| Issue |
179145
|
| Summary |
[WebAssembly] bitcast defeats extadd pattern
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
folkertdev
|
Same general idea as https://github.com/llvm/llvm-project/issues/179143, see:
https://godbolt.org/z/cdnMsrjfe
```llvm
define <4 x i32> @with_bitcast(<4 x i32> %a) {
start:
%a1 = bitcast <4 x i32> %a to <8 x i16>
%0 = shufflevector <8 x i16> %a1, <8 x i16> %a1, <4 x i32> <i32 0, i32 2, i32 4, i32 6>
%1 = shufflevector <8 x i16> %a1, <8 x i16> %a1, <4 x i32> <i32 1, i32 3, i32 5, i32 7>
%2 = sext <4 x i16> %0 to <4 x i32>
%3 = sext <4 x i16> %1 to <4 x i32>
%4 = add nsw <4 x i32> %2, %3
ret <4 x i32> %4
}
define <4 x i32> @without_bitcast(<8 x i16> %a) {
start:
%0 = shufflevector <8 x i16> %a, <8 x i16> %a, <4 x i32> <i32 0, i32 2, i32 4, i32 6>
%1 = shufflevector <8 x i16> %a, <8 x i16> %a, <4 x i32> <i32 1, i32 3, i32 5, i32 7>
%2 = sext <4 x i16> %0 to <4 x i32>
%3 = sext <4 x i16> %1 to <4 x i32>
%4 = add nsw <4 x i32> %2, %3
ret <4 x i32> %4
}
```
```asm
with_bitcast:
local.get 0
i32.const 16
i32x4.shl
i32.const 16
i32x4.shr_s
local.get 0
local.get 0
i8x16.shuffle 2, 3, 6, 7, 10, 11, 14, 15, 0, 1, 0, 1, 0, 1, 0, 1
i32x4.extend_low_i16x8_s
i32x4.add
end_function
without_bitcast:
local.get 0
i32x4.extadd_pairwise_i16x8_s
end_function
```
cc @badumbatish https://github.com/llvm/llvm-project/pull/167960
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