De-LLVM the unchecked shifts [MCP#693]

This is just one part of the MCP, but it's the one that IMHO removes the most noise from the standard library code.

Seems net simpler this way, since MIR already supported heterogeneous shifts anyway, and thus it's not more work for backends than before.

1 files changed, 47 insertions, 2 deletions

diff --git a/tests/codegen/unchecked_shifts.rs b/tests/codegen/unchecked_shifts.rs
index 9cf2f2b0cb6..7d020fbb4d2 100644
--- a/tests/codegen/unchecked_shifts.rs
+++ b/tests/codegen/unchecked_shifts.rs
@@ -2,6 +2,7 @@
 
 #![crate_type = "lib"]
 #![feature(unchecked_shifts)]
+#![feature(core_intrinsics)]
 
 // CHECK-LABEL: @unchecked_shl_unsigned_same
 #[no_mangle]
@@ -19,7 +20,7 @@ pub unsafe fn unchecked_shl_unsigned_smaller(a: u16, b: u32) -> u16 {
     // This uses -DAG to avoid failing on irrelevant reorderings,
     // like emitting the truncation earlier.
 
-    // CHECK-DAG: %[[INRANGE:.+]] = icmp ult i32 %b, 65536
+    // CHECK-DAG: %[[INRANGE:.+]] = icmp ult i32 %b, 16
     // CHECK-DAG: tail call void @llvm.assume(i1 %[[INRANGE]])
     // CHECK-DAG: %[[TRUNC:.+]] = trunc i32 %b to i16
     // CHECK-DAG: shl i16 %a, %[[TRUNC]]
@@ -51,7 +52,7 @@ pub unsafe fn unchecked_shr_signed_smaller(a: i16, b: u32) -> i16 {
     // This uses -DAG to avoid failing on irrelevant reorderings,
     // like emitting the truncation earlier.
 
-    // CHECK-DAG: %[[INRANGE:.+]] = icmp ult i32 %b, 32768
+    // CHECK-DAG: %[[INRANGE:.+]] = icmp ult i32 %b, 16
     // CHECK-DAG: tail call void @llvm.assume(i1 %[[INRANGE]])
     // CHECK-DAG: %[[TRUNC:.+]] = trunc i32 %b to i16
     // CHECK-DAG: ashr i16 %a, %[[TRUNC]]
@@ -66,3 +67,47 @@ pub unsafe fn unchecked_shr_signed_bigger(a: i64, b: u32) -> i64 {
     // CHECK: ashr i64 %a, %[[EXT]]
     a.unchecked_shr(b)
 }
+
+// CHECK-LABEL: @unchecked_shr_u128_i8
+#[no_mangle]
+pub unsafe fn unchecked_shr_u128_i8(a: u128, b: i8) -> u128 {
+    // CHECK-NOT: assume
+    // CHECK: %[[EXT:.+]] = zext{{( nneg)?}} i8 %b to i128
+    // CHECK: lshr i128 %a, %[[EXT]]
+    std::intrinsics::unchecked_shr(a, b)
+}
+
+// CHECK-LABEL: @unchecked_shl_i128_u8
+#[no_mangle]
+pub unsafe fn unchecked_shl_i128_u8(a: i128, b: u8) -> i128 {
+    // CHECK-NOT: assume
+    // CHECK: %[[EXT:.+]] = zext{{( nneg)?}} i8 %b to i128
+    // CHECK: shl i128 %a, %[[EXT]]
+    std::intrinsics::unchecked_shl(a, b)
+}
+
+// CHECK-LABEL: @unchecked_shl_u8_i128
+#[no_mangle]
+pub unsafe fn unchecked_shl_u8_i128(a: u8, b: i128) -> u8 {
+    // This uses -DAG to avoid failing on irrelevant reorderings,
+    // like emitting the truncation earlier.
+
+    // CHECK-DAG: %[[INRANGE:.+]] = icmp ult i128 %b, 8
+    // CHECK-DAG: tail call void @llvm.assume(i1 %[[INRANGE]])
+    // CHECK-DAG: %[[TRUNC:.+]] = trunc i128 %b to i8
+    // CHECK-DAG: shl i8 %a, %[[TRUNC]]
+    std::intrinsics::unchecked_shl(a, b)
+}
+
+// CHECK-LABEL: @unchecked_shr_i8_u128
+#[no_mangle]
+pub unsafe fn unchecked_shr_i8_u128(a: i8, b: u128) -> i8 {
+    // This uses -DAG to avoid failing on irrelevant reorderings,
+    // like emitting the truncation earlier.
+
+    // CHECK-DAG: %[[INRANGE:.+]] = icmp ult i128 %b, 8
+    // CHECK-DAG: tail call void @llvm.assume(i1 %[[INRANGE]])
+    // CHECK-DAG: %[[TRUNC:.+]] = trunc i128 %b to i8
+    // CHECK-DAG: ashr i8 %a, %[[TRUNC]]
+    std::intrinsics::unchecked_shr(a, b)
+}