From 0586c63e070981af7df53e2f778d3e50293d8103 Mon Sep 17 00:00:00 2001 From: Scott McMurray Date: Wed, 9 Jul 2025 23:59:00 -0700 Subject: Allow `Rvalue::Repeat` to return true in `rvalue_creates_operand` too The conversation in 143502 made be realize how easy this is to handle, since the only possibilty is ZSTs -- everything else ends up with the destination being `LocalKind::Memory` and thus doesn't call `codegen_rvalue_operand` at all. This gets us perilously close to a world where `rvalue_creates_operand` only ever returns true. I'll try out such a world next :) --- tests/codegen/repeat-operand.rs | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 tests/codegen/repeat-operand.rs (limited to 'tests/codegen') diff --git a/tests/codegen/repeat-operand.rs b/tests/codegen/repeat-operand.rs new file mode 100644 index 00000000000..6464b35ddca --- /dev/null +++ b/tests/codegen/repeat-operand.rs @@ -0,0 +1,39 @@ +//@ compile-flags: -Copt-level=1 -Cno-prepopulate-passes + +// This test is here to hit the `Rvalue::Repeat` case in `codegen_rvalue_operand`. +// It only applies when the resulting array is a ZST, so the test is written in +// such a way as to keep MIR optimizations from seeing that fact and removing +// the local and statement altogether. (At the time of writing, no other codegen +// test hit that code path, nor did a stage 2 build of the compiler.) + +#![crate_type = "lib"] + +#[repr(transparent)] +pub struct Wrapper([T; N]); + +// CHECK-LABEL: define {{.+}}do_repeat{{.+}}() +// CHECK-NEXT: start: +// CHECK-NOT: alloca +// CHECK-NEXT: ret void +// CHECK-LABEL: define {{.+}}do_repeat{{.+}}(i32 noundef %x) +// CHECK-NEXT: start: +// CHECK-NOT: alloca +// CHECK-NEXT: ret void +#[inline(never)] +pub fn do_repeat(x: T) -> Wrapper { + Wrapper([x; N]) +} + +// CHECK-LABEL: @trigger_repeat_zero_len +#[no_mangle] +pub fn trigger_repeat_zero_len() -> Wrapper { + // CHECK: call void {{.+}}do_repeat{{.+}}(i32 noundef 4) + do_repeat(4) +} + +// CHECK-LABEL: @trigger_repeat_zst +#[no_mangle] +pub fn trigger_repeat_zst() -> Wrapper<(), 8> { + // CHECK: call void {{.+}}do_repeat{{.+}}() + do_repeat(()) +} -- cgit 1.4.1-3-g733a5