bjoernager/rust
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Handle the case where the or disjoint folds immediately to a constant

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This commit is contained in:
Scott McMurray 2025-02-02 19:23:44 -08:00
parent 5e6ae8bb5c
commit f46e6be190
2 changed files with 18 additions and 2 deletions
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8
compiler/rustc_codegen_llvm/src/builder.rs
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@ -424,7 +424,13 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
fn or_disjoint(&mut self, a: &'ll Value, b: &'ll Value) -> &'ll Value {
unsafe {
let or = llvm::LLVMBuildOr(self.llbuilder, a, b, UNNAMED);
llvm::LLVMSetIsDisjoint(or, True);
// If a and b are both values, then `or` is a value, rather than
// an instruction, so we need to check before setting the flag.
// (See also `LLVMBuildNUWNeg` which also needs a check.)
if llvm::LLVMIsAInstruction(or).is_some() {
llvm::LLVMSetIsDisjoint(or, True);
}
or
}
}

12
tests/codegen/intrinsics/disjoint_bitor.rs
View file

@ -1,4 +1,4 @@
//@ compile-flags: -C no-prepopulate-passes
//@ compile-flags: -C no-prepopulate-passes -Z mir-opt-level=0
#![crate_type = "lib"]
#![feature(core_intrinsics)]
@ -18,3 +18,13 @@ pub unsafe fn disjoint_bitor_unsigned(x: u64, y: u64) -> u64 {
// CHECK: or disjoint i64 %x, %y
disjoint_bitor(x, y)
}
// CHECK-LABEL: @disjoint_bitor_literal
#[no_mangle]
pub unsafe fn disjoint_bitor_literal() -> u8 {
// This is a separate check because even without any passes,
// LLVM will fold so it's not an instruction, which can assert in LLVM.
// CHECK: store i8 3
disjoint_bitor(1, 2)
}