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x86: Correctly pass larger structs/types in registers with -Zregparm #147628

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x86: Correctly pass larger structs/types in registers with -Zregparm #147628

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4 changes: 3 additions & 1 deletion compiler/rustc_target/src/callconv/x86.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -183,7 +183,9 @@ pub(crate) fn fill_inregs<'a, Ty, C>(

free_regs -= size_in_regs;

if arg.layout.size.bits() <= 32 && unit.kind == RegKind::Integer {
if opts.flavor != Flavor::FastcallOrVectorcall
|| arg.layout.size.bits() <= 32 && unit.kind == RegKind::Integer
{
attrs.set(ArgAttribute::InReg);
}

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20 changes: 20 additions & 0 deletions tests/assembly-llvm/regparm-module-flag.rs
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Expand Up @@ -19,6 +19,26 @@ use minicore::*;
unsafe extern "C" {
fn memset(p: *mut c_void, val: i32, len: usize) -> *mut c_void;
fn non_builtin_memset(p: *mut c_void, val: i32, len: usize) -> *mut c_void;
fn test_i64_arg(s: i64) -> i64;
}

#[unsafe(no_mangle)]
pub unsafe extern "C" fn test_i64() -> i64 {
// REGPARM1-LABEL: test_i64
// REGPARM1: pushl
// REGPARM1: pushl
// REGPARM1: calll test_i64_arg

// REGPARM2-LABEL: test_i64
// REGPARM2: movl $42, %eax
// REGPARM2: xorl %edx, %edx
// REGPARM2: jmp test_i64_arg

// REGPARM3-LABEL: test_i64
// REGPARM3: movl $42, %eax
// REGPARM3: xorl %edx, %edx
// REGPARM3: jmp test_i64_arg
unsafe { test_i64_arg(42) }
}

#[unsafe(no_mangle)]
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