c
In the current translation of wasm (128-bit) SIMD into CLIF, we work around differences in the
type system models of wasm vs CLIF by inserting `bitcast` (a no-op cast) CLIF instructions before
more or less every use of a SIMD value. Unfortunately this was not being done consistently and
even small examples with a single if-then-else diamond that produces a SIMD value, could cause a
verification failure downstream. In this case, the jump out of the "else" block needed a
bitcast, but didn't have one.
This patch wraps creation of CLIF jumps and conditional branches up into three functions,
`canonicalise_then_jump` and `canonicalise_then_br{z,nz}`, and uses them consistently. They
first cast the relevant block formal parameters, then generate the relevant kind of branch/jump.
Hence, provided they are also used consistently in future to generate branches/jumps in this
file, we are protected against such failures.
The patch also adds a large(ish) comment at the top explaining this in more detail.
16 lines
428 B
Plaintext
16 lines
428 B
Plaintext
(module
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(memory (export "mem") 1 1)
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(func (export "runif") (param $cond i32)
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i32.const 48
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(v128.load (i32.const 0))
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(v128.load (i32.const 16))
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(if (param v128) (param v128) (result v128 v128)
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(local.get $cond)
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(then i64x2.add
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(v128.load (i32.const 32)))
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(else i32x4.sub
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(v128.load (i32.const 0))))
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i16x8.mul
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v128.store)
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)
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