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Fix miscompilation of inline assembly with outputs in cases where we emit an invoke instead of call instruction. #95864

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Merged
merged 2 commits into from
Apr 12, 2022
Merged

Fix miscompilation of inline assembly with outputs in cases where we emit an invoke instead of call instruction. #95864

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bf3ef0d
Switch to the 'normal' basic block for writing asm outputs if needed.
luqmana Apr 9, 2022
0b2f360
Update asm-may_unwind test to handle use of asm with outputs.
luqmana Apr 9, 2022
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5 changes: 5 additions & 0 deletions compiler/rustc_codegen_llvm/src/asm.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -290,6 +290,11 @@ impl<'ll, 'tcx> AsmBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
}
attributes::apply_to_callsite(result, llvm::AttributePlace::Function, &{ attrs });

// Switch to the 'normal' basic block if we did an `invoke` instead of a `call`
if let Some((dest, _, _)) = dest_catch_funclet {
self.switch_to_block(dest);
}

// Write results to outputs
for (idx, op) in operands.iter().enumerate() {
if let InlineAsmOperandRef::Out { reg, place: Some(place), .. }
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17 changes: 15 additions & 2 deletions src/test/codegen/asm-may_unwind.rs
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Expand Up @@ -18,10 +18,23 @@ impl Drop for Foo {
}
}

// CHECK-LABEL: @may_unwind
// CHECK-LABEL: @asm_may_unwind
#[no_mangle]
pub unsafe fn may_unwind() {
pub unsafe fn asm_may_unwind() {
let _m = Foo;
// CHECK: invoke void asm sideeffect alignstack inteldialect unwind ""
asm!("", options(may_unwind));
}

// CHECK-LABEL: @asm_with_result_may_unwind
#[no_mangle]
pub unsafe fn asm_with_result_may_unwind() -> u64 {
let _m = Foo;
let res: u64;
// CHECK: [[RES:%[0-9]+]] = invoke i64 asm sideeffect alignstack inteldialect unwind
// CHECK-NEXT: to label %[[NORMALBB:[a-b0-9]+]]
asm!("mov {}, 1", out(reg) res, options(may_unwind));
// CHECK: [[NORMALBB]]:
// CHECK: ret i64 [[RES:%[0-9]+]]
res
}