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Auto merge of #59577 - dlrobertson:fix_58881, r=nagisa

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Fix LLVM IR generated for C-variadic arguments

It is possible to create malformed LLVM IR given variadic arguments that
are aggregate types. This occurs due to improper tracking of the current
argument in the functions list of arguments.

Fixes: #58881
This commit is contained in:
bors 2019-03-31 20:28:00 +00:00
commit e3428db7c2
2 changed files with 23 additions and 13 deletions
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15
src/librustc_codegen_ssa/mir/block.rs
View file

@ -20,7 +20,7 @@ use syntax_pos::Pos;
use super::{FunctionCx, LocalRef};
use super::place::PlaceRef;
use super::operand::{OperandValue, OperandRef};
use super::operand::OperandRef;
use super::operand::OperandValue::{Pair, Ref, Immediate};
/// Used by `FunctionCx::codegen_terminator` for emitting common patterns
@ -695,18 +695,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
// an "spoofed" `VaList`. This argument is ignored, but we need to
// populate it with a dummy operand so that the users real arguments
// are not overwritten.
let i = if sig.c_variadic && last_arg_idx.map(|x| x == i).unwrap_or(false) {
let layout = match self.cx.tcx().lang_items().va_list() {
Some(did) => bx.cx().layout_of(bx.tcx().type_of(did)),
None => bug!("`va_list` language item required for C-variadics"),
};
let op = OperandRef {
val: OperandValue::Immediate(
bx.cx().const_undef(bx.cx().immediate_backend_type(layout)
)),
layout: layout,
};
self.codegen_argument(&mut bx, op, &mut llargs, &fn_ty.args[i]);
let i = if sig.c_variadic && last_arg_idx.map(|x| i >= x).unwrap_or(false) {
if i + 1 < fn_ty.args.len() {
i + 1
} else {

21
src/test/codegen/issue-58881.rs Normal file
View file

@ -0,0 +1,21 @@
// compile-flags: -C no-prepopulate-passes
//
// only-x86_64
// ignore-windows
#![crate_type = "lib"]
extern "C" {
fn variadic_fn(_: i32, ...);
}
#[repr(C)]
struct Foo(u8);
#[repr(C)]
struct Bar(u64, u64, u64);
// Ensure that emit arguments of the correct type.
pub unsafe fn test_call_variadic() {
// CHECK: call void (i32, ...) @variadic_fn(i32 0, i8 {{.*}}, %Bar* {{.*}})
variadic_fn(0, Foo(0), Bar(0, 0, 0))
}