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add back LLVM-specific funnel shift implementation #149391

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add back LLVM-specific funnel shift implementation #149391

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18 changes: 14 additions & 4 deletions compiler/rustc_codegen_llvm/src/intrinsic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -401,6 +401,8 @@ impl<'ll, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
| sym::ctpop
| sym::bswap
| sym::bitreverse
| sym::rotate_left
| sym::rotate_right
| sym::saturating_add
| sym::saturating_sub
| sym::unchecked_funnel_shl
Expand Down Expand Up @@ -445,11 +447,19 @@ impl<'ll, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
sym::bitreverse => {
self.call_intrinsic("llvm.bitreverse", &[llty], &[args[0].immediate()])
}
sym::unchecked_funnel_shl | sym::unchecked_funnel_shr => {
let is_left = name == sym::unchecked_funnel_shl;
sym::rotate_left
| sym::rotate_right
| sym::unchecked_funnel_shl
| sym::unchecked_funnel_shr => {
let is_left = name == sym::rotate_left || name == sym::unchecked_funnel_shl;
let lhs = args[0].immediate();
let rhs = args[1].immediate();
let raw_shift = args[2].immediate();
let (rhs, raw_shift) =
if name == sym::rotate_left || name == sym::rotate_right {
// rotate = funnel shift with first two args the same
(lhs, args[1].immediate())
} else {
(args[1].immediate(), args[2].immediate())
};
let llvm_name = format!("llvm.fsh{}", if is_left { 'l' } else { 'r' });

// llvm expects shift to be the same type as the values, but rust
Expand Down
8 changes: 4 additions & 4 deletions tests/codegen-llvm/intrinsics/rotate_left.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
//@ compile-flags: -O
//@ compile-flags: -C no-prepopulate-passes

#![crate_type = "lib"]
#![feature(core_intrinsics)]
Expand All @@ -9,7 +9,7 @@ use std::intrinsics::rotate_left;
#[no_mangle]
pub unsafe fn rotate_left_u16(x: u16, shift: u32) -> u16 {
// CHECK: %[[tmp:.*]] = trunc i32 %shift to i16
// CHECK: call noundef i16 @llvm.fshl.i16(i16 %x, i16 %x, i16 %[[tmp]])
// CHECK: call i16 @llvm.fshl.i16(i16 %x, i16 %x, i16 %[[tmp]])
rotate_left(x, shift)
}

Expand All @@ -18,14 +18,14 @@ pub unsafe fn rotate_left_u16(x: u16, shift: u32) -> u16 {
pub unsafe fn rotate_left_u32(x: u32, shift: u32) -> u32 {
// CHECK-NOT: trunc
// CHECK-NOT: zext
// CHECK: call noundef i32 @llvm.fshl.i32(i32 %x, i32 %x, i32 %shift)
// CHECK: call i32 @llvm.fshl.i32(i32 %x, i32 %x, i32 %shift)
rotate_left(x, shift)
}

// CHECK-LABEL: @rotate_left_u64
#[no_mangle]
pub unsafe fn rotate_left_u64(x: u64, shift: u32) -> u64 {
// CHECK: %[[tmp:.*]] = zext i32 %shift to i64
// CHECK: call noundef i64 @llvm.fshl.i64(i64 %x, i64 %x, i64 %[[tmp]])
// CHECK: call i64 @llvm.fshl.i64(i64 %x, i64 %x, i64 %[[tmp]])
rotate_left(x, shift)
}
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