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58ac25b453
Make sure that the loop is not fully unrolled (which allows eliminating the allocas) in LLVM 16 either.
50 lines
1.7 KiB
Rust
50 lines
1.7 KiB
Rust
// compile-flags: -C opt-level=3 -C target-cpu=x86-64-v3
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// no-system-llvm
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// only-x86_64
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// ignore-debug (the extra assertions get in the way)
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#![crate_type = "lib"]
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#![feature(array_zip)]
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// CHECK-LABEL: @short_integer_map
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#[no_mangle]
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pub fn short_integer_map(x: [u32; 8]) -> [u32; 8] {
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// CHECK: load <8 x i32>
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// CHECK: shl <8 x i32>
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// CHECK: or <8 x i32>
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// CHECK: store <8 x i32>
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x.map(|x| 2 * x + 1)
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}
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// CHECK-LABEL: @short_integer_zip_map
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#[no_mangle]
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pub fn short_integer_zip_map(x: [u32; 8], y: [u32; 8]) -> [u32; 8] {
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// CHECK: %[[A:.+]] = load <8 x i32>
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// CHECK: %[[B:.+]] = load <8 x i32>
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// CHECK: sub <8 x i32> %[[A]], %[[B]]
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// CHECK: store <8 x i32>
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x.zip(y).map(|(x, y)| x - y)
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}
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// This test is checking that LLVM can SRoA away a bunch of the overhead,
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// like fully moving the iterators to registers. Notably, previous implementations
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// of `map` ended up `alloca`ing the whole `array::IntoIterator`, meaning both a
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// hard-to-eliminate `memcpy` and that the iteration counts needed to be written
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// out to stack every iteration, even for infallible operations on `Copy` types.
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//
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// This is still imperfect, as there's more copies than would be ideal,
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// but hopefully work like #103830 will improve that in future,
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// and update this test to be stricter.
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//
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// CHECK-LABEL: @long_integer_map
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#[no_mangle]
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pub fn long_integer_map(x: [u32; 512]) -> [u32; 512] {
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// CHECK: start:
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// CHECK-NEXT: alloca [512 x i32]
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// CHECK-NEXT: alloca %"core::mem::manually_drop::ManuallyDrop<[u32; 512]>"
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// CHECK-NOT: alloca
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// CHECK: mul <{{[0-9]+}} x i32>
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// CHECK: add <{{[0-9]+}} x i32>
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x.map(|x| 13 * x + 7)
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}
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