Auto merge of #57269 - gnzlbg:simd_bitmask, r=rkruppe

Add intrinsic to create an integer bitmask from a vector mask

This PR adds a new simd intrinsic: `simd_bitmask(vector) -> unsigned integer` that creates an integer bitmask from a vector mask by extracting one bit of each vector lane.

This is required to implement: https://github.com/rust-lang-nursery/packed_simd/issues/166 .

EDIT: the reason we need an intrinsics for this is that we have to truncate the vector lanes to an `<i1 x N>` vector, and then bitcast that to an `iN` integer (while making sure that we only materialize `i8`, ... , `i64` - that is, no `i1`, `i2`, `i4`, types), and we can't do any of that in a Rust library.

r? @rkruppe

1 files changed, 57 insertions, 0 deletions

diff --git a/src/test/codegen/simd-intrinsic-generic-bitmask.rs b/src/test/codegen/simd-intrinsic-generic-bitmask.rs
new file mode 100644
index 00000000000..cd8130f9231
--- /dev/null
+++ b/src/test/codegen/simd-intrinsic-generic-bitmask.rs
@@ -0,0 +1,57 @@
+// compile-flags: -C no-prepopulate-passes
+// ignore-tidy-linelength
+
+#![crate_type = "lib"]
+
+#![feature(repr_simd, platform_intrinsics)]
+#![allow(non_camel_case_types)]
+
+#[repr(simd)]
+#[derive(Copy, Clone)]
+pub struct u32x2(u32, u32);
+
+#[repr(simd)]
+#[derive(Copy, Clone)]
+pub struct i32x2(i32, i32);
+
+#[repr(simd)]
+#[derive(Copy, Clone)]
+pub struct i8x16(
+    i8, i8, i8, i8, i8, i8, i8, i8,
+    i8, i8, i8, i8, i8, i8, i8, i8,
+);
+
+
+extern "platform-intrinsic" {
+    fn simd_bitmask<T, U>(x: T) -> U;
+}
+
+// CHECK-LABEL: @bitmask_int
+#[no_mangle]
+pub unsafe fn bitmask_int(x: i32x2) -> u8 {
+    // CHECK: [[A:%[0-9]+]] = lshr <2 x i32> %{{[0-9]+}}, <i32 31, i32 31>
+    // CHECK: [[B:%[0-9]+]] = trunc <2 x i32> [[A]] to <2 x i1>
+    // CHECK: [[C:%[0-9]+]] = bitcast <2 x i1> [[B]] to i2
+    // CHECK: %{{[0-9]+}} = zext i2 [[C]] to i8
+    simd_bitmask(x)
+}
+
+// CHECK-LABEL: @bitmask_uint
+#[no_mangle]
+pub unsafe fn bitmask_uint(x: u32x2) -> u8 {
+    // CHECK: [[A:%[0-9]+]] = lshr <2 x i32> %{{[0-9]+}}, <i32 31, i32 31>
+    // CHECK: [[B:%[0-9]+]] = trunc <2 x i32> [[A]] to <2 x i1>
+    // CHECK: [[C:%[0-9]+]] = bitcast <2 x i1> [[B]] to i2
+    // CHECK: %{{[0-9]+}} = zext i2 [[C]] to i8
+    simd_bitmask(x)
+}
+
+// CHECK-LABEL: @bitmask_int16
+#[no_mangle]
+pub unsafe fn bitmask_int16(x: i8x16) -> u16 {
+    // CHECK: [[A:%[0-9]+]] = lshr <16 x i8> %{{[0-9]+}}, <i8 7, i8 7, i8 7, i8 7, i8 7, i8 7, i8 7, i8 7, i8 7, i8 7, i8 7, i8 7, i8 7, i8 7, i8 7, i8 7>
+    // CHECK: [[B:%[0-9]+]] = trunc <16 x i8> [[A]] to <16 x i1>
+    // CHECK: %{{[0-9]+}} = bitcast <16 x i1> [[B]] to i16
+    // CHECK-NOT: zext
+    simd_bitmask(x)
+}