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| author | Scott McMurray <scottmcm@users.noreply.github.com> | 2022-07-12 03:03:19 -0700 |
|---|---|---|
| committer | Scott McMurray <scottmcm@users.noreply.github.com> | 2022-07-13 17:07:41 -0700 |
| commit | a32305a80fd1409b054e97836321bd0621b142fd (patch) | |
| tree | 17c7411681304613c0dc6bb5c7c528de69555dd5 /src/test/codegen | |
| parent | 87588a2afd9ca903366f0deaf84d805f34469384 (diff) | |
| download | rust-a32305a80fd1409b054e97836321bd0621b142fd.tar.gz rust-a32305a80fd1409b054e97836321bd0621b142fd.zip | |
Re-optimize `Layout::array`
This way it's one check instead of two, so hopefully it'll be better Nightly: ``` layout_array_i32: movq %rdi, %rax movl $4, %ecx mulq %rcx jo .LBB1_2 movabsq $9223372036854775805, %rcx cmpq %rcx, %rax jae .LBB1_2 movl $4, %edx retq .LBB1_2: … ``` This PR: ``` movq %rcx, %rax shrq $61, %rax jne .LBB2_1 shlq $2, %rcx movl $4, %edx movq %rcx, %rax retq .LBB2_1: … ```
Diffstat (limited to 'src/test/codegen')
| -rw-r--r-- | src/test/codegen/layout-size-checks.rs | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/src/test/codegen/layout-size-checks.rs b/src/test/codegen/layout-size-checks.rs new file mode 100644 index 00000000000..d067cc10a94 --- /dev/null +++ b/src/test/codegen/layout-size-checks.rs @@ -0,0 +1,31 @@ +// compile-flags: -O +// only-x86_64 +// ignore-debug: the debug assertions get in the way + +#![crate_type = "lib"] + +use std::alloc::Layout; + +type RGB48 = [u16; 3]; + +// CHECK-LABEL: @layout_array_rgb48 +#[no_mangle] +pub fn layout_array_rgb48(n: usize) -> Layout { + // CHECK-NOT: llvm.umul.with.overflow.i64 + // CHECK: icmp ugt i64 %n, 1537228672809129301 + // CHECK-NOT: llvm.umul.with.overflow.i64 + // CHECK: mul nuw nsw i64 %n, 6 + // CHECK-NOT: llvm.umul.with.overflow.i64 + Layout::array::<RGB48>(n).unwrap() +} + +// CHECK-LABEL: @layout_array_i32 +#[no_mangle] +pub fn layout_array_i32(n: usize) -> Layout { + // CHECK-NOT: llvm.umul.with.overflow.i64 + // CHECK: icmp ugt i64 %n, 2305843009213693951 + // CHECK-NOT: llvm.umul.with.overflow.i64 + // CHECK: shl nuw nsw i64 %n, 2 + // CHECK-NOT: llvm.umul.with.overflow.i64 + Layout::array::<i32>(n).unwrap() +} |