Rollup merge of #92425 - calebzulawski:simd-cast, r=workingjubilee

Improve SIMD casts

* Allows `simd_cast` intrinsic to take `usize` and `isize`
* Adds `simd_as` intrinsic, which is the same as `simd_cast` except for saturating float-to-int conversions (matching the behavior of `as`).

cc `@workingjubilee`

1 files changed, 41 insertions, 18 deletions

diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index 5217fa2758f..8a9450c20dd 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -731,27 +731,11 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn fptoui_sat(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> Option<&'ll Value> {
-        if !self.fptoint_sat_broken_in_llvm() {
-            let src_ty = self.cx.val_ty(val);
-            let float_width = self.cx.float_width(src_ty);
-            let int_width = self.cx.int_width(dest_ty);
-            let name = format!("llvm.fptoui.sat.i{}.f{}", int_width, float_width);
-            return Some(self.call_intrinsic(&name, &[val]));
-        }
-
-        None
+        self.fptoint_sat(false, val, dest_ty)
     }
 
     fn fptosi_sat(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> Option<&'ll Value> {
-        if !self.fptoint_sat_broken_in_llvm() {
-            let src_ty = self.cx.val_ty(val);
-            let float_width = self.cx.float_width(src_ty);
-            let int_width = self.cx.int_width(dest_ty);
-            let name = format!("llvm.fptosi.sat.i{}.f{}", int_width, float_width);
-            return Some(self.call_intrinsic(&name, &[val]));
-        }
-
-        None
+        self.fptoint_sat(true, val, dest_ty)
     }
 
     fn fptoui(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
@@ -1455,4 +1439,43 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
             _ => false,
         }
     }
+
+    fn fptoint_sat(
+        &mut self,
+        signed: bool,
+        val: &'ll Value,
+        dest_ty: &'ll Type,
+    ) -> Option<&'ll Value> {
+        if !self.fptoint_sat_broken_in_llvm() {
+            let src_ty = self.cx.val_ty(val);
+            let (float_ty, int_ty, vector_length) = if self.cx.type_kind(src_ty) == TypeKind::Vector
+            {
+                assert_eq!(self.cx.vector_length(src_ty), self.cx.vector_length(dest_ty));
+                (
+                    self.cx.element_type(src_ty),
+                    self.cx.element_type(dest_ty),
+                    Some(self.cx.vector_length(src_ty)),
+                )
+            } else {
+                (src_ty, dest_ty, None)
+            };
+            let float_width = self.cx.float_width(float_ty);
+            let int_width = self.cx.int_width(int_ty);
+
+            let instr = if signed { "fptosi" } else { "fptoui" };
+            let name = if let Some(vector_length) = vector_length {
+                format!(
+                    "llvm.{}.sat.v{}i{}.v{}f{}",
+                    instr, vector_length, int_width, vector_length, float_width
+                )
+            } else {
+                format!("llvm.{}.sat.i{}.f{}", instr, int_width, float_width)
+            };
+            let f =
+                self.declare_cfn(&name, llvm::UnnamedAddr::No, self.type_func(&[src_ty], dest_ty));
+            Some(self.call(self.type_func(&[src_ty], dest_ty), f, &[val], None))
+        } else {
+            None
+        }
+    }
 }