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Auto merge of #138881 - scottmcm:more-chaining-ord, r=Mark-Simulacrum

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Use the chaining methods on PartialOrd for slices too

#138135 added these doc-hidden trait methods to improve the tuple codegen.  This PR adds more implementations and callers so that the codegen for slice (and array) comparisons also improves.
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bors 2025-04-13 11:47:23 +00:00
commit 53d4476111
4 changed files with 262 additions and 32 deletions
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55
tests/codegen/array-cmp.rs
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@ -1,6 +1,7 @@
// Ensure the asm for array comparisons is properly optimized.
//@ compile-flags: -C opt-level=2
//@ needs-deterministic-layouts (checks depend on tuple layout)
#![crate_type = "lib"]
@ -17,3 +18,57 @@ pub fn compare() -> bool {
[0x00, 0x00, 0x48, 0x41]
}
}
// CHECK-LABEL: @array_of_tuple_le
#[no_mangle]
pub fn array_of_tuple_le(a: &[(i16, u16); 2], b: &[(i16, u16); 2]) -> bool {
// Ensure that, after all the optimizations have run, the happy path just checks
// `eq` on each corresponding pair and moves onto the next one if it is.
// Then there's a dedup'd comparison for the place that's different.
// (As opposed to, say, running a full `[su]cmp` as part of checking equality.)
// This is written quite specifically because different library code was triggering
// <https://github.com/llvm/llvm-project/issues/132678> along the way, so this
// has enough checks to make sure that's not happening. It doesn't need to be
// *exactly* this IR, but be careful if you ever need to update these checks.
// CHECK: start:
// CHECK: %[[A00:.+]] = load i16, ptr %a
// CHECK: %[[B00:.+]] = load i16, ptr %b
// CHECK-NOT: cmp
// CHECK: %[[EQ00:.+]] = icmp eq i16 %[[A00]], %[[B00]]
// CHECK-NEXT: br i1 %[[EQ00]], label %[[L01:.+]], label %[[EXIT_S:.+]]
// CHECK: [[L01]]:
// CHECK: %[[PA01:.+]] = getelementptr{{.+}}i8, ptr %a, {{i32|i64}} 2
// CHECK: %[[PB01:.+]] = getelementptr{{.+}}i8, ptr %b, {{i32|i64}} 2
// CHECK: %[[A01:.+]] = load i16, ptr %[[PA01]]
// CHECK: %[[B01:.+]] = load i16, ptr %[[PB01]]
// CHECK-NOT: cmp
// CHECK: %[[EQ01:.+]] = icmp eq i16 %[[A01]], %[[B01]]
// CHECK-NEXT: br i1 %[[EQ01]], label %[[L10:.+]], label %[[EXIT_U:.+]]
// CHECK: [[L10]]:
// CHECK: %[[PA10:.+]] = getelementptr{{.+}}i8, ptr %a, {{i32|i64}} 4
// CHECK: %[[PB10:.+]] = getelementptr{{.+}}i8, ptr %b, {{i32|i64}} 4
// CHECK: %[[A10:.+]] = load i16, ptr %[[PA10]]
// CHECK: %[[B10:.+]] = load i16, ptr %[[PB10]]
// CHECK-NOT: cmp
// CHECK: %[[EQ10:.+]] = icmp eq i16 %[[A10]], %[[B10]]
// CHECK-NEXT: br i1 %[[EQ10]], label %[[L11:.+]], label %[[EXIT_S]]
// CHECK: [[L11]]:
// CHECK: %[[PA11:.+]] = getelementptr{{.+}}i8, ptr %a, {{i32|i64}} 6
// CHECK: %[[PB11:.+]] = getelementptr{{.+}}i8, ptr %b, {{i32|i64}} 6
// CHECK: %[[A11:.+]] = load i16, ptr %[[PA11]]
// CHECK: %[[B11:.+]] = load i16, ptr %[[PB11]]
// CHECK-NOT: cmp
// CHECK: %[[EQ11:.+]] = icmp eq i16 %[[A11]], %[[B11]]
// CHECK-NEXT: br i1 %[[EQ11]], label %[[DONE:.+]], label %[[EXIT_U]]
// CHECK: [[DONE]]:
// CHECK: %[[RET:.+]] = phi i1 [ %{{.+}}, %[[EXIT_S]] ], [ %{{.+}}, %[[EXIT_U]] ], [ true, %[[L11]] ]
// CHECK: ret i1 %[[RET]]
a <= b
}