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rustc_trans: 'assume' intrinsic is only available on LLVM >= 3.6

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Based on the patch from Luca Bruno.

Instead of creating an empty C function in the rt, this version creates an shim
noop function using llvm. This function is declared as internal, and the
unsupported assume intrinsic and the shim gets completly removed by the
optimizer.
This commit is contained in:
David Voit 2015-05-23 23:33:37 +02:00 • committed by Tamir Duberstein
parent ce32f6412e
commit e36e97ba51
1 changed files with 25 additions and 1 deletions
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26
src/librustc_trans/trans/context.rs
View file

@ -933,11 +933,33 @@ fn declare_intrinsic(ccx: &CrateContext, key: & &'static str) -> Option<ValueRef
ifn!("llvm.lifetime.end", fn(t_i64, i8p) -> void);
ifn!("llvm.expect.i1", fn(i1, i1) -> i1);
ifn!("llvm.assume", fn(i1) -> void);
// Some intrinsics were introduced in later versions of LLVM, but they have
// fallbacks in libc or libm and such.
macro_rules! compatible_ifn {
($name:expr, noop($cname:ident ($($arg:expr),*) -> void), $llvm_version:expr) => (
if unsafe { llvm::LLVMVersionMinor() >= $llvm_version } {
// The `if key == $name` is already in ifn!
ifn!($name, fn($($arg),*) -> void);
} else if *key == $name {
let f = declare::declare_cfn(ccx, stringify!($cname),
Type::func(&[$($arg),*], &void),
ty::mk_nil(ccx.tcx()));
llvm::SetLinkage(f, llvm::InternalLinkage);
let bld = ccx.builder();
let llbb = unsafe {
llvm::LLVMAppendBasicBlockInContext(ccx.llcx(), f,
"entry-block\0".as_ptr() as *const _)
};
bld.position_at_end(llbb);
bld.ret_void();
ccx.intrinsics().borrow_mut().insert($name, f.clone());
return Some(f);
}
);
($name:expr, $cname:ident ($($arg:expr),*) -> $ret:expr, $llvm_version:expr) => (
if unsafe { llvm::LLVMVersionMinor() >= $llvm_version } {
// The `if key == $name` is already in ifn!
@ -952,6 +974,8 @@ fn declare_intrinsic(ccx: &CrateContext, key: & &'static str) -> Option<ValueRef
)
}
compatible_ifn!("llvm.assume", noop(llvmcompat_assume(i1) -> void), 6);
if ccx.sess().opts.debuginfo != NoDebugInfo {
ifn!("llvm.dbg.declare", fn(Type::metadata(ccx), Type::metadata(ccx)) -> void);
ifn!("llvm.dbg.value", fn(Type::metadata(ccx), t_i64, Type::metadata(ccx)) -> void);