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Auto merge of #58985 - dlrobertson:fix_58980, r=alexreg

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Fix segfaults in release build C-variadic fns

`va_start` and `va_end` must be called to initialize/cleanup the
"spoofed" `VaList` in a Rust defined C-variadic function even  if
the `VaList` is not used.

r? @alexreg
Fixes: #58980
This commit is contained in:
bors 2019-03-08 23:24:16 +00:00
commit b2ea6c86ae
3 changed files with 27 additions and 9 deletions
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7
src/librustc_codegen_ssa/mir/block.rs
View file

@ -233,9 +233,14 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
mut bx: Bx,
) {
if self.fn_ty.c_variadic {
if let Some(va_list) = self.va_list_ref {
match self.va_list_ref {
Some(va_list) => {
bx.va_end(va_list.llval);
}
None => {
bug!("C-variadic function must have a `va_list_ref`");
}
}
}
let llval = match self.fn_ty.ret.mode {
PassMode::Ignore(IgnoreMode::Zst) | PassMode::Indirect(..) => {

8
src/librustc_codegen_ssa/mir/mod.rs
View file

@ -532,13 +532,7 @@ fn arg_local_refs<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
PassMode::Ignore(IgnoreMode::Zst) => {
return local(OperandRef::new_zst(bx.cx(), arg.layout));
}
PassMode::Ignore(IgnoreMode::CVarArgs) => {
let backend_type = bx.cx().immediate_backend_type(arg.layout);
return local(OperandRef {
val: OperandValue::Immediate(bx.cx().const_undef(backend_type)),
layout: arg.layout,
});
}
PassMode::Ignore(IgnoreMode::CVarArgs) => {}
PassMode::Direct(_) => {
let llarg = bx.get_param(bx.llfn(), llarg_idx as c_uint);
bx.set_value_name(llarg, &name);

19
src/test/codegen/c-variadic-opt.rs Normal file
View file

@ -0,0 +1,19 @@
// compile-flags: -C opt-level=3
#![crate_type = "lib"]
#![feature(c_variadic)]
#![no_std]
use core::ffi::VaList;
extern "C" {
fn vprintf(fmt: *const i8, ap: VaList) -> i32;
}
// Ensure that `va_start` and `va_end` are properly injected even
// when the "spoofed" `VaList` is not used.
#[no_mangle]
pub unsafe extern "C" fn c_variadic_no_use(fmt: *const i8, mut ap: ...) -> i32 {
// CHECK: call void @llvm.va_start
vprintf(fmt, ap)
// CHECK: call void @llvm.va_end
}